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-rw-r--r--spec/ruby/core/process/daemon_spec.rb14
1 files changed, 11 insertions, 3 deletions
diff --git a/spec/ruby/core/process/daemon_spec.rb b/spec/ruby/core/process/daemon_spec.rb
index 70ffd1b320..7198dfa6ee 100644
--- a/spec/ruby/core/process/daemon_spec.rb
+++ b/spec/ruby/core/process/daemon_spec.rb
@@ -1,7 +1,11 @@
require_relative '../../spec_helper'
require_relative 'fixtures/common'
-platform_is_not :windows do
+guard -> {
+ Process.respond_to?(:fork) and
+ # macOS 15 is not working for these examples
+ !(/darwin/ =~ RUBY_PLATFORM && /15/ =~ `sw_vers -productVersion`)
+} do
describe :process_daemon_keep_stdio_open_false, shared: true do
it "redirects stdout to /dev/null" do
@daemon.invoke("keep_stdio_open_false_stdout", @object).should == ""
@@ -104,12 +108,16 @@ platform_is_not :windows do
end
end
-platform_is :windows do
+guard_not -> { Process.respond_to?(:fork) } do
describe "Process.daemon" do
+ it "returns false from #respond_to?" do
+ Process.respond_to?(:daemon).should == false
+ end
+
it "raises a NotImplementedError" do
-> {
Process.daemon
- }.should raise_error(NotImplementedError)
+ }.should.raise(NotImplementedError)
end
end
end
idth: 14.5%;'/> -rw-r--r--include/ruby/internal/arithmetic/intptr_t.h74
-rw-r--r--include/ruby/internal/arithmetic/long.h356
-rw-r--r--include/ruby/internal/arithmetic/long_long.h135
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-rw-r--r--include/ruby/internal/intern/array.h657
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-rw-r--r--include/ruby/internal/intern/gc.h392
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-rw-r--r--include/ruby/internal/intern/io.h661
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-rw-r--r--include/ruby/internal/intern/proc.h353
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-rw-r--r--include/ruby/internal/intern/range.h89
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-rw-r--r--include/ruby/internal/intern/select/posix.h144
-rw-r--r--include/ruby/internal/intern/select/win32.h259
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-rw-r--r--include/ruby/internal/intern/sprintf.h159
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-rw-r--r--include/ruby/internal/intern/variable.h628
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-rw-r--r--include/ruby/internal/memory.h670
-rw-r--r--include/ruby/internal/method.h205
-rw-r--r--include/ruby/internal/module.h177
-rw-r--r--include/ruby/internal/newobj.h195
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-rw-r--r--include/ruby/internal/scan_args.h534
-rw-r--r--include/ruby/internal/special_consts.h295
-rw-r--r--include/ruby/internal/static_assert.h77
-rw-r--r--include/ruby/internal/stdalign.h135
-rw-r--r--include/ruby/internal/stdbool.h51
-rw-r--r--include/ruby/internal/symbol.h332
-rw-r--r--include/ruby/internal/value.h133
-rw-r--r--include/ruby/internal/value_type.h449
-rw-r--r--include/ruby/internal/variable.h337
-rw-r--r--include/ruby/internal/warning_push.h124
-rw-r--r--include/ruby/internal/xmalloc.h392
151 files changed, 31396 insertions, 0 deletions
diff --git a/include/ruby/internal/anyargs.h b/include/ruby/internal/anyargs.h
new file mode 100644
index 0000000000..9d8d16fdab
--- /dev/null
+++ b/include/ruby/internal/anyargs.h
@@ -0,0 +1,375 @@
+#ifndef RBIMPL_ANYARGS_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_ANYARGS_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Function overloads to issue warnings around #ANYARGS.
+ *
+ * For instance ::rb_define_method takes a pointer to #ANYARGS -ed functions,
+ * which in fact varies 18 different prototypes. We still need to preserve
+ * #ANYARGS for storages but why not check the consistencies if possible. With
+ * those complex macro overlays defined in this header file, use of a function
+ * pointer gets checked against the corresponding arity argument.
+ *
+ * ### Q&A ###
+ *
+ * - Q: Where did the magic number "18" came from in the description above?
+ *
+ * - A: Count the case branch of `vm_method.c:call_cfunc_invoker_func()`. Note
+ * also that the 18 branches has lasted for at least 25 years. See also
+ * commit 200e0ee2fd3c1c006c528874a88f684447215524.
+ *
+ * - Q: What is this `__weakref__` thing?
+ *
+ * - A: That is a kind of function overloading mechanism that GCC provides. In
+ * this case for instance `rb_define_method_00` is an alias of
+ * ::rb_define_method, with a strong type.
+ *
+ * - Q: What is this `__transparent_union__` thing?
+ *
+ * A: That is another kind of function overloading mechanism that GCC
+ * provides. In this case the attributed function pointer is either
+ * `VALUE(*)(int,VALUE*,VALUE)` or `VALUE(*)(int,const VALUE*,VALUE)`.
+ *
+ * This is better than `void*` or #ANYARGS because we can reject all other
+ * possibilities than the two.
+ *
+ * - Q: What does this #rb_define_method macro mean?
+ *
+ * - A: It selects appropriate alias of the ::rb_define_method function,
+ * depending on the last (arity) argument.
+ *
+ * - Q: Why the special case for ::rb_f_notimplement ?
+ *
+ * - A: Function pointer to ::rb_f_notimplement is special cased in
+ * `vm_method.c:rb_add_method_cfunc()`. That should be handled by the
+ * `__builtin_choose_expr` chain inside of #rb_define_method macro
+ * expansion. In order to do so, comparison like
+ * `(func == rb_f_notimplement)` is inappropriate for
+ * `__builtin_choose_expr`'s expression (which must be a compile-time
+ * integer constant but the address of ::rb_f_notimplement is not fixed
+ * until the linker). Instead we are using
+ * `__builtin_types_compatible_p`, and in doing so we need to distinguish
+ * ::rb_f_notimplement from others, by type.
+ */
+#include "ruby/internal/attr/maybe_unused.h"
+#include "ruby/internal/attr/nonnull.h"
+#include "ruby/internal/attr/weakref.h"
+#include "ruby/internal/cast.h"
+#include "ruby/internal/config.h"
+#include "ruby/internal/has/attribute.h"
+#include "ruby/internal/intern/class.h"
+#include "ruby/internal/intern/vm.h"
+#include "ruby/internal/method.h"
+#include "ruby/internal/value.h"
+#include "ruby/backward/2/stdarg.h"
+
+#if defined(__cplusplus)
+# include "ruby/backward/cxxanyargs.hpp"
+
+#elif defined(_WIN32) || defined(__CYGWIN__)
+# /* Skip due to [Bug #16134] */
+
+#elif ! RBIMPL_HAS_ATTRIBUTE(transparent_union)
+# /* :TODO: improve here, please find a way to support. */
+
+#elif ! defined(HAVE_VA_ARGS_MACRO)
+# /* :TODO: improve here, please find a way to support. */
+
+#else
+# /** @cond INTERNAL_MACRO */
+# if ! defined(HAVE_BUILTIN___BUILTIN_TYPES_COMPATIBLE_P)
+# define RBIMPL_CFUNC_IS_rb_f_notimplement(f) 0
+# else
+# define RBIMPL_CFUNC_IS_rb_f_notimplement(f) \
+ __builtin_types_compatible_p( \
+ __typeof__(f), \
+ __typeof__(rb_f_notimplement))
+# endif
+
+# if ! defined(HAVE_BUILTIN___BUILTIN_CHOOSE_EXPR_CONSTANT_P)
+# define RBIMPL_ANYARGS_DISPATCH(expr, truthy, falsy) (falsy)
+# else
+# define RBIMPL_ANYARGS_DISPATCH(expr, truthy, falsy) \
+ __builtin_choose_expr( \
+ __builtin_choose_expr( \
+ __builtin_constant_p(expr), \
+ (expr), 0), \
+ (truthy), (falsy))
+# endif
+
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_singleton_method_m2(n) RBIMPL_ANYARGS_DISPATCH((n) == -2, rb_define_singleton_method_m2, rb_define_singleton_method_m3)
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_singleton_method_m1(n) RBIMPL_ANYARGS_DISPATCH((n) == -1, rb_define_singleton_method_m1, RBIMPL_ANYARGS_DISPATCH_rb_define_singleton_method_m2(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_singleton_method_00(n) RBIMPL_ANYARGS_DISPATCH((n) == 0, rb_define_singleton_method_00, RBIMPL_ANYARGS_DISPATCH_rb_define_singleton_method_m1(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_singleton_method_01(n) RBIMPL_ANYARGS_DISPATCH((n) == 1, rb_define_singleton_method_01, RBIMPL_ANYARGS_DISPATCH_rb_define_singleton_method_00(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_singleton_method_02(n) RBIMPL_ANYARGS_DISPATCH((n) == 2, rb_define_singleton_method_02, RBIMPL_ANYARGS_DISPATCH_rb_define_singleton_method_01(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_singleton_method_03(n) RBIMPL_ANYARGS_DISPATCH((n) == 3, rb_define_singleton_method_03, RBIMPL_ANYARGS_DISPATCH_rb_define_singleton_method_02(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_singleton_method_04(n) RBIMPL_ANYARGS_DISPATCH((n) == 4, rb_define_singleton_method_04, RBIMPL_ANYARGS_DISPATCH_rb_define_singleton_method_03(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_singleton_method_05(n) RBIMPL_ANYARGS_DISPATCH((n) == 5, rb_define_singleton_method_05, RBIMPL_ANYARGS_DISPATCH_rb_define_singleton_method_04(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_singleton_method_06(n) RBIMPL_ANYARGS_DISPATCH((n) == 6, rb_define_singleton_method_06, RBIMPL_ANYARGS_DISPATCH_rb_define_singleton_method_05(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_singleton_method_07(n) RBIMPL_ANYARGS_DISPATCH((n) == 7, rb_define_singleton_method_07, RBIMPL_ANYARGS_DISPATCH_rb_define_singleton_method_06(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_singleton_method_08(n) RBIMPL_ANYARGS_DISPATCH((n) == 8, rb_define_singleton_method_08, RBIMPL_ANYARGS_DISPATCH_rb_define_singleton_method_07(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_singleton_method_09(n) RBIMPL_ANYARGS_DISPATCH((n) == 9, rb_define_singleton_method_09, RBIMPL_ANYARGS_DISPATCH_rb_define_singleton_method_08(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_singleton_method_10(n) RBIMPL_ANYARGS_DISPATCH((n) == 10, rb_define_singleton_method_10, RBIMPL_ANYARGS_DISPATCH_rb_define_singleton_method_09(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_singleton_method_11(n) RBIMPL_ANYARGS_DISPATCH((n) == 11, rb_define_singleton_method_11, RBIMPL_ANYARGS_DISPATCH_rb_define_singleton_method_10(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_singleton_method_12(n) RBIMPL_ANYARGS_DISPATCH((n) == 12, rb_define_singleton_method_12, RBIMPL_ANYARGS_DISPATCH_rb_define_singleton_method_11(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_singleton_method_13(n) RBIMPL_ANYARGS_DISPATCH((n) == 13, rb_define_singleton_method_13, RBIMPL_ANYARGS_DISPATCH_rb_define_singleton_method_12(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_singleton_method_14(n) RBIMPL_ANYARGS_DISPATCH((n) == 14, rb_define_singleton_method_14, RBIMPL_ANYARGS_DISPATCH_rb_define_singleton_method_13(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_singleton_method_15(n) RBIMPL_ANYARGS_DISPATCH((n) == 15, rb_define_singleton_method_15, RBIMPL_ANYARGS_DISPATCH_rb_define_singleton_method_14(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_protected_method_m2(n) RBIMPL_ANYARGS_DISPATCH((n) == -2, rb_define_protected_method_m2, rb_define_protected_method_m3)
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_protected_method_m1(n) RBIMPL_ANYARGS_DISPATCH((n) == -1, rb_define_protected_method_m1, RBIMPL_ANYARGS_DISPATCH_rb_define_protected_method_m2(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_protected_method_00(n) RBIMPL_ANYARGS_DISPATCH((n) == 0, rb_define_protected_method_00, RBIMPL_ANYARGS_DISPATCH_rb_define_protected_method_m1(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_protected_method_01(n) RBIMPL_ANYARGS_DISPATCH((n) == 1, rb_define_protected_method_01, RBIMPL_ANYARGS_DISPATCH_rb_define_protected_method_00(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_protected_method_02(n) RBIMPL_ANYARGS_DISPATCH((n) == 2, rb_define_protected_method_02, RBIMPL_ANYARGS_DISPATCH_rb_define_protected_method_01(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_protected_method_03(n) RBIMPL_ANYARGS_DISPATCH((n) == 3, rb_define_protected_method_03, RBIMPL_ANYARGS_DISPATCH_rb_define_protected_method_02(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_protected_method_04(n) RBIMPL_ANYARGS_DISPATCH((n) == 4, rb_define_protected_method_04, RBIMPL_ANYARGS_DISPATCH_rb_define_protected_method_03(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_protected_method_05(n) RBIMPL_ANYARGS_DISPATCH((n) == 5, rb_define_protected_method_05, RBIMPL_ANYARGS_DISPATCH_rb_define_protected_method_04(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_protected_method_06(n) RBIMPL_ANYARGS_DISPATCH((n) == 6, rb_define_protected_method_06, RBIMPL_ANYARGS_DISPATCH_rb_define_protected_method_05(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_protected_method_07(n) RBIMPL_ANYARGS_DISPATCH((n) == 7, rb_define_protected_method_07, RBIMPL_ANYARGS_DISPATCH_rb_define_protected_method_06(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_protected_method_08(n) RBIMPL_ANYARGS_DISPATCH((n) == 8, rb_define_protected_method_08, RBIMPL_ANYARGS_DISPATCH_rb_define_protected_method_07(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_protected_method_09(n) RBIMPL_ANYARGS_DISPATCH((n) == 9, rb_define_protected_method_09, RBIMPL_ANYARGS_DISPATCH_rb_define_protected_method_08(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_protected_method_10(n) RBIMPL_ANYARGS_DISPATCH((n) == 10, rb_define_protected_method_10, RBIMPL_ANYARGS_DISPATCH_rb_define_protected_method_09(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_protected_method_11(n) RBIMPL_ANYARGS_DISPATCH((n) == 11, rb_define_protected_method_11, RBIMPL_ANYARGS_DISPATCH_rb_define_protected_method_10(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_protected_method_12(n) RBIMPL_ANYARGS_DISPATCH((n) == 12, rb_define_protected_method_12, RBIMPL_ANYARGS_DISPATCH_rb_define_protected_method_11(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_protected_method_13(n) RBIMPL_ANYARGS_DISPATCH((n) == 13, rb_define_protected_method_13, RBIMPL_ANYARGS_DISPATCH_rb_define_protected_method_12(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_protected_method_14(n) RBIMPL_ANYARGS_DISPATCH((n) == 14, rb_define_protected_method_14, RBIMPL_ANYARGS_DISPATCH_rb_define_protected_method_13(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_protected_method_15(n) RBIMPL_ANYARGS_DISPATCH((n) == 15, rb_define_protected_method_15, RBIMPL_ANYARGS_DISPATCH_rb_define_protected_method_14(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_private_method_m2(n) RBIMPL_ANYARGS_DISPATCH((n) == -2, rb_define_private_method_m2, rb_define_private_method_m3)
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_private_method_m1(n) RBIMPL_ANYARGS_DISPATCH((n) == -1, rb_define_private_method_m1, RBIMPL_ANYARGS_DISPATCH_rb_define_private_method_m2(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_private_method_00(n) RBIMPL_ANYARGS_DISPATCH((n) == 0, rb_define_private_method_00, RBIMPL_ANYARGS_DISPATCH_rb_define_private_method_m1(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_private_method_01(n) RBIMPL_ANYARGS_DISPATCH((n) == 1, rb_define_private_method_01, RBIMPL_ANYARGS_DISPATCH_rb_define_private_method_00(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_private_method_02(n) RBIMPL_ANYARGS_DISPATCH((n) == 2, rb_define_private_method_02, RBIMPL_ANYARGS_DISPATCH_rb_define_private_method_01(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_private_method_03(n) RBIMPL_ANYARGS_DISPATCH((n) == 3, rb_define_private_method_03, RBIMPL_ANYARGS_DISPATCH_rb_define_private_method_02(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_private_method_04(n) RBIMPL_ANYARGS_DISPATCH((n) == 4, rb_define_private_method_04, RBIMPL_ANYARGS_DISPATCH_rb_define_private_method_03(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_private_method_05(n) RBIMPL_ANYARGS_DISPATCH((n) == 5, rb_define_private_method_05, RBIMPL_ANYARGS_DISPATCH_rb_define_private_method_04(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_private_method_06(n) RBIMPL_ANYARGS_DISPATCH((n) == 6, rb_define_private_method_06, RBIMPL_ANYARGS_DISPATCH_rb_define_private_method_05(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_private_method_07(n) RBIMPL_ANYARGS_DISPATCH((n) == 7, rb_define_private_method_07, RBIMPL_ANYARGS_DISPATCH_rb_define_private_method_06(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_private_method_08(n) RBIMPL_ANYARGS_DISPATCH((n) == 8, rb_define_private_method_08, RBIMPL_ANYARGS_DISPATCH_rb_define_private_method_07(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_private_method_09(n) RBIMPL_ANYARGS_DISPATCH((n) == 9, rb_define_private_method_09, RBIMPL_ANYARGS_DISPATCH_rb_define_private_method_08(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_private_method_10(n) RBIMPL_ANYARGS_DISPATCH((n) == 10, rb_define_private_method_10, RBIMPL_ANYARGS_DISPATCH_rb_define_private_method_09(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_private_method_11(n) RBIMPL_ANYARGS_DISPATCH((n) == 11, rb_define_private_method_11, RBIMPL_ANYARGS_DISPATCH_rb_define_private_method_10(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_private_method_12(n) RBIMPL_ANYARGS_DISPATCH((n) == 12, rb_define_private_method_12, RBIMPL_ANYARGS_DISPATCH_rb_define_private_method_11(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_private_method_13(n) RBIMPL_ANYARGS_DISPATCH((n) == 13, rb_define_private_method_13, RBIMPL_ANYARGS_DISPATCH_rb_define_private_method_12(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_private_method_14(n) RBIMPL_ANYARGS_DISPATCH((n) == 14, rb_define_private_method_14, RBIMPL_ANYARGS_DISPATCH_rb_define_private_method_13(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_private_method_15(n) RBIMPL_ANYARGS_DISPATCH((n) == 15, rb_define_private_method_15, RBIMPL_ANYARGS_DISPATCH_rb_define_private_method_14(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_module_function_m2(n) RBIMPL_ANYARGS_DISPATCH((n) == -2, rb_define_module_function_m2, rb_define_module_function_m3)
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_module_function_m1(n) RBIMPL_ANYARGS_DISPATCH((n) == -1, rb_define_module_function_m1, RBIMPL_ANYARGS_DISPATCH_rb_define_module_function_m2(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_module_function_00(n) RBIMPL_ANYARGS_DISPATCH((n) == 0, rb_define_module_function_00, RBIMPL_ANYARGS_DISPATCH_rb_define_module_function_m1(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_module_function_01(n) RBIMPL_ANYARGS_DISPATCH((n) == 1, rb_define_module_function_01, RBIMPL_ANYARGS_DISPATCH_rb_define_module_function_00(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_module_function_02(n) RBIMPL_ANYARGS_DISPATCH((n) == 2, rb_define_module_function_02, RBIMPL_ANYARGS_DISPATCH_rb_define_module_function_01(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_module_function_03(n) RBIMPL_ANYARGS_DISPATCH((n) == 3, rb_define_module_function_03, RBIMPL_ANYARGS_DISPATCH_rb_define_module_function_02(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_module_function_04(n) RBIMPL_ANYARGS_DISPATCH((n) == 4, rb_define_module_function_04, RBIMPL_ANYARGS_DISPATCH_rb_define_module_function_03(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_module_function_05(n) RBIMPL_ANYARGS_DISPATCH((n) == 5, rb_define_module_function_05, RBIMPL_ANYARGS_DISPATCH_rb_define_module_function_04(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_module_function_06(n) RBIMPL_ANYARGS_DISPATCH((n) == 6, rb_define_module_function_06, RBIMPL_ANYARGS_DISPATCH_rb_define_module_function_05(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_module_function_07(n) RBIMPL_ANYARGS_DISPATCH((n) == 7, rb_define_module_function_07, RBIMPL_ANYARGS_DISPATCH_rb_define_module_function_06(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_module_function_08(n) RBIMPL_ANYARGS_DISPATCH((n) == 8, rb_define_module_function_08, RBIMPL_ANYARGS_DISPATCH_rb_define_module_function_07(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_module_function_09(n) RBIMPL_ANYARGS_DISPATCH((n) == 9, rb_define_module_function_09, RBIMPL_ANYARGS_DISPATCH_rb_define_module_function_08(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_module_function_10(n) RBIMPL_ANYARGS_DISPATCH((n) == 10, rb_define_module_function_10, RBIMPL_ANYARGS_DISPATCH_rb_define_module_function_09(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_module_function_11(n) RBIMPL_ANYARGS_DISPATCH((n) == 11, rb_define_module_function_11, RBIMPL_ANYARGS_DISPATCH_rb_define_module_function_10(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_module_function_12(n) RBIMPL_ANYARGS_DISPATCH((n) == 12, rb_define_module_function_12, RBIMPL_ANYARGS_DISPATCH_rb_define_module_function_11(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_module_function_13(n) RBIMPL_ANYARGS_DISPATCH((n) == 13, rb_define_module_function_13, RBIMPL_ANYARGS_DISPATCH_rb_define_module_function_12(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_module_function_14(n) RBIMPL_ANYARGS_DISPATCH((n) == 14, rb_define_module_function_14, RBIMPL_ANYARGS_DISPATCH_rb_define_module_function_13(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_module_function_15(n) RBIMPL_ANYARGS_DISPATCH((n) == 15, rb_define_module_function_15, RBIMPL_ANYARGS_DISPATCH_rb_define_module_function_14(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_global_function_m2(n) RBIMPL_ANYARGS_DISPATCH((n) == -2, rb_define_global_function_m2, rb_define_global_function_m3)
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_global_function_m1(n) RBIMPL_ANYARGS_DISPATCH((n) == -1, rb_define_global_function_m1, RBIMPL_ANYARGS_DISPATCH_rb_define_global_function_m2(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_global_function_00(n) RBIMPL_ANYARGS_DISPATCH((n) == 0, rb_define_global_function_00, RBIMPL_ANYARGS_DISPATCH_rb_define_global_function_m1(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_global_function_01(n) RBIMPL_ANYARGS_DISPATCH((n) == 1, rb_define_global_function_01, RBIMPL_ANYARGS_DISPATCH_rb_define_global_function_00(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_global_function_02(n) RBIMPL_ANYARGS_DISPATCH((n) == 2, rb_define_global_function_02, RBIMPL_ANYARGS_DISPATCH_rb_define_global_function_01(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_global_function_03(n) RBIMPL_ANYARGS_DISPATCH((n) == 3, rb_define_global_function_03, RBIMPL_ANYARGS_DISPATCH_rb_define_global_function_02(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_global_function_04(n) RBIMPL_ANYARGS_DISPATCH((n) == 4, rb_define_global_function_04, RBIMPL_ANYARGS_DISPATCH_rb_define_global_function_03(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_global_function_05(n) RBIMPL_ANYARGS_DISPATCH((n) == 5, rb_define_global_function_05, RBIMPL_ANYARGS_DISPATCH_rb_define_global_function_04(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_global_function_06(n) RBIMPL_ANYARGS_DISPATCH((n) == 6, rb_define_global_function_06, RBIMPL_ANYARGS_DISPATCH_rb_define_global_function_05(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_global_function_07(n) RBIMPL_ANYARGS_DISPATCH((n) == 7, rb_define_global_function_07, RBIMPL_ANYARGS_DISPATCH_rb_define_global_function_06(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_global_function_08(n) RBIMPL_ANYARGS_DISPATCH((n) == 8, rb_define_global_function_08, RBIMPL_ANYARGS_DISPATCH_rb_define_global_function_07(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_global_function_09(n) RBIMPL_ANYARGS_DISPATCH((n) == 9, rb_define_global_function_09, RBIMPL_ANYARGS_DISPATCH_rb_define_global_function_08(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_global_function_10(n) RBIMPL_ANYARGS_DISPATCH((n) == 10, rb_define_global_function_10, RBIMPL_ANYARGS_DISPATCH_rb_define_global_function_09(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_global_function_11(n) RBIMPL_ANYARGS_DISPATCH((n) == 11, rb_define_global_function_11, RBIMPL_ANYARGS_DISPATCH_rb_define_global_function_10(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_global_function_12(n) RBIMPL_ANYARGS_DISPATCH((n) == 12, rb_define_global_function_12, RBIMPL_ANYARGS_DISPATCH_rb_define_global_function_11(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_global_function_13(n) RBIMPL_ANYARGS_DISPATCH((n) == 13, rb_define_global_function_13, RBIMPL_ANYARGS_DISPATCH_rb_define_global_function_12(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_global_function_14(n) RBIMPL_ANYARGS_DISPATCH((n) == 14, rb_define_global_function_14, RBIMPL_ANYARGS_DISPATCH_rb_define_global_function_13(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_global_function_15(n) RBIMPL_ANYARGS_DISPATCH((n) == 15, rb_define_global_function_15, RBIMPL_ANYARGS_DISPATCH_rb_define_global_function_14(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_method_id_m2(n) RBIMPL_ANYARGS_DISPATCH((n) == -2, rb_define_method_id_m2, rb_define_method_id_m3)
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_method_id_m1(n) RBIMPL_ANYARGS_DISPATCH((n) == -1, rb_define_method_id_m1, RBIMPL_ANYARGS_DISPATCH_rb_define_method_id_m2(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_method_id_00(n) RBIMPL_ANYARGS_DISPATCH((n) == 0, rb_define_method_id_00, RBIMPL_ANYARGS_DISPATCH_rb_define_method_id_m1(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_method_id_01(n) RBIMPL_ANYARGS_DISPATCH((n) == 1, rb_define_method_id_01, RBIMPL_ANYARGS_DISPATCH_rb_define_method_id_00(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_method_id_02(n) RBIMPL_ANYARGS_DISPATCH((n) == 2, rb_define_method_id_02, RBIMPL_ANYARGS_DISPATCH_rb_define_method_id_01(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_method_id_03(n) RBIMPL_ANYARGS_DISPATCH((n) == 3, rb_define_method_id_03, RBIMPL_ANYARGS_DISPATCH_rb_define_method_id_02(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_method_id_04(n) RBIMPL_ANYARGS_DISPATCH((n) == 4, rb_define_method_id_04, RBIMPL_ANYARGS_DISPATCH_rb_define_method_id_03(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_method_id_05(n) RBIMPL_ANYARGS_DISPATCH((n) == 5, rb_define_method_id_05, RBIMPL_ANYARGS_DISPATCH_rb_define_method_id_04(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_method_id_06(n) RBIMPL_ANYARGS_DISPATCH((n) == 6, rb_define_method_id_06, RBIMPL_ANYARGS_DISPATCH_rb_define_method_id_05(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_method_id_07(n) RBIMPL_ANYARGS_DISPATCH((n) == 7, rb_define_method_id_07, RBIMPL_ANYARGS_DISPATCH_rb_define_method_id_06(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_method_id_08(n) RBIMPL_ANYARGS_DISPATCH((n) == 8, rb_define_method_id_08, RBIMPL_ANYARGS_DISPATCH_rb_define_method_id_07(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_method_id_09(n) RBIMPL_ANYARGS_DISPATCH((n) == 9, rb_define_method_id_09, RBIMPL_ANYARGS_DISPATCH_rb_define_method_id_08(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_method_id_10(n) RBIMPL_ANYARGS_DISPATCH((n) == 10, rb_define_method_id_10, RBIMPL_ANYARGS_DISPATCH_rb_define_method_id_09(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_method_id_11(n) RBIMPL_ANYARGS_DISPATCH((n) == 11, rb_define_method_id_11, RBIMPL_ANYARGS_DISPATCH_rb_define_method_id_10(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_method_id_12(n) RBIMPL_ANYARGS_DISPATCH((n) == 12, rb_define_method_id_12, RBIMPL_ANYARGS_DISPATCH_rb_define_method_id_11(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_method_id_13(n) RBIMPL_ANYARGS_DISPATCH((n) == 13, rb_define_method_id_13, RBIMPL_ANYARGS_DISPATCH_rb_define_method_id_12(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_method_id_14(n) RBIMPL_ANYARGS_DISPATCH((n) == 14, rb_define_method_id_14, RBIMPL_ANYARGS_DISPATCH_rb_define_method_id_13(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_method_id_15(n) RBIMPL_ANYARGS_DISPATCH((n) == 15, rb_define_method_id_15, RBIMPL_ANYARGS_DISPATCH_rb_define_method_id_14(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_method_m2(n) RBIMPL_ANYARGS_DISPATCH((n) == -2, rb_define_method_m2, rb_define_method_m3)
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_method_m1(n) RBIMPL_ANYARGS_DISPATCH((n) == -1, rb_define_method_m1, RBIMPL_ANYARGS_DISPATCH_rb_define_method_m2(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_method_00(n) RBIMPL_ANYARGS_DISPATCH((n) == 0, rb_define_method_00, RBIMPL_ANYARGS_DISPATCH_rb_define_method_m1(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_method_01(n) RBIMPL_ANYARGS_DISPATCH((n) == 1, rb_define_method_01, RBIMPL_ANYARGS_DISPATCH_rb_define_method_00(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_method_02(n) RBIMPL_ANYARGS_DISPATCH((n) == 2, rb_define_method_02, RBIMPL_ANYARGS_DISPATCH_rb_define_method_01(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_method_03(n) RBIMPL_ANYARGS_DISPATCH((n) == 3, rb_define_method_03, RBIMPL_ANYARGS_DISPATCH_rb_define_method_02(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_method_04(n) RBIMPL_ANYARGS_DISPATCH((n) == 4, rb_define_method_04, RBIMPL_ANYARGS_DISPATCH_rb_define_method_03(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_method_05(n) RBIMPL_ANYARGS_DISPATCH((n) == 5, rb_define_method_05, RBIMPL_ANYARGS_DISPATCH_rb_define_method_04(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_method_06(n) RBIMPL_ANYARGS_DISPATCH((n) == 6, rb_define_method_06, RBIMPL_ANYARGS_DISPATCH_rb_define_method_05(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_method_07(n) RBIMPL_ANYARGS_DISPATCH((n) == 7, rb_define_method_07, RBIMPL_ANYARGS_DISPATCH_rb_define_method_06(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_method_08(n) RBIMPL_ANYARGS_DISPATCH((n) == 8, rb_define_method_08, RBIMPL_ANYARGS_DISPATCH_rb_define_method_07(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_method_09(n) RBIMPL_ANYARGS_DISPATCH((n) == 9, rb_define_method_09, RBIMPL_ANYARGS_DISPATCH_rb_define_method_08(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_method_10(n) RBIMPL_ANYARGS_DISPATCH((n) == 10, rb_define_method_10, RBIMPL_ANYARGS_DISPATCH_rb_define_method_09(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_method_11(n) RBIMPL_ANYARGS_DISPATCH((n) == 11, rb_define_method_11, RBIMPL_ANYARGS_DISPATCH_rb_define_method_10(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_method_12(n) RBIMPL_ANYARGS_DISPATCH((n) == 12, rb_define_method_12, RBIMPL_ANYARGS_DISPATCH_rb_define_method_11(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_method_13(n) RBIMPL_ANYARGS_DISPATCH((n) == 13, rb_define_method_13, RBIMPL_ANYARGS_DISPATCH_rb_define_method_12(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_method_14(n) RBIMPL_ANYARGS_DISPATCH((n) == 14, rb_define_method_14, RBIMPL_ANYARGS_DISPATCH_rb_define_method_13(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_method_15(n) RBIMPL_ANYARGS_DISPATCH((n) == 15, rb_define_method_15, RBIMPL_ANYARGS_DISPATCH_rb_define_method_14(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_singleton_method(n, f) RBIMPL_ANYARGS_DISPATCH(RBIMPL_CFUNC_IS_rb_f_notimplement(f), rb_define_singleton_method_m3, RBIMPL_ANYARGS_DISPATCH_rb_define_singleton_method_15(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_protected_method(n, f) RBIMPL_ANYARGS_DISPATCH(RBIMPL_CFUNC_IS_rb_f_notimplement(f), rb_define_protected_method_m3, RBIMPL_ANYARGS_DISPATCH_rb_define_protected_method_15(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_private_method(n, f) RBIMPL_ANYARGS_DISPATCH(RBIMPL_CFUNC_IS_rb_f_notimplement(f), rb_define_private_method_m3, RBIMPL_ANYARGS_DISPATCH_rb_define_private_method_15(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_module_function(n, f) RBIMPL_ANYARGS_DISPATCH(RBIMPL_CFUNC_IS_rb_f_notimplement(f), rb_define_module_function_m3, RBIMPL_ANYARGS_DISPATCH_rb_define_module_function_15(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_global_function(n, f) RBIMPL_ANYARGS_DISPATCH(RBIMPL_CFUNC_IS_rb_f_notimplement(f), rb_define_global_function_m3, RBIMPL_ANYARGS_DISPATCH_rb_define_global_function_15(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_method_id(n, f) RBIMPL_ANYARGS_DISPATCH(RBIMPL_CFUNC_IS_rb_f_notimplement(f), rb_define_method_id_m3, RBIMPL_ANYARGS_DISPATCH_rb_define_method_id_15(n))
+# define RBIMPL_ANYARGS_DISPATCH_rb_define_method(n, f) RBIMPL_ANYARGS_DISPATCH(RBIMPL_CFUNC_IS_rb_f_notimplement(f), rb_define_method_m3, RBIMPL_ANYARGS_DISPATCH_rb_define_method_15(n))
+# define RBIMPL_ANYARGS_ATTRSET(sym) RBIMPL_ATTR_MAYBE_UNUSED() RBIMPL_ATTR_NONNULL(()) RBIMPL_ATTR_WEAKREF(sym)
+# define RBIMPL_ANYARGS_DECL(sym, ...) \
+RBIMPL_ANYARGS_ATTRSET(sym) static void sym ## _m3(__VA_ARGS__, VALUE(*)(ANYARGS), int); \
+RBIMPL_ANYARGS_ATTRSET(sym) static void sym ## _m2(__VA_ARGS__, VALUE(*)(VALUE, VALUE), int); \
+RBIMPL_ANYARGS_ATTRSET(sym) static void sym ## _m1(__VA_ARGS__, VALUE(*)(int, union { VALUE *x; const VALUE *y; } __attribute__((__transparent_union__)), VALUE), int); \
+RBIMPL_ANYARGS_ATTRSET(sym) static void sym ## _00(__VA_ARGS__, VALUE(*)(VALUE), int); \
+RBIMPL_ANYARGS_ATTRSET(sym) static void sym ## _01(__VA_ARGS__, VALUE(*)(VALUE, VALUE), int); \
+RBIMPL_ANYARGS_ATTRSET(sym) static void sym ## _02(__VA_ARGS__, VALUE(*)(VALUE, VALUE, VALUE), int); \
+RBIMPL_ANYARGS_ATTRSET(sym) static void sym ## _03(__VA_ARGS__, VALUE(*)(VALUE, VALUE, VALUE, VALUE), int); \
+RBIMPL_ANYARGS_ATTRSET(sym) static void sym ## _04(__VA_ARGS__, VALUE(*)(VALUE, VALUE, VALUE, VALUE, VALUE), int); \
+RBIMPL_ANYARGS_ATTRSET(sym) static void sym ## _05(__VA_ARGS__, VALUE(*)(VALUE, VALUE, VALUE, VALUE, VALUE, VALUE), int); \
+RBIMPL_ANYARGS_ATTRSET(sym) static void sym ## _06(__VA_ARGS__, VALUE(*)(VALUE, VALUE, VALUE, VALUE, VALUE, VALUE, VALUE), int); \
+RBIMPL_ANYARGS_ATTRSET(sym) static void sym ## _07(__VA_ARGS__, VALUE(*)(VALUE, VALUE, VALUE, VALUE, VALUE, VALUE, VALUE, VALUE), int); \
+RBIMPL_ANYARGS_ATTRSET(sym) static void sym ## _08(__VA_ARGS__, VALUE(*)(VALUE, VALUE, VALUE, VALUE, VALUE, VALUE, VALUE, VALUE, VALUE), int); \
+RBIMPL_ANYARGS_ATTRSET(sym) static void sym ## _09(__VA_ARGS__, VALUE(*)(VALUE, VALUE, VALUE, VALUE, VALUE, VALUE, VALUE, VALUE, VALUE, VALUE), int); \
+RBIMPL_ANYARGS_ATTRSET(sym) static void sym ## _10(__VA_ARGS__, VALUE(*)(VALUE, VALUE, VALUE, VALUE, VALUE, VALUE, VALUE, VALUE, VALUE, VALUE, VALUE), int); \
+RBIMPL_ANYARGS_ATTRSET(sym) static void sym ## _11(__VA_ARGS__, VALUE(*)(VALUE, VALUE, VALUE, VALUE, VALUE, VALUE, VALUE, VALUE, VALUE, VALUE, VALUE, VALUE), int); \
+RBIMPL_ANYARGS_ATTRSET(sym) static void sym ## _12(__VA_ARGS__, VALUE(*)(VALUE, VALUE, VALUE, VALUE, VALUE, VALUE, VALUE, VALUE, VALUE, VALUE, VALUE, VALUE, VALUE), int); \
+RBIMPL_ANYARGS_ATTRSET(sym) static void sym ## _13(__VA_ARGS__, VALUE(*)(VALUE, VALUE, VALUE, VALUE, VALUE, VALUE, VALUE, VALUE, VALUE, VALUE, VALUE, VALUE, VALUE, VALUE), int); \
+RBIMPL_ANYARGS_ATTRSET(sym) static void sym ## _14(__VA_ARGS__, VALUE(*)(VALUE, VALUE, VALUE, VALUE, VALUE, VALUE, VALUE, VALUE, VALUE, VALUE, VALUE, VALUE, VALUE, VALUE, VALUE), int); \
+RBIMPL_ANYARGS_ATTRSET(sym) static void sym ## _15(__VA_ARGS__, VALUE(*)(VALUE, VALUE, VALUE, VALUE, VALUE, VALUE, VALUE, VALUE, VALUE, VALUE, VALUE, VALUE, VALUE, VALUE, VALUE, VALUE), int);
+RBIMPL_ANYARGS_DECL(rb_define_singleton_method, VALUE, const char *)
+RBIMPL_ANYARGS_DECL(rb_define_protected_method, VALUE, const char *)
+RBIMPL_ANYARGS_DECL(rb_define_private_method, VALUE, const char *)
+RBIMPL_ANYARGS_DECL(rb_define_module_function, VALUE, const char *)
+RBIMPL_ANYARGS_DECL(rb_define_global_function, const char *)
+RBIMPL_ANYARGS_DECL(rb_define_method_id, VALUE, ID)
+RBIMPL_ANYARGS_DECL(rb_define_method, VALUE, const char *)
+/** @endcond */
+
+/**
+ * @brief Defines klass\#mid.
+ * @see ::rb_define_method
+ * @param klass Where the method lives.
+ * @param mid Name of the defining method.
+ * @param func Implementation of klass\#mid.
+ * @param arity Arity of klass\#mid.
+ */
+#define rb_define_method(klass, mid, func, arity) RBIMPL_ANYARGS_DISPATCH_rb_define_method((arity), (func))((klass), (mid), (func), (arity))
+
+/**
+ * @brief Defines klass\#mid.
+ * @see ::rb_define_method_id
+ * @param klass Where the method lives.
+ * @param mid Name of the defining method.
+ * @param func Implementation of klass\#mid.
+ * @param arity Arity of klass\#mid.
+ */
+#define rb_define_method_id(klass, mid, func, arity) RBIMPL_ANYARGS_DISPATCH_rb_define_method_id((arity), (func))((klass), (mid), (func), (arity))
+
+/**
+ * @brief Defines obj.mid.
+ * @see ::rb_define_singleton_method
+ * @param obj Where the method lives.
+ * @param mid Name of the defining method.
+ * @param func Implementation of obj.mid.
+ * @param arity Arity of obj.mid.
+ */
+#define rb_define_singleton_method(obj, mid, func, arity) RBIMPL_ANYARGS_DISPATCH_rb_define_singleton_method((arity), (func))((obj), (mid), (func), (arity))
+
+/**
+ * @brief Defines klass\#mid and make it protected.
+ * @see ::rb_define_protected_method
+ * @param klass Where the method lives.
+ * @param mid Name of the defining method.
+ * @param func Implementation of klass\#mid.
+ * @param arity Arity of klass\#mid.
+ */
+#define rb_define_protected_method(klass, mid, func, arity) RBIMPL_ANYARGS_DISPATCH_rb_define_protected_method((arity), (func))((klass), (mid), (func), (arity))
+
+/**
+ * @brief Defines klass\#mid and make it private.
+ * @see ::rb_define_private_method
+ * @param klass Where the method lives.
+ * @param mid Name of the defining method.
+ * @param func Implementation of klass\#mid.
+ * @param arity Arity of klass\#mid.
+ */
+#define rb_define_private_method(klass, mid, func, arity) RBIMPL_ANYARGS_DISPATCH_rb_define_private_method((arity), (func))((klass), (mid), (func), (arity))
+
+/**
+ * @brief Defines mod\#mid and make it a module function.
+ * @see ::rb_define_module_function
+ * @param mod Where the method lives.
+ * @param mid Name of the defining method.
+ * @param func Implementation of mod\#mid.
+ * @param arity Arity of mod\#mid.
+ */
+#define rb_define_module_function(mod, mid, func, arity) RBIMPL_ANYARGS_DISPATCH_rb_define_module_function((arity), (func))((mod), (mid), (func), (arity))
+
+/**
+ * @brief Defines ::rb_mKerbel \#mid.
+ * @see ::rb_define_global_function
+ * @param mid Name of the defining method.
+ * @param func Implementation of ::rb_mKernel \#mid.
+ * @param arity Arity of ::rb_mKernel \#mid.
+ */
+#define rb_define_global_function(mid, func, arity) RBIMPL_ANYARGS_DISPATCH_rb_define_global_function((arity), (func))((mid), (func), (arity))
+
+#endif /* __cplusplus */
+
+/**
+ * This macro is to properly cast a function parameter of *_define_method
+ * family. It has been around since 1.x era so you can maximise backwards
+ * compatibility by using it.
+ *
+ * ```CXX
+ * rb_define_method(klass, "method", RUBY_METHOD_FUNC(func), arity);
+ * ```
+ *
+ * @param func A pointer to a function that implements a method.
+ */
+#if ! defined(RUBY_DEVEL)
+# define RUBY_METHOD_FUNC(func) RBIMPL_CAST((VALUE (*)(ANYARGS))(func))
+
+#elif ! RUBY_DEVEL
+# define RUBY_METHOD_FUNC(func) RBIMPL_CAST((VALUE (*)(ANYARGS))(func))
+
+#elif ! defined(rb_define_method)
+# define RUBY_METHOD_FUNC(func) RBIMPL_CAST((VALUE (*)(ANYARGS))(func))
+
+#else
+# define RUBY_METHOD_FUNC(func) (func)
+
+#endif
+
+#endif /* RBIMPL_ANYARGS_H */
diff --git a/include/ruby/internal/arithmetic.h b/include/ruby/internal/arithmetic.h
new file mode 100644
index 0000000000..3f7840c384
--- /dev/null
+++ b/include/ruby/internal/arithmetic.h
@@ -0,0 +1,38 @@
+#ifndef RBIMPL_ARITHMETIC_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_ARITHMETIC_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Conversion between C's arithmtic types and Ruby's numeric types.
+ */
+#include "ruby/internal/arithmetic/char.h"
+#include "ruby/internal/arithmetic/double.h"
+#include "ruby/internal/arithmetic/fixnum.h"
+#include "ruby/internal/arithmetic/gid_t.h"
+#include "ruby/internal/arithmetic/int.h"
+#include "ruby/internal/arithmetic/intptr_t.h"
+#include "ruby/internal/arithmetic/long.h"
+#include "ruby/internal/arithmetic/long_long.h"
+#include "ruby/internal/arithmetic/mode_t.h"
+#include "ruby/internal/arithmetic/off_t.h"
+#include "ruby/internal/arithmetic/pid_t.h"
+#include "ruby/internal/arithmetic/short.h"
+#include "ruby/internal/arithmetic/size_t.h"
+#include "ruby/internal/arithmetic/st_data_t.h"
+#include "ruby/internal/arithmetic/uid_t.h"
+#endif /* RBIMPL_ARITHMETIC_H */
diff --git a/include/ruby/internal/arithmetic/char.h b/include/ruby/internal/arithmetic/char.h
new file mode 100644
index 0000000000..920fdc0c9d
--- /dev/null
+++ b/include/ruby/internal/arithmetic/char.h
@@ -0,0 +1,81 @@
+#ifndef RBIMPL_ARITHMETIC_CHAR_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_ARITHMETIC_CHAR_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Arithmetic conversion between C's `char` and Ruby's.
+ */
+#include "ruby/internal/arithmetic/int.h" /* NUM2INT is here, but */
+#include "ruby/internal/arithmetic/long.h" /* INT2FIX is here.*/
+#include "ruby/internal/attr/artificial.h"
+#include "ruby/internal/attr/const.h"
+#include "ruby/internal/attr/constexpr.h"
+#include "ruby/internal/cast.h"
+#include "ruby/internal/core/rstring.h"
+#include "ruby/internal/value_type.h"
+
+#define RB_NUM2CHR rb_num2char_inline /**< @alias{rb_num2char_inline} */
+#define NUM2CHR RB_NUM2CHR /**< @old{RB_NUM2CHR} */
+#define CHR2FIX RB_CHR2FIX /**< @old{RB_CHR2FIX} */
+
+/** @cond INTERNAL_MACRO */
+#define RB_CHR2FIX RB_CHR2FIX
+/** @endcond */
+
+RBIMPL_ATTR_CONST_UNLESS_DEBUG()
+RBIMPL_ATTR_CONSTEXPR_UNLESS_DEBUG(CXX14)
+RBIMPL_ATTR_ARTIFICIAL()
+/**
+ * Converts a C's `unsigned char` into an instance of ::rb_cInteger.
+ *
+ * @param[in] c Arbitrary `unsigned char` value.
+ * @return An instance of ::rb_cInteger.
+ *
+ * @internal
+ *
+ * Nobody explicitly states this but in Ruby, a char means an unsigned integer
+ * value of range 0..255. This is a general principle. AFAIK there is no
+ * single line of code where char is signed.
+ */
+static inline VALUE
+RB_CHR2FIX(unsigned char c)
+{
+ return RB_INT2FIX(c);
+}
+
+/**
+ * Converts an instance of ::rb_cNumeric into C's `char`. At the same time it
+ * accepts a String of more than one character, and returns its first byte. In
+ * the early days there was a Ruby level "character" literal `?c`, which
+ * roughly worked this way.
+ *
+ * @param[in] x Either a string or a numeric.
+ * @exception rb_eTypeError `x` is not a numeric.
+ * @exception rb_eRangeError `x` is out of range of `unsigned int`.
+ * @return The passed value converted into C's `char`.
+ */
+static inline char
+rb_num2char_inline(VALUE x)
+{
+ if (RB_TYPE_P(x, RUBY_T_STRING) && (RSTRING_LEN(x)>=1))
+ return RSTRING_PTR(x)[0];
+ else
+ return RBIMPL_CAST((char)RB_NUM2INT(x));
+}
+
+#endif /* RBIMPL_ARITHMETIC_CHAR_H */
diff --git a/include/ruby/internal/arithmetic/double.h b/include/ruby/internal/arithmetic/double.h
new file mode 100644
index 0000000000..229de47aef
--- /dev/null
+++ b/include/ruby/internal/arithmetic/double.h
@@ -0,0 +1,72 @@
+#ifndef RBIMPL_ARITHMETIC_DOUBLE_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_ARITHMETIC_DOUBLE_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Arithmetic conversion between C's `double` and Ruby's.
+ */
+#include "ruby/internal/attr/pure.h"
+#include "ruby/internal/dllexport.h"
+#include "ruby/internal/value.h"
+
+#define NUM2DBL rb_num2dbl /**< @old{rb_num2dbl} */
+#define RFLOAT_VALUE rb_float_value /**< @old{rb_float_value} */
+#define DBL2NUM rb_float_new /**< @old{rb_float_new} */
+
+RBIMPL_SYMBOL_EXPORT_BEGIN()
+/**
+ * Converts an instance of ::rb_cNumeric into C's `double`.
+ *
+ * @param[in] num Something numeric.
+ * @exception rb_eTypeError `num` is not a numeric.
+ * @return The passed value converted into C's `double`.
+ */
+double rb_num2dbl(VALUE num);
+
+RBIMPL_ATTR_PURE()
+/**
+ * Extracts its double value from an instance of ::rb_cFloat.
+ *
+ * @param[in] num An instance of ::rb_cFloat.
+ * @pre Must not pass anything other than a Fixnum.
+ * @return The passed value converted into C's `double`.
+ */
+double rb_float_value(VALUE num);
+
+/**
+ * Converts a C's `double` into an instance of ::rb_cFloat.
+ *
+ * @param[in] d Arbitrary `double` value.
+ * @return An instance of ::rb_cFloat.
+ */
+VALUE rb_float_new(double d);
+
+/**
+ * Identical to rb_float_new(), except it does not generate Flonums.
+ *
+ * @param[in] d Arbitrary `double` value.
+ * @return An instance of ::rb_cFloat.
+ *
+ * @internal
+ *
+ * @shyouhei has no idea why it is here.
+ */
+VALUE rb_float_new_in_heap(double d);
+RBIMPL_SYMBOL_EXPORT_END()
+
+#endif /* RBIMPL_ARITHMETIC_DOUBLE_H */
diff --git a/include/ruby/internal/arithmetic/fixnum.h b/include/ruby/internal/arithmetic/fixnum.h
new file mode 100644
index 0000000000..c8927ac824
--- /dev/null
+++ b/include/ruby/internal/arithmetic/fixnum.h
@@ -0,0 +1,60 @@
+#ifndef RBIMPL_ARITHMETIC_FIXNUM_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_ARITHMETIC_FIXNUM_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Handling of integers formerly known as Fixnums.
+ */
+#include "ruby/backward/2/limits.h"
+
+#define FIXABLE RB_FIXABLE /**< @old{RB_FIXABLE} */
+#define FIXNUM_MAX RUBY_FIXNUM_MAX /**< @old{RUBY_FIXNUM_MAX} */
+#define FIXNUM_MIN RUBY_FIXNUM_MIN /**< @old{RUBY_FIXNUM_MIN} */
+#define NEGFIXABLE RB_NEGFIXABLE /**< @old{RB_NEGFIXABLE} */
+#define POSFIXABLE RB_POSFIXABLE /**< @old{RB_POSFIXABLE} */
+
+/**
+ * Checks if the passed value is in range of fixnum, assuming it is a positive
+ * number. Can sometimes be useful for C's unsigned integer types.
+ *
+ * @internal
+ *
+ * FIXABLE can be applied to anything, from double to intmax_t. The problem is
+ * double. On a 64bit system RUBY_FIXNUM_MAX is 4,611,686,018,427,387,903,
+ * which is not representable by a double. The nearest value that a double can
+ * represent is 4,611,686,018,427,387,904, which is not fixable. The
+ * seemingly-strange "< FIXNUM_MAX + 1" expression below is due to this.
+ */
+#define RB_POSFIXABLE(_) ((_) < RUBY_FIXNUM_MAX + 1)
+
+/**
+ * Checks if the passed value is in range of fixnum, assuming it is a negative
+ * number. This is an implementation of #RB_FIXABLE. Rarely used stand alone.
+ */
+#define RB_NEGFIXABLE(_) ((_) >= RUBY_FIXNUM_MIN)
+
+/** Checks if the passed value is in range of fixnum */
+#define RB_FIXABLE(_) (RB_POSFIXABLE(_) && RB_NEGFIXABLE(_))
+
+/** Maximum possible value that a fixnum can represent. */
+#define RUBY_FIXNUM_MAX (LONG_MAX / 2)
+
+/** Minimum possible value that a fixnum can represent. */
+#define RUBY_FIXNUM_MIN (LONG_MIN / 2)
+
+#endif /* RBIMPL_ARITHMETIC_FIXNUM_H */
diff --git a/include/ruby/internal/arithmetic/gid_t.h b/include/ruby/internal/arithmetic/gid_t.h
new file mode 100644
index 0000000000..361220bfab
--- /dev/null
+++ b/include/ruby/internal/arithmetic/gid_t.h
@@ -0,0 +1,41 @@
+#ifndef RBIMPL_ARITHMETIC_GID_T_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_ARITHMETIC_GID_T_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Arithmetic conversion between C's `gid_t` and Ruby's.
+ */
+#include "ruby/internal/config.h"
+#include "ruby/internal/arithmetic/long.h"
+
+/** Converts a C's `gid_t` into an instance of ::rb_cInteger. */
+#ifndef GIDT2NUM
+# define GIDT2NUM RB_LONG2NUM
+#endif
+
+/** Converts an instance of ::rb_cNumeric into C's `gid_t`. */
+#ifndef NUM2GIDT
+# define NUM2GIDT RB_NUM2LONG
+#endif
+
+/** A rb_sprintf() format prefix to be used for a `gid_t` parameter. */
+#ifndef PRI_GIDT_PREFIX
+# define PRI_GIDT_PREFIX PRI_LONG_PREFIX
+#endif
+
+#endif /* RBIMPL_ARITHMETIC_GID_T_H */
diff --git a/include/ruby/internal/arithmetic/int.h b/include/ruby/internal/arithmetic/int.h
new file mode 100644
index 0000000000..6bd8ec2184
--- /dev/null
+++ b/include/ruby/internal/arithmetic/int.h
@@ -0,0 +1,264 @@
+#ifndef RBIMPL_ARITHMETIC_INT_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_ARITHMETIC_INT_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Arithmetic conversion between C's `int` and Ruby's.
+ */
+#include "ruby/internal/config.h"
+#include "ruby/internal/arithmetic/fixnum.h"
+#include "ruby/internal/arithmetic/intptr_t.h"
+#include "ruby/internal/arithmetic/long.h"
+#include "ruby/internal/attr/artificial.h"
+#include "ruby/internal/attr/const.h"
+#include "ruby/internal/attr/constexpr.h"
+#include "ruby/internal/compiler_is.h"
+#include "ruby/internal/dllexport.h"
+#include "ruby/internal/special_consts.h"
+#include "ruby/internal/value.h"
+#include "ruby/internal/warning_push.h"
+#include "ruby/assert.h"
+
+#define RB_INT2NUM rb_int2num_inline /**< @alias{rb_int2num_inline} */
+#define RB_NUM2INT rb_num2int_inline /**< @alias{rb_num2int_inline} */
+#define RB_UINT2NUM rb_uint2num_inline /**< @alias{rb_uint2num_inline} */
+
+#define FIX2INT RB_FIX2INT /**< @old{RB_FIX2INT} */
+#define FIX2UINT RB_FIX2UINT /**< @old{RB_FIX2UINT} */
+#define INT2NUM RB_INT2NUM /**< @old{RB_INT2NUM} */
+#define NUM2INT RB_NUM2INT /**< @old{RB_NUM2INT} */
+#define NUM2UINT RB_NUM2UINT /**< @old{RB_NUM2UINT} */
+#define UINT2NUM RB_UINT2NUM /**< @old{RB_UINT2NUM} */
+
+/** @cond INTERNAL_MACRO */
+#define RB_FIX2INT RB_FIX2INT
+#define RB_NUM2UINT RB_NUM2UINT
+#define RB_FIX2UINT RB_FIX2UINT
+/** @endcond */
+
+RBIMPL_SYMBOL_EXPORT_BEGIN()
+
+/**
+ * Converts an instance of ::rb_cNumeric into C's `long`.
+ *
+ * @param[in] num Something numeric.
+ * @exception rb_eTypeError `num` is not a numeric.
+ * @exception rb_eRangeError `num` is out of range of `int`.
+ * @return The passed value converted into C's `long`.
+ *
+ * @internal
+ *
+ * Yes, the API is really strange. It returns `long`, but raises when the
+ * value is out of `int`. This seems to be due to the fact that Matz favoured
+ * K&R before, and his machine at that moment was an ILP32 architecture.
+ */
+long rb_num2int(VALUE num);
+
+/**
+ * Identical to rb_num2int().
+ *
+ * @param[in] num Something numeric.
+ * @exception rb_eTypeError `num` is not a numeric.
+ * @exception rb_eRangeError `num` is out of range of `int`.
+ * @return The passed value converted into C's `long`.
+ *
+ * @internal
+ *
+ * This function seems to be a complete waste of disk space. @shyouhei has no
+ * idea why this is a different thing from rb_num2short().
+ */
+long rb_fix2int(VALUE num);
+
+/**
+ * Converts an instance of ::rb_cNumeric into C's `unsigned long`.
+ *
+ * @param[in] num Something numeric.
+ * @exception rb_eTypeError `num` is not a numeric.
+ * @exception rb_eRangeError `num` is out of range of `unsigned int`.
+ * @return The passed value converted into C's `unsigned long`.
+ *
+ * @internal
+ *
+ * Yes, the API is really strange. It returns `unsigned long`, but raises when
+ * the value is out of `unsigned int`. This seems to be due to the fact that
+ * Matz favoured K&R before, and his machine at that moment was an ILP32
+ * architecture.
+ */
+unsigned long rb_num2uint(VALUE num);
+
+/**
+ * Identical to rb_num2uint().
+ *
+ * @param[in] num Something numeric.
+ * @exception rb_eTypeError `num` is not a numeric.
+ * @exception rb_eRangeError `num` is out of range of `unsigned int`.
+ * @return The passed value converted into C's `unsigned long`.
+ *
+ * @internal
+ *
+ * This function seems to be a complete waste of disk space. @shyouhei has no
+ * idea why this is a different thing from rb_num2short().
+ */
+unsigned long rb_fix2uint(VALUE num);
+RBIMPL_SYMBOL_EXPORT_END()
+
+RBIMPL_ATTR_ARTIFICIAL()
+/**
+ * Converts a Fixnum into C's `int`.
+ *
+ * @param[in] x Some Fixnum.
+ * @pre Must not pass anything other than a Fixnum.
+ * @return The passed value converted into C's `int`.
+ */
+static inline int
+RB_FIX2INT(VALUE x)
+{
+ /* "FIX2INT raises a TypeError if passed nil", says rubyspec. Not sure if
+ * that is a desired behaviour but just preserve backwards compatilibily.
+ */
+#if 0
+ RBIMPL_ASSERT_OR_ASSUME(RB_FIXNUM_P(x));
+#endif
+ long ret;
+
+ if /* constexpr */ (sizeof(int) < sizeof(long)) {
+ ret = rb_fix2int(x);
+ }
+ else {
+ ret = RB_FIX2LONG(x);
+ }
+
+ return RBIMPL_CAST((int)ret);
+}
+
+/**
+ * Converts an instance of ::rb_cNumeric into C's `int`.
+ *
+ * @param[in] x Something numeric.
+ * @exception rb_eTypeError `x` is not a numeric.
+ * @exception rb_eRangeError `x` is out of range of `int`.
+ * @return The passed value converted into C's `int`.
+ */
+static inline int
+rb_num2int_inline(VALUE x)
+{
+ long ret;
+
+ if /* constexpr */ (sizeof(int) == sizeof(long)) {
+ ret = RB_NUM2LONG(x);
+ }
+ else if (RB_FIXNUM_P(x)) {
+ ret = rb_fix2int(x);
+ }
+ else {
+ ret = rb_num2int(x);
+ }
+
+ return RBIMPL_CAST((int)ret);
+}
+
+/**
+ * Converts an instance of ::rb_cNumeric into C's `unsigned int`.
+ *
+ * @param[in] x Something numeric.
+ * @exception rb_eTypeError `x` is not a numeric.
+ * @exception rb_eRangeError `x` is out of range of `unsigned int`.
+ * @return The passed value converted into C's `unsigned int`.
+ */
+RBIMPL_ATTR_ARTIFICIAL()
+static inline unsigned int
+RB_NUM2UINT(VALUE x)
+{
+ unsigned long ret;
+
+ if /* constexpr */ (sizeof(int) < sizeof(long)) {
+ ret = rb_num2uint(x);
+ }
+ else {
+ ret = RB_NUM2ULONG(x);
+ }
+
+ return RBIMPL_CAST((unsigned int)ret);
+}
+
+RBIMPL_ATTR_ARTIFICIAL()
+/**
+ * Converts a Fixnum into C's `int`.
+ *
+ * @param[in] x Some Fixnum.
+ * @pre Must not pass anything other than a Fixnum.
+ * @return The passed value converted into C's `int`.
+ */
+static inline unsigned int
+RB_FIX2UINT(VALUE x)
+{
+#if 0 /* Ditto for RB_FIX2INT. */
+ RBIMPL_ASSERT_OR_ASSUME(RB_FIXNUM_P(x));
+#endif
+ unsigned long ret;
+
+ if /* constexpr */ (sizeof(int) < sizeof(long)) {
+ ret = rb_fix2uint(x);
+ }
+ else {
+ ret = RB_FIX2ULONG(x);
+ }
+
+ return RBIMPL_CAST((unsigned int)ret);
+}
+
+RBIMPL_WARNING_PUSH()
+#if RBIMPL_COMPILER_IS(GCC)
+RBIMPL_WARNING_IGNORED(-Wtype-limits) /* We can ignore them here. */
+#elif RBIMPL_HAS_WARNING("-Wtautological-constant-out-of-range-compare")
+RBIMPL_WARNING_IGNORED(-Wtautological-constant-out-of-range-compare)
+#endif
+
+/**
+ * Converts a C's `int` into an instance of ::rb_cInteger.
+ *
+ * @param[in] v Arbitrary `int` value.
+ * @return An instance of ::rb_cInteger.
+ */
+static inline VALUE
+rb_int2num_inline(int v)
+{
+ if (RB_FIXABLE(v))
+ return RB_INT2FIX(v);
+ else
+ return rb_int2big(v);
+}
+
+/**
+ * Converts a C's `unsigned int` into an instance of ::rb_cInteger.
+ *
+ * @param[in] v Arbitrary `unsigned int` value.
+ * @return An instance of ::rb_cInteger.
+ */
+static inline VALUE
+rb_uint2num_inline(unsigned int v)
+{
+ if (RB_POSFIXABLE(v))
+ return RB_LONG2FIX(v);
+ else
+ return rb_uint2big(v);
+}
+
+RBIMPL_WARNING_POP()
+
+#endif /* RBIMPL_ARITHMETIC_INT_H */
diff --git a/include/ruby/internal/arithmetic/intptr_t.h b/include/ruby/internal/arithmetic/intptr_t.h
new file mode 100644
index 0000000000..a354f4469c
--- /dev/null
+++ b/include/ruby/internal/arithmetic/intptr_t.h
@@ -0,0 +1,74 @@
+#ifndef RBIMPL_ARITHMETIC_INTPTR_T_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_ARITHMETIC_INTPTR_T_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Arithmetic conversion between C's `intptr_t` and Ruby's.
+ */
+#include "ruby/internal/config.h"
+
+#ifdef HAVE_STDINT_H
+# include <stdint.h>
+#endif
+
+#include "ruby/internal/value.h"
+#include "ruby/internal/dllexport.h"
+
+#define rb_int_new rb_int2inum /**< @alias{rb_int2inum} */
+#define rb_uint_new rb_uint2inum /**< @alias{rb_uint2inum} */
+
+RBIMPL_SYMBOL_EXPORT_BEGIN()
+
+/**
+ * Converts a C's `intptr_t` into an instance of ::rb_cInteger.
+ *
+ * @param[in] i Arbitrary `intptr_t` value.
+ * @return An instance of ::rb_cInteger.
+ * @note This function always allocates Bignums, even if the given number
+ * is small enough to fit into a Fixnum.
+ */
+VALUE rb_int2big(intptr_t i);
+
+/**
+ * Converts a C's `intptr_t` into an instance of ::rb_cInteger.
+ *
+ * @param[in] i Arbitrary `intptr_t` value.
+ * @return An instance of ::rb_cInteger.
+ */
+VALUE rb_int2inum(intptr_t i);
+
+/**
+ * Converts a C's `intptr_t` into an instance of ::rb_cInteger.
+ *
+ * @param[in] i Arbitrary `intptr_t` value.
+ * @return An instance of ::rb_cInteger.
+ * @note This function always allocates Bignums, even if the given number
+ * is small enough to fit into a Fixnum.
+ */
+VALUE rb_uint2big(uintptr_t i);
+
+/**
+ * Converts a C's `uintptr_t` into an instance of ::rb_cInteger.
+ *
+ * @param[in] i Arbitrary `uintptr_t` value.
+ * @return An instance of ::rb_cInteger.
+ */
+VALUE rb_uint2inum(uintptr_t i);
+RBIMPL_SYMBOL_EXPORT_END()
+
+#endif /* RBIMPL_ARITHMETIC_INTPTR_T_H */
diff --git a/include/ruby/internal/arithmetic/long.h b/include/ruby/internal/arithmetic/long.h
new file mode 100644
index 0000000000..792f7be179
--- /dev/null
+++ b/include/ruby/internal/arithmetic/long.h
@@ -0,0 +1,356 @@
+#ifndef RBIMPL_ARITHMETIC_LONG_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_ARITHMETIC_LONG_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Arithmetic conversion between C's `long` and Ruby's.
+ *
+ * ### Q&A ###
+ *
+ * - Q: Why are INT2FIX etc. here, not in `int.h`?
+ *
+ * - A: Because they are in fact handling `long`. It seems someone did not
+ * understand the difference of `int` and `long` when they designed those
+ * macros.
+ */
+#include "ruby/internal/config.h"
+#include "ruby/internal/arithmetic/fixnum.h" /* FIXABLE */
+#include "ruby/internal/arithmetic/intptr_t.h" /* rb_int2big etc.*/
+#include "ruby/internal/assume.h"
+#include "ruby/internal/attr/artificial.h"
+#include "ruby/internal/attr/cold.h"
+#include "ruby/internal/attr/const.h"
+#include "ruby/internal/attr/constexpr.h"
+#include "ruby/internal/attr/noreturn.h"
+#include "ruby/internal/cast.h"
+#include "ruby/internal/dllexport.h"
+#include "ruby/internal/special_consts.h" /* FIXNUM_FLAG */
+#include "ruby/internal/value.h"
+#include "ruby/assert.h"
+
+#define FIX2LONG RB_FIX2LONG /**< @old{RB_FIX2LONG} */
+#define FIX2ULONG RB_FIX2ULONG /**< @old{RB_FIX2ULONG} */
+#define INT2FIX RB_INT2FIX /**< @old{RB_INT2FIX} */
+#define LONG2FIX RB_INT2FIX /**< @old{RB_INT2FIX} */
+#define LONG2NUM RB_LONG2NUM /**< @old{RB_LONG2NUM} */
+#define NUM2LONG RB_NUM2LONG /**< @old{RB_NUM2LONG} */
+#define NUM2ULONG RB_NUM2ULONG /**< @old{RB_NUM2ULONG} */
+#define RB_FIX2LONG rb_fix2long /**< @alias{rb_fix2long} */
+#define RB_FIX2ULONG rb_fix2ulong /**< @alias{rb_fix2ulong} */
+#define RB_LONG2FIX RB_INT2FIX /**< @alias{RB_INT2FIX} */
+#define RB_LONG2NUM rb_long2num_inline /**< @alias{rb_long2num_inline} */
+#define RB_NUM2LONG rb_num2long_inline /**< @alias{rb_num2long_inline} */
+#define RB_NUM2ULONG rb_num2ulong_inline /**< @alias{rb_num2ulong_inline} */
+#define RB_ULONG2NUM rb_ulong2num_inline /**< @alias{rb_ulong2num_inline} */
+#define ULONG2NUM RB_ULONG2NUM /**< @old{RB_ULONG2NUM} */
+#define rb_fix_new RB_INT2FIX /**< @alias{RB_INT2FIX} */
+#define rb_long2int rb_long2int_inline /**< @alias{rb_long2int_inline} */
+
+/** @cond INTERNAL_MACRO */
+#define RB_INT2FIX RB_INT2FIX
+/** @endcond */
+
+RBIMPL_SYMBOL_EXPORT_BEGIN()
+
+RBIMPL_ATTR_NORETURN()
+RBIMPL_ATTR_COLD()
+/**
+ * This is an utility function to raise an ::rb_eRangeError.
+ *
+ * @param[in] num A signed value about to overflow.
+ * @exception rb_eRangeError `num` is out of range of `int`.
+ */
+void rb_out_of_int(SIGNED_VALUE num);
+
+/**
+ * Converts an instance of ::rb_cNumeric into C's `long`.
+ *
+ * @param[in] num Something numeric.
+ * @exception rb_eTypeError `num` is not a numeric.
+ * @exception rb_eRangeError `num` is out of range of `long`.
+ * @return The passed value converted into C's `long`.
+ */
+long rb_num2long(VALUE num);
+
+/**
+ * Converts an instance of ::rb_cNumeric into C's `unsigned long`.
+ *
+ * @param[in] num Something numeric.
+ * @exception rb_eTypeError `num` is not a numeric.
+ * @exception rb_eRangeError `num` is out of range of `unsigned long`.
+ * @return The passed value converted into C's `unsigned long`.
+ */
+unsigned long rb_num2ulong(VALUE num);
+RBIMPL_SYMBOL_EXPORT_END()
+
+RBIMPL_ATTR_CONST_UNLESS_DEBUG()
+RBIMPL_ATTR_CONSTEXPR_UNLESS_DEBUG(CXX14)
+RBIMPL_ATTR_ARTIFICIAL()
+/**
+ * Converts a C's `long` into an instance of ::rb_cInteger.
+ *
+ * @param[in] i Arbitrary `long` value.
+ * @return An instance of ::rb_cInteger.
+ */
+static inline VALUE
+RB_INT2FIX(long i)
+{
+ RBIMPL_ASSERT_OR_ASSUME(RB_FIXABLE(i));
+
+ /* :NOTE: VALUE can be wider than long. As j being unsigned, 2j+1 is fully
+ * defined. Also it can be compiled into a single LEA instruction. */
+ const unsigned long j = i;
+ const unsigned long k = 2 * j + RUBY_FIXNUM_FLAG;
+ const long l = k;
+ const SIGNED_VALUE m = l; /* Sign extend */
+ const VALUE n = m;
+
+ RBIMPL_ASSERT_OR_ASSUME(RB_FIXNUM_P(n));
+ return n;
+}
+
+/**
+ * Checks if `int` can hold the given integer.
+ *
+ * @param[in] n Arbitrary `long` value.
+ * @exception rb_eRangeError `n` is out of range of `int`.
+ * @return Identical value of type `int`
+ */
+static inline int
+rb_long2int_inline(long n)
+{
+ int i = RBIMPL_CAST((int)n);
+
+ if /* constexpr */ (sizeof(long) <= sizeof(int)) {
+ RBIMPL_ASSUME(i == n);
+ }
+
+ if (i != n)
+ rb_out_of_int(n);
+
+ return i;
+}
+
+RBIMPL_ATTR_CONST_UNLESS_DEBUG()
+RBIMPL_ATTR_CONSTEXPR_UNLESS_DEBUG(CXX14)
+/**
+ * @private
+ *
+ * This is an implementation detail of rb_fix2long(). People don't use it
+ * directly.
+ *
+ * @param[in] x A Fixnum.
+ * @return Identical value of type `long`
+ * @pre Must not pass anything other than a Fixnum.
+ */
+static inline long
+rbimpl_fix2long_by_idiv(VALUE x)
+{
+ RBIMPL_ASSERT_OR_ASSUME(RB_FIXNUM_P(x));
+
+ /* :NOTE: VALUE can be wider than long. (x-1)/2 never overflows because
+ * RB_FIXNUM_P(x) holds. Also it has no portability issue like y>>1
+ * below. */
+ const SIGNED_VALUE y = x - RUBY_FIXNUM_FLAG;
+ const SIGNED_VALUE z = y / 2;
+ const long w = RBIMPL_CAST((long)z);
+
+ RBIMPL_ASSERT_OR_ASSUME(RB_FIXABLE(w));
+ return w;
+}
+
+RBIMPL_ATTR_CONST_UNLESS_DEBUG()
+RBIMPL_ATTR_CONSTEXPR_UNLESS_DEBUG(CXX14)
+/**
+ * @private
+ *
+ * This is an implementation detail of rb_fix2long(). People don't use it
+ * directly.
+ *
+ * @param[in] x A Fixnum.
+ * @return Identical value of type `long`
+ * @pre Must not pass anything other than a Fixnum.
+ */
+static inline long
+rbimpl_fix2long_by_shift(VALUE x)
+{
+ RBIMPL_ASSERT_OR_ASSUME(RB_FIXNUM_P(x));
+
+ /* :NOTE: VALUE can be wider than long. If right shift is arithmetic, this
+ * is noticeably faster than above. */
+ const SIGNED_VALUE y = x;
+ const SIGNED_VALUE z = y >> 1;
+ const long w = RBIMPL_CAST((long)z);
+
+ RBIMPL_ASSERT_OR_ASSUME(RB_FIXABLE(w));
+ return w;
+}
+
+RBIMPL_ATTR_CONST()
+RBIMPL_ATTR_CONSTEXPR(CXX11)
+/**
+ * @private
+ *
+ * This is an implementation detail of rb_fix2long(). People don't use it
+ * directly.
+ *
+ * @retval true This C compiler's right shift operator is arithmetic.
+ * @retval false This C compiler's right shift operator is logical.
+ */
+static inline bool
+rbimpl_right_shift_is_arithmetic_p(void)
+{
+ return (-1 >> 1) == -1;
+}
+
+RBIMPL_ATTR_CONST_UNLESS_DEBUG()
+RBIMPL_ATTR_CONSTEXPR_UNLESS_DEBUG(CXX14)
+/**
+ * Converts a Fixnum into C's `long`.
+ *
+ * @param[in] x Some Fixnum.
+ * @pre Must not pass anything other than a Fixnum.
+ * @return The passed value converted into C's `long`.
+ */
+static inline long
+rb_fix2long(VALUE x)
+{
+ if /* constexpr */ (rbimpl_right_shift_is_arithmetic_p()) {
+ return rbimpl_fix2long_by_shift(x);
+ }
+ else {
+ return rbimpl_fix2long_by_idiv(x);
+ }
+}
+
+RBIMPL_ATTR_CONST_UNLESS_DEBUG()
+RBIMPL_ATTR_CONSTEXPR_UNLESS_DEBUG(CXX14)
+/**
+ * Converts a Fixnum into C's `unsigned long`.
+ *
+ * @param[in] x Some Fixnum.
+ * @pre Must not pass anything other than a Fixnum.
+ * @return The passed value converted into C's `unsigned long`.
+ * @note Negative fixnums will be converted into large unsigned longs.
+ */
+static inline unsigned long
+rb_fix2ulong(VALUE x)
+{
+ RBIMPL_ASSERT_OR_ASSUME(RB_FIXNUM_P(x));
+ return rb_fix2long(x);
+}
+
+/**
+ * Converts an instance of ::rb_cNumeric into C's `long`.
+ *
+ * @param[in] x Something numeric.
+ * @exception rb_eTypeError `x` is not a numeric.
+ * @exception rb_eRangeError `x` is out of range of `long`.
+ * @return The passed value converted into C's `long`.
+ */
+static inline long
+rb_num2long_inline(VALUE x)
+{
+ if (RB_FIXNUM_P(x))
+ return RB_FIX2LONG(x);
+ else
+ return rb_num2long(x);
+}
+
+/**
+ * Converts an instance of ::rb_cNumeric into C's `unsigned long`.
+ *
+ * @param[in] x Something numeric.
+ * @exception rb_eTypeError `x` is not a numeric.
+ * @exception rb_eRangeError `x` is out of range of `unsigned long`.
+ * @return The passed value converted into C's `unsigned long`.
+ *
+ * @internal
+ *
+ * This (negative fixnum would become a large unsigned long while negative
+ * bignum is an exception) has been THE behaviour of NUM2ULONG since the
+ * beginning. It is strange, but we can no longer change how it works at this
+ * moment. We have to get by with it.
+ *
+ * @see https://bugs.ruby-lang.org/issues/9089
+ */
+static inline unsigned long
+rb_num2ulong_inline(VALUE x)
+{
+ if (RB_FIXNUM_P(x))
+ return RB_FIX2ULONG(x);
+ else
+ return rb_num2ulong(x);
+}
+
+/**
+ * Converts a C's `long` into an instance of ::rb_cInteger.
+ *
+ * @param[in] v Arbitrary `long` value.
+ * @return An instance of ::rb_cInteger.
+ */
+static inline VALUE
+rb_long2num_inline(long v)
+{
+ if (RB_FIXABLE(v))
+ return RB_LONG2FIX(v);
+ else
+ return rb_int2big(v);
+}
+
+/**
+ * Converts a C's `unsigned long` into an instance of ::rb_cInteger.
+ *
+ * @param[in] v Arbitrary `unsigned long` value.
+ * @return An instance of ::rb_cInteger.
+ */
+static inline VALUE
+rb_ulong2num_inline(unsigned long v)
+{
+ if (RB_POSFIXABLE(v))
+ return RB_LONG2FIX(v);
+ else
+ return rb_uint2big(v);
+}
+
+/**
+ * @cond INTERNAL_MACRO
+ *
+ * Following overload is necessary because sometimes INT2FIX is used as a enum
+ * value (e.g. `enum { FOO = INT2FIX(0) };`). THIS IS NG in theory because a
+ * VALUE does not fit into an enum (which must be a signed int). But we cannot
+ * break existing codes.
+ */
+#if RBIMPL_HAS_ATTR_CONSTEXPR_CXX14
+# /* C++ can write constexpr as enum values. */
+
+#elif ! defined(HAVE_BUILTIN___BUILTIN_CHOOSE_EXPR_CONSTANT_P)
+# undef INT2FIX
+# define INT2FIX(i) (RBIMPL_CAST((VALUE)(i)) << 1 | RUBY_FIXNUM_FLAG)
+
+#else
+# undef INT2FIX
+# define INT2FIX(i) \
+ __builtin_choose_expr( \
+ __builtin_constant_p(i), \
+ RBIMPL_CAST((VALUE)(i)) << 1 | RUBY_FIXNUM_FLAG, \
+ RB_INT2FIX(i))
+#endif
+/** @endcond */
+
+#endif /* RBIMPL_ARITHMETIC_LONG_H */
diff --git a/include/ruby/internal/arithmetic/long_long.h b/include/ruby/internal/arithmetic/long_long.h
new file mode 100644
index 0000000000..65dec8729d
--- /dev/null
+++ b/include/ruby/internal/arithmetic/long_long.h
@@ -0,0 +1,135 @@
+#ifndef RBIMPL_ARITHMETIC_LONG_LONG_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_ARITHMETIC_LONG_LONG_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Arithmetic conversion between C's `long long` and Ruby's.
+ */
+#include "ruby/internal/value.h"
+#include "ruby/internal/dllexport.h"
+#include "ruby/internal/special_consts.h"
+#include "ruby/backward/2/long_long.h"
+
+#define RB_LL2NUM rb_ll2num_inline /**< @alias{rb_ll2num_inline} */
+#define RB_ULL2NUM rb_ull2num_inline /**< @alias{rb_ull2num_inline} */
+#define LL2NUM RB_LL2NUM /**< @old{RB_LL2NUM} */
+#define ULL2NUM RB_ULL2NUM /**< @old{RB_ULL2NUM} */
+#define RB_NUM2LL rb_num2ll_inline /**< @alias{rb_num2ll_inline} */
+#define RB_NUM2ULL rb_num2ull_inline /**< @alias{rb_num2ull_inline} */
+#define NUM2LL RB_NUM2LL /**< @old{RB_NUM2LL} */
+#define NUM2ULL RB_NUM2ULL /**< @old{RB_NUM2ULL} */
+
+RBIMPL_SYMBOL_EXPORT_BEGIN()
+/**
+ * Converts a C's `long long` into an instance of ::rb_cInteger.
+ *
+ * @param[in] num Arbitrary `long long` value.
+ * @return An instance of ::rb_cInteger.
+ */
+VALUE rb_ll2inum(LONG_LONG num);
+
+/**
+ * Converts a C's `unsigned long long` into an instance of ::rb_cInteger.
+ *
+ * @param[in] num Arbitrary `unsigned long long` value.
+ * @return An instance of ::rb_cInteger.
+ */
+VALUE rb_ull2inum(unsigned LONG_LONG num);
+
+/**
+ * Converts an instance of ::rb_cNumeric into C's `long long`.
+ *
+ * @param[in] num Something numeric.
+ * @exception rb_eTypeError `num` is not a numeric.
+ * @exception rb_eRangeError `num` is out of range of `long long`.
+ * @return The passed value converted into C's `long long`.
+ */
+LONG_LONG rb_num2ll(VALUE num);
+
+/**
+ * Converts an instance of ::rb_cNumeric into C's `unsigned long long`.
+ *
+ * @param[in] num Something numeric.
+ * @exception rb_eTypeError `num` is not a numeric.
+ * @exception rb_eRangeError `num` is out of range of `unsigned long long`.
+ * @return The passed value converted into C's `unsigned long long`.
+ */
+unsigned LONG_LONG rb_num2ull(VALUE num);
+RBIMPL_SYMBOL_EXPORT_END()
+
+/**
+ * Converts a C's `long long` into an instance of ::rb_cInteger.
+ *
+ * @param[in] n Arbitrary `long long` value.
+ * @return An instance of ::rb_cInteger
+ */
+static inline VALUE
+rb_ll2num_inline(LONG_LONG n)
+{
+ if (FIXABLE(n)) return LONG2FIX((long)n);
+ return rb_ll2inum(n);
+}
+
+/**
+ * Converts a C's `unsigned long long` into an instance of ::rb_cInteger.
+ *
+ * @param[in] n Arbitrary `unsigned long long` value.
+ * @return An instance of ::rb_cInteger
+ */
+static inline VALUE
+rb_ull2num_inline(unsigned LONG_LONG n)
+{
+ if (POSFIXABLE(n)) return LONG2FIX((long)n);
+ return rb_ull2inum(n);
+}
+
+/**
+ * Converts an instance of ::rb_cNumeric into C's `long long`.
+ *
+ * @param[in] x Something numeric.
+ * @exception rb_eTypeError `x` is not a numeric.
+ * @exception rb_eRangeError `x` is out of range of `long long`.
+ * @return The passed value converted into C's `long long`.
+ */
+static inline LONG_LONG
+rb_num2ll_inline(VALUE x)
+{
+ if (RB_FIXNUM_P(x))
+ return RB_FIX2LONG(x);
+ else
+ return rb_num2ll(x);
+}
+
+/**
+ * Converts an instance of ::rb_cNumeric into C's `unsigned long long`.
+ *
+ * @param[in] x Something numeric.
+ * @exception rb_eTypeError `x` is not a numeric.
+ * @exception rb_eRangeError `x` is out of range of `unsigned long long`.
+ * @return The passed value converted into C's `unsigned long long`.
+ */
+static inline unsigned LONG_LONG
+rb_num2ull_inline(VALUE x)
+{
+ if (RB_FIXNUM_P(x))
+ return RB_FIX2LONG(x);
+ else
+ return rb_num2ull(x);
+}
+
+#endif /* RBIMPL_ARITHMETIC_LONG_LONG_H */
diff --git a/include/ruby/internal/arithmetic/mode_t.h b/include/ruby/internal/arithmetic/mode_t.h
new file mode 100644
index 0000000000..5b7ad35fbc
--- /dev/null
+++ b/include/ruby/internal/arithmetic/mode_t.h
@@ -0,0 +1,41 @@
+#ifndef RBIMPL_ARITHMETIC_MODE_T_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_ARITHMETIC_MODE_T_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Arithmetic conversion between C's `mode_t` and Ruby's.
+ */
+#include "ruby/internal/config.h"
+#include "ruby/internal/arithmetic/int.h"
+
+/** Converts a C's `mode_t` into an instance of ::rb_cInteger. */
+#ifndef NUM2MODET
+# define NUM2MODET RB_NUM2INT
+#endif
+
+/** Converts an instance of ::rb_cNumeric into C's `mode_t`. */
+#ifndef MODET2NUM
+# define MODET2NUM RB_INT2NUM
+#endif
+
+/** A rb_sprintf() format prefix to be used for a `mode_t` parameter. */
+#ifndef PRI_MODET_PREFIX
+# define PRI_MODET_PREFIX PRI_INT_PREFIX
+#endif
+
+#endif /* RBIMPL_ARITHMETIC_MODE_T_H */
diff --git a/include/ruby/internal/arithmetic/off_t.h b/include/ruby/internal/arithmetic/off_t.h
new file mode 100644
index 0000000000..0ec9362cc9
--- /dev/null
+++ b/include/ruby/internal/arithmetic/off_t.h
@@ -0,0 +1,62 @@
+#ifndef RBIMPL_ARITHMETIC_OFF_T_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_ARITHMETIC_OFF_T_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Arithmetic conversion between C's `off_t` and Ruby's.
+ */
+#include "ruby/internal/config.h"
+#include "ruby/internal/arithmetic/int.h"
+#include "ruby/internal/arithmetic/long.h"
+#include "ruby/internal/arithmetic/long_long.h"
+#include "ruby/backward/2/long_long.h"
+
+/** Converts a C's `off_t` into an instance of ::rb_cInteger. */
+#ifdef OFFT2NUM
+# /* take that. */
+#elif SIZEOF_OFF_T == SIZEOF_LONG_LONG
+# define OFFT2NUM RB_LL2NUM
+#elif SIZEOF_OFF_T == SIZEOF_LONG
+# define OFFT2NUM RB_LONG2NUM
+#else
+# define OFFT2NUM RB_INT2NUM
+#endif
+
+/** Converts an instance of ::rb_cNumeric into C's `off_t`. */
+#ifdef NUM2OFFT
+# /* take that. */
+#elif SIZEOF_OFF_T == SIZEOF_LONG_LONG
+# define NUM2OFFT RB_NUM2LL
+#elif SIZEOF_OFF_T == SIZEOF_LONG
+# define NUM2OFFT RB_NUM2LONG
+#else
+# define NUM2OFFT RB_NUM2INT
+#endif
+
+/** A rb_sprintf() format prefix to be used for an `off_t` parameter. */
+#ifdef PRI_OFFT_PREFIX
+# /* take that. */
+#elif SIZEOF_OFF_T == SIZEOF_LONG_LONG
+# define PRI_OFFT_PREFIX PRI_LL_PREFIX
+#elif SIZEOF_OFF_T == SIZEOF_LONG
+# define PRI_OFFT_PREFIX PRI_LONG_PREFIX
+#else
+# define PRI_OFFT_PREFIX PRI_INT_PREFIX
+#endif
+
+#endif /* RBIMPL_ARITHMETIC_OFF_T_H */
diff --git a/include/ruby/internal/arithmetic/pid_t.h b/include/ruby/internal/arithmetic/pid_t.h
new file mode 100644
index 0000000000..df9704e8f5
--- /dev/null
+++ b/include/ruby/internal/arithmetic/pid_t.h
@@ -0,0 +1,41 @@
+#ifndef RBIMPL_ARITHMETIC_PID_T_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_ARITHMETIC_PID_T_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Arithmetic conversion between C's `pid_t` and Ruby's.
+ */
+#include "ruby/internal/config.h"
+#include "ruby/internal/arithmetic/long.h"
+
+/** Converts a C's `pid_t` into an instance of ::rb_cInteger. */
+#ifndef PIDT2NUM
+# define PIDT2NUM RB_LONG2NUM
+#endif
+
+/** Converts an instance of ::rb_cNumeric into C's `pid_t`. */
+#ifndef NUM2PIDT
+# define NUM2PIDT RB_NUM2LONG
+#endif
+
+/** A rb_sprintf() format prefix to be used for a `pid_t` parameter. */
+#ifndef PRI_PIDT_PREFIX
+# define PRI_PIDT_PREFIX PRI_LONG_PREFIX
+#endif
+
+#endif /* RBIMPL_ARITHMETIC_PID_T_H */
diff --git a/include/ruby/internal/arithmetic/short.h b/include/ruby/internal/arithmetic/short.h
new file mode 100644
index 0000000000..7a324d945b
--- /dev/null
+++ b/include/ruby/internal/arithmetic/short.h
@@ -0,0 +1,113 @@
+#ifndef RBIMPL_ARITHMETIC_SHORT_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_ARITHMETIC_SHORT_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Arithmetic conversion between C's `short` and Ruby's.
+ *
+ * Shyouhei wonders: why there is no SHORT2NUM, given there are both
+ * #USHORT2NUM and #CHR2FIX?
+ */
+#include "ruby/internal/value.h"
+#include "ruby/internal/dllexport.h"
+#include "ruby/internal/special_consts.h"
+
+#define RB_NUM2SHORT rb_num2short_inline /**< @alias{rb_num2short_inline} */
+#define RB_NUM2USHORT rb_num2ushort /**< @alias{rb_num2ushort} */
+#define NUM2SHORT RB_NUM2SHORT /**< @old{RB_NUM2SHORT} */
+#define NUM2USHORT RB_NUM2USHORT /**< @old{RB_NUM2USHORT} */
+#define USHORT2NUM RB_INT2FIX /**< @old{RB_INT2FIX} */
+#define RB_FIX2SHORT rb_fix2short /**< @alias{rb_fix2ushort} */
+#define FIX2SHORT RB_FIX2SHORT /**< @old{RB_FIX2SHORT} */
+
+RBIMPL_SYMBOL_EXPORT_BEGIN()
+
+/**
+ * Converts an instance of ::rb_cNumeric into C's `short`.
+ *
+ * @param[in] num Something numeric.
+ * @exception rb_eTypeError `num` is not a numeric.
+ * @exception rb_eRangeError `num` is out of range of `short`.
+ * @return The passed value converted into C's `short`.
+ */
+short rb_num2short(VALUE num);
+
+/**
+ * Converts an instance of ::rb_cNumeric into C's `unsigned short`.
+ *
+ * @param[in] num Something numeric.
+ * @exception rb_eTypeError `num` is not a numeric.
+ * @exception rb_eRangeError `num` is out of range of `unsigned short`.
+ * @return The passed value converted into C's `unsigned short`.
+ */
+unsigned short rb_num2ushort(VALUE num);
+
+/**
+ * Identical to rb_num2short().
+ *
+ * @param[in] num Something numeric.
+ * @exception rb_eTypeError `num` is not a numeric.
+ * @exception rb_eRangeError `num` is out of range of `short`.
+ * @return The passed value converted into C's `short`.
+ *
+ * @internal
+ *
+ * This function seems to be a complete waste of disk space. @shyouhei has no
+ * idea why this is a different thing from rb_num2short().
+ */
+short rb_fix2short(VALUE num);
+
+/**
+ * Identical to rb_num2ushort().
+ *
+ * @param[in] num Something numeric.
+ * @exception rb_eTypeError `num` is not a numeric.
+ * @exception rb_eRangeError `num` is out of range of `unsigned short`.
+ * @return The passed value converted into C's `unsigned short`.
+ *
+ * @internal
+ *
+ * This function seems to be a complete waste of disk space. @shyouhei has no
+ * idea why this is a different thing from rb_num2ushort().
+ */
+unsigned short rb_fix2ushort(VALUE num);
+RBIMPL_SYMBOL_EXPORT_END()
+
+/**
+ * Identical to rb_num2short().
+ *
+ * @param[in] x Something numeric.
+ * @exception rb_eTypeError `x` is not a numeric.
+ * @exception rb_eRangeError `x` is out of range of `short`.
+ * @return The passed value converted into C's `short`.
+ *
+ * @internal
+ *
+ * This function seems to be a complete waste of time. @shyouhei has no idea
+ * why this is a different thing from rb_num2short().
+ */
+static inline short
+rb_num2short_inline(VALUE x)
+{
+ if (RB_FIXNUM_P(x))
+ return rb_fix2short(x);
+ else
+ return rb_num2short(x);
+}
+
+#endif /* RBIMPL_ARITHMETIC_SHORT_H */
diff --git a/include/ruby/internal/arithmetic/size_t.h b/include/ruby/internal/arithmetic/size_t.h
new file mode 100644
index 0000000000..1082160b8e
--- /dev/null
+++ b/include/ruby/internal/arithmetic/size_t.h
@@ -0,0 +1,66 @@
+#ifndef RBIMPL_ARITHMETIC_SIZE_T_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_ARITHMETIC_SIZE_T_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Arithmetic conversion between C's `size_t` and Ruby's.
+ */
+#include "ruby/internal/config.h"
+#include "ruby/internal/arithmetic/int.h"
+#include "ruby/internal/arithmetic/long.h"
+#include "ruby/internal/arithmetic/long_long.h"
+#include "ruby/backward/2/long_long.h"
+
+#if defined(__DOXYGEN__)
+# /** Converts a C's `size_t` into an instance of ::rb_cInteger. */
+# define RB_SIZE2NUM RB_ULONG2NUM
+# /** Converts a C's `ssize_t` into an instance of ::rb_cInteger. */
+# define RB_SSIZE2NUM RB_LONG2NUM
+#elif SIZEOF_SIZE_T == SIZEOF_LONG_LONG
+# define RB_SIZE2NUM RB_ULL2NUM
+# define RB_SSIZE2NUM RB_LL2NUM
+#elif SIZEOF_SIZE_T == SIZEOF_LONG
+# define RB_SIZE2NUM RB_ULONG2NUM
+# define RB_SSIZE2NUM RB_LONG2NUM
+#else
+# define RB_SIZE2NUM RB_UINT2NUM
+# define RB_SSIZE2NUM RB_INT2NUM
+#endif
+
+#if defined(__DOXYGEN__)
+# /** Converts an instance of ::rb_cInteger into C's `size_t`. */
+# define RB_NUM2SIZE RB_NUM2ULONG
+# /** Converts an instance of ::rb_cInteger into C's `ssize_t`. */
+# define RB_NUM2SSIZE RB_NUM2LONG
+#elif SIZEOF_SIZE_T == SIZEOF_LONG_LONG
+# define RB_NUM2SIZE RB_NUM2ULL
+# define RB_NUM2SSIZE RB_NUM2LL
+#elif SIZEOF_SIZE_T == SIZEOF_LONG
+# define RB_NUM2SIZE RB_NUM2ULONG
+# define RB_NUM2SSIZE RB_NUM2LONG
+#else
+# define RB_NUM2SIZE RB_NUM2UINT
+# define RB_NUM2SSIZE RB_NUM2INT
+#endif
+
+#define NUM2SIZET RB_NUM2SIZE /**< @old{RB_NUM2SIZE} */
+#define SIZET2NUM RB_SIZE2NUM /**< @old{RB_SIZE2NUM} */
+#define NUM2SSIZET RB_NUM2SSIZE /**< @old{RB_NUM2SSIZE} */
+#define SSIZET2NUM RB_SSIZE2NUM /**< @old{RB_SSIZE2NUM} */
+
+#endif /* RBIMPL_ARITHMETIC_SIZE_T_H */
diff --git a/include/ruby/internal/arithmetic/st_data_t.h b/include/ruby/internal/arithmetic/st_data_t.h
new file mode 100644
index 0000000000..3bff4ffc0b
--- /dev/null
+++ b/include/ruby/internal/arithmetic/st_data_t.h
@@ -0,0 +1,75 @@
+#ifndef RBIMPL_ARITHMERIC_ST_DATA_T_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_ARITHMERIC_ST_DATA_T_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Arithmetic conversion between C's `st_data_t` and Ruby's.
+ */
+#include "ruby/internal/arithmetic/fixnum.h"
+#include "ruby/internal/arithmetic/long.h"
+#include "ruby/internal/attr/artificial.h"
+#include "ruby/internal/attr/const.h"
+#include "ruby/internal/attr/constexpr.h"
+#include "ruby/internal/cast.h"
+#include "ruby/internal/value.h"
+#include "ruby/assert.h"
+#include "ruby/st.h"
+
+#define ST2FIX RB_ST2FIX /**< @old{RB_ST2FIX} */
+/** @cond INTERNAL_MACRO */
+#define RB_ST2FIX RB_ST2FIX
+/** @endcond */
+
+RBIMPL_ATTR_CONST_UNLESS_DEBUG()
+RBIMPL_ATTR_CONSTEXPR_UNLESS_DEBUG(CXX14)
+RBIMPL_ATTR_ARTIFICIAL()
+/**
+ * Converts a C's `st_data_t` into an instance of ::rb_cInteger.
+ *
+ * @param[in] i The data in question.
+ * @return A converted result
+ * @warning THIS CONVERSION LOSES DATA! Be warned.
+ * @see https://bugs.ruby-lang.org/issues/13877
+ * @see https://bugs.ruby-lang.org/issues/14218
+ *
+ * @internal
+ *
+ * This is needed because of hash functions. Hash functions return
+ * `st_data_t`, which could theoretically be bigger than Fixnums. However
+ * allocating Bignums for them every time we calculate hash values is just too
+ * heavy. To avoid penalty we need to ignore some upper bit(s) and stick to
+ * Fixnums. This function is used for that purpose.
+ */
+static inline VALUE
+RB_ST2FIX(st_data_t i)
+{
+ SIGNED_VALUE x = i;
+
+ if (x >= 0) {
+ x &= RUBY_FIXNUM_MAX;
+ }
+ else {
+ x |= RUBY_FIXNUM_MIN;
+ }
+
+ RBIMPL_ASSERT_OR_ASSUME(RB_FIXABLE(x));
+ unsigned long y = RBIMPL_CAST((unsigned long)x);
+ return RB_LONG2FIX(y);
+}
+
+#endif /* RBIMPL_ARITHMETIC_ST_DATA_T_H */
diff --git a/include/ruby/internal/arithmetic/uid_t.h b/include/ruby/internal/arithmetic/uid_t.h
new file mode 100644
index 0000000000..12cde2a9c8
--- /dev/null
+++ b/include/ruby/internal/arithmetic/uid_t.h
@@ -0,0 +1,41 @@
+#ifndef RBIMPL_ARITHMETIC_UID_T_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_ARITHMETIC_UID_T_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Arithmetic conversion between C's `uid_t` and Ruby's.
+ */
+#include "ruby/internal/config.h"
+#include "ruby/internal/arithmetic/long.h"
+
+/** Converts a C's `uid_t` into an instance of ::rb_cInteger. */
+#ifndef UIDT2NUM
+# define UIDT2NUM RB_LONG2NUM
+#endif
+
+/** Converts an instance of ::rb_cNumeric into C's `uid_t`. */
+#ifndef NUM2UIDT
+# define NUM2UIDT RB_NUM2LONG
+#endif
+
+/** A rb_sprintf() format prefix to be used for a `uid_t` parameter. */
+#ifndef PRI_UIDT_PREFIX
+# define PRI_UIDT_PREFIX PRI_LONG_PREFIX
+#endif
+
+#endif /* RBIMPL_ARITHMETIC_UID_T_H */
diff --git a/include/ruby/internal/assume.h b/include/ruby/internal/assume.h
new file mode 100644
index 0000000000..65d34d4ac8
--- /dev/null
+++ b/include/ruby/internal/assume.h
@@ -0,0 +1,90 @@
+#ifndef RBIMPL_ASSUME_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_ASSUME_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Defines #RBIMPL_ASSUME / #RBIMPL_UNREACHABLE.
+ *
+ * These macros must be defined at once because:
+ *
+ * - #RBIMPL_ASSUME could fallback to #RBIMPL_UNREACHABLE.
+ * - #RBIMPL_UNREACHABLE could fallback to #RBIMPL_ASSUME.
+ */
+#include "ruby/internal/config.h"
+#include "ruby/internal/cast.h"
+#include "ruby/internal/compiler_since.h"
+#include "ruby/internal/has/builtin.h"
+#include "ruby/internal/warning_push.h"
+
+/** @cond INTERNAL_MACRO */
+#if RBIMPL_COMPILER_SINCE(MSVC, 13, 10, 0)
+# define RBIMPL_HAVE___ASSUME
+
+#elif RBIMPL_COMPILER_SINCE(Intel, 13, 0, 0)
+# define RBIMPL_HAVE___ASSUME
+#endif
+/** @endcond */
+
+/** Wraps (or simulates) `__builtin_unreachable`. */
+#if RBIMPL_HAS_BUILTIN(__builtin_unreachable)
+# define RBIMPL_UNREACHABLE_RETURN(_) __builtin_unreachable()
+
+#elif defined(RBIMPL_HAVE___ASSUME)
+# define RBIMPL_UNREACHABLE_RETURN(_) return (__assume(0), (_))
+
+#else
+# define RBIMPL_UNREACHABLE_RETURN(_) return (_)
+#endif
+
+/** Wraps (or simulates) `__builtin_unreachable`. */
+#if RBIMPL_HAS_BUILTIN(__builtin_unreachable)
+# define RBIMPL_UNREACHABLE __builtin_unreachable
+
+#elif defined(RBIMPL_HAVE___ASSUME)
+# define RBIMPL_UNREACHABLE() __assume(0)
+#endif
+
+/** Wraps (or simulates) `__assume`. */
+#if RBIMPL_COMPILER_SINCE(Intel, 13, 0, 0)
+# /* icc warnings are false positives. Ignore them. */
+# /* "warning #2261: __assume expression with side effects discarded" */
+# define RBIMPL_ASSUME(expr) \
+ RBIMPL_WARNING_PUSH() \
+ RBIMPL_WARNING_IGNORED(2261) \
+ __assume(expr) \
+ RBIMPL_WARNING_POP()
+
+#elif defined(RBIMPL_HAVE___ASSUME)
+# define RBIMPL_ASSUME __assume
+
+#elif RBIMPL_HAS_BUILTIN(__builtin_assume)
+# define RBIMPL_ASSUME __builtin_assume
+
+#elif ! defined(RBIMPL_UNREACHABLE)
+# define RBIMPL_ASSUME(_) RBIMPL_CAST((void)(_))
+
+#else
+# define RBIMPL_ASSUME(_) \
+ (RB_LIKELY(!!(_)) ? RBIMPL_CAST((void)0) : RBIMPL_UNREACHABLE())
+#endif
+
+#if ! defined(RBIMPL_UNREACHABLE)
+# define RBIMPL_UNREACHABLE() RBIMPL_ASSUME(0)
+#endif
+
+#endif /* RBIMPL_ASSUME_H */
diff --git a/include/ruby/internal/attr/alloc_size.h b/include/ruby/internal/attr/alloc_size.h
new file mode 100644
index 0000000000..954a2010f6
--- /dev/null
+++ b/include/ruby/internal/attr/alloc_size.h
@@ -0,0 +1,32 @@
+#ifndef RBIMPL_ATTR_ALLOC_SIZE_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_ATTR_ALLOC_SIZE_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Defines #RBIMPL_ATTR_ALLOC_SIZE.
+ */
+#include "ruby/internal/has/attribute.h"
+
+/** Wraps (or simulates) `__attribute__((alloc_size))` */
+#if RBIMPL_HAS_ATTRIBUTE(alloc_size)
+# define RBIMPL_ATTR_ALLOC_SIZE(tuple) __attribute__((__alloc_size__ tuple))
+#else
+# define RBIMPL_ATTR_ALLOC_SIZE(tuple) /* void */
+#endif
+
+#endif /* RBIMPL_ATTR_ALLOC_SIZE_H */
diff --git a/include/ruby/internal/attr/artificial.h b/include/ruby/internal/attr/artificial.h
new file mode 100644
index 0000000000..ef5f36abff
--- /dev/null
+++ b/include/ruby/internal/attr/artificial.h
@@ -0,0 +1,46 @@
+#ifndef RBIMPL_ATTR_ARTIFICIAL_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_ATTR_ARTIFICIAL_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Defines #RBIMPL_ATTR_ARTIFICIAL.
+ *
+ * ### Q&A ###
+ *
+ * - Q: What is this attribute? I don't get what GCC manual is talking about.
+ *
+ * - A: In short it is an attribute to manipulate GDB backtraces. The
+ * attribute makes the best sense when it comes with
+ * __attribute__((always_inline)). When a function annotated with this
+ * attribute gets inlined, and when you somehow look at a backtrace which
+ * includes such inlined call site, then the backtrace shows the caller
+ * and not the callee. This is handy for instance when an identical
+ * function is inlined more than once in a single big function. On such
+ * case it gets vital to know where the inlining happened in the callee.
+ * See also https://stackoverflow.com/a/21936099
+ */
+#include "ruby/internal/has/attribute.h"
+
+/** Wraps (or simulates) `__attribute__((artificial))` */
+#if RBIMPL_HAS_ATTRIBUTE(artificial)
+# define RBIMPL_ATTR_ARTIFICIAL() __attribute__((__artificial__))
+#else
+# define RBIMPL_ATTR_ARTIFICIAL() /* void */
+#endif
+
+#endif /* RBIMPL_ATTR_ARTIFICIAL_H */
diff --git a/include/ruby/internal/attr/cold.h b/include/ruby/internal/attr/cold.h
new file mode 100644
index 0000000000..c68b3ae784
--- /dev/null
+++ b/include/ruby/internal/attr/cold.h
@@ -0,0 +1,37 @@
+#ifndef RBIMPL_ATTR_COLD_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_ATTR_COLD_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Defines #RBIMPL_ATTR_COLD.
+ */
+#include "ruby/internal/compiler_is.h"
+#include "ruby/internal/has/attribute.h"
+
+/** Wraps (or simulates) `__attribute__((cold))` */
+#if RBIMPL_COMPILER_IS(SunPro)
+# /* Recent SunPro has __has_attribute, and is broken. */
+# /* It reports it has attribute cold, reality isn't (warnings issued). */
+# define RBIMPL_ATTR_COLD() /* void */
+#elif RBIMPL_HAS_ATTRIBUTE(cold)
+# define RBIMPL_ATTR_COLD() __attribute__((__cold__))
+#else
+# define RBIMPL_ATTR_COLD() /* void */
+#endif
+
+#endif /* RBIMPL_ATTR_COLD_H */
diff --git a/include/ruby/internal/attr/const.h b/include/ruby/internal/attr/const.h
new file mode 100644
index 0000000000..e66aa17c70
--- /dev/null
+++ b/include/ruby/internal/attr/const.h
@@ -0,0 +1,46 @@
+#ifndef RBIMPL_ATTR_CONST_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_ATTR_CONST_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Defines #RBIMPL_ATTR_CONST.
+ */
+#include "ruby/internal/compiler_since.h"
+#include "ruby/internal/has/attribute.h"
+#include "ruby/internal/has/declspec_attribute.h"
+
+/** Wraps (or simulates) `__attribute__((const))` */
+#if RBIMPL_HAS_ATTRIBUTE(const)
+# define RBIMPL_ATTR_CONST() __attribute__((__const__))
+#elif RBIMPL_HAS_DECLSPEC_ATTRIBUTE(noalias)
+# /* If a function can be a const, that is also a noalias. */
+# define RBIMPL_ATTR_CONST() __declspec(noalias)
+#elif RBIMPL_COMPILER_SINCE(SunPro, 5, 10, 0)
+# define RBIMPL_ATTR_CONST() _Pragma("no_side_effect")
+#else
+# define RBIMPL_ATTR_CONST() /* void */
+#endif
+
+/** Enables #RBIMPL_ATTR_CONST if and only if. ! #RUBY_DEBUG. */
+#if !defined(RUBY_DEBUG) || !RUBY_DEBUG
+# define RBIMPL_ATTR_CONST_UNLESS_DEBUG() RBIMPL_ATTR_CONST()
+#else
+# define RBIMPL_ATTR_CONST_UNLESS_DEBUG() /* void */
+#endif
+
+#endif /* RBIMPL_ATTR_CONST_H */
diff --git a/include/ruby/internal/attr/constexpr.h b/include/ruby/internal/attr/constexpr.h
new file mode 100644
index 0000000000..abc4f238b5
--- /dev/null
+++ b/include/ruby/internal/attr/constexpr.h
@@ -0,0 +1,84 @@
+#ifndef RBIMPL_ATTR_CONSTEXPR_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_ATTR_CONSTEXPR_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief #RBIMPL_ATTR_CONSTEXPR.
+ */
+#include "ruby/internal/has/feature.h"
+#include "ruby/internal/compiler_is.h"
+
+/** @cond INTERNAL_MACRO */
+#if ! defined(__cplusplus)
+# /* Makes no sense. */
+# define RBIMPL_HAS_ATTR_CONSTEXPR_CXX11 0
+# define RBIMPL_HAS_ATTR_CONSTEXPR_CXX14 0
+
+#elif defined(__cpp_constexpr)
+# /* https://isocpp.org/std/standing-documents/sd-6-sg10-feature-test-recommendations */
+# define RBIMPL_HAS_ATTR_CONSTEXPR_CXX11 (__cpp_constexpr >= 200704L)
+# define RBIMPL_HAS_ATTR_CONSTEXPR_CXX14 (__cpp_constexpr >= 201304L)
+
+#elif RBIMPL_COMPILER_SINCE(MSVC, 19, 0, 0)
+# define RBIMPL_HAS_ATTR_CONSTEXPR_CXX11 RBIMPL_COMPILER_SINCE(MSVC, 19, 00, 00)
+# define RBIMPL_HAS_ATTR_CONSTEXPR_CXX14 RBIMPL_COMPILER_SINCE(MSVC, 19, 11, 00)
+
+#elif RBIMPL_COMPILER_SINCE(SunPro, 5, 13, 0)
+# define RBIMPL_HAS_ATTR_CONSTEXPR_CXX11 (__cplusplus >= 201103L)
+# define RBIMPL_HAS_ATTR_CONSTEXPR_CXX14 (__cplusplus >= 201402L)
+
+#elif RBIMPL_COMPILER_SINCE(GCC, 4, 9, 0)
+# define RBIMPL_HAS_ATTR_CONSTEXPR_CXX11 (__cplusplus >= 201103L)
+# define RBIMPL_HAS_ATTR_CONSTEXPR_CXX14 (__cplusplus >= 201402L)
+
+#elif RBIMPL_HAS_FEATURE(cxx_relaxed_constexpr)
+# define RBIMPL_HAS_ATTR_CONSTEXPR_CXX11 1
+# define RBIMPL_HAS_ATTR_CONSTEXPR_CXX14 1
+
+#elif RBIMPL_HAS_FEATURE(cxx_constexpr)
+# define RBIMPL_HAS_ATTR_CONSTEXPR_CXX11 1
+# define RBIMPL_HAS_ATTR_CONSTEXPR_CXX14 0
+
+#else
+# /* :FIXME: icpc must have constexpr but don't know how to detect. */
+# define RBIMPL_HAS_ATTR_CONSTEXPR_CXX11 0
+# define RBIMPL_HAS_ATTR_CONSTEXPR_CXX14 0
+#endif
+/** @endcond */
+
+/** Wraps (or simulates) C++11 `constexpr`. */
+#if RBIMPL_HAS_ATTR_CONSTEXPR_CXX14
+# define RBIMPL_ATTR_CONSTEXPR(_) constexpr
+
+#elif RBIMPL_HAS_ATTR_CONSTEXPR_CXX11
+# define RBIMPL_ATTR_CONSTEXPR(_) RBIMPL_ATTR_CONSTEXPR_ ## _
+# define RBIMPL_ATTR_CONSTEXPR_CXX11 constexpr
+# define RBIMPL_ATTR_CONSTEXPR_CXX14 /* void */
+
+#else
+# define RBIMPL_ATTR_CONSTEXPR(_) /* void */
+#endif
+
+/** Enables #RBIMPL_ATTR_CONSTEXPR if and only if. ! #RUBY_DEBUG. */
+#if !RUBY_DEBUG
+# define RBIMPL_ATTR_CONSTEXPR_UNLESS_DEBUG(_) RBIMPL_ATTR_CONSTEXPR(_)
+#else
+# define RBIMPL_ATTR_CONSTEXPR_UNLESS_DEBUG(_) /* void */
+#endif
+
+#endif /* RBIMPL_ATTR_CONSTEXPR_H */
diff --git a/include/ruby/internal/attr/deprecated.h b/include/ruby/internal/attr/deprecated.h
new file mode 100644
index 0000000000..e1bbdbd15a
--- /dev/null
+++ b/include/ruby/internal/attr/deprecated.h
@@ -0,0 +1,75 @@
+#ifndef RBIMPL_ATTR_DEPRECATED_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_ATTR_DEPRECATED_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Defines #RBIMPL_ATTR_DEPRECATED.
+ */
+#include "ruby/internal/compiler_since.h"
+#include "ruby/internal/has/attribute.h"
+#include "ruby/internal/has/c_attribute.h"
+#include "ruby/internal/has/cpp_attribute.h"
+#include "ruby/internal/has/declspec_attribute.h"
+#include "ruby/internal/has/extension.h"
+
+/** Wraps (or simulates) `[[deprecated]]` */
+#if defined(__COVERITY__)
+/* Coverity Scan emulates gcc but seems not to support this attribute correctly */
+# define RBIMPL_ATTR_DEPRECATED(msg)
+
+#elif RBIMPL_HAS_EXTENSION(attribute_deprecated_with_message)
+# define RBIMPL_ATTR_DEPRECATED(msg) __attribute__((__deprecated__ msg))
+
+#elif defined(__cplusplus) && RBIMPL_COMPILER_SINCE(GCC, 10, 1, 0) && RBIMPL_COMPILER_BEFORE(GCC, 10, 3, 0)
+# /* https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95302 */
+# define RBIMPL_ATTR_DEPRECATED(msg) /* disable until they fix this bug */
+
+#elif RBIMPL_COMPILER_SINCE(GCC, 4, 5, 0)
+# define RBIMPL_ATTR_DEPRECATED(msg) __attribute__((__deprecated__ msg))
+
+#elif RBIMPL_COMPILER_SINCE(Intel, 13, 0, 0)
+# define RBIMPL_ATTR_DEPRECATED(msg) __attribute__((__deprecated__ msg))
+
+#elif RBIMPL_HAS_ATTRIBUTE(deprecated) /* but not with message. */
+# define RBIMPL_ATTR_DEPRECATED(msg) __attribute__((__deprecated__))
+
+#elif RBIMPL_COMPILER_SINCE(MSVC, 14, 0, 0)
+# define RBIMPL_ATTR_DEPRECATED(msg) __declspec(deprecated msg)
+
+#elif RBIMPL_HAS_DECLSPEC_ATTRIBUTE(deprecated)
+# define RBIMPL_ATTR_DEPRECATED(msg) __declspec(deprecated)
+
+#elif RBIMPL_HAS_CPP_ATTRIBUTE(deprecated)
+# define RBIMPL_ATTR_DEPRECATED(msg) [[deprecated msg]]
+
+#elif RBIMPL_HAS_C_ATTRIBUTE(deprecated)
+# define RBIMPL_ATTR_DEPRECATED(msg) [[deprecated msg]]
+
+#else
+# define RBIMPL_ATTR_DEPRECATED(msg) /* void */
+#endif
+
+/** This is when a function is used internally (for backwards compatibility
+ * etc.), but extension libraries must consider it deprecated. */
+#if defined(RUBY_EXPORT)
+# define RBIMPL_ATTR_DEPRECATED_EXT(msg) /* void */
+#else
+# define RBIMPL_ATTR_DEPRECATED_EXT(msg) RBIMPL_ATTR_DEPRECATED(msg)
+#endif
+
+#endif /* RBIMPL_ATTR_DEPRECATED_H */
diff --git a/include/ruby/internal/attr/diagnose_if.h b/include/ruby/internal/attr/diagnose_if.h
new file mode 100644
index 0000000000..cadc6ce258
--- /dev/null
+++ b/include/ruby/internal/attr/diagnose_if.h
@@ -0,0 +1,42 @@
+#ifndef RBIMPL_ATTR_DIAGNOSE_IF_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_ATTR_DIAGNOSE_IF_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Defines #RBIMPL_ATTR_DIAGNOSE_IF.
+ */
+#include "ruby/internal/has/attribute.h"
+#include "ruby/internal/warning_push.h"
+
+/** Wraps (or simulates) `__attribute__((diagnose_if))` */
+#if RBIMPL_COMPILER_BEFORE(Clang, 5, 0, 0)
+# /* https://bugs.llvm.org/show_bug.cgi?id=34319 */
+# define RBIMPL_ATTR_DIAGNOSE_IF(_, __, ___) /* void */
+
+#elif RBIMPL_HAS_ATTRIBUTE(diagnose_if)
+# define RBIMPL_ATTR_DIAGNOSE_IF(_, __, ___) \
+ RBIMPL_WARNING_PUSH() \
+ RBIMPL_WARNING_IGNORED(-Wgcc-compat) \
+ __attribute__((__diagnose_if__(_, __, ___))) \
+ RBIMPL_WARNING_POP()
+
+#else
+# define RBIMPL_ATTR_DIAGNOSE_IF(_, __, ___) /* void */
+#endif
+
+#endif /* RBIMPL_ATTR_DIAGNOSE_IF_H */
diff --git a/include/ruby/internal/attr/enum_extensibility.h b/include/ruby/internal/attr/enum_extensibility.h
new file mode 100644
index 0000000000..eb0d5b6e9b
--- /dev/null
+++ b/include/ruby/internal/attr/enum_extensibility.h
@@ -0,0 +1,32 @@
+#ifndef RBIMPL_ATTR_ENUM_EXTENSIBILITY_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_ATTR_ENUM_EXTENSIBILITY_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief #RBIMPL_ATTR_ENUM_EXTENSIBILITY.
+ */
+#include "ruby/internal/has/attribute.h"
+
+/** Wraps (or simulates) `__attribute__((enum_extensibility))` */
+#if RBIMPL_HAS_ATTRIBUTE(enum_extensibility)
+# define RBIMPL_ATTR_ENUM_EXTENSIBILITY(_) __attribute__((__enum_extensibility__(_)))
+#else
+# define RBIMPL_ATTR_ENUM_EXTENSIBILITY(_) /* void */
+#endif
+
+#endif /* RBIMPL_ATTR_ENUM_EXTENSIBILITY_H */
diff --git a/include/ruby/internal/attr/error.h b/include/ruby/internal/attr/error.h
new file mode 100644
index 0000000000..2ed388a770
--- /dev/null
+++ b/include/ruby/internal/attr/error.h
@@ -0,0 +1,32 @@
+#ifndef RBIMPL_ATTR_ERROR_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_ATTR_ERROR_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Defines #RBIMPL_ATTR_ERROR.
+ */
+#include "ruby/internal/has/attribute.h"
+
+/** Wraps (or simulates) `__attribute__((error))` */
+#if RBIMPL_HAS_ATTRIBUTE(error)
+# define RBIMPL_ATTR_ERROR(msg) __attribute__((__error__ msg))
+#else
+# define RBIMPL_ATTR_ERROR(msg) /* void */
+#endif
+
+#endif /* RBIMPL_ATTR_ERROR_H */
diff --git a/include/ruby/internal/attr/flag_enum.h b/include/ruby/internal/attr/flag_enum.h
new file mode 100644
index 0000000000..3053d75074
--- /dev/null
+++ b/include/ruby/internal/attr/flag_enum.h
@@ -0,0 +1,33 @@
+#ifndef RBIMPL_ATTR_FLAG_ENUM_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_ATTR_FLAG_ENUM_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Defines #RBIMPL_ATTR_FLAG_ENUM.
+ * @see https://clang.llvm.org/docs/AttributeReference.html#flag_enum
+ */
+#include "ruby/internal/has/attribute.h"
+
+/** Wraps (or simulates) `__attribute__((flag_enum)` */
+#if RBIMPL_HAS_ATTRIBUTE(flag_enum)
+# define RBIMPL_ATTR_FLAG_ENUM() __attribute__((__flag_enum__))
+#else
+# define RBIMPL_ATTR_FLAG_ENUM() /* void */
+#endif
+
+#endif /* RBIMPLATTR_FLAG_ENUM_H */
diff --git a/include/ruby/internal/attr/forceinline.h b/include/ruby/internal/attr/forceinline.h
new file mode 100644
index 0000000000..b7daafede7
--- /dev/null
+++ b/include/ruby/internal/attr/forceinline.h
@@ -0,0 +1,40 @@
+#ifndef RBIMPL_ATTR_FORCEINLINE_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_ATTR_FORCEINLINE_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Defines #RBIMPL_ATTR_FORCEINLINE.
+ */
+#include "ruby/internal/compiler_since.h"
+#include "ruby/internal/has/attribute.h"
+
+/**
+ * Wraps (or simulates) `__forceinline`. MSVC complains on declarations like
+ * `static inline __forceinline void foo()`. It seems MSVC's `inline` and
+ * `__forceinline` are mutually exclusive. We have to mimic that behaviour for
+ * non-MSVC compilers.
+ */
+#if RBIMPL_COMPILER_SINCE(MSVC, 12, 0, 0)
+# define RBIMPL_ATTR_FORCEINLINE() __forceinline
+#elif RBIMPL_HAS_ATTRIBUTE(always_inline)
+# define RBIMPL_ATTR_FORCEINLINE() __attribute__((__always_inline__)) inline
+#else
+# define RBIMPL_ATTR_FORCEINLINE() inline
+#endif
+
+#endif /* RBIMPL_ATTR_FORCEINLINE_H */
diff --git a/include/ruby/internal/attr/format.h b/include/ruby/internal/attr/format.h
new file mode 100644
index 0000000000..b3488ee00a
--- /dev/null
+++ b/include/ruby/internal/attr/format.h
@@ -0,0 +1,38 @@
+#ifndef RBIMPL_ATTR_FORMAT_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_ATTR_FORMAT_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Defines #RBIMPL_ATTR_FORMAT.
+ */
+#include "ruby/internal/has/attribute.h"
+
+/** Wraps (or simulates) `__attribute__((format))` */
+#if RBIMPL_HAS_ATTRIBUTE(format)
+# define RBIMPL_ATTR_FORMAT(x, y, z) __attribute__((__format__(x, y, z)))
+#else
+# define RBIMPL_ATTR_FORMAT(x, y, z) /* void */
+#endif
+
+#if defined(__MINGW_PRINTF_FORMAT)
+# define RBIMPL_PRINTF_FORMAT __MINGW_PRINTF_FORMAT
+#else
+# define RBIMPL_PRINTF_FORMAT __printf__
+#endif
+
+#endif /* RBIMPL_ATTR_FORMAT_H */
diff --git a/include/ruby/internal/attr/maybe_unused.h b/include/ruby/internal/attr/maybe_unused.h
new file mode 100644
index 0000000000..3ee8be4540
--- /dev/null
+++ b/include/ruby/internal/attr/maybe_unused.h
@@ -0,0 +1,38 @@
+#ifndef RBIMPL_ATTR_MAYBE_UNUSED_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_ATTR_MAYBE_UNUSED_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Defines #RBIMPL_ATTR_MAYBE_UNUSED.
+ */
+#include "ruby/internal/has/attribute.h"
+#include "ruby/internal/has/c_attribute.h"
+#include "ruby/internal/has/cpp_attribute.h"
+
+/** Wraps (or simulates) `[[maybe_unused]]` */
+#if RBIMPL_HAS_CPP_ATTRIBUTE(maybe_unused)
+# define RBIMPL_ATTR_MAYBE_UNUSED() [[maybe_unused]]
+#elif RBIMPL_HAS_C_ATTRIBUTE(maybe_unused)
+# define RBIMPL_ATTR_MAYBE_UNUSED() [[maybe_unused]]
+#elif RBIMPL_HAS_ATTRIBUTE(unused)
+# define RBIMPL_ATTR_MAYBE_UNUSED() __attribute__((__unused__))
+#else
+# define RBIMPL_ATTR_MAYBE_UNUSED() /* void */
+#endif
+
+#endif /* RBIMPL_ATTR_MAYBE_UNUSED */
diff --git a/include/ruby/internal/attr/noalias.h b/include/ruby/internal/attr/noalias.h
new file mode 100644
index 0000000000..0790ef60e5
--- /dev/null
+++ b/include/ruby/internal/attr/noalias.h
@@ -0,0 +1,69 @@
+#ifndef RBIMPL_ATTR_NOALIAS_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_ATTR_NOALIAS_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Defines #RBIMPL_ATTR_NOALIAS.
+ *
+ * ### Q&A ###
+ *
+ * - Q: There are seemingly similar attributes named #RBIMPL_ATTR_CONST,
+ * #RBIMPL_ATTR_PURE, and #RBIMPL_ATTR_NOALIAS. What are the difference?
+ *
+ * - A: Allowed operations are different.
+ *
+ * - #RBIMPL_ATTR_CONST ... Functions attributed by this are not allowed to
+ * read/write _any_ pointers at all (there are exceptional situations
+ * when reading a pointer is possible but forget that; they are too
+ * exceptional to be useful). Just remember that everything pointer-
+ * related are NG.
+ *
+ * - #RBIMPL_ATTR_PURE ... Functions attributed by this can read any
+ * nonvolatile pointers, but no writes are allowed at all. The ability
+ * to read _any_ nonvolatile pointers makes it possible to mark ::VALUE-
+ * taking functions as being pure, as long as they are read-only.
+ *
+ * - #RBIMPL_ATTR_NOALIAS ... Can both read/write, but only through
+ * pointers passed to the function as parameters. This is a typical
+ * situation when you create a C++ non-static member function which only
+ * concerns `this`. No global variables are allowed to read/write. So
+ * this is not a super-set of being pure. If you want to read something,
+ * that has to be passed to the function as a pointer. ::VALUE -taking
+ * functions thus cannot be attributed as such.
+ */
+#include "ruby/internal/compiler_since.h"
+#include "ruby/internal/has/declspec_attribute.h"
+
+/** Wraps (or simulates) `__declspec((noalias))` */
+#if RBIMPL_COMPILER_BEFORE(Clang, 12, 0, 0)
+# /*
+# * `::llvm::Attribute::ArgMemOnly` was buggy before. Maybe because nobody
+# * actually seriously used it. It seems they somehow mitigated the situation
+# * in LLVM 12. Still not found the exact changeset which fiexed the
+# * attribute, though.
+# *
+# * :FIXME: others (armclang, xlclang, ...) can also be affected?
+# */
+# define RBIMPL_ATTR_NOALIAS() /* void */
+#elif RBIMPL_HAS_DECLSPEC_ATTRIBUTE(noalias)
+# define RBIMPL_ATTR_NOALIAS() __declspec(noalias)
+#else
+# define RBIMPL_ATTR_NOALIAS() /* void */
+#endif
+
+#endif /* RBIMPL_ATTR_NOALIAS_H */
diff --git a/include/ruby/internal/attr/nodiscard.h b/include/ruby/internal/attr/nodiscard.h
new file mode 100644
index 0000000000..087192a7a8
--- /dev/null
+++ b/include/ruby/internal/attr/nodiscard.h
@@ -0,0 +1,45 @@
+#ifndef RBIMPL_ATTR_NODISCARD_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_ATTR_NODISCARD_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Defines #RBIMPL_ATTR_NODISCARD.
+ */
+#include "ruby/internal/has/attribute.h"
+#include "ruby/internal/has/c_attribute.h"
+#include "ruby/internal/has/cpp_attribute.h"
+
+/**
+ * Wraps (or simulates) `[[nodiscard]]`. In C++ (at least since C++20) a
+ * nodiscard attribute can have a message why the result shall not be ignoed.
+ * However GCC attribute and SAL annotation cannot take them.
+ */
+#if RBIMPL_HAS_CPP_ATTRIBUTE(nodiscard)
+# define RBIMPL_ATTR_NODISCARD() [[nodiscard]]
+#elif RBIMPL_HAS_C_ATTRIBUTE(nodiscard)
+# define RBIMPL_ATTR_NODISCARD() [[nodiscard]]
+#elif RBIMPL_HAS_ATTRIBUTE(warn_unused_result)
+# define RBIMPL_ATTR_NODISCARD() __attribute__((__warn_unused_result__))
+#elif defined(_Check_return_)
+# /* Take SAL definition. */
+# define RBIMPL_ATTR_NODISCARD() _Check_return_
+#else
+# define RBIMPL_ATTR_NODISCARD() /* void */
+#endif
+
+#endif /* RBIMPL_ATTR_NODISCARD_H */
diff --git a/include/ruby/internal/attr/noexcept.h b/include/ruby/internal/attr/noexcept.h
new file mode 100644
index 0000000000..ea3001df2a
--- /dev/null
+++ b/include/ruby/internal/attr/noexcept.h
@@ -0,0 +1,91 @@
+#ifndef RBIMPL_ATTR_NOEXCEPT_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_ATTR_NOEXCEPT_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Defines #RBIMPL_ATTR_NOEXCEPT.
+ *
+ * This isn't actually an attribute in C++ but who cares...
+ *
+ * Mainly due to aesthetic reasons, this one is rarely used in the project.
+ * But can be handy on occasions, especially when a function's noexcept-ness
+ * depends on its calling functions.
+ *
+ * ### Q&A ###
+ *
+ * - Q: Can a function that raises Ruby exceptions be attributed `noexcept`?
+ *
+ * - A: Yes. `noexcept` is about C++ exceptions, not Ruby's. They don't
+ * interface each other. You can safely attribute a function that raises
+ * Ruby exceptions as `noexcept`.
+ *
+ * - Q: How, then, can I assert that a function I wrote doesn't raise any Ruby
+ * exceptions?
+ *
+ * - A: `__attribute__((__leaf__))` is for that purpose. A function attributed
+ * as leaf can still throw C++ exceptions, but not Ruby's. Note however,
+ * that it's extremely difficult -- if not impossible -- to assert that a
+ * function doesn't raise any Ruby exceptions at all. Use of that
+ * attribute is not recommended; mere mortals can't properly use that by
+ * hand.
+ *
+ * - Q: Does it make sense to attribute an inline function `noexcept`?
+ *
+ * - A: I thought so before. But no, I don't think they are useful any longer.
+ *
+ * - When an inline function attributed `noexcept` actually doesn't throw
+ * any exceptions at all: these days I don't see any difference in
+ * generated assembly by adding/removing this attribute. C++ compilers
+ * get smarter and smarter. Today they can infer if it actually throws
+ * or not without any annotations by humans (correct me if I'm wrong).
+ *
+ * - When an inline function attributed `noexcepr` actually _does_ throw an
+ * exception: they have to call `std::terminate` then (C++ standard
+ * mandates so). This means exception handling routines are actually
+ * enforced, not omitted. This doesn't impact runtime performance (The
+ * Itanium C++ ABI has zero-cost exception handling), but does impact on
+ * generated binary size. This is bad.
+ */
+#include "ruby/internal/compiler_since.h"
+#include "ruby/internal/has/feature.h"
+
+/** Wraps (or simulates) C++11 `noexcept` */
+#if ! defined(__cplusplus)
+# /* Doesn't make sense. */
+# define RBIMPL_ATTR_NOEXCEPT(_) /* void */
+
+#elif RBIMPL_HAS_FEATURE(cxx_noexcept)
+# define RBIMPL_ATTR_NOEXCEPT(_) noexcept(noexcept(_))
+
+#elif defined(__GXX_EXPERIMENTAL_CXX0X__) && __GXX_EXPERIMENTAL_CXX0X__
+# define RBIMPL_ATTR_NOEXCEPT(_) noexcept(noexcept(_))
+
+#elif defined(__INTEL_CXX11_MODE__)
+# define RBIMPL_ATTR_NOEXCEPT(_) noexcept(noexcept(_))
+
+#elif RBIMPL_COMPILER_SINCE(MSVC, 19, 0, 0)
+# define RBIMPL_ATTR_NOEXCEPT(_) noexcept(noexcept(_))
+
+#elif __cplusplus >= 201103L
+# define RBIMPL_ATTR_NOEXCEPT(_) noexcept(noexcept(_))
+
+#else
+# define RBIMPL_ATTR_NOEXCEPT(_) /* void */
+#endif
+
+#endif /* RBIMPL_ATTR_NOEXCEPT_H */
diff --git a/include/ruby/internal/attr/noinline.h b/include/ruby/internal/attr/noinline.h
new file mode 100644
index 0000000000..b7605a0c91
--- /dev/null
+++ b/include/ruby/internal/attr/noinline.h
@@ -0,0 +1,35 @@
+#ifndef RBIMPL_ATTR_NOINLINE_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_ATTR_NOINLINE_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Defines #RBIMPL_ATTR_NOINLINE.
+ */
+#include "ruby/internal/has/attribute.h"
+#include "ruby/internal/has/declspec_attribute.h"
+
+/** Wraps (or simulates) `__declspec(noinline)` */
+#if RBIMPL_HAS_DECLSPEC_ATTRIBUTE(noinline)
+# define RBIMPL_ATTR_NOINLINE() __declspec(noinline)
+#elif RBIMPL_HAS_ATTRIBUTE(noinline)
+# define RBIMPL_ATTR_NOINLINE() __attribute__((__noinline__))
+#else
+# define RBIMPL_ATTR_NOINLINE() /* void */
+#endif
+
+#endif /* RBIMPL_ATTR_NOINLINE_H */
diff --git a/include/ruby/internal/attr/nonnull.h b/include/ruby/internal/attr/nonnull.h
new file mode 100644
index 0000000000..778d5be208
--- /dev/null
+++ b/include/ruby/internal/attr/nonnull.h
@@ -0,0 +1,34 @@
+#ifndef RBIMPL_ATTR_NONNULL_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_ATTR_NONNULL_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Defines #RBIMPL_ATTR_NONNULL.
+ */
+#include "ruby/internal/has/attribute.h"
+
+/** Wraps (or simulates) `__attribute__((nonnull))` */
+#if RBIMPL_HAS_ATTRIBUTE(nonnull)
+# define RBIMPL_ATTR_NONNULL(list) __attribute__((__nonnull__ list))
+# define RBIMPL_NONNULL_ARG(arg) RBIMPL_ASSERT_NOTHING
+#else
+# define RBIMPL_ATTR_NONNULL(list) /* void */
+# define RBIMPL_NONNULL_ARG(arg) RUBY_ASSERT(arg)
+#endif
+
+#endif /* RBIMPL_ATTR_NONNULL_H */
diff --git a/include/ruby/internal/attr/noreturn.h b/include/ruby/internal/attr/noreturn.h
new file mode 100644
index 0000000000..5839212037
--- /dev/null
+++ b/include/ruby/internal/attr/noreturn.h
@@ -0,0 +1,48 @@
+#ifndef RBIMPL_ATTR_NORETURN_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_ATTR_NORETURN_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Defines #RBIMPL_ATTR_NORETURN.
+ */
+#include "ruby/internal/has/attribute.h"
+#include "ruby/internal/has/cpp_attribute.h"
+#include "ruby/internal/has/declspec_attribute.h"
+
+/** Wraps (or simulates) `[[noreturn]]` */
+#if RBIMPL_HAS_DECLSPEC_ATTRIBUTE(noreturn)
+# define RBIMPL_ATTR_NORETURN() __declspec(noreturn)
+
+#elif RBIMPL_HAS_ATTRIBUTE(noreturn)
+# define RBIMPL_ATTR_NORETURN() __attribute__((__noreturn__))
+
+#elif RBIMPL_HAS_CPP_ATTRIBUTE(noreturn)
+# define RBIMPL_ATTR_NORETURN() [[noreturn]]
+
+#elif defined(__STDC_VERSION__) && (__STDC_VERSION__ >= 201112)
+# define RBIMPL_ATTR_NORETURN() _Noreturn
+
+#elif defined(_Noreturn)
+# /* glibc <sys/cdefs.h> has this macro. */
+# define RBIMPL_ATTR_NORETURN() _Noreturn
+
+#else
+# define RBIMPL_ATTR_NORETURN() /* void */
+#endif
+
+#endif /* RBIMPL_ATTR_NORETURN_H */
diff --git a/include/ruby/internal/attr/pure.h b/include/ruby/internal/attr/pure.h
new file mode 100644
index 0000000000..015711bdab
--- /dev/null
+++ b/include/ruby/internal/attr/pure.h
@@ -0,0 +1,43 @@
+#ifndef RBIMPL_ATTR_PURE_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_ATTR_PURE_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Defines #RBIMPL_ATTR_PURE.
+ */
+#include "ruby/internal/compiler_since.h"
+#include "ruby/internal/has/attribute.h"
+#include "ruby/assert.h"
+
+/** Wraps (or simulates) `__attribute__((pure))` */
+#if RBIMPL_HAS_ATTRIBUTE(pure)
+# define RBIMPL_ATTR_PURE() __attribute__((__pure__))
+#elif RBIMPL_COMPILER_SINCE(SunPro, 5, 10, 0)
+# define RBIMPL_ATTR_PURE() _Pragma("does_not_write_global_data")
+#else
+# define RBIMPL_ATTR_PURE() /* void */
+#endif
+
+/** Enables #RBIMPL_ATTR_PURE if and only if. ! #RUBY_DEBUG. */
+#if !RUBY_DEBUG
+# define RBIMPL_ATTR_PURE_UNLESS_DEBUG() RBIMPL_ATTR_PURE()
+#else
+# define RBIMPL_ATTR_PURE_UNLESS_DEBUG() /* void */
+#endif
+
+#endif /* RBIMPL_ATTR_PURE_H */
diff --git a/include/ruby/internal/attr/restrict.h b/include/ruby/internal/attr/restrict.h
new file mode 100644
index 0000000000..e39104138c
--- /dev/null
+++ b/include/ruby/internal/attr/restrict.h
@@ -0,0 +1,44 @@
+#ifndef RBIMPL_ATTR_RESTRICT_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_ATTR_RESTRICT_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Defines #RBIMPL_ATTR_RESTRICT.
+ */
+#include "ruby/internal/compiler_since.h"
+#include "ruby/internal/has/attribute.h"
+
+/* :FIXME: config.h includes conflicting `#define restrict`. MSVC can be
+ * detected using `RBIMPL_COMPILER_SINCE()`, but Clang & family cannot use
+ * `__has_declspec_attribute()` which involves macro substitution. */
+
+/** Wraps (or simulates) `__declspec(restrict)` */
+#if RBIMPL_COMPILER_SINCE(MSVC, 14, 0, 0)
+# define RBIMPL_ATTR_RESTRICT() __declspec(re ## strict)
+
+#elif RBIMPL_HAS_ATTRIBUTE(malloc)
+# define RBIMPL_ATTR_RESTRICT() __attribute__((__malloc__))
+
+#elif RBIMPL_COMPILER_SINCE(SunPro, 5, 10, 0)
+# define RBIMPL_ATTR_RESTRICT() _Pragma("returns_new_memory")
+
+#else
+# define RBIMPL_ATTR_RESTRICT() /* void */
+#endif
+
+#endif /* RBIMPL_ATTR_RESTRICT_H */
diff --git a/include/ruby/internal/attr/returns_nonnull.h b/include/ruby/internal/attr/returns_nonnull.h
new file mode 100644
index 0000000000..5d6f1d1459
--- /dev/null
+++ b/include/ruby/internal/attr/returns_nonnull.h
@@ -0,0 +1,37 @@
+#ifndef RBIMPL_ATTR_RETURNS_NONNULL_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_ATTR_RETURNS_NONNULL_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Defines #RBIMPL_ATTR_RETURNS_NONNULL.
+ */
+#include "ruby/internal/has/attribute.h"
+
+/** Wraps (or simulates) `__attribute__((returns_nonnull))` */
+#if defined(_Ret_nonnull_)
+# /* Take SAL definition. */
+# define RBIMPL_ATTR_RETURNS_NONNULL() _Ret_nonnull_
+
+#elif RBIMPL_HAS_ATTRIBUTE(returns_nonnull)
+# define RBIMPL_ATTR_RETURNS_NONNULL() __attribute__((__returns_nonnull__))
+
+#else
+# define RBIMPL_ATTR_RETURNS_NONNULL() /* void */
+#endif
+
+#endif /* RBIMPL_ATTR_RETURNS_NONNULL_H */
diff --git a/include/ruby/internal/attr/warning.h b/include/ruby/internal/attr/warning.h
new file mode 100644
index 0000000000..e5ced269b8
--- /dev/null
+++ b/include/ruby/internal/attr/warning.h
@@ -0,0 +1,32 @@
+#ifndef RBIMPL_ATTR_WARNING_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_ATTR_WARNING_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Defines #RBIMPL_ATTR_WARNING.
+ */
+#include "ruby/internal/has/attribute.h"
+
+/** Wraps (or simulates) `__attribute__((warning))` */
+#if RBIMPL_HAS_ATTRIBUTE(warning)
+# define RBIMPL_ATTR_WARNING(msg) __attribute__((__warning__ msg))
+#else
+# define RBIMPL_ATTR_WARNING(msg) /* void */
+#endif
+
+#endif /* RBIMPL_ATTR_WARNING_H */
diff --git a/include/ruby/internal/attr/weakref.h b/include/ruby/internal/attr/weakref.h
new file mode 100644
index 0000000000..f118bb62b8
--- /dev/null
+++ b/include/ruby/internal/attr/weakref.h
@@ -0,0 +1,32 @@
+#ifndef RBIMPL_ATTR_WEAKREF_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_ATTR_WEAKREF_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Defines #RBIMPL_ATTR_WEAKREF.
+ */
+#include "ruby/internal/has/attribute.h"
+
+/** Wraps (or simulates) `__attribute__((weakref))` */
+#if RBIMPL_HAS_ATTRIBUTE(weakref)
+# define RBIMPL_ATTR_WEAKREF(sym) __attribute__((__weakref__(# sym)))
+#else
+# define RBIMPL_ATTR_WEAKREF(sym) /* void */
+#endif
+
+#endif /* RBIMPL_ATTR_WEAKREF_H */
diff --git a/include/ruby/internal/cast.h b/include/ruby/internal/cast.h
new file mode 100644
index 0000000000..a31fddbe4c
--- /dev/null
+++ b/include/ruby/internal/cast.h
@@ -0,0 +1,50 @@
+#ifndef RBIMPL_CAST_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_CAST_H
+/**
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Defines RBIMPL_CAST.
+ *
+ * This casting macro makes sense only inside of other macros that are part of
+ * public headers. They could be used from C++, and C-style casts could issue
+ * warnings. Ruby internals are pure C so they should not bother.
+ */
+#include "ruby/internal/compiler_since.h"
+#include "ruby/internal/has/warning.h"
+#include "ruby/internal/warning_push.h"
+
+#if ! defined(__cplusplus)
+# define RBIMPL_CAST(expr) (expr)
+
+#elif RBIMPL_COMPILER_SINCE(GCC, 4, 6, 0)
+# /* g++ has -Wold-style-cast since 1997 or so, but its _Pragma is broken. */
+# /* See https://gcc.godbolt.org/z/XWhU6J */
+# define RBIMPL_CAST(expr) (expr)
+# pragma GCC diagnostic ignored "-Wold-style-cast"
+
+#elif RBIMPL_HAS_WARNING("-Wold-style-cast")
+# define RBIMPL_CAST(expr) \
+ RBIMPL_WARNING_PUSH() \
+ RBIMPL_WARNING_IGNORED(-Wold-style-cast) \
+ (expr) \
+ RBIMPL_WARNING_POP()
+
+#else
+# define RBIMPL_CAST(expr) (expr)
+#endif
+
+#endif /* RBIMPL_CAST_H */
diff --git a/include/ruby/internal/compiler_is.h b/include/ruby/internal/compiler_is.h
new file mode 100644
index 0000000000..7070b033a0
--- /dev/null
+++ b/include/ruby/internal/compiler_is.h
@@ -0,0 +1,45 @@
+#ifndef RBIMPL_COMPILER_IS_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_COMPILER_IS_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Defines #RBIMPL_COMPILER_IS.
+ */
+
+/**
+ * @brief Checks if the compiler is of given brand.
+ * @param cc Compiler brand, like `MSVC`.
+ * @retval true It is.
+ * @retval false It isn't.
+ */
+#define RBIMPL_COMPILER_IS(cc) RBIMPL_COMPILER_IS_ ## cc
+
+#include "ruby/internal/compiler_is/apple.h"
+#include "ruby/internal/compiler_is/clang.h"
+#include "ruby/internal/compiler_is/gcc.h"
+#include "ruby/internal/compiler_is/intel.h"
+#include "ruby/internal/compiler_is/msvc.h"
+#include "ruby/internal/compiler_is/sunpro.h"
+/* :TODO: Other possible compilers to support:
+ *
+ * - IBM XL: recent XL are clang-backended so some tweaks like we do for
+ * Apple's might be needed.
+ *
+ * - ARM's armclang: ditto, it can be clang-backended. */
+
+#endif /* RBIMPL_COMPILER_IS_H */
diff --git a/include/ruby/internal/compiler_is/apple.h b/include/ruby/internal/compiler_is/apple.h
new file mode 100644
index 0000000000..a81f1f2c8f
--- /dev/null
+++ b/include/ruby/internal/compiler_is/apple.h
@@ -0,0 +1,40 @@
+#ifndef RBIMPL_COMPILER_IS_APPLE_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_COMPILER_IS_APPLE_H
+/**
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Defines RBIMPL_COMPILER_IS_Apple.
+ *
+ * Apple ships clang. Problem is, its `__clang_major__` etc. are not the
+ * upstream LLVM version, but XCode's. We have to think Apple's is distinct
+ * from LLVM's, when it comes to compiler detection business in this header
+ * file.
+ */
+#if ! defined(__clang__)
+# define RBIMPL_COMPILER_IS_Apple 0
+
+#elif ! defined(__apple_build_version__)
+# define RBIMPL_COMPILER_IS_Apple 0
+
+#else
+# define RBIMPL_COMPILER_IS_Apple 1
+# define RBIMPL_COMPILER_VERSION_MAJOR __clang_major__
+# define RBIMPL_COMPILER_VERSION_MINOR __clang_minor__
+# define RBIMPL_COMPILER_VERSION_PATCH __clang_patchlevel__
+#endif
+
+#endif /* RBIMPL_COMPILER_IS_APPLE_H */
diff --git a/include/ruby/internal/compiler_is/clang.h b/include/ruby/internal/compiler_is/clang.h
new file mode 100644
index 0000000000..169ff789f6
--- /dev/null
+++ b/include/ruby/internal/compiler_is/clang.h
@@ -0,0 +1,37 @@
+#ifndef RBIMPL_COMPILER_IS_CLANG_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_COMPILER_IS_CLANG_H
+/**
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Defines RBIMPL_COMPILER_IS_Clang.
+ */
+#include "ruby/internal/compiler_is/apple.h"
+
+#if ! defined(__clang__)
+# define RBIMPL_COMPILER_IS_Clang 0
+
+#elif RBIMPL_COMPILER_IS(Apple)
+# define RBIMPL_COMPILER_IS_Clang 0
+
+#else
+# define RBIMPL_COMPILER_IS_Clang 1
+# define RBIMPL_COMPILER_VERSION_MAJOR __clang_major__
+# define RBIMPL_COMPILER_VERSION_MINOR __clang_minor__
+# define RBIMPL_COMPILER_VERSION_PATCH __clang_patchlevel__
+#endif
+
+#endif /* RBIMPL_COMPILER_IS_CLANG_H */
diff --git a/include/ruby/internal/compiler_is/gcc.h b/include/ruby/internal/compiler_is/gcc.h
new file mode 100644
index 0000000000..accc80e9aa
--- /dev/null
+++ b/include/ruby/internal/compiler_is/gcc.h
@@ -0,0 +1,45 @@
+#ifndef RBIMPL_COMPILER_IS_GCC_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_COMPILER_IS_GCC_H
+/**
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Defines RBIMPL_COMPILER_IS_GCC.
+ */
+#include "ruby/internal/compiler_is/apple.h"
+#include "ruby/internal/compiler_is/clang.h"
+#include "ruby/internal/compiler_is/intel.h"
+
+#if ! defined(__GNUC__)
+# define RBIMPL_COMPILER_IS_GCC 0
+
+#elif RBIMPL_COMPILER_IS(Apple)
+# define RBIMPL_COMPILER_IS_GCC 0
+
+#elif RBIMPL_COMPILER_IS(Clang)
+# define RBIMPL_COMPILER_IS_GCC 0
+
+#elif RBIMPL_COMPILER_IS(Intel)
+# define RBIMPL_COMPILER_IS_GCC 0
+
+#else
+# define RBIMPL_COMPILER_IS_GCC 1
+# define RBIMPL_COMPILER_VERSION_MAJOR __GNUC__
+# define RBIMPL_COMPILER_VERSION_MINOR __GNUC_MINOR__
+# define RBIMPL_COMPILER_VERSION_PATCH __GNUC_PATCHLEVEL__
+#endif
+
+#endif /* RBIMPL_COMPILER_IS_GCC_H */
diff --git a/include/ruby/internal/compiler_is/intel.h b/include/ruby/internal/compiler_is/intel.h
new file mode 100644
index 0000000000..377946ace0
--- /dev/null
+++ b/include/ruby/internal/compiler_is/intel.h
@@ -0,0 +1,40 @@
+#ifndef RBIMPL_COMPILER_IS_INTEL_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_COMPILER_IS_INTEL_H
+/**
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Defines RBIMPL_COMPILER_IS_Intel.
+ */
+#if ! defined(__INTEL_COMPILER)
+# define RBIMPL_COMPILER_IS_Intel 0
+
+#elif ! defined(__INTEL_COMPILER_UPDATE)
+# define RBIMPL_COMPILER_IS_Intel 1
+# /* __INTEL_COMPILER = XXYZ */
+# define RBIMPL_COMPILER_VERSION_MAJOR (__INTEL_COMPILER / 100)
+# define RBIMPL_COMPILER_VERSION_MINOR (__INTEL_COMPILER % 100 / 10)
+# define RBIMPL_COMPILER_VERSION_PATCH (__INTEL_COMPILER % 10)
+
+#else
+# define RBIMPL_COMPILER_IS_Intel 1
+# /* __INTEL_COMPILER = XXYZ */
+# define RBIMPL_COMPILER_VERSION_MAJOR (__INTEL_COMPILER / 100)
+# define RBIMPL_COMPILER_VERSION_MINOR (__INTEL_COMPILER % 100 / 10)
+# define RBIMPL_COMPILER_VERSION_PATCH __INTEL_COMPILER_UPDATE
+#endif
+
+#endif /* RBIMPL_COMPILER_IS_INTEL_H */
diff --git a/include/ruby/internal/compiler_is/msvc.h b/include/ruby/internal/compiler_is/msvc.h
new file mode 100644
index 0000000000..8a864ea558
--- /dev/null
+++ b/include/ruby/internal/compiler_is/msvc.h
@@ -0,0 +1,56 @@
+#ifndef RBIMPL_COMPILER_IS_MSVC_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_COMPILER_IS_MSVC_H
+/**
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Defines RBIMPL_COMPILER_IS_MSVC.
+ */
+#include "ruby/internal/compiler_is/clang.h"
+#include "ruby/internal/compiler_is/intel.h"
+
+#if ! defined(_MSC_VER)
+# define RBIMPL_COMPILER_IS_MSVC 0
+
+#elif RBIMPL_COMPILER_IS(Clang)
+# define RBIMPL_COMPILER_IS_MSVC 0
+
+#elif RBIMPL_COMPILER_IS(Intel)
+# define RBIMPL_COMPILER_IS_MSVC 0
+
+#elif _MSC_VER >= 1400
+# define RBIMPL_COMPILER_IS_MSVC 1
+# /* _MSC_FULL_VER = XXYYZZZZZ */
+# define RBIMPL_COMPILER_VERSION_MAJOR (_MSC_FULL_VER / 10000000)
+# define RBIMPL_COMPILER_VERSION_MINOR (_MSC_FULL_VER % 10000000 / 100000)
+# define RBIMPL_COMPILER_VERSION_PATCH (_MSC_FULL_VER % 100000)
+
+#elif defined(_MSC_FULL_VER)
+# define RBIMPL_COMPILER_IS_MSVC 1
+# /* _MSC_FULL_VER = XXYYZZZZ */
+# define RBIMPL_COMPILER_VERSION_MAJOR (_MSC_FULL_VER / 1000000)
+# define RBIMPL_COMPILER_VERSION_MINOR (_MSC_FULL_VER % 1000000 / 10000)
+# define RBIMPL_COMPILER_VERSION_PATCH (_MSC_FULL_VER % 10000)
+
+#else
+# define RBIMPL_COMPILER_IS_MSVC 1
+# /* _MSC_VER = XXYY */
+# define RBIMPL_COMPILER_VERSION_MAJOR (_MSC_VER / 100)
+# define RBIMPL_COMPILER_VERSION_MINOR (_MSC_VER % 100)
+# define RBIMPL_COMPILER_VERSION_PATCH 0
+#endif
+
+#endif /* RBIMPL_COMPILER_IS_MSVC_H */
diff --git a/include/ruby/internal/compiler_is/sunpro.h b/include/ruby/internal/compiler_is/sunpro.h
new file mode 100644
index 0000000000..c11c8452e7
--- /dev/null
+++ b/include/ruby/internal/compiler_is/sunpro.h
@@ -0,0 +1,54 @@
+#ifndef RBIMPL_COMPILER_IS_SUNPRO_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_COMPILER_IS_SUNPRO_H
+/**
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Defines RBIMPL_COMPILER_IS_SunPro.
+ */
+#if ! (defined(__SUNPRO_C) || defined(__SUNPRO_CC))
+# define RBIMPL_COMPILER_IS_SunPro 0
+
+#elif defined(__SUNPRO_C) && __SUNPRO_C >= 0x5100
+# define RBIMPL_COMPILER_IS_SunPro 1
+# /* __SUNPRO_C = 0xXYYZ */
+# define RBIMPL_COMPILER_VERSION_MAJOR (__SUNPRO_C >> 12)
+# define RBIMPL_COMPILER_VERSION_MINOR ((__SUNPRO_C >> 8 & 0xF) * 10 + (__SUNPRO_C >> 4 & 0xF))
+# define RBIMPL_COMPILER_VERSION_PATCH (__SUNPRO_C & 0xF)
+
+#elif defined(__SUNPRO_CC) && __SUNPRO_CC >= 0x5100
+# define RBIMPL_COMPILER_IS_SunPro 1
+# /* __SUNPRO_CC = 0xXYYZ */
+# define RBIMPL_COMPILER_VERSION_MAJOR (__SUNPRO_CC >> 12)
+# define RBIMPL_COMPILER_VERSION_MINOR ((__SUNPRO_CC >> 8 & 0xF) * 10 + (__SUNPRO_CC >> 4 & 0xF))
+# define RBIMPL_COMPILER_VERSION_PATCH (__SUNPRO_CC & 0xF)
+
+#elif defined(__SUNPRO_C)
+# define RBIMPL_COMPILER_IS_SunPro 1
+# /* __SUNPRO_C = 0xXYZ */
+# define RBIMPL_COMPILER_VERSION_MAJOR (__SUNPRO_C >> 8)
+# define RBIMPL_COMPILER_VERSION_MINOR (__SUNPRO_C >> 4 & 0xF)
+# define RBIMPL_COMPILER_VERSION_PATCH (__SUNPRO_C & 0xF)
+
+#else
+# define RBIMPL_COMPILER_IS_SunPro 1
+# /* __SUNPRO_CC = 0xXYZ */
+# define RBIMPL_COMPILER_VERSION_MAJOR (__SUNPRO_CC >> 8)
+# define RBIMPL_COMPILER_VERSION_MINOR (__SUNPRO_CC >> 4 & 0xF)
+# define RBIMPL_COMPILER_VERSION_PATCH (__SUNPRO_CC & 0xF)
+#endif
+
+#endif /* RBIMPL_COMPILER_IS_SUNPRO_H */
diff --git a/include/ruby/internal/compiler_since.h b/include/ruby/internal/compiler_since.h
new file mode 100644
index 0000000000..1929032884
--- /dev/null
+++ b/include/ruby/internal/compiler_since.h
@@ -0,0 +1,61 @@
+#ifndef RBIMPL_COMPILER_SINCE_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_COMPILER_SINCE_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Defines #RBIMPL_COMPILER_SINCE.
+ */
+#include "ruby/internal/compiler_is.h"
+
+/**
+ * @brief Checks if the compiler is of given brand and is newer than or equal
+ * to the passed version.
+ * @param cc Compiler brand, like `MSVC`.
+ * @param x Major version.
+ * @param y Minor version.
+ * @param z Patchlevel.
+ * @retval true cc >= x.y.z.
+ * @retval false otherwise.
+ */
+#define RBIMPL_COMPILER_SINCE(cc, x, y, z) \
+ (RBIMPL_COMPILER_IS(cc) && \
+ ((RBIMPL_COMPILER_VERSION_MAJOR > (x)) || \
+ ((RBIMPL_COMPILER_VERSION_MAJOR == (x)) && \
+ ((RBIMPL_COMPILER_VERSION_MINOR > (y)) || \
+ ((RBIMPL_COMPILER_VERSION_MINOR == (y)) && \
+ (RBIMPL_COMPILER_VERSION_PATCH >= (z)))))))
+
+/**
+ * @brief Checks if the compiler is of given brand and is older than the
+ * passed version.
+ * @param cc Compiler brand, like `MSVC`.
+ * @param x Major version.
+ * @param y Minor version.
+ * @param z Patchlevel.
+ * @retval true cc < x.y.z.
+ * @retval false otherwise.
+ */
+#define RBIMPL_COMPILER_BEFORE(cc, x, y, z) \
+ (RBIMPL_COMPILER_IS(cc) && \
+ ((RBIMPL_COMPILER_VERSION_MAJOR < (x)) || \
+ ((RBIMPL_COMPILER_VERSION_MAJOR == (x)) && \
+ ((RBIMPL_COMPILER_VERSION_MINOR < (y)) || \
+ ((RBIMPL_COMPILER_VERSION_MINOR == (y)) && \
+ (RBIMPL_COMPILER_VERSION_PATCH < (z)))))))
+
+#endif /* RBIMPL_COMPILER_SINCE_H */
diff --git a/include/ruby/internal/config.h b/include/ruby/internal/config.h
new file mode 100644
index 0000000000..51f863fc29
--- /dev/null
+++ b/include/ruby/internal/config.h
@@ -0,0 +1,153 @@
+#ifndef RBIMPL_CONFIG_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_CONFIG_H
+/**
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Thin wrapper to ruby/config.h
+ */
+#include "ruby/config.h"
+
+#ifdef RUBY_EXTCONF_H
+# include RUBY_EXTCONF_H
+#endif
+
+#include "ruby/internal/compiler_since.h"
+
+#undef HAVE_PROTOTYPES
+#define HAVE_PROTOTYPES 1
+
+#undef HAVE_STDARG_PROTOTYPES
+#define HAVE_STDARG_PROTOTYPES 1
+
+#undef TOKEN_PASTE
+#define TOKEN_PASTE(x,y) x##y
+
+#if defined(__cplusplus)
+#/* __builtin_choose_expr and __builtin_types_compatible aren't available
+# * on C++. See https://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html */
+# undef HAVE_BUILTIN___BUILTIN_CHOOSE_EXPR_CONSTANT_P
+# undef HAVE_BUILTIN___BUILTIN_TYPES_COMPATIBLE_P
+
+/* HAVE_VA_ARGS_MACRO is for C. C++ situations might be different. */
+# undef HAVE_VA_ARGS_MACRO
+# if __cplusplus >= 201103L
+# define HAVE_VA_ARGS_MACRO
+# elif defined(__GXX_EXPERIMENTAL_CXX0X__) && __GXX_EXPERIMENTAL_CXX0X__
+# define HAVE_VA_ARGS_MACRO
+# elif defined(__INTEL_CXX11_MODE__)
+# define HAVE_VA_ARGS_MACRO
+# elif RBIMPL_COMPILER_SINCE(MSVC, 16, 0, 0)
+# define HAVE_VA_ARGS_MACRO
+# else
+# /* NG, not known. */
+# endif
+#endif
+
+#if RBIMPL_COMPILER_BEFORE(GCC, 4, 9, 0)
+# /* See https://bugs.ruby-lang.org/issues/14221 */
+# undef HAVE_BUILTIN___BUILTIN_CHOOSE_EXPR_CONSTANT_P
+#endif
+
+#if RBIMPL_COMPILER_BEFORE(GCC, 5, 0, 0)
+# /* GCC 4.9.2 reportedly has this feature and is broken. The function is not
+# * officially documented below. Seems we should not use it.
+# * https://gcc.gnu.org/onlinedocs/gcc-4.9.4/gcc/Other-Builtins.html */
+# undef HAVE_BUILTIN___BUILTIN_ALLOCA_WITH_ALIGN
+#endif
+
+#if defined(__SUNPRO_CC)
+# /* Oracle Developer Studio 12.5: GCC compatibility guide says it supports
+# * statement expressions. But to our knowledge they support the extension
+# * only for C and not for C++. Prove me wrong. Am happy to support them if
+# * there is a way. */
+# undef HAVE_STMT_AND_DECL_IN_EXPR
+#endif
+
+#ifndef STRINGIZE0
+# define STRINGIZE(expr) STRINGIZE0(expr)
+# define STRINGIZE0(expr) #expr
+#endif
+
+#ifdef AC_APPLE_UNIVERSAL_BUILD
+# undef WORDS_BIGENDIAN
+# ifdef __BIG_ENDIAN__
+# define WORDS_BIGENDIAN
+# endif
+#endif
+
+#ifndef DLEXT_MAXLEN
+# define DLEXT_MAXLEN 4
+#endif
+
+#ifndef RUBY_PLATFORM
+# define RUBY_PLATFORM "unknown-unknown"
+#endif
+
+#ifdef UNALIGNED_WORD_ACCESS
+# /* Take that. */
+#elif defined(__i386)
+# define UNALIGNED_WORD_ACCESS 1
+#elif defined(__i386__)
+# define UNALIGNED_WORD_ACCESS 1
+#elif defined(_M_IX86)
+# define UNALIGNED_WORD_ACCESS 1
+#elif defined(__x86_64)
+# define UNALIGNED_WORD_ACCESS 1
+#elif defined(__x86_64__)
+# define UNALIGNED_WORD_ACCESS 1
+#elif defined(_M_AMD64)
+# define UNALIGNED_WORD_ACCESS 1
+#elif defined(__powerpc64__)
+# define UNALIGNED_WORD_ACCESS 1
+#elif defined(__aarch64__)
+# define UNALIGNED_WORD_ACCESS 1
+#elif defined(__mc68020__)
+# define UNALIGNED_WORD_ACCESS 1
+#else
+# define UNALIGNED_WORD_ACCESS 0
+#endif
+
+/* Detection of __VA_OPT__ */
+#if ! defined(HAVE_VA_ARGS_MACRO)
+# undef HAVE___VA_OPT__
+
+#elif defined(__cplusplus)
+# if __cplusplus > 201703L
+# define HAVE___VA_OPT__
+# else
+# undef HAVE___VA_OPT__
+# endif
+#else
+# /* Idea taken from: https://stackoverflow.com/a/48045656 */
+# define RBIMPL_TEST3(q, w, e, ...) e
+# define RBIMPL_TEST2(...) RBIMPL_TEST3(__VA_OPT__(,),1,0,0)
+# define RBIMPL_TEST1() RBIMPL_TEST2("ruby")
+# if RBIMPL_TEST1()
+# define HAVE___VA_OPT__
+# else
+# undef HAVE___VA_OPT__
+# endif
+# undef RBIMPL_TEST1
+# undef RBIMPL_TEST2
+# undef RBIMPL_TEST3
+#endif /* HAVE_VA_ARGS_MACRO */
+
+#ifndef USE_RVARGC
+# define USE_RVARGC 0
+#endif
+
+#endif /* RBIMPL_CONFIG_H */
diff --git a/include/ruby/internal/constant_p.h b/include/ruby/internal/constant_p.h
new file mode 100644
index 0000000000..92d69cb972
--- /dev/null
+++ b/include/ruby/internal/constant_p.h
@@ -0,0 +1,38 @@
+#ifndef RBIMPL_CONSTANT_P_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_CONSTANT_P_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Defines #RBIMPL_CONSTANT_P.
+ *
+ * Note that __builtin_constant_p can be applicable inside of inline functions,
+ * according to GCC manual. Clang lacks that feature, though.
+ *
+ * @see https://bugs.llvm.org/show_bug.cgi?id=4898
+ * @see https://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html
+ */
+#include "ruby/internal/has/builtin.h"
+
+/** Wraps (or simulates) `__builtin_constant_p` */
+#if RBIMPL_HAS_BUILTIN(__builtin_constant_p)
+# define RBIMPL_CONSTANT_P(expr) __builtin_constant_p(expr)
+#else
+# define RBIMPL_CONSTANT_P(expr) 0
+#endif
+
+#endif /* RBIMPL_CONSTANT_P_H */
diff --git a/include/ruby/internal/core.h b/include/ruby/internal/core.h
new file mode 100644
index 0000000000..3f4561c6a6
--- /dev/null
+++ b/include/ruby/internal/core.h
@@ -0,0 +1,35 @@
+#ifndef RBIMPL_CORE_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_CORE_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Core data structures, definitions and manipulations.
+ */
+#include "ruby/internal/core/rarray.h"
+#include "ruby/internal/core/rbasic.h"
+#include "ruby/internal/core/rbignum.h"
+#include "ruby/internal/core/rclass.h"
+#include "ruby/internal/core/rdata.h"
+#include "ruby/internal/core/rfile.h"
+#include "ruby/internal/core/rhash.h"
+#include "ruby/internal/core/robject.h"
+#include "ruby/internal/core/rregexp.h"
+#include "ruby/internal/core/rstring.h"
+#include "ruby/internal/core/rstruct.h"
+#include "ruby/internal/core/rtypeddata.h"
+#endif /* RBIMPL_CORE_H */
diff --git a/include/ruby/internal/core/rarray.h b/include/ruby/internal/core/rarray.h
new file mode 100644
index 0000000000..9f1d0509ea
--- /dev/null
+++ b/include/ruby/internal/core/rarray.h
@@ -0,0 +1,590 @@
+#ifndef RBIMPL_RARRAY_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_RARRAY_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Defines struct ::RArray.
+ */
+#include "ruby/internal/arithmetic/long.h"
+#include "ruby/internal/attr/artificial.h"
+#include "ruby/internal/attr/constexpr.h"
+#include "ruby/internal/attr/maybe_unused.h"
+#include "ruby/internal/attr/pure.h"
+#include "ruby/internal/cast.h"
+#include "ruby/internal/core/rbasic.h"
+#include "ruby/internal/dllexport.h"
+#include "ruby/internal/fl_type.h"
+#include "ruby/internal/rgengc.h"
+#include "ruby/internal/stdbool.h"
+#include "ruby/internal/value.h"
+#include "ruby/internal/value_type.h"
+#include "ruby/assert.h"
+
+/**
+ * @private
+ * @warning Do not touch this macro.
+ * @warning It is an implementation detail.
+ * @warning The value of this macro must match for ruby itself and all
+ * extension libraries, otherwise serious memory corruption shall
+ * occur.
+ */
+#ifndef USE_TRANSIENT_HEAP
+# define USE_TRANSIENT_HEAP 1
+#endif
+
+/**
+ * Convenient casting macro.
+ *
+ * @param obj An object, which is in fact an ::RArray.
+ * @return The passed object casted to ::RArray.
+ */
+#define RARRAY(obj) RBIMPL_CAST((struct RArray *)(obj))
+/** @cond INTERNAL_MACRO */
+#define RARRAY_EMBED_FLAG RARRAY_EMBED_FLAG
+#define RARRAY_EMBED_LEN_MASK RARRAY_EMBED_LEN_MASK
+#define RARRAY_EMBED_LEN_MAX RARRAY_EMBED_LEN_MAX
+#define RARRAY_EMBED_LEN_SHIFT RARRAY_EMBED_LEN_SHIFT
+#if USE_TRANSIENT_HEAP
+# define RARRAY_TRANSIENT_FLAG RARRAY_TRANSIENT_FLAG
+#else
+# define RARRAY_TRANSIENT_FLAG 0
+#endif
+/** @endcond */
+#define RARRAY_LEN rb_array_len /**< @alias{rb_array_len} */
+#define RARRAY_CONST_PTR rb_array_const_ptr /**< @alias{rb_array_const_ptr} */
+#define RARRAY_CONST_PTR_TRANSIENT rb_array_const_ptr_transient /**< @alias{rb_array_const_ptr_transient} */
+
+/** @cond INTERNAL_MACRO */
+#if defined(__fcc__) || defined(__fcc_version) || \
+ defined(__FCC__) || defined(__FCC_VERSION)
+/* workaround for old version of Fujitsu C Compiler (fcc) */
+# define FIX_CONST_VALUE_PTR(x) ((const VALUE *)(x))
+#else
+# define FIX_CONST_VALUE_PTR(x) (x)
+#endif
+
+#define RARRAY_EMBED_LEN RARRAY_EMBED_LEN
+#define RARRAY_LENINT RARRAY_LENINT
+#define RARRAY_TRANSIENT_P RARRAY_TRANSIENT_P
+#define RARRAY_ASET RARRAY_ASET
+#define RARRAY_PTR RARRAY_PTR
+/** @endcond */
+
+/**
+ * @private
+ *
+ * Bits that you can set to ::RBasic::flags.
+ *
+ * @warning These enums are not the only bits we use for arrays.
+ *
+ * @internal
+ *
+ * Unlike strings, flag usages for arrays are scattered across the entire
+ * source codes. @shyouhei doesn't know the complete list. But what is listed
+ * here is at least incomplete.
+ */
+enum ruby_rarray_flags {
+ /**
+ * This flag has something to do with memory footprint. If the array is
+ * "small" enough, ruby tries to be creative to abuse padding bits of
+ * struct ::RArray for storing its contents. This flag denotes that
+ * situation.
+ *
+ * @warning This bit has to be considered read-only. Setting/clearing
+ * this bit without corresponding fix up must cause immediate
+ * SEGV. Also, internal structures of an array change
+ * dynamically and transparently throughout of its lifetime.
+ * Don't assume it being persistent.
+ *
+ * @internal
+ *
+ * 3rd parties must not be aware that there even is more than one way to
+ * store array elements. It was a bad idea to expose this to them.
+ */
+ RARRAY_EMBED_FLAG = RUBY_FL_USER1,
+
+ /* RUBY_FL_USER2 is for ELTS_SHARED */
+
+ /**
+ * When an array employs embedded strategy (see ::RARRAY_EMBED_FLAG), these
+ * bits are used to store the number of elements actually filled into
+ * ::RArray::ary.
+ *
+ * @internal
+ *
+ * 3rd parties must not be aware that there even is more than one way to
+ * store array elements. It was a bad idea to expose this to them.
+ */
+ RARRAY_EMBED_LEN_MASK = RUBY_FL_USER4 | RUBY_FL_USER3
+#if USE_TRANSIENT_HEAP
+ ,
+
+ /**
+ * This flag has something to do with an array's "transiency". A transient
+ * array is an array of young generation (of generational GC), who stores
+ * its elements inside of dedicated memory pages called a transient heap.
+ * Not every young generation share that storage scheme, but elder
+ * generations must no join.
+ *
+ * @internal
+ *
+ * 3rd parties must not be aware that there even is more than one way to
+ * store array elements. It was a bad idea to expose this to them.
+ */
+ RARRAY_TRANSIENT_FLAG = RUBY_FL_USER13
+#endif
+};
+
+/**
+ * This is an enum because GDB wants it (rather than a macro). People need not
+ * bother.
+ */
+enum ruby_rarray_consts {
+ /** Where ::RARRAY_EMBED_LEN_MASK resides. */
+ RARRAY_EMBED_LEN_SHIFT = RUBY_FL_USHIFT + 3,
+
+ /** Max possible number elements that can be embedded. */
+ RARRAY_EMBED_LEN_MAX = RBIMPL_EMBED_LEN_MAX_OF(VALUE)
+};
+
+/** Ruby's array. */
+struct RArray {
+
+ /** Basic part, including flags and class. */
+ struct RBasic basic;
+
+ /** Array's specific fields. */
+ union {
+
+ /**
+ * Arrays that use separated memory region for elements use this
+ * pattern.
+ */
+ struct {
+
+ /** Number of elements of the array. */
+ long len;
+
+ /** Auxiliary info. */
+ union {
+
+ /**
+ * Capacity of `*ptr`. A continuous memory region of at least
+ * `capa` elements is expected to exist at `*ptr`. This can be
+ * bigger than `len`.
+ */
+ long capa;
+
+ /**
+ * Parent of the array. Nowadays arrays can share their
+ * backend memory regions each other, constructing gigantic
+ * nest of objects. This situation is called "shared", and
+ * this is the field to control such properties.
+ */
+#if defined(__clang__) /* <- clang++ is sane */ || \
+ !defined(__cplusplus) /* <- C99 is sane */ || \
+ (__cplusplus > 199711L) /* <- C++11 is sane */
+ const
+#endif
+ VALUE shared_root;
+ } aux;
+
+ /**
+ * Pointer to the C array that holds the elements of the array. In
+ * the old days each array had dedicated memory regions. That is
+ * no longer true today, but there still are arrays of such
+ * properties. This field could be used to point such things.
+ */
+ const VALUE *ptr;
+ } heap;
+
+ /**
+ * Embedded elements. When an array is short enough, it uses this area
+ * to store its elements. In this case the length is encoded into the
+ * flags.
+ */
+ const VALUE ary[RARRAY_EMBED_LEN_MAX];
+ } as;
+};
+
+RBIMPL_SYMBOL_EXPORT_BEGIN()
+/**
+ * @private
+ *
+ * Declares a section of code where raw pointers are used. This is an
+ * implementation detail of #RARRAY_PTR_USE. People don't use it directly.
+ *
+ * @param[in] ary An object of ::RArray.
+ * @return `ary`'s backend C array.
+ */
+VALUE *rb_ary_ptr_use_start(VALUE ary);
+
+/**
+ * @private
+ *
+ * Declares an end of a section formerly started by rb_ary_ptr_use_start().
+ * This is an implementation detail of #RARRAY_PTR_USE. People don't use it
+ * directly.
+ *
+ * @param[in] a An object of ::RArray.
+ */
+void rb_ary_ptr_use_end(VALUE a);
+
+#if USE_TRANSIENT_HEAP
+/**
+ * Destructively converts an array of transient backend into ordinal one.
+ *
+ * @param[out] a An object of ::RArray.
+ * @pre `a` must be a transient array.
+ * @post `a` gets out of transient heap, destructively.
+ */
+void rb_ary_detransient(VALUE a);
+#endif
+RBIMPL_SYMBOL_EXPORT_END()
+
+RBIMPL_ATTR_PURE_UNLESS_DEBUG()
+RBIMPL_ATTR_ARTIFICIAL()
+/**
+ * Queries the length of the array.
+ *
+ * @param[in] ary Array in question.
+ * @return Its number of elements.
+ * @pre `ary` must be an instance of ::RArray, and must has its
+ * ::RARRAY_EMBED_FLAG flag set.
+ *
+ * @internal
+ *
+ * This was a macro before. It was inevitable to be public, since macros are
+ * global constructs. But should it be forever? Now that it is a function,
+ * @shyouhei thinks it could just be eliminated, hidden into implementation
+ * details.
+ */
+static inline long
+RARRAY_EMBED_LEN(VALUE ary)
+{
+ RBIMPL_ASSERT_TYPE(ary, RUBY_T_ARRAY);
+ RBIMPL_ASSERT_OR_ASSUME(RB_FL_ANY_RAW(ary, RARRAY_EMBED_FLAG));
+
+ VALUE f = RBASIC(ary)->flags;
+ f &= RARRAY_EMBED_LEN_MASK;
+ f >>= RARRAY_EMBED_LEN_SHIFT;
+ return RBIMPL_CAST((long)f);
+}
+
+RBIMPL_ATTR_PURE_UNLESS_DEBUG()
+/**
+ * Queries the length of the array.
+ *
+ * @param[in] a Array in question.
+ * @return Its number of elements.
+ * @pre `a` must be an instance of ::RArray.
+ */
+static inline long
+rb_array_len(VALUE a)
+{
+ RBIMPL_ASSERT_TYPE(a, RUBY_T_ARRAY);
+
+ if (RB_FL_ANY_RAW(a, RARRAY_EMBED_FLAG)) {
+ return RARRAY_EMBED_LEN(a);
+ }
+ else {
+ return RARRAY(a)->as.heap.len;
+ }
+}
+
+RBIMPL_ATTR_ARTIFICIAL()
+/**
+ * Identical to rb_array_len(), except it differs for the return type.
+ *
+ * @param[in] ary Array in question.
+ * @exception rb_eRangeError Too long.
+ * @return Its number of elements.
+ * @pre `ary` must be an instance of ::RArray.
+ *
+ * @internal
+ *
+ * This API seems redundant but has actual usages.
+ */
+static inline int
+RARRAY_LENINT(VALUE ary)
+{
+ return rb_long2int(RARRAY_LEN(ary));
+}
+
+RBIMPL_ATTR_PURE_UNLESS_DEBUG()
+RBIMPL_ATTR_ARTIFICIAL()
+/**
+ * Queries if the array is a transient array.
+ *
+ * @param[in] ary Array in question.
+ * @retval true Yes it is.
+ * @retval false No it isn't.
+ * @pre `ary` must be an instance of ::RArray.
+ *
+ * @internal
+ *
+ * @shyouhei doesn't understand the benefit of this function called from
+ * extension libraries.
+ */
+static inline bool
+RARRAY_TRANSIENT_P(VALUE ary)
+{
+ RBIMPL_ASSERT_TYPE(ary, RUBY_T_ARRAY);
+
+#if USE_TRANSIENT_HEAP
+ return RB_FL_ANY_RAW(ary, RARRAY_TRANSIENT_FLAG);
+#else
+ return false;
+#endif
+}
+
+RBIMPL_ATTR_PURE_UNLESS_DEBUG()
+/**
+ * @private
+ *
+ * This is an implementation detail of RARRAY_PTR(). People do not use it
+ * directly.
+ *
+ * @param[in] a An object of ::RArray.
+ * @return Its backend storage.
+ */
+static inline const VALUE *
+rb_array_const_ptr_transient(VALUE a)
+{
+ RBIMPL_ASSERT_TYPE(a, RUBY_T_ARRAY);
+
+ if (RB_FL_ANY_RAW(a, RARRAY_EMBED_FLAG)) {
+ return FIX_CONST_VALUE_PTR(RARRAY(a)->as.ary);
+ }
+ else {
+ return FIX_CONST_VALUE_PTR(RARRAY(a)->as.heap.ptr);
+ }
+}
+
+#if ! USE_TRANSIENT_HEAP
+RBIMPL_ATTR_PURE_UNLESS_DEBUG()
+#endif
+/**
+ * @private
+ *
+ * This is an implementation detail of RARRAY_PTR(). People do not use it
+ * directly.
+ *
+ * @param[in] a An object of ::RArray.
+ * @return Its backend storage.
+ * @post `a` is not a transient array.
+ */
+static inline const VALUE *
+rb_array_const_ptr(VALUE a)
+{
+ RBIMPL_ASSERT_TYPE(a, RUBY_T_ARRAY);
+
+#if USE_TRANSIENT_HEAP
+ if (RARRAY_TRANSIENT_P(a)) {
+ rb_ary_detransient(a);
+ }
+#endif
+ return rb_array_const_ptr_transient(a);
+}
+
+/**
+ * @private
+ *
+ * This is an implementation detail of #RARRAY_PTR_USE. People do not use it
+ * directly.
+ *
+ * @param[in] a An object of ::RArray.
+ * @param[in] allow_transient Whether `a` can be transient or not.
+ * @return Its backend storage.
+ * @post `a` is not a transient array unless `allow_transient`.
+ */
+static inline VALUE *
+rb_array_ptr_use_start(VALUE a,
+ RBIMPL_ATTR_MAYBE_UNUSED()
+ int allow_transient)
+{
+ RBIMPL_ASSERT_TYPE(a, RUBY_T_ARRAY);
+
+#if USE_TRANSIENT_HEAP
+ if (!allow_transient) {
+ if (RARRAY_TRANSIENT_P(a)) {
+ rb_ary_detransient(a);
+ }
+ }
+#endif
+
+ return rb_ary_ptr_use_start(a);
+}
+
+/**
+ * @private
+ *
+ * This is an implementation detail of #RARRAY_PTR_USE. People do not use it
+ * directly.
+ *
+ * @param[in] a An object of ::RArray.
+ * @param[in] allow_transient Whether `a` can be transient or not.
+ */
+static inline void
+rb_array_ptr_use_end(VALUE a,
+ RBIMPL_ATTR_MAYBE_UNUSED()
+ int allow_transient)
+{
+ RBIMPL_ASSERT_TYPE(a, RUBY_T_ARRAY);
+ rb_ary_ptr_use_end(a);
+}
+
+/**
+ * @private
+ *
+ * This is an implementation detail of #RARRAY_PTR_USE. People do not use it
+ * directly.
+ */
+#define RBIMPL_RARRAY_STMT(flag, ary, var, expr) do { \
+ RBIMPL_ASSERT_TYPE((ary), RUBY_T_ARRAY); \
+ const VALUE rbimpl_ary = (ary); \
+ VALUE *var = rb_array_ptr_use_start(rbimpl_ary, (flag)); \
+ expr; \
+ rb_array_ptr_use_end(rbimpl_ary, (flag)); \
+} while (0)
+
+/**
+ * @private
+ *
+ * This is an implementation detail of #RARRAY_PTR_USE. People do not use it
+ * directly.
+ */
+#define RARRAY_PTR_USE_START(a) rb_array_ptr_use_start(a, 0)
+
+/**
+ * @private
+ *
+ * This is an implementation detail of #RARRAY_PTR_USE. People do not use it
+ * directly.
+ */
+#define RARRAY_PTR_USE_END(a) rb_array_ptr_use_end(a, 0)
+
+/**
+ * Declares a section of code where raw pointers are used. In case you need to
+ * touch the raw C array instead of polite CAPIs, then that operation shall be
+ * wrapped using this macro.
+ *
+ * ```CXX
+ * const auto ary = rb_eval_string("[...]");
+ * const auto len = RARRAY_LENINT(ary);
+ * const auto symwrite = rb_intern("write");
+ *
+ * RARRAY_PTR_USE(ary, ptr, {
+ * rb_funcallv(rb_stdout, symwrite, len, ptr);
+ * });
+ * ```
+ *
+ * @param ary An object of ::RArray.
+ * @param ptr_name A variable name which points the C array in `expr`.
+ * @param expr The expression that touches `ptr_name`.
+ *
+ * @internal
+ *
+ * For historical reasons use of this macro is not enforced. There are
+ * extension libraries in the wild which call RARRAY_PTR() without it. We want
+ * them use it... Maybe some transition path can be implemented later.
+ */
+#define RARRAY_PTR_USE(ary, ptr_name, expr) \
+ RBIMPL_RARRAY_STMT(0, ary, ptr_name, expr)
+
+/**
+ * @private
+ *
+ * This is an implementation detail of #RARRAY_PTR_USE_TRANSIENT. People do
+ * not use it directly.
+ */
+#define RARRAY_PTR_USE_START_TRANSIENT(a) rb_array_ptr_use_start(a, 1)
+
+/**
+ * @private
+ *
+ * This is an implementation detail of #RARRAY_PTR_USE_TRANSIENT. People do
+ * not use it directly.
+ */
+#define RARRAY_PTR_USE_END_TRANSIENT(a) rb_array_ptr_use_end(a, 1)
+
+/**
+ * Identical to #RARRAY_PTR_USE, except the pointer can be a transient one.
+ *
+ * @param ary An object of ::RArray.
+ * @param ptr_name A variable name which points the C array in `expr`.
+ * @param expr The expression that touches `ptr_name`.
+ */
+#define RARRAY_PTR_USE_TRANSIENT(ary, ptr_name, expr) \
+ RBIMPL_RARRAY_STMT(1, ary, ptr_name, expr)
+
+/**
+ * Wild use of a C pointer. This function accesses the backend storage
+ * directly. This is slower than #RARRAY_PTR_USE_TRANSIENT. It exercises
+ * extra manoeuvres to protect our generational GC. Use of this function is
+ * considered archaic. Use a modern way instead.
+ *
+ * @param[in] ary An object of ::RArray.
+ * @return The backend C array.
+ *
+ * @internal
+ *
+ * That said... there are extension libraries in the wild who uses it. We
+ * cannot but continue supporting.
+ */
+static inline VALUE *
+RARRAY_PTR(VALUE ary)
+{
+ RBIMPL_ASSERT_TYPE(ary, RUBY_T_ARRAY);
+
+ VALUE tmp = RB_OBJ_WB_UNPROTECT_FOR(ARRAY, ary);
+ return RBIMPL_CAST((VALUE *)RARRAY_CONST_PTR(tmp));
+}
+
+/**
+ * Assigns an object in an array.
+ *
+ * @param[out] ary Destination array object.
+ * @param[in] i Index of `ary`.
+ * @param[in] v Arbitrary ruby object.
+ * @pre `ary` must be an instance of ::RArray.
+ * @pre `ary`'s length must be longer than or equal to `i`.
+ * @pre `i` must be greater than or equal to zero.
+ * @post `ary`'s `i`th element is set to `v`.
+ */
+static inline void
+RARRAY_ASET(VALUE ary, long i, VALUE v)
+{
+ RARRAY_PTR_USE_TRANSIENT(ary, ptr,
+ RB_OBJ_WRITE(ary, &ptr[i], v));
+}
+
+/**
+ * @deprecated
+ *
+ * :FIXME: we want to convert RARRAY_AREF into an inline function (to add rooms
+ * for more sanity checks). However there were situations where the address of
+ * this macro is taken i.e. &RARRAY_AREF(...). They cannot be possible if this
+ * is not a macro. Such usages are abuse, and we eliminated them internally.
+ * However we are afraid of similar things to remain in the wild. This macro
+ * remains as it is due to that. If we could warn such usages we can set a
+ * transition path, but currently no way is found to do so.
+ */
+#define RARRAY_AREF(a, i) RARRAY_CONST_PTR_TRANSIENT(a)[i]
+
+#endif /* RBIMPL_RARRAY_H */
diff --git a/include/ruby/internal/core/rbasic.h b/include/ruby/internal/core/rbasic.h
new file mode 100644
index 0000000000..4617f743a7
--- /dev/null
+++ b/include/ruby/internal/core/rbasic.h
@@ -0,0 +1,158 @@
+#ifndef RBIMPL_RBASIC_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_RBASIC_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Defines struct ::RBasic.
+ */
+#include "ruby/internal/attr/artificial.h"
+#include "ruby/internal/attr/constexpr.h"
+#include "ruby/internal/attr/forceinline.h"
+#include "ruby/internal/attr/noalias.h"
+#include "ruby/internal/attr/pure.h"
+#include "ruby/internal/cast.h"
+#include "ruby/internal/dllexport.h"
+#include "ruby/internal/special_consts.h"
+#include "ruby/internal/value.h"
+#include "ruby/assert.h"
+
+/**
+ * Convenient casting macro.
+ *
+ * @param obj Arbitrary Ruby object.
+ * @return The passed object casted to ::RBasic.
+ */
+#define RBASIC(obj) RBIMPL_CAST((struct RBasic *)(obj))
+/** @cond INTERNAL_MACRO */
+#define RBASIC_CLASS RBASIC_CLASS
+#define RBIMPL_RVALUE_EMBED_LEN_MAX 3
+#define RVALUE_EMBED_LEN_MAX RVALUE_EMBED_LEN_MAX
+#define RBIMPL_EMBED_LEN_MAX_OF(T) \
+ RBIMPL_CAST((int)(sizeof(VALUE[RBIMPL_RVALUE_EMBED_LEN_MAX]) / (sizeof(T))))
+/** @endcond */
+
+/**
+ * This is an enum because GDB wants it (rather than a macro). People need not
+ * bother.
+ */
+enum ruby_rvalue_flags {
+ /** Max possible number of objects that can be embedded. */
+ RVALUE_EMBED_LEN_MAX = RBIMPL_RVALUE_EMBED_LEN_MAX
+};
+
+/**
+ * Ruby's object's, base components. Every single ruby objects have them in
+ * common.
+ */
+struct
+RUBY_ALIGNAS(SIZEOF_VALUE)
+RBasic {
+
+ /**
+ * Per-object flags. Each ruby objects have their own characteristics
+ * apart from their classes. For instance whether an object is frozen or
+ * not is not controlled by its class. This is where such properties are
+ * stored.
+ *
+ * @see enum ::ruby_fl_type
+ *
+ * @note This is ::VALUE rather than an enum for alignment purpose. Back
+ * in the 1990s there were no such thing like `_Alignas` in C.
+ */
+ VALUE flags;
+
+ /**
+ * Class of an object. Every object has its class. Also, everything is an
+ * object in Ruby. This means classes are also objects. Classes have
+ * their own classes, classes of classes have their classes, too ... and
+ * it recursively continues forever.
+ *
+ * Also note the `const` qualifier. In ruby an object cannot "change" its
+ * class.
+ */
+ const VALUE klass;
+
+#ifdef __cplusplus
+ public:
+ RBIMPL_ATTR_CONSTEXPR(CXX11)
+ RBIMPL_ATTR_ARTIFICIAL()
+ RBIMPL_ATTR_FORCEINLINE()
+ RBIMPL_ATTR_NOALIAS()
+ /**
+ * We need to define this explicit constructor because the field `klass` is
+ * const-qualified above, which effectively defines the implicit default
+ * constructor as "deleted" (as of C++11) -- No way but to define one by
+ * ourselves.
+ */
+ RBasic() :
+ flags(RBIMPL_VALUE_NULL),
+ klass(RBIMPL_VALUE_NULL)
+ {
+ }
+#endif
+};
+
+RBIMPL_SYMBOL_EXPORT_BEGIN()
+/**
+ * Make the object invisible from Ruby code.
+ *
+ * It is useful to let Ruby's GC manage your internal data structure -- The
+ * object keeps being managed by GC, but `ObjectSpace.each_object` never yields
+ * the object.
+ *
+ * Note that the object also lose a way to call a method on it.
+ *
+ * @param[out] obj A Ruby object.
+ * @return The passed object.
+ * @post The object is destructively modified to be invisible.
+ * @see rb_obj_reveal
+ */
+VALUE rb_obj_hide(VALUE obj);
+
+/**
+ * Make a hidden object visible again.
+ *
+ * It is the caller's responsibility to pass the right `klass` which `obj`
+ * originally used to belong to.
+ *
+ * @param[out] obj A Ruby object.
+ * @param[in] klass Class of `obj`.
+ * @return Passed `obj`.
+ * @pre `obj` was previously hidden.
+ * @post `obj`'s class is `klass`.
+ * @see rb_obj_hide
+ */
+VALUE rb_obj_reveal(VALUE obj, VALUE klass); /* do not use this API to change klass information */
+RBIMPL_SYMBOL_EXPORT_END()
+
+RBIMPL_ATTR_PURE_UNLESS_DEBUG()
+RBIMPL_ATTR_ARTIFICIAL()
+/**
+ * Queries the class of an object.
+ *
+ * @param[in] obj An object.
+ * @return Its class.
+ */
+static inline VALUE
+RBASIC_CLASS(VALUE obj)
+{
+ RBIMPL_ASSERT_OR_ASSUME(! RB_SPECIAL_CONST_P(obj));
+ return RBASIC(obj)->klass;
+}
+
+#endif /* RBIMPL_RBASIC_H */
diff --git a/include/ruby/internal/core/rbignum.h b/include/ruby/internal/core/rbignum.h
new file mode 100644
index 0000000000..1d31743235
--- /dev/null
+++ b/include/ruby/internal/core/rbignum.h
@@ -0,0 +1,80 @@
+#ifndef RBIMPL_RBIGNUM_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_RBIGNUM_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Routines to manipulate struct RBignum.
+ * @note The struct RBignum itself is opaque.
+ */
+#include "ruby/internal/dllexport.h"
+#include "ruby/internal/value.h"
+#include "ruby/internal/value_type.h"
+#include "ruby/internal/stdbool.h"
+
+#define RBIGNUM_SIGN rb_big_sign /**< @alias{rb_big_sign} */
+
+/** @cond INTERNAL_MACRO */
+#define RBIGNUM_POSITIVE_P RBIGNUM_POSITIVE_P
+#define RBIGNUM_NEGATIVE_P RBIGNUM_NEGATIVE_P
+/** @endcond */
+
+RBIMPL_SYMBOL_EXPORT_BEGIN()
+/**
+ * The "sign" of a bignum.
+ *
+ * @param[in] num An object of RBignum.
+ * @retval 1 It is greater than or equal to zero.
+ * @retval 0 It is less than zero.
+ *
+ * @internal
+ *
+ * Implementation wise, unlike fixnums (which are 2's complement), bignums are
+ * signed magnitude system. Theoretically it could be possible to have
+ * negative zero instances. But in reality there is no way to create such
+ * thing. Nobody ever needed that kind of insanity.
+ */
+int rb_big_sign(VALUE num);
+RBIMPL_SYMBOL_EXPORT_END()
+
+/**
+ * Checks if the bignum is positive.
+ * @param[in] b An object of RBignum.
+ * @retval false `b` is less than zero.
+ * @retval true Otherwise.
+ */
+static inline bool
+RBIGNUM_POSITIVE_P(VALUE b)
+{
+ RBIMPL_ASSERT_TYPE(b, RUBY_T_BIGNUM);
+ return RBIGNUM_SIGN(b);
+}
+
+/**
+ * Checks if the bignum is negative.
+ * @param[in] b An object of RBignum.
+ * @retval true `b` is less than zero.
+ * @retval false Otherwise.
+ */
+static inline bool
+RBIGNUM_NEGATIVE_P(VALUE b)
+{
+ RBIMPL_ASSERT_TYPE(b, RUBY_T_BIGNUM);
+ return ! RBIGNUM_POSITIVE_P(b);
+}
+
+#endif /* RBIMPL_RBIGNUM_H */
diff --git a/include/ruby/internal/core/rclass.h b/include/ruby/internal/core/rclass.h
new file mode 100644
index 0000000000..13a33a28bd
--- /dev/null
+++ b/include/ruby/internal/core/rclass.h
@@ -0,0 +1,140 @@
+#ifndef RBIMPL_RCLASS_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_RCLASS_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Routines to manipulate struct RClass.
+ * @note The struct RClass itself is opaque.
+ */
+#include "ruby/internal/dllexport.h"
+#include "ruby/internal/value.h"
+#include "ruby/internal/cast.h"
+
+/** @cond INTERNAL_MACRO */
+#define RMODULE_IS_OVERLAID RMODULE_IS_OVERLAID
+#define RMODULE_IS_REFINEMENT RMODULE_IS_REFINEMENT
+#define RMODULE_INCLUDED_INTO_REFINEMENT RMODULE_INCLUDED_INTO_REFINEMENT
+/** @endcond */
+
+/**
+ * Convenient casting macro.
+ *
+ * @param obj An object, which is in fact an RClass.
+ * @return The passed object casted to RClass.
+ */
+#define RCLASS(obj) RBIMPL_CAST((struct RClass *)(obj))
+
+/** @alias{RCLASS} */
+#define RMODULE RCLASS
+
+/** @alias{rb_class_get_superclass} */
+#define RCLASS_SUPER rb_class_get_superclass
+
+/**
+ * @private
+ *
+ * Bits that you can set to ::RBasic::flags.
+ *
+ * @internal
+ *
+ * Why is it here, given RClass itself is not?
+ */
+enum ruby_rmodule_flags {
+
+ /**
+ * This flag has something to do with refinements... I guess? It is set on
+ * occasions for modules that are refined by refinements, but it seems
+ * ... nobody cares about such things? Not sure but this flag could
+ * perhaps be a write-only information.
+ */
+ RMODULE_IS_OVERLAID = RUBY_FL_USER2,
+
+ /**
+ * This flag has something to do with refinements. A module created using
+ * rb_mod_refine() has this flag set. This is the bit which controls
+ * difference between normal inclusion versus refinements.
+ */
+ RMODULE_IS_REFINEMENT = RUBY_FL_USER3,
+
+ /**
+ * This flag has something to do with refinements. This is set when a
+ * (non-refinement) module is included into another module, which is a
+ * refinement. This amends the way `super` searches for a super method.
+ *
+ * ```ruby
+ * class Foo
+ * def foo
+ * "Foo"
+ * end
+ * end
+ *
+ * module Bar
+ * def foo
+ * "[#{super}]" # this
+ * end
+ * end
+ *
+ * module Baz
+ * refine Foo do
+ * include Bar
+ * def foo
+ * "<#{super}>"
+ * end
+ * end
+ * end
+ *
+ * using Baz
+ * Foo.new.foo # => "[<Foo>]"
+ * ```
+ *
+ * The `super` marked with "this" comment shall look for overlaid
+ * `Foo#foo`, which is not the ordinal method lookup direction.
+ */
+ RMODULE_INCLUDED_INTO_REFINEMENT = RUBY_FL_USER4
+};
+
+struct RClass; /* Opaque, declared here for RCLASS() macro. */
+
+RBIMPL_SYMBOL_EXPORT_BEGIN()
+/**
+ * Returns the superclass of a class.
+ * @param[in] klass An object of RClass.
+ * @retval RUBY_Qfalse `klass` has no super class.
+ * @retval otherwise Raw superclass of `klass`
+ * @see rb_class_superclass
+ *
+ * ### Q&A ###
+ *
+ * - Q: How can a class have no super class?
+ *
+ * - A: `klass` could be a module. Or it could be ::rb_cBasicObject.
+ *
+ * - Q: What do you mean by "raw" superclass?
+ *
+ * - A: This is a really good question. The answer is that this function
+ * returns something different from what you would normally expect. On
+ * occasions ruby inserts hidden classes in a hierarchy of class
+ * inheritance behind-the-scene. Such classes are called "iclass"es and
+ * distinguished using ::RUBY_T_ICLASS in C level. They are truly
+ * transparent from Ruby level but can be accessed from C, by using this
+ * API.
+ */
+VALUE rb_class_get_superclass(VALUE klass);
+RBIMPL_SYMBOL_EXPORT_END()
+
+#endif /* RBIMPL_RCLASS_H */
diff --git a/include/ruby/internal/core/rdata.h b/include/ruby/internal/core/rdata.h
new file mode 100644
index 0000000000..f6656b6546
--- /dev/null
+++ b/include/ruby/internal/core/rdata.h
@@ -0,0 +1,410 @@
+#ifndef RBIMPL_RDATA_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_RDATA_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Defines struct ::RData.
+ */
+#include "ruby/internal/config.h"
+
+#ifdef STDC_HEADERS
+# include <stddef.h>
+#endif
+
+#include "ruby/internal/attr/deprecated.h"
+#include "ruby/internal/attr/warning.h"
+#include "ruby/internal/cast.h"
+#include "ruby/internal/core/rbasic.h"
+#include "ruby/internal/dllexport.h"
+#include "ruby/internal/fl_type.h"
+#include "ruby/internal/value.h"
+#include "ruby/internal/value_type.h"
+#include "ruby/defines.h"
+
+/** @cond INTERNAL_MACRO */
+#ifdef RUBY_UNTYPED_DATA_WARNING
+# /* Take that. */
+#elif defined(RUBY_EXPORT)
+# define RUBY_UNTYPED_DATA_WARNING 1
+#else
+# define RUBY_UNTYPED_DATA_WARNING 0
+#endif
+
+#define RBIMPL_DATA_FUNC(f) RBIMPL_CAST((void (*)(void *))(f))
+#define RBIMPL_ATTRSET_UNTYPED_DATA_FUNC() \
+ RBIMPL_ATTR_WARNING(("untyped Data is unsafe; use TypedData instead")) \
+ RBIMPL_ATTR_DEPRECATED(("by TypedData"))
+
+#define RBIMPL_MACRO_SELECT(x, y) x ## y
+#define RUBY_MACRO_SELECT(x, y) RBIMPL_MACRO_SELECT(x, y)
+/** @endcond */
+
+/**
+ * Convenient casting macro.
+ *
+ * @param obj An object, which is in fact an ::RData.
+ * @return The passed object casted to ::RData.
+ */
+#define RDATA(obj) RBIMPL_CAST((struct RData *)(obj))
+
+/**
+ * Convenient getter macro.
+ *
+ * @param obj An object, which is in fact an ::RData.
+ * @return The passed object's ::RData::data field.
+ */
+#define DATA_PTR(obj) RDATA(obj)->data
+
+/**
+ * This is a value you can set to ::RData::dfree. Setting this means the data
+ * was allocated using ::ruby_xmalloc() (or variants), and shall be freed using
+ * ::ruby_xfree().
+ *
+ * @warning Do not use this if you want to use system malloc, because the
+ * system and Ruby might or might not share the same malloc
+ * implementation.
+ */
+#define RUBY_DEFAULT_FREE RBIMPL_DATA_FUNC(-1)
+
+/**
+ * This is a value you can set to ::RData::dfree. Setting this means the data
+ * is managed by someone else, like, statically allocated. Of course you are
+ * on your own then.
+ */
+#define RUBY_NEVER_FREE RBIMPL_DATA_FUNC(0)
+
+/**
+ * @private
+ *
+ * @deprecated This macro once was a thing in the old days, but makes no sense
+ * any longer today. Exists here for backwards compatibility
+ * only. You can safely forget about it.
+ */
+#define RUBY_UNTYPED_DATA_FUNC(f) f RBIMPL_ATTRSET_UNTYPED_DATA_FUNC()
+
+/*
+#define RUBY_DATA_FUNC(func) ((void (*)(void*))(func))
+*/
+
+/**
+ * This is the type of callbacks registered to ::RData. The argument is the
+ * `data` field.
+ */
+typedef void (*RUBY_DATA_FUNC)(void*);
+
+/**
+ * @deprecated
+ *
+ * Old "untyped" user data. It has roughly the same usage as struct
+ * ::RTypedData, but lacked several features such as support for compaction GC.
+ * Use of this struct is not recommended any longer. If it is dead necessary,
+ * please inform the core devs about your usage.
+ *
+ * @internal
+ *
+ * @shyouhei tried to add RBIMPL_ATTR_DEPRECATED for this type but that yielded
+ * too many warnings in the core. Maybe we want to retry later... Just add
+ * deprecated document for now.
+ */
+struct RData {
+
+ /** Basic part, including flags and class. */
+ struct RBasic basic;
+
+ /**
+ * This function is called when the object is experiencing GC marks. If it
+ * contains references to other Ruby objects, you need to mark them also.
+ * Otherwise GC will smash your data.
+ *
+ * @see rb_gc_mark()
+ * @warning This is called during GC runs. Object allocations are
+ * impossible at that moment (that is why GC runs).
+ */
+ RUBY_DATA_FUNC dmark;
+
+ /**
+ * This function is called when the object is no longer used. You need to
+ * do whatever necessary to avoid memory leaks.
+ *
+ * @warning This is called during GC runs. Object allocations are
+ * impossible at that moment (that is why GC runs).
+ */
+ RUBY_DATA_FUNC dfree;
+
+ /** Pointer to the actual C level struct that you want to wrap. */
+ void *data;
+};
+
+RBIMPL_SYMBOL_EXPORT_BEGIN()
+
+/**
+ * This is the primitive way to wrap an existing C struct into ::RData.
+ *
+ * @param[in] klass Ruby level class of the returning object.
+ * @param[in] datap Pointer to the target C struct.
+ * @param[in] dmark Mark function.
+ * @param[in] dfree Free function.
+ * @exception rb_eTypeError `klass` is not a class.
+ * @exception rb_eNoMemError Out of memory.
+ * @return An allocated object that wraps `datap`.
+ */
+VALUE rb_data_object_wrap(VALUE klass, void *datap, RUBY_DATA_FUNC dmark, RUBY_DATA_FUNC dfree);
+
+/**
+ * Identical to rb_data_object_wrap(), except it allocates a new data region
+ * internally instead of taking an existing one. The allocation is done using
+ * ruby_calloc(). Hence it makes no sense to pass anything other than
+ * ::RUBY_DEFAULT_FREE to the last argument.
+ *
+ * @param[in] klass Ruby level class of the returning object.
+ * @param[in] size Requested size of memory to allocate.
+ * @param[in] dmark Mark function.
+ * @param[in] dfree Free function.
+ * @exception rb_eTypeError `klass` is not a class.
+ * @exception rb_eNoMemError Out of memory.
+ * @return An allocated object that wraps a new `size` byte region.
+ */
+VALUE rb_data_object_zalloc(VALUE klass, size_t size, RUBY_DATA_FUNC dmark, RUBY_DATA_FUNC dfree);
+
+/**
+ * @private
+ * Documented in include/ruby/internal/globals.h
+ */
+RUBY_EXTERN VALUE rb_cObject;
+RBIMPL_SYMBOL_EXPORT_END()
+
+/**
+ * Converts sval, a pointer to your struct, into a Ruby object.
+ *
+ * @param klass A ruby level class.
+ * @param mark Mark function.
+ * @param free Free function.
+ * @param sval A pointer to your struct.
+ * @exception rb_eTypeError `klass` is not a class.
+ * @exception rb_eNoMemError Out of memory.
+ * @return A created Ruby object.
+ */
+#define Data_Wrap_Struct(klass, mark, free, sval) \
+ rb_data_object_wrap( \
+ (klass), \
+ (sval), \
+ RBIMPL_DATA_FUNC(mark), \
+ RBIMPL_DATA_FUNC(free))
+
+/**
+ * @private
+ *
+ * This is an implementation detail of #Data_Make_Struct. People don't use it
+ * directly.
+ *
+ * @param result Variable name of created Ruby object.
+ * @param klass Ruby level class of the object.
+ * @param type Type name of the C struct.
+ * @param size Size of the C struct.
+ * @param mark Mark function.
+ * @param free Free function.
+ * @param sval Variable name of created C struct.
+ */
+#define Data_Make_Struct0(result, klass, type, size, mark, free, sval) \
+ VALUE result = rb_data_object_zalloc( \
+ (klass), \
+ (size), \
+ RBIMPL_DATA_FUNC(mark), \
+ RBIMPL_DATA_FUNC(free)); \
+ (sval) = RBIMPL_CAST((type *)DATA_PTR(result)); \
+ RBIMPL_CAST(/*suppress unused variable warnings*/(void)(sval))
+
+/**
+ * Identical to #Data_Wrap_Struct, except it allocates a new data region
+ * internally instead of taking an existing one. The allocation is done using
+ * ruby_calloc(). Hence it makes no sense to pass anything other than
+ * ::RUBY_DEFAULT_FREE to the `free` argument.
+ *
+ * @param klass Ruby level class of the returning object.
+ * @param type Type name of the C struct.
+ * @param mark Mark function.
+ * @param free Free function.
+ * @param sval Variable name of created C struct.
+ * @exception rb_eTypeError `klass` is not a class.
+ * @exception rb_eNoMemError Out of memory.
+ * @return A created Ruby object.
+ */
+#ifdef HAVE_STMT_AND_DECL_IN_EXPR
+#define Data_Make_Struct(klass, type, mark, free, sval) \
+ RB_GNUC_EXTENSION({ \
+ Data_Make_Struct0( \
+ data_struct_obj, \
+ klass, \
+ type, \
+ sizeof(type), \
+ mark, \
+ free, \
+ sval); \
+ data_struct_obj; \
+ })
+#else
+#define Data_Make_Struct(klass, type, mark, free, sval) \
+ rb_data_object_make( \
+ (klass), \
+ RBIMPL_DATA_FUNC(mark), \
+ RBIMPL_DATA_FUNC(free), \
+ RBIMPL_CAST((void **)&(sval)), \
+ sizeof(type))
+#endif
+
+/**
+ * Obtains a C struct from inside of a wrapper Ruby object.
+ *
+ * @param obj An instance of ::RData.
+ * @param type Type name of the C struct.
+ * @param sval Variable name of obtained C struct.
+ * @return Unwrapped C struct that `obj` holds.
+ */
+#define Data_Get_Struct(obj, type, sval) \
+ ((sval) = RBIMPL_CAST((type*)rb_data_object_get(obj)))
+
+RBIMPL_ATTRSET_UNTYPED_DATA_FUNC()
+/**
+ * @private
+ *
+ * This is an implementation detail of rb_data_object_wrap(). People don't use
+ * it directly.
+ *
+ * @param[in] klass Ruby level class of the returning object.
+ * @param[in] ptr Pointer to the target C struct.
+ * @param[in] mark Mark function.
+ * @param[in] free Free function.
+ * @exception rb_eTypeError `klass` is not a class.
+ * @exception rb_eNoMemError Out of memory.
+ * @return An allocated object that wraps `datap`.
+ */
+static inline VALUE
+rb_data_object_wrap_warning(VALUE klass, void *ptr, RUBY_DATA_FUNC mark, RUBY_DATA_FUNC free)
+{
+ return rb_data_object_wrap(klass, ptr, mark, free);
+}
+
+/**
+ * @private
+ *
+ * This is an implementation detail of #Data_Get_Struct. People don't use it
+ * directly.
+ *
+ * @param[in] obj An instance of ::RData.
+ * @return Unwrapped C struct that `obj` holds.
+ */
+static inline void *
+rb_data_object_get(VALUE obj)
+{
+ Check_Type(obj, RUBY_T_DATA);
+ return DATA_PTR(obj);
+}
+
+RBIMPL_ATTRSET_UNTYPED_DATA_FUNC()
+/**
+ * @private
+ *
+ * This is an implementation detail of #Data_Get_Struct. People don't use it
+ * directly.
+ *
+ * @param[in] obj An instance of ::RData.
+ * @return Unwrapped C struct that `obj` holds.
+ */
+static inline void *
+rb_data_object_get_warning(VALUE obj)
+{
+ return rb_data_object_get(obj);
+}
+
+#if defined(HAVE_BUILTIN___BUILTIN_CHOOSE_EXPR_CONSTANT_P)
+# define rb_data_object_wrap_warning(klass, ptr, mark, free) \
+ RB_GNUC_EXTENSION( \
+ __builtin_choose_expr( \
+ __builtin_constant_p(klass) && !(klass), \
+ rb_data_object_wrap(klass, ptr, mark, free), \
+ (rb_data_object_wrap_warning)(klass, ptr, mark, free)))
+#endif
+
+/**
+ * This is an implementation detail of #Data_Make_Struct. People don't use it
+ * directly.
+ *
+ * @param[in] klass Ruby level class of the returning object.
+ * @param[in] mark_func Mark function.
+ * @param[in] free_func Free function.
+ * @param[in] datap Variable of created C struct.
+ * @param[in] size Requested size of allocation.
+ * @exception rb_eTypeError `klass` is not a class.
+ * @exception rb_eNoMemError Out of memory.
+ * @return A created Ruby object.
+ * @post `*datap` holds the created C struct.
+ */
+static inline VALUE
+rb_data_object_make(VALUE klass, RUBY_DATA_FUNC mark_func, RUBY_DATA_FUNC free_func, void **datap, size_t size)
+{
+ Data_Make_Struct0(result, klass, void, size, mark_func, free_func, *datap);
+ return result;
+}
+
+RBIMPL_ATTR_DEPRECATED(("by: rb_data_object_wrap"))
+/** @deprecated This function was renamed to rb_data_object_wrap(). */
+static inline VALUE
+rb_data_object_alloc(VALUE klass, void *data, RUBY_DATA_FUNC dmark, RUBY_DATA_FUNC dfree)
+{
+ return rb_data_object_wrap(klass, data, dmark, dfree);
+}
+
+RBIMPL_ATTR_DEPRECATED(("by: rb_cObject. Will be removed in 3.1."))
+RBIMPL_ATTR_PURE()
+/**
+ * @private
+ *
+ * @deprecated There once was a variable called rb_cData, which no longer
+ * exists today. This function is a function because we want
+ * warnings for the usages.
+ */
+static inline VALUE
+rb_cData(void)
+{
+ return rb_cObject;
+}
+
+/**
+ * @private
+ *
+ * @deprecated This macro once was a thing in the old days, but makes no sense
+ * any longer today. Exists here for backwards compatibility
+ * only. You can safely forget about it.
+ */
+#define rb_cData rb_cData()
+
+/** @cond INTERNAL_MACRO */
+#define rb_data_object_wrap_0 rb_data_object_wrap
+#define rb_data_object_wrap_1 rb_data_object_wrap_warning
+#define rb_data_object_wrap_2 rb_data_object_wrap_ /* Used here vvvv */
+#define rb_data_object_wrap RUBY_MACRO_SELECT(rb_data_object_wrap_2, RUBY_UNTYPED_DATA_WARNING)
+#define rb_data_object_get_0 rb_data_object_get
+#define rb_data_object_get_1 rb_data_object_get_warning
+#define rb_data_object_get_2 rb_data_object_get_ /* Used here vvvv */
+#define rb_data_object_get RUBY_MACRO_SELECT(rb_data_object_get_2, RUBY_UNTYPED_DATA_WARNING)
+#define rb_data_object_make_0 rb_data_object_make
+#define rb_data_object_make_1 rb_data_object_make_warning
+#define rb_data_object_make_2 rb_data_object_make_ /* Used here vvvv */
+#define rb_data_object_make RUBY_MACRO_SELECT(rb_data_object_make_2, RUBY_UNTYPED_DATA_WARNING)
+/** @endcond */
+#endif /* RBIMPL_RDATA_H */
diff --git a/include/ruby/internal/core/rfile.h b/include/ruby/internal/core/rfile.h
new file mode 100644
index 0000000000..f8dddde9e5
--- /dev/null
+++ b/include/ruby/internal/core/rfile.h
@@ -0,0 +1,51 @@
+#ifndef RBIMPL_RFILE_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_RFILE_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Defines struct ::RFile.
+ */
+#include "ruby/internal/core/rbasic.h"
+#include "ruby/internal/cast.h"
+
+/* rb_io_t is in ruby/io.h. The header file has historically not been included
+ * into ruby/ruby.h. We follow that tradition. */
+struct rb_io_t;
+
+/**
+ * Ruby's File and IO. Ruby's IO are not just file descriptors. They have
+ * buffers. They also have encodings. Various information are controlled
+ * using this struct.
+ */
+struct RFile {
+
+ /** Basic part, including flags and class. */
+ struct RBasic basic;
+
+ /** IO's specific fields. */
+ struct rb_io_t *fptr;
+};
+
+/**
+ * Convenient casting macro.
+ *
+ * @param obj An object, which is in fact an ::RFile.
+ * @return The passed object casted to ::RFile.
+ */
+#define RFILE(obj) RBIMPL_CAST((struct RFile *)(obj))
+#endif /* RBIMPL_RFILE_H */
diff --git a/include/ruby/internal/core/rhash.h b/include/ruby/internal/core/rhash.h
new file mode 100644
index 0000000000..61d2c15d87
--- /dev/null
+++ b/include/ruby/internal/core/rhash.h
@@ -0,0 +1,144 @@
+#ifndef RBIMPL_RHASH_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_RHASH_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Routines to manipulate struct RHash.
+ * @note The struct RHash itself is opaque.
+ */
+#include "ruby/internal/config.h"
+
+#ifdef STDC_HEADERS
+# include <stddef.h>
+#endif
+
+#include "ruby/internal/dllexport.h"
+#include "ruby/internal/value.h"
+#if !defined RUBY_EXPORT && !defined RUBY_NO_OLD_COMPATIBILITY
+# include "ruby/backward.h"
+#endif
+
+/**
+ * Retrieves the internal table.
+ *
+ * @param[in] h An instance of RHash.
+ * @pre `h` must be of ::RUBY_T_HASH.
+ * @return A struct st_table which has the contents of this hash.
+ * @note Nowadays as Ruby evolved over ages, RHash has multiple backend
+ * storage engines. `h`'s backend is not guaranteed to be a
+ * st_table. This function creates one when necessary.
+ */
+#define RHASH_TBL(h) rb_hash_tbl(h, __FILE__, __LINE__)
+
+/**
+ * @private
+ *
+ * @deprecated This macro once was a thing in the old days, but makes no sense
+ * any longer today. Exists here for backwards compatibility
+ * only. You can safely forget about it.
+ *
+ * @internal
+ *
+ * Declaration of rb_hash_iter_lev() is at include/ruby/backward.h.
+ */
+#define RHASH_ITER_LEV(h) rb_hash_iter_lev(h)
+
+/**
+ * @private
+ *
+ * @deprecated This macro once was a thing in the old days, but makes no sense
+ * any longer today. Exists here for backwards compatibility
+ * only. You can safely forget about it.
+ *
+ * @internal
+ *
+ * Declaration of rb_hash_ifnone() is at include/ruby/backward.h.
+ */
+#define RHASH_IFNONE(h) rb_hash_ifnone(h)
+
+/**
+ * Queries the size of the hash. Size here means the number of keys that the
+ * hash stores.
+ *
+ * @param[in] h An instance of RHash.
+ * @pre `h` must be of ::RUBY_T_HASH.
+ * @return The size of the hash.
+ */
+#define RHASH_SIZE(h) rb_hash_size_num(h)
+
+/**
+ * Checks if the hash is empty.
+ *
+ * @param[in] h An instance of RHash.
+ * @pre `h` must be of ::RUBY_T_HASH.
+ * @retval true It is.
+ * @retval false It isn't.
+ */
+#define RHASH_EMPTY_P(h) (RHASH_SIZE(h) == 0)
+
+/**
+ * Destructively updates the default value of the hash.
+ *
+ * @param[out] h An instance of RHash.
+ * @param[in] ifnone Arbitrary default value.
+ * @pre `h` must be of ::RUBY_T_HASH.
+ *
+ * @internal
+ *
+ * But why you can set this, given rb_hash_ifnone() doesn't exist?
+ */
+#define RHASH_SET_IFNONE(h, ifnone) rb_hash_set_ifnone((VALUE)h, ifnone)
+
+struct st_table; /* in ruby/st.h */
+
+RBIMPL_SYMBOL_EXPORT_BEGIN()
+
+/**
+ * This is the implementation detail of #RHASH_SIZE. People don't call this
+ * directly.
+ *
+ * @param[in] hash An instance of RHash.
+ * @pre `hash` must be of ::RUBY_T_HASH.
+ * @return The size of the hash.
+ */
+size_t rb_hash_size_num(VALUE hash);
+
+/**
+ * This is the implementation detail of #RHASH_TBL. People don't call this
+ * directly.
+ *
+ * @param[in] hash An instance of RHash.
+ * @param[in] file The `__FILE__`.
+ * @param[in] line The `__LINE__`.
+ * @pre `hash` must be of ::RUBY_T_HASH.
+ * @return Table that has the contents of the hash.
+ */
+struct st_table *rb_hash_tbl(VALUE hash, const char *file, int line);
+
+/**
+ * This is the implementation detail of #RHASH_SET_IFNONE. People don't call
+ * this directly.
+ *
+ * @param[out] hash An instance of RHash.
+ * @param[in] ifnone Arbitrary default value.
+ * @pre `hash` must be of ::RUBY_T_HASH.
+ */
+VALUE rb_hash_set_ifnone(VALUE hash, VALUE ifnone);
+RBIMPL_SYMBOL_EXPORT_END()
+
+#endif /* RBIMPL_RHASH_H */
diff --git a/include/ruby/internal/core/rmatch.h b/include/ruby/internal/core/rmatch.h
new file mode 100644
index 0000000000..2d2fd897f5
--- /dev/null
+++ b/include/ruby/internal/core/rmatch.h
@@ -0,0 +1,146 @@
+#ifndef RBIMPL_RMATCH_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_RMATCH_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Defines struct ::RMatch.
+ */
+#include "ruby/internal/attr/artificial.h"
+#include "ruby/internal/attr/pure.h"
+#include "ruby/internal/cast.h"
+#include "ruby/internal/core/rbasic.h"
+#include "ruby/internal/value.h"
+#include "ruby/internal/value_type.h"
+#include "ruby/assert.h"
+
+/**
+ * Convenient casting macro.
+ *
+ * @param obj An object, which is in fact an ::RMatch.
+ * @return The passed object casted to ::RMatch.
+ */
+#define RMATCH(obj) RBIMPL_CAST((struct RMatch *)(obj))
+/** @cond INTERNAL_MACRO */
+#define RMATCH_REGS RMATCH_REGS
+/** @endcond */
+
+struct re_patter_buffer; /* a.k.a. OnigRegexType, defined in onigmo.h */
+struct re_registers; /* Also in onigmo.h */
+
+/**
+ * @old{re_pattern_buffer}
+ *
+ * @internal
+ *
+ * @shyouhei wonders: is anyone actively using this typedef ...?
+ */
+typedef struct re_pattern_buffer Regexp;
+
+/**
+ * Represents the region of a capture group. This is basically for caching
+ * purpose. re_registers have similar concepts (`beg` and `end`) but they are
+ * in `ptrdiff_t*`. In order for us to implement `MatchData#offset` that info
+ * has to be converted to offset integers. This is the struct to hold such
+ * things.
+ *
+ * @internal
+ *
+ * But why on earth it has to be visible from extension libraries?
+ */
+struct rmatch_offset {
+ long beg; /**< Beginning of a group. */
+ long end; /**< End of a group. */
+};
+
+/** Represents a match. */
+struct rmatch {
+ /**
+ * "Registers" of a match. This is a quasi-opaque struct that holds
+ * execution result of a match. Roughly resembles `&~`.
+ */
+ struct re_registers regs;
+
+ /** Capture group offsets, in C array. */
+ struct rmatch_offset *char_offset;
+
+ /** Number of ::rmatch_offset that ::rmatch::char_offset holds. */
+ int char_offset_num_allocated;
+};
+
+/**
+ * Regular expression execution context. When a regular expression "matches"
+ * to a string, it generates capture groups etc. This struct holds that info.
+ * Visible from Ruby as an instance of `MatchData`.
+ *
+ * @note There is no way for extension libraries to manually generate this
+ * struct except by actually exercising the match operation of a regular
+ * expression.
+ */
+struct RMatch {
+
+ /** Basic part, including flags and class. */
+ struct RBasic basic;
+
+ /**
+ * The target string that the match was made against.
+ */
+ VALUE str;
+
+ /**
+ * The result of this match.
+ */
+ struct rmatch *rmatch;
+
+ /**
+ * The expression of this match.
+ */
+ VALUE regexp; /* RRegexp */
+};
+
+RBIMPL_ATTR_PURE_UNLESS_DEBUG()
+RBIMPL_ATTR_ARTIFICIAL()
+/**
+ * Queries the raw ::re_registers.
+ *
+ * @param[in] match A match object
+ * @pre `match` must be of ::RMatch.
+ * @return Its execution result.
+ * @note Good. So you are aware of the fact that it could return NULL.
+ * Yes. It actually does. This is a really bizarre thing. The
+ * situation is about `String#gsub` and its family. They take
+ * strings as arguments, like `"foo".sub("bar", "baz")`. On such
+ * situations, in order to optimise memory allocations, these
+ * methods do not involve regular expressions at all. They just
+ * sequentially scan the receiver. Okay. The story begins here.
+ * Even when they do not kick our regexp engine, there must be
+ * backref objects e.g. `$&`. But how? You know what? Ruby fakes
+ * them. It allocates an empty ::RMatch and behaves as if there
+ * were execution contexts. In reality there weren't. No
+ * ::re_registers are allocated then. There is no way for this
+ * function but to return NULL for those fake ::RMatch. This is
+ * the reason for the nullability of this function.
+ */
+static inline struct re_registers *
+RMATCH_REGS(VALUE match)
+{
+ RBIMPL_ASSERT_TYPE(match, RUBY_T_MATCH);
+ RBIMPL_ASSERT_OR_ASSUME(RMATCH(match)->rmatch != NULL);
+ return &RMATCH(match)->rmatch->regs;
+}
+
+#endif /* RBIMPL_RMATCH_H */
diff --git a/include/ruby/internal/core/robject.h b/include/ruby/internal/core/robject.h
new file mode 100644
index 0000000000..f2028063a6
--- /dev/null
+++ b/include/ruby/internal/core/robject.h
@@ -0,0 +1,185 @@
+#ifndef RBIMPL_ROBJECT_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_ROBJECT_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Defines struct ::RObject.
+ */
+#include "ruby/internal/config.h"
+
+#ifdef HAVE_STDINT_H
+# include <stdint.h>
+#endif
+
+#include "ruby/internal/attr/artificial.h"
+#include "ruby/internal/attr/deprecated.h"
+#include "ruby/internal/attr/pure.h"
+#include "ruby/internal/cast.h"
+#include "ruby/internal/fl_type.h"
+#include "ruby/internal/value.h"
+#include "ruby/internal/value_type.h"
+
+/**
+ * Convenient casting macro.
+ *
+ * @param obj An object, which is in fact an ::RRegexp.
+ * @return The passed object casted to ::RRegexp.
+ */
+#define ROBJECT(obj) RBIMPL_CAST((struct RObject *)(obj))
+/** @cond INTERNAL_MACRO */
+#define ROBJECT_EMBED_LEN_MAX ROBJECT_EMBED_LEN_MAX
+#define ROBJECT_EMBED ROBJECT_EMBED
+#define ROBJECT_NUMIV ROBJECT_NUMIV
+#define ROBJECT_IVPTR ROBJECT_IVPTR
+#define ROBJECT_IV_INDEX_TBL ROBJECT_IV_INDEX_TBL
+/** @endcond */
+
+/**
+ * @private
+ *
+ * Bits that you can set to ::RBasic::flags.
+ */
+enum ruby_robject_flags {
+ /**
+ * This flag has something to do with memory footprint. If the object is
+ * "small" enough, ruby tries to be creative to abuse padding bits of
+ * struct ::RObject for storing instance variables. This flag denotes that
+ * situation.
+ *
+ * @warning This bit has to be considered read-only. Setting/clearing
+ * this bit without corresponding fix up must cause immediate
+ * SEGV. Also, internal structures of an object change
+ * dynamically and transparently throughout of its lifetime.
+ * Don't assume it being persistent.
+ *
+ * @internal
+ *
+ * 3rd parties must not be aware that there even is more than one way to
+ * store instance variables. Might better be hidden.
+ */
+ ROBJECT_EMBED = RUBY_FL_USER1
+};
+
+/**
+ * This is an enum because GDB wants it (rather than a macro). People need not
+ * bother.
+ */
+enum ruby_robject_consts {
+ /** Max possible number of instance variables that can be embedded. */
+ ROBJECT_EMBED_LEN_MAX = RBIMPL_EMBED_LEN_MAX_OF(VALUE)
+};
+
+struct st_table;
+
+/**
+ * Ruby's ordinal objects. Unless otherwise special cased, all predefined and
+ * user-defined classes share this struct to hold their instances.
+ */
+struct RObject {
+
+ /** Basic part, including flags and class. */
+ struct RBasic basic;
+
+ /** Object's specific fields. */
+ union {
+
+ /**
+ * Object that use separated memory region for instance variables use
+ * this pattern.
+ */
+ struct {
+
+ /**
+ * Number of instance variables. This is per object; objects might
+ * differ in this field even if they have the identical classes.
+ */
+ uint32_t numiv;
+
+ /** Pointer to a C array that holds instance variables. */
+ VALUE *ivptr;
+
+ /**
+ * This is a table that holds instance variable name to index
+ * mapping. Used when accessing instance variables using names.
+ *
+ * @internal
+ *
+ * This is a shortcut for `RCLASS_IV_INDEX_TBL(rb_obj_class(obj))`.
+ */
+ struct st_table *iv_index_tbl;
+ } heap;
+
+ /**
+ * Embedded instance variables. When an object is small enough, it
+ * uses this area to store the instance variables.
+ */
+ VALUE ary[ROBJECT_EMBED_LEN_MAX];
+ } as;
+};
+
+RBIMPL_ATTR_PURE_UNLESS_DEBUG()
+RBIMPL_ATTR_ARTIFICIAL()
+/**
+ * Queries the number of instance variables.
+ *
+ * @param[in] obj Object in question.
+ * @return Its number of instance variables.
+ * @pre `obj` must be an instance of ::RObject.
+ */
+static inline uint32_t
+ROBJECT_NUMIV(VALUE obj)
+{
+ RBIMPL_ASSERT_TYPE(obj, RUBY_T_OBJECT);
+
+ if (RB_FL_ANY_RAW(obj, ROBJECT_EMBED)) {
+ return ROBJECT_EMBED_LEN_MAX;
+ }
+ else {
+ return ROBJECT(obj)->as.heap.numiv;
+ }
+}
+
+RBIMPL_ATTR_PURE_UNLESS_DEBUG()
+RBIMPL_ATTR_ARTIFICIAL()
+/**
+ * Queries the instance variables.
+ *
+ * @param[in] obj Object in question.
+ * @return Its instance variables, in C array.
+ * @pre `obj` must be an instance of ::RObject.
+ *
+ * @internal
+ *
+ * @shyouhei finds no reason for this to be visible from extension libraries.
+ */
+static inline VALUE *
+ROBJECT_IVPTR(VALUE obj)
+{
+ RBIMPL_ASSERT_TYPE(obj, RUBY_T_OBJECT);
+
+ struct RObject *const ptr = ROBJECT(obj);
+
+ if (RB_FL_ANY_RAW(obj, ROBJECT_EMBED)) {
+ return ptr->as.ary;
+ }
+ else {
+ return ptr->as.heap.ivptr;
+ }
+}
+
+#endif /* RBIMPL_ROBJECT_H */
diff --git a/include/ruby/internal/core/rregexp.h b/include/ruby/internal/core/rregexp.h
new file mode 100644
index 0000000000..cf54a399f1
--- /dev/null
+++ b/include/ruby/internal/core/rregexp.h
@@ -0,0 +1,168 @@
+#ifndef RBIMPL_RREGEXP_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_RREGEXP_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Defines struct ::RRegexp.
+ */
+#include "ruby/internal/attr/artificial.h"
+#include "ruby/internal/attr/pure.h"
+#include "ruby/internal/cast.h"
+#include "ruby/internal/core/rbasic.h"
+#include "ruby/internal/core/rstring.h"
+#include "ruby/internal/value.h"
+#include "ruby/internal/value_type.h"
+
+/**
+ * Convenient casting macro.
+ *
+ * @param obj An object, which is in fact an ::RRegexp.
+ * @return The passed object casted to ::RRegexp.
+ */
+#define RREGEXP(obj) RBIMPL_CAST((struct RRegexp *)(obj))
+
+/**
+ * Convenient accessor macro.
+ *
+ * @param obj An object, which is in fact an ::RRegexp.
+ * @return The passed object's pattern buffer.
+ */
+#define RREGEXP_PTR(obj) (RREGEXP(obj)->ptr)
+/** @cond INTERNAL_MACRO */
+#define RREGEXP_SRC RREGEXP_SRC
+#define RREGEXP_SRC_PTR RREGEXP_SRC_PTR
+#define RREGEXP_SRC_LEN RREGEXP_SRC_LEN
+#define RREGEXP_SRC_END RREGEXP_SRC_END
+/** @endcond */
+
+struct re_patter_buffer; /* a.k.a. OnigRegexType, defined in onigmo.h */
+
+/**
+ * Ruby's regular expression. A regexp is compiled into its own intermediate
+ * representation. This one holds that info. Regexp "match" operation then
+ * executes that IR.
+ */
+struct RRegexp {
+
+ /** Basic part, including flags and class. */
+ struct RBasic basic;
+
+ /**
+ * The pattern buffer. This is a quasi-opaque struct that holds compiled
+ * intermediate representation of the regular expression.
+ *
+ * @note Compilation of a regexp could be delayed until actual match.
+ */
+ struct re_pattern_buffer *ptr;
+
+ /** Source code of this expression. */
+ const VALUE src;
+
+ /**
+ * Reference count. A regexp match can take extraordinarily long time to
+ * run. Ruby's regular expression is heavily extended and not a regular
+ * language any longer; runs in NP-time in practice. Now, Ruby also has
+ * threads and GVL. In order to prevent long GVL lockup, our regexp engine
+ * can release it on occasions. This means that multiple threads can touch
+ * a regular expressions at once. That itself is okay. But their cleanup
+ * phase shall wait for all the concurrent runs, to prevent use-after-free
+ * situation. This field is used to count such threads that are executing
+ * this particular pattern buffer.
+ *
+ * @warning Of course, touching this field from extension libraries causes
+ * catastrophic effects. Just leave it.
+ */
+ unsigned long usecnt;
+};
+
+RBIMPL_ATTR_PURE_UNLESS_DEBUG()
+RBIMPL_ATTR_ARTIFICIAL()
+/**
+ * Convenient getter function.
+ *
+ * @param[in] rexp The regular expression in question.
+ * @return The source code of the regular expression.
+ * @pre `rexp` must be of ::RRegexp.
+ */
+static inline VALUE
+RREGEXP_SRC(VALUE rexp)
+{
+ RBIMPL_ASSERT_TYPE(rexp, RUBY_T_REGEXP);
+ VALUE ret = RREGEXP(rexp)->src;
+ RBIMPL_ASSERT_TYPE(ret, RUBY_T_STRING);
+ return ret;
+}
+
+RBIMPL_ATTR_PURE_UNLESS_DEBUG()
+RBIMPL_ATTR_ARTIFICIAL()
+/**
+ * Convenient getter function.
+ *
+ * @param[in] rexp The regular expression in question.
+ * @return The source code of the regular expression, in C's string.
+ * @pre `rexp` must be of ::RRegexp.
+ *
+ * @internal
+ *
+ * It seems nobody uses this function in the wild. Subject to hide?
+ */
+static inline char *
+RREGEXP_SRC_PTR(VALUE rexp)
+{
+ return RSTRING_PTR(RREGEXP_SRC(rexp));
+}
+
+RBIMPL_ATTR_PURE_UNLESS_DEBUG()
+RBIMPL_ATTR_ARTIFICIAL()
+/**
+ * Convenient getter function.
+ *
+ * @param[in] rexp The regular expression in question.
+ * @return The length of the source code of the regular expression.
+ * @pre `rexp` must be of ::RRegexp.
+ *
+ * @internal
+ *
+ * It seems nobody uses this function in the wild. Subject to hide?
+ */
+static inline long
+RREGEXP_SRC_LEN(VALUE rexp)
+{
+ return RSTRING_LEN(RREGEXP_SRC(rexp));
+}
+
+RBIMPL_ATTR_PURE_UNLESS_DEBUG()
+RBIMPL_ATTR_ARTIFICIAL()
+/**
+ * Convenient getter function.
+ *
+ * @param[in] rexp The regular expression in question.
+ * @return The end of the source code of the regular expression.
+ * @pre `rexp` must be of ::RRegexp.
+ *
+ * @internal
+ *
+ * It seems nobody uses this function in the wild. Subject to hide?
+ */
+static inline char *
+RREGEXP_SRC_END(VALUE rexp)
+{
+ return RSTRING_END(RREGEXP_SRC(rexp));
+}
+
+#endif /* RBIMPL_RREGEXP_H */
diff --git a/include/ruby/internal/core/rstring.h b/include/ruby/internal/core/rstring.h
new file mode 100644
index 0000000000..a682dbe22f
--- /dev/null
+++ b/include/ruby/internal/core/rstring.h
@@ -0,0 +1,577 @@
+#ifndef RBIMPL_RSTRING_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_RSTRING_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Defines struct ::RString.
+ */
+#include "ruby/internal/config.h"
+#include "ruby/internal/arithmetic/long.h"
+#include "ruby/internal/attr/artificial.h"
+#include "ruby/internal/attr/pure.h"
+#include "ruby/internal/cast.h"
+#include "ruby/internal/core/rbasic.h"
+#include "ruby/internal/dllexport.h"
+#include "ruby/internal/fl_type.h"
+#include "ruby/internal/value_type.h"
+#include "ruby/internal/warning_push.h"
+#include "ruby/assert.h"
+
+/**
+ * Convenient casting macro.
+ *
+ * @param obj An object, which is in fact an ::RString.
+ * @return The passed object casted to ::RString.
+ */
+#define RSTRING(obj) RBIMPL_CAST((struct RString *)(obj))
+
+/** @cond INTERNAL_MACRO */
+#define RSTRING_NOEMBED RSTRING_NOEMBED
+#if !USE_RVARGC
+#define RSTRING_EMBED_LEN_MASK RSTRING_EMBED_LEN_MASK
+#define RSTRING_EMBED_LEN_SHIFT RSTRING_EMBED_LEN_SHIFT
+#define RSTRING_EMBED_LEN_MAX RSTRING_EMBED_LEN_MAX
+#endif
+#define RSTRING_FSTR RSTRING_FSTR
+#define RSTRING_EMBED_LEN RSTRING_EMBED_LEN
+#define RSTRING_LEN RSTRING_LEN
+#define RSTRING_LENINT RSTRING_LENINT
+#define RSTRING_PTR RSTRING_PTR
+#define RSTRING_END RSTRING_END
+/** @endcond */
+
+/**
+ * @name Conversion of Ruby strings into C's
+ *
+ * @{
+ */
+
+/**
+ * Ensures that the parameter object is a String. This is done by calling its
+ * `to_str` method.
+ *
+ * @param[in,out] v Arbitrary Ruby object.
+ * @exception rb_eTypeError No implicit conversion defined.
+ * @post `v` is a String.
+ */
+#define StringValue(v) rb_string_value(&(v))
+
+/**
+ * Identical to #StringValue, except it returns a `char*`.
+ *
+ * @param[in,out] v Arbitrary Ruby object.
+ * @exception rb_eTypeError No implicit conversion defined.
+ * @return Converted Ruby string's backend C string.
+ * @post `v` is a String.
+ */
+#define StringValuePtr(v) rb_string_value_ptr(&(v))
+
+/**
+ * Identical to #StringValuePtr, except it additionally checks for the contents
+ * for viability as a C string. Ruby can accept wider range of contents as
+ * strings, compared to C. This function is to check that.
+ *
+ * @param[in,out] v Arbitrary Ruby object.
+ * @exception rb_eTypeError No implicit conversion defined.
+ * @exception rb_eArgError String is not C-compatible.
+ * @return Converted Ruby string's backend C string.
+ * @post `v` is a String.
+ */
+#define StringValueCStr(v) rb_string_value_cstr(&(v))
+
+/**
+ * @private
+ *
+ * @deprecated This macro once was a thing in the old days, but makes no sense
+ * any longer today. Exists here for backwards compatibility
+ * only. You can safely forget about it.
+ */
+#define SafeStringValue(v) StringValue(v)
+
+/**
+ * Identical to #StringValue, except it additionally converts the string's
+ * encoding to default external encoding. Ruby has a concept called encodings.
+ * A string can have different encoding than the environment expects. Someone
+ * has to make sure its contents be converted to something suitable. This is
+ * that routine. Call it when necessary.
+ *
+ * @param[in,out] v Arbitrary Ruby object.
+ * @exception rb_eTypeError No implicit conversion defined.
+ * @return Converted Ruby string's backend C string.
+ * @post `v` is a String.
+ *
+ * @internal
+ *
+ * Not sure but it seems this macro does not raise on encoding
+ * incompatibilities? Doesn't sound right to @shyouhei.
+ */
+#define ExportStringValue(v) do { \
+ StringValue(v); \
+ (v) = rb_str_export(v); \
+} while (0)
+
+/** @} */
+
+/**
+ * @private
+ *
+ * Bits that you can set to ::RBasic::flags.
+ *
+ * @warning These enums are not the only bits we use for strings.
+ *
+ * @internal
+ *
+ * Actually all bits through FL_USER1 to FL_USER19 are used for strings. Why
+ * only this tiny part of them are made public here? @shyouhei can find no
+ * reason.
+ */
+enum ruby_rstring_flags {
+
+ /**
+ * This flag has something to do with memory footprint. If the string is
+ * short enough, ruby tries to be creative to abuse padding bits of struct
+ * ::RString for storing contents. If this flag is set that string does
+ * _not_ do that, to resort to good old fashioned external allocation
+ * strategy instead.
+ *
+ * @warning This bit has to be considered read-only. Setting/clearing
+ * this bit without corresponding fix up must cause immediate
+ * SEGV. Also, internal structures of a string change
+ * dynamically and transparently throughout of its lifetime.
+ * Don't assume it being persistent.
+ *
+ * @internal
+ *
+ * 3rd parties must not be aware that there even is more than one way to
+ * store a string. Might better be hidden.
+ */
+ RSTRING_NOEMBED = RUBY_FL_USER1,
+
+#if !USE_RVARGC
+ /**
+ * When a string employs embedded strategy (see ::RSTRING_NOEMBED), these
+ * bits are used to store the number of bytes actually filled into
+ * ::RString::ary.
+ *
+ * @internal
+ *
+ * 3rd parties must not be aware that there even is more than one way to
+ * store a string. Might better be hidden.
+ */
+ RSTRING_EMBED_LEN_MASK = RUBY_FL_USER2 | RUBY_FL_USER3 | RUBY_FL_USER4 |
+ RUBY_FL_USER5 | RUBY_FL_USER6,
+#endif
+
+ /* Actually, string encodings are also encoded into the flags, using
+ * remaining bits.*/
+
+ /**
+ * This flag has something to do with infamous "f"string. What is a
+ * fstring? Well it is a special subkind of strings that is immutable,
+ * deduped globally, and managed by our GC. It is much like a Symbol (in
+ * fact Symbols are dynamic these days and are backended using fstrings).
+ * This concept has been silently introduced at some point in 2.x era.
+ * Since then it gained wider acceptance in the core. But extension
+ * libraries could not know that until very recently. Strings of this flag
+ * live in a special Limbo deep inside of the interpreter. Never try to
+ * manipulate it by hand.
+ *
+ * @internal
+ *
+ * Fstrings are not the only variant strings that we implement today.
+ * Other things are behind-the-scene. This is the only one that is visible
+ * from extension library. There is no clear reason why it has to be.
+ * Given there are more "polite" ways to create fstrings, it seems this bit
+ * need not be exposed to extension libraries. Might better be hidden.
+ */
+ RSTRING_FSTR = RUBY_FL_USER17
+};
+
+#if !USE_RVARGC
+/**
+ * This is an enum because GDB wants it (rather than a macro). People need not
+ * bother.
+ */
+enum ruby_rstring_consts {
+ /** Where ::RSTRING_EMBED_LEN_MASK resides. */
+ RSTRING_EMBED_LEN_SHIFT = RUBY_FL_USHIFT + 2,
+
+ /** Max possible number of characters that can be embedded. */
+ RSTRING_EMBED_LEN_MAX = RBIMPL_EMBED_LEN_MAX_OF(char) - 1
+};
+#endif
+
+/**
+ * Ruby's String. A string in ruby conceptually has these information:
+ *
+ * - Encoding of the string.
+ * - Length of the string.
+ * - Contents of the string.
+ *
+ * It is worth noting that a string is _not_ an array of characters in ruby.
+ * It has never been. In 1.x a string was an array of integers. Since 2.x a
+ * string is no longer an array of anything. A string is a string -- just like
+ * a Time is not an integer.
+ */
+struct RString {
+
+ /** Basic part, including flags and class. */
+ struct RBasic basic;
+
+ /** String's specific fields. */
+ union {
+
+ /**
+ * Strings that use separated memory region for contents use this
+ * pattern.
+ */
+ struct {
+
+ /**
+ * Length of the string, not including terminating NUL character.
+ *
+ * @note This is in bytes.
+ */
+ long len;
+
+ /**
+ * Pointer to the contents of the string. In the old days each
+ * string had dedicated memory regions. That is no longer true
+ * today, but there still are strings of such properties. This
+ * field could be used to point such things.
+ */
+ char *ptr;
+
+ /** Auxiliary info. */
+ union {
+
+ /**
+ * Capacity of `*ptr`. A continuous memory region of at least
+ * `capa` bytes is expected to exist at `*ptr`. This can be
+ * bigger than `len`.
+ */
+ long capa;
+
+ /**
+ * Parent of the string. Nowadays strings can share their
+ * contents each other, constructing gigantic nest of objects.
+ * This situation is called "shared", and this is the field to
+ * control such properties.
+ */
+ VALUE shared;
+ } aux;
+ } heap;
+
+ /** Embedded contents. */
+ struct {
+#if USE_RVARGC
+ short len;
+ /* This is a length 1 array because:
+ * 1. GCC has a bug that does not optimize C flexible array members
+ * (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102452)
+ * 2. Zero length arrays are not supported by all compilers
+ */
+ char ary[1];
+#else
+ /**
+ * When a string is short enough, it uses this area to store the
+ * contents themselves. This was impractical in the 20th century,
+ * but these days 64 bit machines can typically hold 24 bytes here.
+ * Could be sufficiently large. In this case the length is encoded
+ * into the flags.
+ */
+ char ary[RSTRING_EMBED_LEN_MAX + 1];
+#endif
+ } embed;
+ } as;
+};
+
+RBIMPL_SYMBOL_EXPORT_BEGIN()
+/**
+ * Identical to rb_check_string_type(), except it raises exceptions in case of
+ * conversion failures.
+ *
+ * @param[in] obj Target object.
+ * @exception rb_eTypeError No implicit conversion to String.
+ * @return Return value of `obj.to_str`.
+ * @see rb_io_get_io
+ * @see rb_ary_to_ary
+ */
+VALUE rb_str_to_str(VALUE obj);
+
+/**
+ * Identical to rb_str_to_str(), except it fills the passed pointer with the
+ * converted object.
+ *
+ * @param[in,out] ptr Pointer to a variable of target object.
+ * @exception rb_eTypeError No implicit conversion to String.
+ * @return Return value of `obj.to_str`.
+ * @post `*ptr` is the return value.
+ */
+VALUE rb_string_value(volatile VALUE *ptr);
+
+/**
+ * Identical to rb_str_to_str(), except it returns the converted string's
+ * backend memory region.
+ *
+ * @param[in,out] ptr Pointer to a variable of target object.
+ * @exception rb_eTypeError No implicit conversion to String.
+ * @post `*ptr` is the return value of `obj.to_str`.
+ * @return Pointer to the contents of the return value.
+ */
+char *rb_string_value_ptr(volatile VALUE *ptr);
+
+/**
+ * Identical to rb_string_value_ptr(), except it additionally checks for the
+ * contents for viability as a C string. Ruby can accept wider range of
+ * contents as strings, compared to C. This function is to check that.
+ *
+ * @param[in,out] ptr Pointer to a variable of target object.
+ * @exception rb_eTypeError No implicit conversion to String.
+ * @exception rb_eArgError String is not C-compatible.
+ * @post `*ptr` is the return value of `obj.to_str`.
+ * @return Pointer to the contents of the return value.
+ */
+char *rb_string_value_cstr(volatile VALUE *ptr);
+
+/**
+ * Identical to rb_str_to_str(), except it additionally converts the string
+ * into default external encoding. Ruby has a concept called encodings. A
+ * string can have different encoding than the environment expects. Someone
+ * has to make sure its contents be converted to something suitable. This is
+ * that routine. Call it when necessary.
+ *
+ * @param[in] obj Target object.
+ * @exception rb_eTypeError No implicit conversion to String.
+ * @return Converted ruby string of default external encoding.
+ */
+VALUE rb_str_export(VALUE obj);
+
+/**
+ * Identical to rb_str_export(), except it converts into the locale encoding
+ * instead.
+ *
+ * @param[in] obj Target object.
+ * @exception rb_eTypeError No implicit conversion to String.
+ * @return Converted ruby string of locale encoding.
+ */
+VALUE rb_str_export_locale(VALUE obj);
+
+RBIMPL_ATTR_ERROR(("rb_check_safe_str() and Check_SafeStr() are obsolete; use StringValue() instead"))
+/**
+ * @private
+ *
+ * @deprecated This function once was a thing in the old days, but makes no
+ * sense any longer today. Exists here for backwards
+ * compatibility only. You can safely forget about it.
+ */
+void rb_check_safe_str(VALUE);
+
+/**
+ * @private
+ *
+ * @deprecated This macro once was a thing in the old days, but makes no sense
+ * any longer today. Exists here for backwards compatibility
+ * only. You can safely forget about it.
+ */
+#define Check_SafeStr(v) rb_check_safe_str(RBIMPL_CAST((VALUE)(v)))
+
+/**
+ * @private
+ *
+ * Prints diagnostic message to stderr when RSTRING_PTR or RSTRING_END
+ * is NULL.
+ *
+ * @param[in] func The function name where encountered NULL pointer.
+ */
+void rb_debug_rstring_null_ptr(const char *func);
+RBIMPL_SYMBOL_EXPORT_END()
+
+RBIMPL_ATTR_PURE_UNLESS_DEBUG()
+RBIMPL_ATTR_ARTIFICIAL()
+/**
+ * Queries the length of the string.
+ *
+ * @param[in] str String in question.
+ * @return Its length, in bytes.
+ * @pre `str` must be an instance of ::RString, and must has its
+ * ::RSTRING_NOEMBED flag off.
+ *
+ * @internal
+ *
+ * This was a macro before. It was inevitable to be public, since macros are
+ * global constructs. But should it be forever? Now that it is a function,
+ * @shyouhei thinks it could just be eliminated, hidden into implementation
+ * details.
+ */
+static inline long
+RSTRING_EMBED_LEN(VALUE str)
+{
+ RBIMPL_ASSERT_TYPE(str, RUBY_T_STRING);
+ RBIMPL_ASSERT_OR_ASSUME(! RB_FL_ANY_RAW(str, RSTRING_NOEMBED));
+
+#if USE_RVARGC
+ short f = RSTRING(str)->as.embed.len;
+#else
+ VALUE f = RBASIC(str)->flags;
+ f &= RSTRING_EMBED_LEN_MASK;
+ f >>= RSTRING_EMBED_LEN_SHIFT;
+#endif
+ return RBIMPL_CAST((long)f);
+}
+
+RBIMPL_WARNING_PUSH()
+#if RBIMPL_COMPILER_IS(Intel)
+RBIMPL_WARNING_IGNORED(413)
+#endif
+
+RBIMPL_ATTR_PURE_UNLESS_DEBUG()
+RBIMPL_ATTR_ARTIFICIAL()
+/**
+ * @private
+ *
+ * "Expands" an embedded string into an ordinal one. This is a function that
+ * returns aggregated type. The returned struct always has its `as.heap.len`
+ * an `as.heap.ptr` fields set appropriately.
+ *
+ * This is an implementation detail that 3rd parties should never bother.
+ */
+static inline struct RString
+rbimpl_rstring_getmem(VALUE str)
+{
+ RBIMPL_ASSERT_TYPE(str, RUBY_T_STRING);
+
+ if (RB_FL_ANY_RAW(str, RSTRING_NOEMBED)) {
+ return *RSTRING(str);
+ }
+ else {
+ /* Expecting compilers to optimize this on-stack struct away. */
+ struct RString retval;
+ retval.as.heap.len = RSTRING_EMBED_LEN(str);
+ retval.as.heap.ptr = RSTRING(str)->as.embed.ary;
+ return retval;
+ }
+}
+
+RBIMPL_WARNING_POP()
+
+RBIMPL_ATTR_PURE_UNLESS_DEBUG()
+RBIMPL_ATTR_ARTIFICIAL()
+/**
+ * Queries the length of the string.
+ *
+ * @param[in] str String in question.
+ * @return Its length, in bytes.
+ * @pre `str` must be an instance of ::RString.
+ */
+static inline long
+RSTRING_LEN(VALUE str)
+{
+ return rbimpl_rstring_getmem(str).as.heap.len;
+}
+
+RBIMPL_ATTR_ARTIFICIAL()
+/**
+ * Queries the contents pointer of the string.
+ *
+ * @param[in] str String in question.
+ * @return Pointer to its contents.
+ * @pre `str` must be an instance of ::RString.
+ */
+static inline char *
+RSTRING_PTR(VALUE str)
+{
+ char *ptr = rbimpl_rstring_getmem(str).as.heap.ptr;
+
+ if (RB_UNLIKELY(! ptr)) {
+ /* :BEWARE: @shyouhei thinks that currently, there are rooms for this
+ * function to return NULL. In the 20th century that was a pointless
+ * concern. However struct RString can hold fake strings nowadays. It
+ * seems no check against NULL are exercised around handling of them
+ * (one of such usages is located in marshal.c, which scares
+ * @shyouhei). Better check here for maximum safety.
+ *
+ * Also, this is not rb_warn() because RSTRING_PTR() can be called
+ * during GC (see what obj_info() does). rb_warn() needs to allocate
+ * Ruby objects. That is not possible at this moment. */
+ rb_debug_rstring_null_ptr("RSTRING_PTR");
+ }
+
+ return ptr;
+}
+
+RBIMPL_ATTR_ARTIFICIAL()
+/**
+ * Queries the end of the contents pointer of the string.
+ *
+ * @param[in] str String in question.
+ * @return Pointer to its end of contents.
+ * @pre `str` must be an instance of ::RString.
+ */
+static inline char *
+RSTRING_END(VALUE str)
+{
+ struct RString buf = rbimpl_rstring_getmem(str);
+
+ if (RB_UNLIKELY(! buf.as.heap.ptr)) {
+ /* Ditto. */
+ rb_debug_rstring_null_ptr("RSTRING_END");
+ }
+
+ return &buf.as.heap.ptr[buf.as.heap.len];
+}
+
+RBIMPL_ATTR_ARTIFICIAL()
+/**
+ * Identical to RSTRING_LEN(), except it differs for the return type.
+ *
+ * @param[in] str String in question.
+ * @exception rb_eRangeError Too long.
+ * @return Its length, in bytes.
+ * @pre `str` must be an instance of ::RString.
+ *
+ * @internal
+ *
+ * This API seems redundant but has actual usages.
+ */
+static inline int
+RSTRING_LENINT(VALUE str)
+{
+ return rb_long2int(RSTRING_LEN(str));
+}
+
+/**
+ * Convenient macro to obtain the contents and length at once.
+ *
+ * @param str String in question.
+ * @param ptrvar Variable where its contents is stored.
+ * @param lenvar Variable where its length is stored.
+ */
+#ifdef HAVE_STMT_AND_DECL_IN_EXPR
+# define RSTRING_GETMEM(str, ptrvar, lenvar) \
+ __extension__ ({ \
+ struct RString rbimpl_str = rbimpl_rstring_getmem(str); \
+ (ptrvar) = rbimpl_str.as.heap.ptr; \
+ (lenvar) = rbimpl_str.as.heap.len; \
+ })
+#else
+# define RSTRING_GETMEM(str, ptrvar, lenvar) \
+ ((ptrvar) = RSTRING_PTR(str), \
+ (lenvar) = RSTRING_LEN(str))
+#endif /* HAVE_STMT_AND_DECL_IN_EXPR */
+#endif /* RBIMPL_RSTRING_H */
diff --git a/include/ruby/internal/core/rstruct.h b/include/ruby/internal/core/rstruct.h
new file mode 100644
index 0000000000..69be487b59
--- /dev/null
+++ b/include/ruby/internal/core/rstruct.h
@@ -0,0 +1,121 @@
+#ifndef RBIMPL_RSTRUCT_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_RSTRUCT_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Routines to manipulate struct RStruct.
+ * @note The struct RStruct itself is opaque.
+ */
+#include "ruby/internal/attr/artificial.h"
+#include "ruby/internal/dllexport.h"
+#include "ruby/internal/value.h"
+#include "ruby/internal/value_type.h"
+#include "ruby/internal/arithmetic/long.h"
+#include "ruby/internal/arithmetic/int.h"
+#if !defined RUBY_EXPORT && !defined RUBY_NO_OLD_COMPATIBILITY
+# include "ruby/backward.h"
+#endif
+
+/**
+ * @private
+ *
+ * @deprecated This macro once was a thing in the old days, but makes no sense
+ * any longer today. Exists here for backwards compatibility
+ * only. You can safely forget about it.
+ *
+ * @internal
+ *
+ * Declaration of rb_struct_ptr() is at include/ruby/backward.h.
+ */
+#define RSTRUCT_PTR(st) rb_struct_ptr(st)
+/** @cond INTERNAL_MACRO */
+#define RSTRUCT_LEN RSTRUCT_LEN
+#define RSTRUCT_SET RSTRUCT_SET
+#define RSTRUCT_GET RSTRUCT_GET
+/** @endcond */
+
+RBIMPL_SYMBOL_EXPORT_BEGIN()
+/**
+ * Returns the number of struct members.
+ *
+ * @param[in] st An instance of RStruct.
+ * @return The number of members of `st`.
+ * @pre `st` must be of ::RUBY_T_STRUCT.
+ */
+VALUE rb_struct_size(VALUE st);
+
+/**
+ * Resembles `Struct#[]`.
+ *
+ * @param[in] st An instance of RStruct.
+ * @param[in] k Index a.k.a. key of the struct.
+ * @exception rb_eTypeError `k` is neither Numeric, Symbol, nor String.
+ * @exception rb_eIndexError Numerical index out of range.
+ * @exception rb_eNameError No such key.
+ * @return The member stored at `k` in `st`.
+ * @pre `st` must be of ::RUBY_T_STRUCT.
+ */
+VALUE rb_struct_aref(VALUE st, VALUE k);
+
+/**
+ * Resembles `Struct#[]=`.
+ *
+ * @param[out] st An instance of RStruct.
+ * @param[in] k Index a.k.a. key of the struct.
+ * @param[in] v Value to store.
+ * @exception rb_eTypeError `k` is neither Numeric, Symbol, nor String.
+ * @exception rb_eIndexError Numerical index out of range.
+ * @exception rb_eNameError No such key.
+ * @return Passed `v`.
+ * @pre `st` must be of ::RUBY_T_STRUCT.
+ * @post `v` is stored at `k` in `st`.
+ */
+VALUE rb_struct_aset(VALUE st, VALUE k, VALUE v);
+RBIMPL_SYMBOL_EXPORT_END()
+
+RBIMPL_ATTR_ARTIFICIAL()
+/** @copydoc rb_struct_size() */
+static inline long
+RSTRUCT_LEN(VALUE st)
+{
+ RBIMPL_ASSERT_TYPE(st, RUBY_T_STRUCT);
+
+ return RB_NUM2LONG(rb_struct_size(st));
+}
+
+RBIMPL_ATTR_ARTIFICIAL()
+/** @copydoc rb_struct_aset() */
+static inline VALUE
+RSTRUCT_SET(VALUE st, int k, VALUE v)
+{
+ RBIMPL_ASSERT_TYPE(st, RUBY_T_STRUCT);
+
+ return rb_struct_aset(st, INT2NUM(k), (v));
+}
+
+RBIMPL_ATTR_ARTIFICIAL()
+/** @copydoc rb_struct_aref() */
+static inline VALUE
+RSTRUCT_GET(VALUE st, int k)
+{
+ RBIMPL_ASSERT_TYPE(st, RUBY_T_STRUCT);
+
+ return rb_struct_aref(st, INT2NUM(k));
+}
+
+#endif /* RBIMPL_RSTRUCT_H */
diff --git a/include/ruby/internal/core/rtypeddata.h b/include/ruby/internal/core/rtypeddata.h
new file mode 100644
index 0000000000..bbf208867d
--- /dev/null
+++ b/include/ruby/internal/core/rtypeddata.h
@@ -0,0 +1,604 @@
+#ifndef RBIMPL_RTYPEDDATA_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_RTYPEDDATA_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Defines struct ::RTypedData.
+ */
+#include "ruby/internal/config.h"
+
+#ifdef STDC_HEADERS
+# include <stddef.h>
+#endif
+
+#include "ruby/internal/assume.h"
+#include "ruby/internal/attr/artificial.h"
+#include "ruby/internal/attr/flag_enum.h"
+#include "ruby/internal/attr/nonnull.h"
+#include "ruby/internal/attr/pure.h"
+#include "ruby/internal/cast.h"
+#include "ruby/internal/core/rbasic.h"
+#include "ruby/internal/core/rdata.h"
+#include "ruby/internal/dllexport.h"
+#include "ruby/internal/error.h"
+#include "ruby/internal/fl_type.h"
+#include "ruby/internal/stdbool.h"
+#include "ruby/internal/value_type.h"
+
+/**
+ * @private
+ *
+ * @deprecated This macro once was a thing in the old days, but makes no sense
+ * any longer today. Exists here for backwards compatibility
+ * only. You can safely forget about it.
+ */
+#define HAVE_TYPE_RB_DATA_TYPE_T 1
+
+/**
+ * @private
+ *
+ * @deprecated This macro once was a thing in the old days, but makes no sense
+ * any longer today. Exists here for backwards compatibility
+ * only. You can safely forget about it.
+ */
+#define HAVE_RB_DATA_TYPE_T_FUNCTION 1
+
+/**
+ * @private
+ *
+ * @deprecated This macro once was a thing in the old days, but makes no sense
+ * any longer today. Exists here for backwards compatibility
+ * only. You can safely forget about it.
+ */
+#define HAVE_RB_DATA_TYPE_T_PARENT 1
+
+/**
+ * This is a value you can set to ::rb_data_type_struct::dfree. Setting this
+ * means the data was allocated using ::ruby_xmalloc() (or variants), and shall
+ * be freed using ::ruby_xfree().
+ *
+ * @warning Do not use this if you want to use system malloc, because the
+ * system and Ruby might or might not share the same malloc
+ * implementation.
+ */
+#define RUBY_TYPED_DEFAULT_FREE RUBY_DEFAULT_FREE
+
+/**
+ * This is a value you can set to ::rb_data_type_struct::dfree. Setting this
+ * means the data is managed by someone else, like, statically allocated. Of
+ * course you are on your own then.
+ */
+#define RUBY_TYPED_NEVER_FREE RUBY_NEVER_FREE
+
+/**
+ * Convenient casting macro.
+ *
+ * @param obj An object, which is in fact an ::RTypedData.
+ * @return The passed object casted to ::RTypedData.
+ */
+#define RTYPEDDATA(obj) RBIMPL_CAST((struct RTypedData *)(obj))
+
+/**
+ * Convenient getter macro.
+ *
+ * @param v An object, which is in fact an ::RTypedData.
+ * @return The passed object's ::RTypedData::data field.
+ */
+#define RTYPEDDATA_DATA(v) (RTYPEDDATA(v)->data)
+
+/** @old{rb_check_typeddata} */
+#define Check_TypedStruct(v, t) \
+ rb_check_typeddata(RBIMPL_CAST((VALUE)(v)), (t))
+
+/** @cond INTERNAL_MACRO */
+#define RTYPEDDATA_P RTYPEDDATA_P
+#define RTYPEDDATA_TYPE RTYPEDDATA_TYPE
+#define RUBY_TYPED_FREE_IMMEDIATELY RUBY_TYPED_FREE_IMMEDIATELY
+#define RUBY_TYPED_FROZEN_SHAREABLE RUBY_TYPED_FROZEN_SHAREABLE
+#define RUBY_TYPED_WB_PROTECTED RUBY_TYPED_WB_PROTECTED
+#define RUBY_TYPED_PROMOTED1 RUBY_TYPED_PROMOTED1
+/** @endcond */
+
+/**
+ * @private
+ *
+ * Bits for rb_data_type_struct::flags.
+ */
+enum
+RBIMPL_ATTR_FLAG_ENUM()
+rbimpl_typeddata_flags {
+ /**
+ * This flag has something to do with Ruby's global interpreter lock. For
+ * maximum safety, Ruby locks the entire VM during GC. However your
+ * callback functions could unintentionally unlock it, for instance when
+ * they try to flush an IO buffer. Such operations are dangerous (threads
+ * then run alongside of GC). By default, to prevent those scenario,
+ * callbacks are deferred until the GC engine is 100% sure threads can run.
+ * This flag skips that; structs with it are deallocated during the sweep
+ * phase.
+ *
+ * Using this flag needs deep understanding of both GC and threads. You
+ * would better leave it unspecified.
+ */
+ RUBY_TYPED_FREE_IMMEDIATELY = 1,
+
+ /**
+ * This flag has something to do with Ractor. Multiple Ractors run without
+ * protecting each other. Sharing an object among Ractors is basically
+ * dangerous, disabled by default. This flag is used to bypass that
+ * restriction. but setting it is not enough. In addition to do so, an
+ * object also has to be frozen, and be passed to
+ * rb_ractor_make_shareable() before being actually shareable. Of course,
+ * you have to manually prevent race conditions then.
+ *
+ * Using this flag needs deep understanding of multithreaded programming.
+ * You would better leave it unspecified.
+ */
+ RUBY_TYPED_FROZEN_SHAREABLE = RUBY_FL_SHAREABLE,
+
+ /**
+ * This flag has something to do with our garbage collector. These days
+ * ruby objects are "generational". There are those who are young and
+ * those who are old. Young objects are prone to die; monitored relatively
+ * extensively by the garbage collector. OTOH old objects tend to live
+ * longer. They are relatively rarely considered. This basically works.
+ * But there is one tweak that has to be exercised. When an elder object
+ * has reference(s) to younger one(s), that referenced objects must not
+ * die. In order to detect additions of such references, old generations
+ * are protected by write barriers. It is a very difficult hack to
+ * appropriately insert write barriers everywhere. This mechanism is
+ * disabled by default for 3rd party extensions (they never get aged). By
+ * specifying this flag you can enable the generational feature to your
+ * data structure. Of course, you have to manually insert write barriers
+ * then.
+ *
+ * Using this flag needs deep understanding of GC internals, often at the
+ * level of source code. You would better leave it unspecified.
+ */
+ RUBY_TYPED_WB_PROTECTED = RUBY_FL_WB_PROTECTED, /* THIS FLAG DEPENDS ON Ruby version */
+
+ /**
+ * This flag is mysterious. It seems nobody is currently using it. The
+ * intention of this flag is also unclear. We need further investigations.
+ */
+ RUBY_TYPED_PROMOTED1 = RUBY_FL_PROMOTED1 /* THIS FLAG DEPENDS ON Ruby version */
+};
+
+/**
+ * This is the struct that holds necessary info for a struct. It roughly
+ * resembles a Ruby level class; multiple objects can share a ::rb_data_type_t
+ * instance.
+ */
+typedef struct rb_data_type_struct rb_data_type_t;
+
+/** @copydoc rb_data_type_t */
+struct rb_data_type_struct {
+
+ /**
+ * Name of structs of this kind. This is used for diagnostic purposes.
+ * This has to be unique in the process, but doesn't has to be a valid
+ * C/Ruby identifier.
+ */
+ const char *wrap_struct_name;
+
+ /** Function pointers. Resembles C++ `vtbl`.*/
+ struct {
+
+ /**
+ * This function is called when the object is experiencing GC marks.
+ * If it contains references to other Ruby objects, you need to mark
+ * them also. Otherwise GC will smash your data.
+ *
+ * @see rb_gc_mark()
+ * @warning This is called during GC runs. Object allocations are
+ * impossible at that moment (that is why GC runs).
+ */
+ RUBY_DATA_FUNC dmark;
+
+ /**
+ * This function is called when the object is no longer used. You need
+ * to do whatever necessary to avoid memory leaks.
+ *
+ * @warning This is called during GC runs. Object allocations are
+ * impossible at that moment (that is why GC runs).
+ */
+ RUBY_DATA_FUNC dfree;
+
+ /**
+ * This function is to query the size of the underlying memory regions.
+ *
+ * @internal
+ *
+ * This function has only one usage, which is form inside of
+ * `ext/objspace`.
+ */
+ size_t (*dsize)(const void *);
+
+ /**
+ * This function is called when the object is relocated. Like
+ * ::rb_data_type_struct::dmark, you need to update references to Ruby
+ * objects inside of your structs.
+ *
+ * @see rb_gc_location()
+ * @warning This is called during GC runs. Object allocations are
+ * impossible at that moment (that is why GC runs).
+ */
+ RUBY_DATA_FUNC dcompact;
+
+ /**
+ * This field is reserved for future extension. For now, it must be
+ * filled with zeros.
+ */
+ void *reserved[1]; /* For future extension.
+ This array *must* be filled with ZERO. */
+ } function;
+
+ /**
+ * Parent of this class. Sometimes C structs have inheritance-like
+ * relationships. An example is `struct sockaddr` and its family. If you
+ * design such things, make ::rb_data_type_t for each of them and connect
+ * using this field. Ruby can then transparently cast your data back and
+ * forth when you call #TypedData_Get_Struct().
+ *
+ * ```CXX
+ * struct parent { };
+ * static inline const rb_data_type_t parent_type = {
+ * .wrap_struct_name = "parent",
+ * };
+ *
+ * struct child: public parent { };
+ * static inline const rb_data_type_t child_type = {
+ * .wrap_struct_name = "child",
+ * .parent = &parent_type,
+ * };
+ *
+ * // This function can take both parent_class and child_class.
+ * static inline struct parent *
+ * get_parent(VALUE v)
+ * {
+ * struct parent *p;
+ * TypedData_Get_Struct(v, parent_type, struct parent, p);
+ * return p;
+ * }
+ * ```
+ */
+ const rb_data_type_t *parent;
+
+ /**
+ * Type-specific static data. This area can be used for any purpose by a
+ * programmer who define the type. Ruby does not manage this at all.
+ */
+ void *data; /* This area can be used for any purpose
+ by a programmer who define the type. */
+
+ /**
+ * Type-specific behavioural characteristics. This is a bitfield. It is
+ * an EXTREMELY WISE IDEA to leave this field blank. It is designed so
+ * that setting zero is the safest thing to do. If you risk to set any
+ * bits on, you have to know exactly what you are doing.
+ *
+ * @internal
+ *
+ * Why it has to be a ::VALUE? @shyouhei doesn't understand the design.
+ */
+ VALUE flags; /* RUBY_FL_WB_PROTECTED */
+};
+
+/**
+ * "Typed" user data. By using this, extension libraries can wrap a C struct
+ * to make it visible from Ruby. For instance if you have a `struct timeval`,
+ * and you want users to use it,
+ *
+ * ```CXX
+ * static inline const rb_data_type_t timeval_type = {
+ * // Note that unspecified fields are 0-filled by default.
+ * .wrap_struct_name = "timeval",
+ * .function = {
+ * .dmark = nullptr, // no need to mark
+ * .dfree = RUBY_TYPED_DEFAULT_FREE, // use ruby_xfree()
+ * .dsize = [](auto) {
+ * return sizeof(struct timeval);
+ * },
+ * },
+ * };
+ *
+ * extern "C" void
+ * Init_timeval(void)
+ * {
+ * auto klass = rb_define_class("YourName", rb_cObject);
+ *
+ * rb_define_alloc_func(klass, [](auto klass) {
+ * struct timeval *t;
+ * auto ret = TypedData_Make_Struct(
+ * klass, struct timeval, &timeval_type, t);
+ *
+ * if (auto i = gettimeofday(t, nullptr); i == -1) {
+ * rb_sys_fail("gettimeofday(3)");
+ * }
+ * else {
+ * return ret;
+ * }
+ * });
+ * }
+ * ```
+ */
+struct RTypedData {
+
+ /** The part that all ruby objects have in common. */
+ struct RBasic basic;
+
+ /**
+ * This field stores various information about how Ruby should handle a
+ * data. This roughly resembles a Ruby level class (apart from method
+ * definition etc.)
+ */
+ const rb_data_type_t *type;
+
+ /**
+ * This has to be always 1.
+ *
+ * @internal
+ *
+ * Why, then, this is not a const ::VALUE?
+ */
+ VALUE typed_flag;
+
+ /** Pointer to the actual C level struct that you want to wrap. */
+ void *data;
+};
+
+RBIMPL_SYMBOL_EXPORT_BEGIN()
+RBIMPL_ATTR_NONNULL((3))
+/**
+ * This is the primitive way to wrap an existing C struct into ::RTypedData.
+ *
+ * @param[in] klass Ruby level class of the returning object.
+ * @param[in] datap Pointer to the target C struct.
+ * @param[in] type The characteristics of the passed data.
+ * @exception rb_eTypeError `klass` is not a class.
+ * @exception rb_eNoMemError Out of memory.
+ * @return An allocated object that wraps `datap`.
+ */
+VALUE rb_data_typed_object_wrap(VALUE klass, void *datap, const rb_data_type_t *type);
+
+/**
+ * Identical to rb_data_typed_object_wrap(), except it allocates a new data
+ * region internally instead of taking an existing one. The allocation is done
+ * using ruby_calloc(). Hence it makes no sense for `type->function.dfree` to
+ * be anything other than ::RUBY_TYPED_DEFAULT_FREE.
+ *
+ * @param[in] klass Ruby level class of the returning object.
+ * @param[in] size Requested size of memory to allocate.
+ * @param[in] type The characteristics of the passed data.
+ * @exception rb_eTypeError `klass` is not a class.
+ * @exception rb_eNoMemError Out of memory.
+ * @return An allocated object that wraps a new `size` byte region.
+ */
+VALUE rb_data_typed_object_zalloc(VALUE klass, size_t size, const rb_data_type_t *type);
+
+/**
+ * Checks for the domestic relationship between the two.
+ *
+ * @param[in] child A data type supposed to be a child of `parent`.
+ * @param[in] parent A data type supposed to be a parent of `child`.
+ * @retval true `child` is a descendent of `parent`.
+ * @retval false Otherwise.
+ *
+ * @internal
+ *
+ * You can path NULL to both arguments, don't know what that means though.
+ */
+int rb_typeddata_inherited_p(const rb_data_type_t *child, const rb_data_type_t *parent);
+
+/**
+ * Checks if the given object is of given kind.
+ *
+ * @param[in] obj An instance of ::RTypedData.
+ * @param[in] data_type Expected data type of `obj`.
+ * @retval true `obj` is of `data_type`.
+ * @retval false Otherwise.
+ */
+int rb_typeddata_is_kind_of(VALUE obj, const rb_data_type_t *data_type);
+
+/**
+ * Identical to rb_typeddata_is_kind_of(), except it raises exceptions instead
+ * of returning false.
+ *
+ * @param[in] obj An instance of ::RTypedData.
+ * @param[in] data_type Expected data type of `obj`.
+ * @exception rb_eTypeError obj is not of `data_type`.
+ * @return Unwrapped C struct that `obj` holds.
+ * @post Upon successful return `obj`'s type is guaranteed `data_type`.
+ */
+void *rb_check_typeddata(VALUE obj, const rb_data_type_t *data_type);
+RBIMPL_SYMBOL_EXPORT_END()
+
+/**
+ * Converts sval, a pointer to your struct, into a Ruby object.
+ *
+ * @param klass A ruby level class.
+ * @param data_type The type of `sval`.
+ * @param sval A pointer to your struct.
+ * @exception rb_eTypeError `klass` is not a class.
+ * @exception rb_eNoMemError Out of memory.
+ * @return A created Ruby object.
+ */
+#define TypedData_Wrap_Struct(klass,data_type,sval)\
+ rb_data_typed_object_wrap((klass),(sval),(data_type))
+
+/**
+ * @private
+ *
+ * This is an implementation detail of #TypedData_Make_Struct. People don't
+ * use it directly.
+ *
+ * @param result Variable name of created Ruby object.
+ * @param klass Ruby level class of the object.
+ * @param type Type name of the C struct.
+ * @param size Size of the C struct.
+ * @param data_type The data type describing `type`.
+ * @param sval Variable name of created C struct.
+ */
+#define TypedData_Make_Struct0(result, klass, type, size, data_type, sval) \
+ VALUE result = rb_data_typed_object_zalloc(klass, size, data_type); \
+ (sval) = RBIMPL_CAST((type *)RTYPEDDATA_DATA(result)); \
+ RBIMPL_CAST(/*suppress unused variable warnings*/(void)(sval))
+
+/**
+ * Identical to #TypedData_Wrap_Struct, except it allocates a new data region
+ * internally instead of taking an existing one. The allocation is done using
+ * ruby_calloc(). Hence it makes no sense for `data_type->function.dfree` to
+ * be anything other than ::RUBY_TYPED_DEFAULT_FREE.
+ *
+ * @param klass Ruby level class of the object.
+ * @param type Type name of the C struct.
+ * @param data_type The data type describing `type`.
+ * @param sval Variable name of created C struct.
+ * @exception rb_eTypeError `klass` is not a class.
+ * @exception rb_eNoMemError Out of memory.
+ * @return A created Ruby object.
+ */
+#ifdef HAVE_STMT_AND_DECL_IN_EXPR
+#define TypedData_Make_Struct(klass, type, data_type, sval) \
+ RB_GNUC_EXTENSION({ \
+ TypedData_Make_Struct0( \
+ data_struct_obj, \
+ klass, \
+ type, \
+ sizeof(type), \
+ data_type, \
+ sval); \
+ data_struct_obj; \
+ })
+#else
+#define TypedData_Make_Struct(klass, type, data_type, sval) \
+ rb_data_typed_object_make( \
+ (klass), \
+ (data_type), \
+ RBIMPL_CAST((void **)&(sval)), \
+ sizeof(type))
+#endif
+
+/**
+ * Obtains a C struct from inside of a wrapper Ruby object.
+ *
+ * @param obj An instance of ::RTypedData.
+ * @param type Type name of the C struct.
+ * @param data_type The data type describing `type`.
+ * @param sval Variable name of obtained C struct.
+ * @exception rb_eTypeError `obj` is not a kind of `data_type`.
+ * @return Unwrapped C struct that `obj` holds.
+ */
+#define TypedData_Get_Struct(obj,type,data_type,sval) \
+ ((sval) = RBIMPL_CAST((type *)rb_check_typeddata((obj), (data_type))))
+
+RBIMPL_ATTR_PURE()
+RBIMPL_ATTR_ARTIFICIAL()
+/**
+ * @private
+ *
+ * This is an implementation detail of Check_Type(). People don't use it
+ * directly.
+ *
+ * @param[in] obj Object in question
+ * @retval true `obj` is an instance of ::RTypedData.
+ * @retval false `obj` is an instance of ::RData.
+ * @pre `obj` must be a Ruby object of ::RUBY_T_DATA.
+ */
+static inline bool
+rbimpl_rtypeddata_p(VALUE obj)
+{
+ return RTYPEDDATA(obj)->typed_flag == 1;
+}
+
+RBIMPL_ATTR_PURE_UNLESS_DEBUG()
+RBIMPL_ATTR_ARTIFICIAL()
+/**
+ * Checks whether the passed object is ::RTypedData or ::RData.
+ *
+ * @param[in] obj Object in question
+ * @retval true `obj` is an instance of ::RTypedData.
+ * @retval false `obj` is an instance of ::RData.
+ * @pre `obj` must be a Ruby object of ::RUBY_T_DATA.
+ */
+static inline bool
+RTYPEDDATA_P(VALUE obj)
+{
+#if RUBY_DEBUG
+ if (RB_UNLIKELY(! RB_TYPE_P(obj, RUBY_T_DATA))) {
+ Check_Type(obj, RUBY_T_DATA);
+ RBIMPL_UNREACHABLE_RETURN(false);
+ }
+#endif
+
+ return rbimpl_rtypeddata_p(obj);
+}
+
+RBIMPL_ATTR_PURE_UNLESS_DEBUG()
+RBIMPL_ATTR_ARTIFICIAL()
+/* :TODO: can this function be __attribute__((returns_nonnull)) or not? */
+/**
+ * Queries for the type of given object.
+ *
+ * @param[in] obj Object in question
+ * @return Data type struct that corresponds to `obj`.
+ * @pre `obj` must be an instance of ::RTypedData.
+ */
+static inline const struct rb_data_type_struct *
+RTYPEDDATA_TYPE(VALUE obj)
+{
+#if RUBY_DEBUG
+ if (RB_UNLIKELY(! RTYPEDDATA_P(obj))) {
+ rb_unexpected_type(obj, RUBY_T_DATA);
+ RBIMPL_UNREACHABLE_RETURN(NULL);
+ }
+#endif
+
+ return RTYPEDDATA(obj)->type;
+}
+
+/**
+ * While we don't stop you from using this function, it seems to be an
+ * implementation detail of #TypedData_Make_Struct, which is preferred over
+ * this one.
+ *
+ * @param[in] klass Ruby level class of the returning object.
+ * @param[in] type The data type
+ * @param[out] datap Return pointer.
+ * @param[in] size Size of the C struct.
+ * @exception rb_eTypeError `klass` is not a class.
+ * @exception rb_eNoMemError Out of memory.
+ * @return A created Ruby object.
+ * @post `*datap` points to the C struct wrapped by the returned object.
+ */
+static inline VALUE
+rb_data_typed_object_make(VALUE klass, const rb_data_type_t *type, void **datap, size_t size)
+{
+ TypedData_Make_Struct0(result, klass, void, size, type, *datap);
+ return result;
+}
+
+RBIMPL_ATTR_DEPRECATED(("by: rb_data_typed_object_wrap"))
+/** @deprecated This function was renamed to rb_data_typed_object_wrap(). */
+static inline VALUE
+rb_data_typed_object_alloc(VALUE klass, void *datap, const rb_data_type_t *type)
+{
+ return rb_data_typed_object_wrap(klass, datap, type);
+}
+
+#endif /* RBIMPL_RTYPEDDATA_H */
diff --git a/include/ruby/internal/ctype.h b/include/ruby/internal/ctype.h
new file mode 100644
index 0000000000..0f7ca6c516
--- /dev/null
+++ b/include/ruby/internal/ctype.h
@@ -0,0 +1,545 @@
+#ifndef RBIMPL_CTYPE_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_CTYPE_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Our own, locale independent, character handling routines.
+ */
+#include "ruby/internal/config.h"
+
+#ifdef STDC_HEADERS
+# include <ctype.h>
+#endif
+
+#include "ruby/internal/attr/artificial.h"
+#include "ruby/internal/attr/const.h"
+#include "ruby/internal/attr/constexpr.h"
+#include "ruby/internal/attr/nonnull.h"
+#include "ruby/internal/dllexport.h"
+
+/**
+ * @name Old character classification macros
+ *
+ * What is this #ISPRINT business? Well, according to our VCS and some
+ * internet surfing, it appears that the initial intent of these macros were to
+ * mimic codes appear in common in several GNU projects. As far as @shyouhei
+ * detects they seem to originate GNU regex (that standalone one rather than
+ * Gnulib or Glibc), and at least date back to 1995.
+ *
+ * Let me lawfully quote from a GNU coreutils commit
+ * https://git.savannah.gnu.org/cgit/coreutils.git/commit/?id=49803907f5dbd7646184a8912c9db9b09dcd0f22
+ *
+ * > Jim Meyering writes:
+ * >
+ * > "... Some ctype macros are valid only for character codes that
+ * > isascii says are ASCII (SGI's IRIX-4.0.5 is one such system --when
+ * > using /bin/cc or gcc but without giving an ansi option). So, all
+ * > ctype uses should be through macros like ISPRINT... If
+ * > STDC_HEADERS is defined, then autoconf has verified that the ctype
+ * > macros don't need to be guarded with references to isascii. ...
+ * > Defining isascii to 1 should let any compiler worth its salt
+ * > eliminate the && through constant folding."
+ * >
+ * > Bruno Haible adds:
+ * >
+ * > "... Furthermore, isupper(c) etc. have an undefined result if c is
+ * > outside the range -1 <= c <= 255. One is tempted to write isupper(c)
+ * > with c being of type `char', but this is wrong if c is an 8-bit
+ * > character >= 128 which gets sign-extended to a negative value.
+ * > The macro ISUPPER protects against this as well."
+ *
+ * So the intent was to reroute old problematic systems that no longer exist.
+ * At the same time the problems described above no longer hurt us, because we
+ * decided to completely avoid using system-provided isupper etc. to reinvent
+ * the wheel. These macros are entirely legacy; please ignore them.
+ *
+ * But let me also put stress that GNU people are wise; they use those macros
+ * only inside of their own implementations and never let them be public. On
+ * the other hand ruby has thoughtlessly publicised them to 3rd party libraries
+ * since its beginning, which is a very bad idea. These macros are too easy to
+ * get conflicted with definitions elsewhere.
+ *
+ * New programs should stick to the `rb_` prefixed names.
+ *
+ * @note It seems we just mimic the API. We do not share their implementation
+ * with GPL-ed programs.
+ *
+ * @{
+ */
+#ifndef ISPRINT
+# define ISASCII rb_isascii /**< @old{rb_isascii}*/
+# define ISPRINT rb_isprint /**< @old{rb_isprint}*/
+# define ISGRAPH rb_isgraph /**< @old{rb_isgraph}*/
+# define ISSPACE rb_isspace /**< @old{rb_isspace}*/
+# define ISUPPER rb_isupper /**< @old{rb_isupper}*/
+# define ISLOWER rb_islower /**< @old{rb_islower}*/
+# define ISALNUM rb_isalnum /**< @old{rb_isalnum}*/
+# define ISALPHA rb_isalpha /**< @old{rb_isalpha}*/
+# define ISDIGIT rb_isdigit /**< @old{rb_isdigit}*/
+# define ISXDIGIT rb_isxdigit /**< @old{rb_isxdigit}*/
+# define ISBLANK rb_isblank /**< @old{rb_isblank}*/
+# define ISCNTRL rb_iscntrl /**< @old{rb_iscntrl}*/
+# define ISPUNCT rb_ispunct /**< @old{rb_ispunct}*/
+#endif
+
+#define TOUPPER rb_toupper /**< @old{rb_toupper}*/
+#define TOLOWER rb_tolower /**< @old{rb_tolower}*/
+#define STRCASECMP st_locale_insensitive_strcasecmp /**< @old{st_locale_insensitive_strcasecmp}*/
+#define STRNCASECMP st_locale_insensitive_strncasecmp /**< @old{st_locale_insensitive_strncasecmp}*/
+#define STRTOUL ruby_strtoul /**< @old{ruby_strtoul}*/
+
+/** @} */
+
+RBIMPL_SYMBOL_EXPORT_BEGIN()
+/** @name locale insensitive functions
+ * @{
+ */
+
+/* In descriptions below, `the POSIX Locale` and `the "C" locale` are tactfully
+ * used as to whether the described function mimics POSIX or C99. */
+
+RBIMPL_ATTR_NONNULL(())
+/**
+ * Our own locale-insensitive version of `strcasecmp(3)`. The "case" here
+ * always means that of the POSIX Locale. It doesn't depend on runtime locale
+ * settings.
+ *
+ * @param[in] s1 Comparison LHS.
+ * @param[in] s2 Comparison RHS.
+ * @retval -1 `s1` is "less" than `s2`.
+ * @retval 0 Both strings converted into lowercase would be identical.
+ * @retval 1 `s1` is "greater" than `s2`.
+ * @note Not only does this function works under the POSIX Locale, but
+ * also assumes its execution character set be what ruby calls an
+ * ASCII-compatible character set; which does not include for
+ * instance EBCDIC or UTF-16LE.
+ */
+int st_locale_insensitive_strcasecmp(const char *s1, const char *s2);
+
+RBIMPL_ATTR_NONNULL(())
+/**
+ * Our own locale-insensitive version of `strcnasecmp(3)`. The "case" here
+ * always means that of the POSIX Locale. It doesn't depend on runtime locale
+ * settings.
+ *
+ * @param[in] s1 Comparison LHS.
+ * @param[in] s2 Comparison RHS.
+ * @param[in] n Comparison shall stop after first `n` bytes are scanned.
+ * @retval -1 `s1` is "less" than `s2`.
+ * @retval 0 Both strings converted into lowercase would be identical.
+ * @retval 1 `s1` is "greater" than `s2`.
+ * @note Not only does this function works under the POSIX Locale, but
+ * also assumes its execution character set be what ruby calls an
+ * ASCII-compatible character set; which does not include for
+ * instance EBCDIC or UTF-16LE.
+ * @warning This function is _not_ timing safe.
+ */
+int st_locale_insensitive_strncasecmp(const char *s1, const char *s2, size_t n);
+
+RBIMPL_ATTR_NONNULL((1))
+/**
+ * Our own locale-insensitive version of `strtoul(3)`. The conversion is done
+ * as if the current locale is set to the "C" locale, no matter actual runtime
+ * locale settings.
+ *
+ * @note This is needed because `strtoul("i", 0, 36)` would return zero
+ * if it is locale sensitive and the current locale is `tr_TR`.
+ * @param[in] str String of digits, optionally preceded with whitespaces
+ * (ignored) and optionally `+` or `-` sign.
+ * @param[out] endptr NULL, or an arbitrary pointer (overwritten on return).
+ * @param[in] base `2` to `36` inclusive for each base, or special case
+ * `0` to detect the base from the contents of the string.
+ * @return Converted integer, casted to unsigned long.
+ * @post If `endptr` is not NULL, it is updated to point the first such
+ * byte where conversion failed.
+ * @note This function sets `errno` on failure.
+ * - `EINVAL`: Passed `base` is out of range.
+ * - `ERANGE`: Converted integer is out of range of `long`.
+ * @warning As far as @shyouhei reads ISO/IEC 9899:2018 section 7.22.1.4, a
+ * conforming `strtoul` implementation shall render `ERANGE`
+ * whenever it finds the input string represents a negative
+ * integer. Such thing can never be representable using `unsigned
+ * long`. However this implementation does not honour that
+ * language. It just casts such negative value to the return
+ * type, resulting a very big return value. This behaviour is at
+ * least questionable. But we can no longer change that at this
+ * point.
+ * @note Not only does this function works under the "C" locale, but
+ * also assumes its execution character set be what ruby calls an
+ * ASCII-compatible character set; which does not include for
+ * instance EBCDIC or UTF-16LE.
+ */
+unsigned long ruby_strtoul(const char *str, char **endptr, int base);
+RBIMPL_SYMBOL_EXPORT_END()
+
+/*
+ * We are making the functions below to return `int` instead of `bool`. They
+ * have been as such since their birth at 5f237d79033b2109afb768bc889611fa9630.
+ */
+
+RBIMPL_ATTR_CONST()
+RBIMPL_ATTR_CONSTEXPR(CXX11)
+RBIMPL_ATTR_ARTIFICIAL()
+/**
+ * Our own locale-insensitive version of `isascii(3)`.
+ *
+ * @param[in] c Byte in question to query.
+ * @retval false `c` is out of range of ASCII character set.
+ * @retval true Yes it is.
+ * @warning `c` is an int. This means that when you pass a `char` value
+ * here, it experiences "integer promotion" as defined in ISO/IEC
+ * 9899:2018 section 6.3.1.1 paragraph 1.
+ */
+static inline int
+rb_isascii(int c)
+{
+ return '\0' <= c && c <= '\x7f';
+}
+
+RBIMPL_ATTR_CONST()
+RBIMPL_ATTR_CONSTEXPR(CXX11)
+RBIMPL_ATTR_ARTIFICIAL()
+/**
+ * Our own locale-insensitive version of `isupper(3)`.
+ *
+ * @param[in] c Byte in question to query.
+ * @retval true `c` is listed in IEEE 1003.1 section 7.3.1.1 "upper".
+ * @retval false Anything else.
+ * @note Not only does this function works under the POSIX Locale, but
+ * also assumes its execution character set be what ruby calls an
+ * ASCII-compatible character set; which does not include for
+ * instance EBCDIC or UTF-16LE.
+ * @warning `c` is an int. This means that when you pass a `char` value
+ * here, it experiences "integer promotion" as defined in ISO/IEC
+ * 9899:2018 section 6.3.1.1 paragraph 1.
+ */
+static inline int
+rb_isupper(int c)
+{
+ return 'A' <= c && c <= 'Z';
+}
+
+RBIMPL_ATTR_CONST()
+RBIMPL_ATTR_CONSTEXPR(CXX11)
+RBIMPL_ATTR_ARTIFICIAL()
+/**
+ * Our own locale-insensitive version of `islower(3)`.
+ *
+ * @param[in] c Byte in question to query.
+ * @retval true `c` is listed in IEEE 1003.1 section 7.3.1.1 "lower".
+ * @retval false Anything else.
+ * @note Not only does this function works under the POSIX Locale, but
+ * also assumes its execution character set be what ruby calls an
+ * ASCII-compatible character set; which does not include for
+ * instance EBCDIC or UTF-16LE.
+ * @warning `c` is an int. This means that when you pass a `char` value
+ * here, it experiences "integer promotion" as defined in ISO/IEC
+ * 9899:2018 section 6.3.1.1 paragraph 1.
+ */
+static inline int
+rb_islower(int c)
+{
+ return 'a' <= c && c <= 'z';
+}
+
+RBIMPL_ATTR_CONST()
+RBIMPL_ATTR_CONSTEXPR(CXX11)
+RBIMPL_ATTR_ARTIFICIAL()
+/**
+ * Our own locale-insensitive version of `isalpha(3)`.
+ *
+ * @param[in] c Byte in question to query.
+ * @retval true `c` is listed in either IEEE 1003.1 section 7.3.1.1
+ * "upper" or "lower".
+ * @retval false Anything else.
+ * @note Not only does this function works under the POSIX Locale, but
+ * also assumes its execution character set be what ruby calls an
+ * ASCII-compatible character set; which does not include for
+ * instance EBCDIC or UTF-16LE.
+ * @warning `c` is an int. This means that when you pass a `char` value
+ * here, it experiences "integer promotion" as defined in ISO/IEC
+ * 9899:2018 section 6.3.1.1 paragraph 1.
+ */
+static inline int
+rb_isalpha(int c)
+{
+ return rb_isupper(c) || rb_islower(c);
+}
+
+RBIMPL_ATTR_CONST()
+RBIMPL_ATTR_CONSTEXPR(CXX11)
+RBIMPL_ATTR_ARTIFICIAL()
+/**
+ * Our own locale-insensitive version of `isdigit(3)`.
+ *
+ * @param[in] c Byte in question to query.
+ * @retval true `c` is listed in IEEE 1003.1 section 7.3.1.1 "digit".
+ * @retval false Anything else.
+ * @note Not only does this function works under the POSIX Locale, but
+ * also assumes its execution character set be what ruby calls an
+ * ASCII-compatible character set; which does not include for
+ * instance EBCDIC or UTF-16LE.
+ * @warning `c` is an int. This means that when you pass a `char` value
+ * here, it experiences "integer promotion" as defined in ISO/IEC
+ * 9899:2018 section 6.3.1.1 paragraph 1.
+ */
+static inline int
+rb_isdigit(int c)
+{
+ return '0' <= c && c <= '9';
+}
+
+RBIMPL_ATTR_CONST()
+RBIMPL_ATTR_CONSTEXPR(CXX11)
+RBIMPL_ATTR_ARTIFICIAL()
+/**
+ * Our own locale-insensitive version of `isalnum(3)`.
+ *
+ * @param[in] c Byte in question to query.
+ * @retval true `c` is listed in either IEEE 1003.1 section 7.3.1.1
+ * "upper", "lower", or "digit".
+ * @retval false Anything else.
+ * @note Not only does this function works under the POSIX Locale, but
+ * also assumes its execution character set be what ruby calls an
+ * ASCII-compatible character set; which does not include for
+ * instance EBCDIC or UTF-16LE.
+ * @warning `c` is an int. This means that when you pass a `char` value
+ * here, it experiences "integer promotion" as defined in ISO/IEC
+ * 9899:2018 section 6.3.1.1 paragraph 1.
+ */
+static inline int
+rb_isalnum(int c)
+{
+ return rb_isalpha(c) || rb_isdigit(c);
+}
+
+RBIMPL_ATTR_CONST()
+RBIMPL_ATTR_CONSTEXPR(CXX11)
+RBIMPL_ATTR_ARTIFICIAL()
+/**
+ * Our own locale-insensitive version of `isxdigit(3)`.
+ *
+ * @param[in] c Byte in question to query.
+ * @retval true `c` is listed in IEEE 1003.1 section 7.3.1.1 "xdigit".
+ * @retval false Anything else.
+ * @note Not only does this function works under the POSIX Locale, but
+ * also assumes its execution character set be what ruby calls an
+ * ASCII-compatible character set; which does not include for
+ * instance EBCDIC or UTF-16LE.
+ * @warning `c` is an int. This means that when you pass a `char` value
+ * here, it experiences "integer promotion" as defined in ISO/IEC
+ * 9899:2018 section 6.3.1.1 paragraph 1.
+ */
+static inline int
+rb_isxdigit(int c)
+{
+ return rb_isdigit(c) || ('A' <= c && c <= 'F') || ('a' <= c && c <= 'f');
+}
+
+RBIMPL_ATTR_CONST()
+RBIMPL_ATTR_CONSTEXPR(CXX11)
+RBIMPL_ATTR_ARTIFICIAL()
+/**
+ * Our own locale-insensitive version of `isblank(3)`.
+ *
+ * @param[in] c Byte in question to query.
+ * @retval true `c` is listed in IEEE 1003.1 section 7.3.1.1 "blank".
+ * @retval false Anything else.
+ * @note Not only does this function works under the POSIX Locale, but
+ * also assumes its execution character set be what ruby calls an
+ * ASCII-compatible character set; which does not include for
+ * instance EBCDIC or UTF-16LE.
+ * @warning `c` is an int. This means that when you pass a `char` value
+ * here, it experiences "integer promotion" as defined in ISO/IEC
+ * 9899:2018 section 6.3.1.1 paragraph 1.
+ */
+static inline int
+rb_isblank(int c)
+{
+ return c == ' ' || c == '\t';
+}
+
+RBIMPL_ATTR_CONST()
+RBIMPL_ATTR_CONSTEXPR(CXX11)
+RBIMPL_ATTR_ARTIFICIAL()
+/**
+ * Our own locale-insensitive version of `isspace(3)`.
+ *
+ * @param[in] c Byte in question to query.
+ * @retval true `c` is listed in IEEE 1003.1 section 7.3.1.1 "space".
+ * @retval false Anything else.
+ * @note Not only does this function works under the POSIX Locale, but
+ * also assumes its execution character set be what ruby calls an
+ * ASCII-compatible character set; which does not include for
+ * instance EBCDIC or UTF-16LE.
+ * @warning `c` is an int. This means that when you pass a `char` value
+ * here, it experiences "integer promotion" as defined in ISO/IEC
+ * 9899:2018 section 6.3.1.1 paragraph 1.
+ */
+static inline int
+rb_isspace(int c)
+{
+ return c == ' ' || ('\t' <= c && c <= '\r');
+}
+
+RBIMPL_ATTR_CONST()
+RBIMPL_ATTR_CONSTEXPR(CXX11)
+RBIMPL_ATTR_ARTIFICIAL()
+/**
+ * Our own locale-insensitive version of `iscntrl(3)`.
+ *
+ * @param[in] c Byte in question to query.
+ * @retval true `c` is listed in IEEE 1003.1 section 7.3.1.1 "cntrl".
+ * @retval false Anything else.
+ * @note Not only does this function works under the POSIX Locale, but
+ * also assumes its execution character set be what ruby calls an
+ * ASCII-compatible character set; which does not include for
+ * instance EBCDIC or UTF-16LE.
+ * @warning `c` is an int. This means that when you pass a `char` value
+ * here, it experiences "integer promotion" as defined in ISO/IEC
+ * 9899:2018 section 6.3.1.1 paragraph 1.
+ */
+static inline int
+rb_iscntrl(int c)
+{
+ return ('\0' <= c && c < ' ') || c == '\x7f';
+}
+
+RBIMPL_ATTR_CONST()
+RBIMPL_ATTR_CONSTEXPR(CXX11)
+RBIMPL_ATTR_ARTIFICIAL()
+/**
+ * Identical to rb_isgraph(), except it also returns true for `' '`.
+ *
+ * @param[in] c Byte in question to query.
+ * @retval true `c` is listed in either IEEE 1003.1 section 7.3.1.1
+ * "upper", "lower", "digit", "punct", or a `' '`.
+ * @retval false Anything else.
+ * @note Not only does this function works under the POSIX Locale, but
+ * also assumes its execution character set be what ruby calls an
+ * ASCII-compatible character set; which does not include for
+ * instance EBCDIC or UTF-16LE.
+ * @warning `c` is an int. This means that when you pass a `char` value
+ * here, it experiences "integer promotion" as defined in ISO/IEC
+ * 9899:2018 section 6.3.1.1 paragraph 1.
+ */
+static inline int
+rb_isprint(int c)
+{
+ return ' ' <= c && c <= '\x7e';
+}
+
+RBIMPL_ATTR_CONST()
+RBIMPL_ATTR_CONSTEXPR(CXX11)
+RBIMPL_ATTR_ARTIFICIAL()
+/**
+ * Our own locale-insensitive version of `ispunct(3)`.
+ *
+ * @param[in] c Byte in question to query.
+ * @retval true `c` is listed in IEEE 1003.1 section 7.3.1.1 "punct".
+ * @retval false Anything else.
+ * @note Not only does this function works under the POSIX Locale, but
+ * also assumes its execution character set be what ruby calls an
+ * ASCII-compatible character set; which does not include for
+ * instance EBCDIC or UTF-16LE.
+ * @warning `c` is an int. This means that when you pass a `char` value
+ * here, it experiences "integer promotion" as defined in ISO/IEC
+ * 9899:2018 section 6.3.1.1 paragraph 1.
+ */
+static inline int
+rb_ispunct(int c)
+{
+ return !rb_isalnum(c);
+}
+
+RBIMPL_ATTR_CONST()
+RBIMPL_ATTR_CONSTEXPR(CXX11)
+RBIMPL_ATTR_ARTIFICIAL()
+/**
+ * Our own locale-insensitive version of `isgraph(3)`.
+ *
+ * @param[in] c Byte in question to query.
+ * @retval true `c` is listed in either IEEE 1003.1 section 7.3.1.1
+ * "upper", "lower", "digit", or "punct".
+ * @retval false Anything else.
+ * @note Not only does this function works under the POSIX Locale, but
+ * also assumes its execution character set be what ruby calls an
+ * ASCII-compatible character set; which does not include for
+ * instance EBCDIC or UTF-16LE.
+ * @warning `c` is an int. This means that when you pass a `char` value
+ * here, it experiences "integer promotion" as defined in ISO/IEC
+ * 9899:2018 section 6.3.1.1 paragraph 1.
+ */
+static inline int
+rb_isgraph(int c)
+{
+ return '!' <= c && c <= '\x7e';
+}
+
+RBIMPL_ATTR_CONST()
+RBIMPL_ATTR_CONSTEXPR(CXX11)
+RBIMPL_ATTR_ARTIFICIAL()
+/**
+ * Our own locale-insensitive version of `tolower(3)`.
+ *
+ * @param[in] c Byte in question to convert.
+ * @retval c The byte is not listed in in IEEE 1003.1 section
+ * 7.3.1.1 "upper".
+ * @retval otherwise Byte converted using the map defined in IEEE 1003.1
+ * section 7.3.1 "tolower".
+ * @note Not only does this function works under the POSIX Locale, but
+ * also assumes its execution character set be what ruby calls an
+ * ASCII-compatible character set; which does not include for
+ * instance EBCDIC or UTF-16LE.
+ * @warning `c` is an int. This means that when you pass a `char` value
+ * here, it experiences "integer promotion" as defined in ISO/IEC
+ * 9899:2018 section 6.3.1.1 paragraph 1.
+ */
+static inline int
+rb_tolower(int c)
+{
+ return rb_isupper(c) ? (c|0x20) : c;
+}
+
+RBIMPL_ATTR_CONST()
+RBIMPL_ATTR_CONSTEXPR(CXX11)
+RBIMPL_ATTR_ARTIFICIAL()
+/**
+ * Our own locale-insensitive version of `toupper(3)`.
+ *
+ * @param[in] c Byte in question to convert.
+ * @retval c The byte is not listed in in IEEE 1003.1 section
+ * 7.3.1.1 "lower".
+ * @retval otherwise Byte converted using the map defined in IEEE 1003.1
+ * section 7.3.1 "toupper".
+ * @note Not only does this function works under the POSIX Locale, but
+ * also assumes its execution character set be what ruby calls an
+ * ASCII-compatible character set; which does not include for
+ * instance EBCDIC or UTF-16LE.
+ * @warning `c` is an int. This means that when you pass a `char` value
+ * here, it experiences "integer promotion" as defined in ISO/IEC
+ * 9899:2018 section 6.3.1.1 paragraph 1.
+ */
+static inline int
+rb_toupper(int c)
+{
+ return rb_islower(c) ? (c&0x5f) : c;
+}
+
+/** @} */
+#endif /* RBIMPL_CTYPE_H */
diff --git a/include/ruby/internal/dllexport.h b/include/ruby/internal/dllexport.h
new file mode 100644
index 0000000000..08a262209d
--- /dev/null
+++ b/include/ruby/internal/dllexport.h
@@ -0,0 +1,112 @@
+#ifndef RBIMPL_DLLEXPORT_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_DLLEXPORT_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Tweaking visibility of C variables/functions.
+ */
+#include "ruby/internal/config.h"
+#include "ruby/internal/compiler_is.h"
+
+/**
+ * Declaration of externally visible global variables. Here "externally" means
+ * they should be visible from extension libraries. Depending on operating
+ * systems (dynamic linkers, to be precise), global variables inside of a DLL
+ * may or may not be visible form outside of that DLL by default. This
+ * declaration manually tweaks that default and ensures the declared variable
+ * be truly globally visible.
+ *
+ * ```CXX
+ * extern VALUE foo; // hidden on some OS
+ * RUBY_EXTERN VALUE foo; // ensure visible
+ * ```
+ */
+#undef RUBY_EXTERN
+#if defined(MJIT_HEADER) && defined(_WIN32)
+# define RUBY_EXTERN extern __declspec(dllimport)
+#elif defined(RUBY_EXPORT)
+# define RUBY_EXTERN extern
+#elif defined(_WIN32)
+# define RUBY_EXTERN extern __declspec(dllimport)
+#else
+# define RUBY_EXTERN extern
+#endif
+
+#ifndef RUBY_SYMBOL_EXPORT_BEGIN
+# define RUBY_SYMBOL_EXPORT_BEGIN /* begin */
+#endif
+
+#ifndef RUBY_SYMBOL_EXPORT_END
+# define RUBY_SYMBOL_EXPORT_END /* end */
+#endif
+
+#ifndef RUBY_FUNC_EXPORTED
+# define RUBY_FUNC_EXPORTED /* void */
+#endif
+
+/**
+ * @cond INTERNAL_MACRO
+ *
+ * These MJIT related macros are placed here because translate_mjit_header can
+ * need them. Extension libraries should not touch.
+ */
+
+/* These macros are used for functions which are exported only for MJIT
+ and NOT ensured to be exported in future versions. */
+
+#if ! defined(MJIT_HEADER)
+# define MJIT_FUNC_EXPORTED RUBY_FUNC_EXPORTED
+#elif ! RBIMPL_COMPILER_IS(MSVC)
+# define MJIT_FUNC_EXPORTED RUBY_FUNC_EXPORTED
+#else
+# define MJIT_FUNC_EXPORTED static
+#endif
+
+#define MJIT_SYMBOL_EXPORT_BEGIN RUBY_SYMBOL_EXPORT_BEGIN
+#define MJIT_SYMBOL_EXPORT_END RUBY_SYMBOL_EXPORT_END
+
+/* On mswin, MJIT header transformation can't be used since cl.exe can't output
+ preprocessed output preserving macros. So this `MJIT_STATIC` is needed
+ to force non-static function to static on MJIT header to avoid symbol conflict. */
+#ifdef MJIT_HEADER
+# define MJIT_STATIC static
+#else
+# define MJIT_STATIC
+#endif
+
+/** @endcond */
+
+/** Shortcut macro equivalent to `RUBY_SYMBOL_EXPORT_BEGIN extern "C" {`.
+ * \@shyouhei finds it handy. */
+#if defined(__DOXYGEN__)
+# define RBIMPL_SYMBOL_EXPORT_BEGIN() /* void */
+#elif defined(__cplusplus)
+# define RBIMPL_SYMBOL_EXPORT_BEGIN() RUBY_SYMBOL_EXPORT_BEGIN extern "C" {
+#else
+# define RBIMPL_SYMBOL_EXPORT_BEGIN() RUBY_SYMBOL_EXPORT_BEGIN
+#endif
+
+/** Counterpart of #RBIMPL_SYMBOL_EXPORT_BEGIN */
+#if defined(__DOXYGEN__)
+# define RBIMPL_SYMBOL_EXPORT_END() /* void */
+#elif defined(__cplusplus)
+# define RBIMPL_SYMBOL_EXPORT_END() } RUBY_SYMBOL_EXPORT_END
+#else
+# define RBIMPL_SYMBOL_EXPORT_END() RUBY_SYMBOL_EXPORT_END
+#endif
+#endif /* RBIMPL_DLLEXPORT_H */
diff --git a/include/ruby/internal/dosish.h b/include/ruby/internal/dosish.h
new file mode 100644
index 0000000000..7d354ddd1a
--- /dev/null
+++ b/include/ruby/internal/dosish.h
@@ -0,0 +1,89 @@
+#ifndef RBIMPL_DOSISH_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_DOSISH_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Support for so-called dosish systems.
+ */
+#ifdef __CYGWIN__
+#undef _WIN32
+#endif
+
+#if defined(_WIN32)
+/*
+ DOSISH mean MS-Windows style filesystem.
+ But you should use more precise macros like DOSISH_DRIVE_LETTER, PATH_SEP,
+ ENV_IGNORECASE or CASEFOLD_FILESYSTEM.
+ */
+#define DOSISH 1
+# define DOSISH_DRIVE_LETTER
+#endif
+
+#ifdef _WIN32
+#include "ruby/win32.h"
+#endif
+
+/** The delimiter of `PATH` environment variable. */
+#if defined(DOSISH)
+#define PATH_SEP ";"
+#else
+#define PATH_SEP ":"
+#endif
+
+/** Identical to #PATH_SEP, except it is of type `char`. */
+#define PATH_SEP_CHAR PATH_SEP[0]
+
+/**
+ * @private
+ *
+ * @deprecated This macro once was a thing in the old days, but makes no sense
+ * any longer today. Exists here for backwards compatibility
+ * only. You can safely forget about it.
+ *
+ * @internal
+ *
+ * For historical interests: there was an operating system called Human68k
+ * which used an environment variable called `"path"` for this purpose.
+ */
+#define PATH_ENV "PATH"
+
+#if defined(DOSISH)
+#define ENV_IGNORECASE
+#endif
+
+/**
+ * Stone age assumption was that an operating system supports only one file
+ * system at a moment. This macro was to detect if such (one and only) file
+ * system has case sensitivity. This assumption is largely not true any
+ * longer; most operating systems can mount many kinds of file systems side by
+ * side. Also there are file systems that do or do not ignore cases depending
+ * on configuration (e.g. EXT4's `casefold` feature).
+ *
+ * This macro is still used internally (for instance Ruby level constant
+ * `File::FNM_SYSCASE` depends on it), but it is basically a wrong idea for you
+ * to use it today. Please just find another way.
+ */
+#ifndef CASEFOLD_FILESYSTEM
+# if defined DOSISH
+# define CASEFOLD_FILESYSTEM 1
+# else
+# define CASEFOLD_FILESYSTEM 0
+# endif
+#endif
+
+#endif /* RBIMPL_DOSISH_H */
diff --git a/include/ruby/internal/encoding/coderange.h b/include/ruby/internal/encoding/coderange.h
new file mode 100644
index 0000000000..7a81208c9e
--- /dev/null
+++ b/include/ruby/internal/encoding/coderange.h
@@ -0,0 +1,202 @@
+#ifndef RUBY_INTERNAL_ENCODING_CODERANGE_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RUBY_INTERNAL_ENCODING_CODERANGE_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Routines for code ranges.
+ */
+
+#include "ruby/internal/attr/const.h"
+#include "ruby/internal/attr/pure.h"
+#include "ruby/internal/dllexport.h"
+#include "ruby/internal/fl_type.h"
+#include "ruby/internal/value.h"
+
+RBIMPL_SYMBOL_EXPORT_BEGIN()
+
+/** What rb_enc_str_coderange() returns. */
+enum ruby_coderange_type {
+
+ /** The object's coderange is unclear yet. */
+ RUBY_ENC_CODERANGE_UNKNOWN = 0,
+
+ /** The object holds 0 to 127 inclusive and nothing else. */
+ RUBY_ENC_CODERANGE_7BIT = ((int)RUBY_FL_USER8),
+
+ /** The object's encoding and contents are consistent each other */
+ RUBY_ENC_CODERANGE_VALID = ((int)RUBY_FL_USER9),
+
+ /** The object holds invalid/malformed/broken character(s). */
+ RUBY_ENC_CODERANGE_BROKEN = ((int)(RUBY_FL_USER8|RUBY_FL_USER9)),
+
+ /** Where the coderange resides. */
+ RUBY_ENC_CODERANGE_MASK = (RUBY_ENC_CODERANGE_7BIT|
+ RUBY_ENC_CODERANGE_VALID|
+ RUBY_ENC_CODERANGE_BROKEN)
+};
+
+RBIMPL_ATTR_CONST()
+/**
+ * @private
+ *
+ * This is an implementation detail of #RB_ENC_CODERANGE_CLEAN_P. People don't
+ * use it directly.
+ *
+ * @param[in] cr An enum ::ruby_coderange_type.
+ * @retval 1 It is.
+ * @retval 0 It isn't.
+ */
+static inline int
+rb_enc_coderange_clean_p(int cr)
+{
+ return (cr ^ (cr >> 1)) & RUBY_ENC_CODERANGE_7BIT;
+}
+
+RBIMPL_ATTR_CONST()
+/**
+ * Queries if a code range is "clean". "Clean" in this context means it is
+ * known and valid.
+ *
+ * @param[in] cr An enum ::ruby_coderange_type.
+ * @retval 1 It is.
+ * @retval 0 It isn't.
+ */
+static inline bool
+RB_ENC_CODERANGE_CLEAN_P(enum ruby_coderange_type cr)
+{
+ return rb_enc_coderange_clean_p(cr);
+}
+
+RBIMPL_ATTR_PURE_UNLESS_DEBUG()
+/**
+ * Queries the (inline) code range of the passed object. The object must be
+ * capable of having inline encoding. Using this macro needs deep
+ * understanding of bit level object binary layout.
+ *
+ * @param[in] obj Target object.
+ * @return An enum ::ruby_coderange_type.
+ */
+static inline enum ruby_coderange_type
+RB_ENC_CODERANGE(VALUE obj)
+{
+ VALUE ret = RB_FL_TEST_RAW(obj, RUBY_ENC_CODERANGE_MASK);
+
+ return RBIMPL_CAST((enum ruby_coderange_type)ret);
+}
+
+RBIMPL_ATTR_PURE_UNLESS_DEBUG()
+/**
+ * Queries the (inline) code range of the passed object is
+ * ::RUBY_ENC_CODERANGE_7BIT. The object must be capable of having inline
+ * encoding. Using this macro needs deep understanding of bit level object
+ * binary layout.
+ *
+ * @param[in] obj Target object.
+ * @retval 1 It is ascii only.
+ * @retval 0 Otherwise (including cases when the range is not known).
+ */
+static inline bool
+RB_ENC_CODERANGE_ASCIIONLY(VALUE obj)
+{
+ return RB_ENC_CODERANGE(obj) == RUBY_ENC_CODERANGE_7BIT;
+}
+
+/**
+ * Destructively modifies the passed object so that its (inline) code range is
+ * the passed one. The object must be capable of having inline encoding.
+ * Using this macro needs deep understanding of bit level object binary layout.
+ *
+ * @param[out] obj Target object.
+ * @param[out] cr An enum ::ruby_coderange_type.
+ * @post `obj`'s code range is `cr`.
+ */
+static inline void
+RB_ENC_CODERANGE_SET(VALUE obj, enum ruby_coderange_type cr)
+{
+ RB_FL_UNSET_RAW(obj, RUBY_ENC_CODERANGE_MASK);
+ RB_FL_SET_RAW(obj, cr);
+}
+
+/**
+ * Destructively clears the passed object's (inline) code range. The object
+ * must be capable of having inline encoding. Using this macro needs deep
+ * understanding of bit level object binary layout.
+ *
+ * @param[out] obj Target object.
+ * @post `obj`'s code range is ::RUBY_ENC_CODERANGE_UNKNOWN.
+ */
+static inline void
+RB_ENC_CODERANGE_CLEAR(VALUE obj)
+{
+ RB_FL_UNSET_RAW(obj, RUBY_ENC_CODERANGE_MASK);
+}
+
+RBIMPL_ATTR_CONST()
+/* assumed ASCII compatibility */
+/**
+ * "Mix" two code ranges into one. This is handy for instance when you
+ * concatenate two strings into one. Consider one of then is valid but the
+ * other isn't. The result must be invalid. This macro computes that kind of
+ * mixture.
+ *
+ * @param[in] a An enum ::ruby_coderange_type.
+ * @param[in] b Another enum ::ruby_coderange_type.
+ * @return The `a` "and" `b`.
+ */
+static inline enum ruby_coderange_type
+RB_ENC_CODERANGE_AND(enum ruby_coderange_type a, enum ruby_coderange_type b)
+{
+ if (a == RUBY_ENC_CODERANGE_7BIT) {
+ return b;
+ }
+ else if (a != RUBY_ENC_CODERANGE_VALID) {
+ return RUBY_ENC_CODERANGE_UNKNOWN;
+ }
+ else if (b == RUBY_ENC_CODERANGE_7BIT) {
+ return RUBY_ENC_CODERANGE_VALID;
+ }
+ else {
+ return b;
+ }
+}
+
+#define ENC_CODERANGE_MASK RUBY_ENC_CODERANGE_MASK /**< @old{RUBY_ENC_CODERANGE_MASK} */
+#define ENC_CODERANGE_UNKNOWN RUBY_ENC_CODERANGE_UNKNOWN /**< @old{RUBY_ENC_CODERANGE_UNKNOWN} */
+#define ENC_CODERANGE_7BIT RUBY_ENC_CODERANGE_7BIT /**< @old{RUBY_ENC_CODERANGE_7BIT} */
+#define ENC_CODERANGE_VALID RUBY_ENC_CODERANGE_VALID /**< @old{RUBY_ENC_CODERANGE_VALID} */
+#define ENC_CODERANGE_BROKEN RUBY_ENC_CODERANGE_BROKEN /**< @old{RUBY_ENC_CODERANGE_BROKEN} */
+#define ENC_CODERANGE_CLEAN_P(cr) RB_ENC_CODERANGE_CLEAN_P(cr) /**< @old{RB_ENC_CODERANGE_CLEAN_P} */
+#define ENC_CODERANGE(obj) RB_ENC_CODERANGE(obj) /**< @old{RB_ENC_CODERANGE} */
+#define ENC_CODERANGE_ASCIIONLY(obj) RB_ENC_CODERANGE_ASCIIONLY(obj) /**< @old{RB_ENC_CODERANGE_ASCIIONLY} */
+#define ENC_CODERANGE_SET(obj,cr) RB_ENC_CODERANGE_SET(obj,cr) /**< @old{RB_ENC_CODERANGE_SET} */
+#define ENC_CODERANGE_CLEAR(obj) RB_ENC_CODERANGE_CLEAR(obj) /**< @old{RB_ENC_CODERANGE_CLEAR} */
+#define ENC_CODERANGE_AND(a, b) RB_ENC_CODERANGE_AND(a, b) /**< @old{RB_ENC_CODERANGE_AND} */
+#define ENCODING_CODERANGE_SET(obj, encindex, cr) RB_ENCODING_CODERANGE_SET(obj, encindex, cr) /**< @old{RB_ENCODING_CODERANGE_SET} */
+
+/** @cond INTERNAL_MACRO */
+#define RB_ENC_CODERANGE RB_ENC_CODERANGE
+#define RB_ENC_CODERANGE_AND RB_ENC_CODERANGE_AND
+#define RB_ENC_CODERANGE_ASCIIONLY RB_ENC_CODERANGE_ASCIIONLY
+#define RB_ENC_CODERANGE_CLEAN_P RB_ENC_CODERANGE_CLEAN_P
+#define RB_ENC_CODERANGE_CLEAR RB_ENC_CODERANGE_CLEAR
+#define RB_ENC_CODERANGE_SET RB_ENC_CODERANGE_SET
+/** @endcond */
+
+RBIMPL_SYMBOL_EXPORT_END()
+
+#endif /* RUBY_INTERNAL_ENCODING_CODERANGE_H */
diff --git a/include/ruby/internal/encoding/ctype.h b/include/ruby/internal/encoding/ctype.h
new file mode 100644
index 0000000000..64aaf0a990
--- /dev/null
+++ b/include/ruby/internal/encoding/ctype.h
@@ -0,0 +1,243 @@
+#ifndef RUBY_INTERNAL_ENCODING_CTYPE_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RUBY_INTERNAL_ENCODING_CTYPE_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Routines to query chacater types.
+ */
+
+#include "ruby/onigmo.h"
+#include "ruby/internal/attr/const.h"
+#include "ruby/internal/dllexport.h"
+#include "ruby/internal/encoding/encoding.h"
+#include "ruby/internal/value.h"
+
+RBIMPL_SYMBOL_EXPORT_BEGIN()
+
+/**
+ * Queries if the passed pointer points to a newline character. What is a
+ * newline and what is not depends on the passed encoding.
+ *
+ * @param[in] p Pointer to a possibly-middle of a character.
+ * @param[in] end End of the string.
+ * @param[in] enc Encoding.
+ * @retval 0 It isn't.
+ * @retval otherwise It is.
+ */
+static inline bool
+rb_enc_is_newline(const char *p, const char *e, rb_encoding *enc)
+{
+ OnigUChar *up = RBIMPL_CAST((OnigUChar *)p);
+ OnigUChar *ue = RBIMPL_CAST((OnigUChar *)e);
+
+ return ONIGENC_IS_MBC_NEWLINE(enc, up, ue);
+}
+
+/**
+ * Queries if the passed code point is of passed character type in the passed
+ * encoding. The "character type" here is a set of macros defined in onigmo.h,
+ * like `ONIGENC_CTYPE_PUNCT`.
+ *
+ * @param[in] c An `OnigCodePoint` value.
+ * @param[in] t An `OnigCtype` value.
+ * @param[in] enc A `rb_encoding*` value.
+ * @retval 1 `c` is of `t` in `enc`.
+ * @retval 0 Otherwise.
+ */
+static inline bool
+rb_enc_isctype(OnigCodePoint c, OnigCtype t, rb_encoding *enc)
+{
+ return ONIGENC_IS_CODE_CTYPE(enc, c, t);
+}
+
+/**
+ * Identical to rb_isascii(), except it additionally takes an encoding.
+ *
+ * @param[in] c A code point.
+ * @param[in] enc An encoding.
+ * @retval 0 `c` is out of range of ASCII character set in `enc`.
+ * @retval 1 Otherwise.
+ *
+ * @internal
+ *
+ * `enc` is ignored. This is at least an intentional implementation detail
+ * (not a bug). But there could be rooms for future extensions.
+ */
+static inline bool
+rb_enc_isascii(OnigCodePoint c, rb_encoding *enc)
+{
+ return ONIGENC_IS_CODE_ASCII(c);
+}
+
+/**
+ * Identical to rb_isalpha(), except it additionally takes an encoding.
+ *
+ * @param[in] c A code point.
+ * @param[in] enc An encoding.
+ * @retval 1 `enc` classifies `c` as "ALPHA".
+ * @retval 0 Otherwise.
+ */
+static inline bool
+rb_enc_isalpha(OnigCodePoint c, rb_encoding *enc)
+{
+ return ONIGENC_IS_CODE_ALPHA(enc, c);
+}
+
+/**
+ * Identical to rb_islower(), except it additionally takes an encoding.
+ *
+ * @param[in] c A code point.
+ * @param[in] enc An encoding.
+ * @retval 1 `enc` classifies `c` as "LOWER".
+ * @retval 0 Otherwise.
+ */
+static inline bool
+rb_enc_islower(OnigCodePoint c, rb_encoding *enc)
+{
+ return ONIGENC_IS_CODE_LOWER(enc, c);
+}
+
+/**
+ * Identical to rb_isupper(), except it additionally takes an encoding.
+ *
+ * @param[in] c A code point.
+ * @param[in] enc An encoding.
+ * @retval 1 `enc` classifies `c` as "UPPER".
+ * @retval 0 Otherwise.
+ */
+static inline bool
+rb_enc_isupper(OnigCodePoint c, rb_encoding *enc)
+{
+ return ONIGENC_IS_CODE_UPPER(enc, c);
+}
+
+/**
+ * Identical to rb_ispunct(), except it additionally takes an encoding.
+ *
+ * @param[in] c A code point.
+ * @param[in] enc An encoding.
+ * @retval 1 `enc` classifies `c` as "PUNCT".
+ * @retval 0 Otherwise.
+ */
+static inline bool
+rb_enc_ispunct(OnigCodePoint c, rb_encoding *enc)
+{
+ return ONIGENC_IS_CODE_PUNCT(enc, c);
+}
+
+/**
+ * Identical to rb_isalnum(), except it additionally takes an encoding.
+ *
+ * @param[in] c A code point.
+ * @param[in] enc An encoding.
+ * @retval 1 `enc` classifies `c` as "ANUM".
+ * @retval 0 Otherwise.
+ */
+static inline bool
+rb_enc_isalnum(OnigCodePoint c, rb_encoding *enc)
+{
+ return ONIGENC_IS_CODE_ALNUM(enc, c);
+}
+
+/**
+ * Identical to rb_isprint(), except it additionally takes an encoding.
+ *
+ * @param[in] c A code point.
+ * @param[in] enc An encoding.
+ * @retval 1 `enc` classifies `c` as "PRINT".
+ * @retval 0 Otherwise.
+ */
+static inline bool
+rb_enc_isprint(OnigCodePoint c, rb_encoding *enc)
+{
+ return ONIGENC_IS_CODE_PRINT(enc, c);
+}
+
+/**
+ * Identical to rb_isspace(), except it additionally takes an encoding.
+ *
+ * @param[in] c A code point.
+ * @param[in] enc An encoding.
+ * @retval 1 `enc` classifies `c` as "PRINT".
+ * @retval 0 Otherwise.
+ */
+static inline bool
+rb_enc_isspace(OnigCodePoint c, rb_encoding *enc)
+{
+ return ONIGENC_IS_CODE_SPACE(enc, c);
+}
+
+/**
+ * Identical to rb_isdigit(), except it additionally takes an encoding.
+ *
+ * @param[in] c A code point.
+ * @param[in] enc An encoding.
+ * @retval 1 `enc` classifies `c` as "DIGIT".
+ * @retval 0 Otherwise.
+ */
+static inline bool
+rb_enc_isdigit(OnigCodePoint c, rb_encoding *enc)
+{
+ return ONIGENC_IS_CODE_DIGIT(enc, c);
+}
+
+RBIMPL_ATTR_CONST()
+/**
+ * Identical to rb_toupper(), except it additionally takes an encoding.
+ *
+ * @param[in] c A code point.
+ * @param[in] enc An encoding.
+ * @return `c`'s (Ruby's definition of) upper case counterpart.
+ *
+ * @internal
+ *
+ * As `RBIMPL_ATTR_CONST` implies this function ignores `enc`.
+ */
+int rb_enc_toupper(int c, rb_encoding *enc);
+
+RBIMPL_ATTR_CONST()
+/**
+ * Identical to rb_tolower(), except it additionally takes an encoding.
+ *
+ * @param[in] c A code point.
+ * @param[in] enc An encoding.
+ * @return `c`'s (Ruby's definition of) lower case counterpart.
+ *
+ * @internal
+ *
+ * As `RBIMPL_ATTR_CONST` implies this function ignores `enc`.
+ */
+int rb_enc_tolower(int c, rb_encoding *enc);
+
+RBIMPL_SYMBOL_EXPORT_END()
+
+/** @cond INTERNAL_MACRO */
+#define rb_enc_is_newline rb_enc_is_newline
+#define rb_enc_isalnum rb_enc_isalnum
+#define rb_enc_isalpha rb_enc_isalpha
+#define rb_enc_isascii rb_enc_isascii
+#define rb_enc_isctype rb_enc_isctype
+#define rb_enc_isdigit rb_enc_isdigit
+#define rb_enc_islower rb_enc_islower
+#define rb_enc_isprint rb_enc_isprint
+#define rb_enc_ispunct rb_enc_ispunct
+#define rb_enc_isspace rb_enc_isspace
+#define rb_enc_isupper rb_enc_isupper
+/** @endcond */
+
+#endif /* RUBY_INTERNAL_ENCODING_CTYPE_H */
diff --git a/include/ruby/internal/encoding/encoding.h b/include/ruby/internal/encoding/encoding.h
new file mode 100644
index 0000000000..9208d27ecf
--- /dev/null
+++ b/include/ruby/internal/encoding/encoding.h
@@ -0,0 +1,1058 @@
+#ifndef RUBY_INTERNAL_ENCODING_ENCODING_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RUBY_INTERNAL_ENCODING_ENCODING_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Defines ::rb_encoding
+ */
+
+#include "ruby/oniguruma.h"
+#include "ruby/internal/attr/const.h"
+#include "ruby/internal/attr/deprecated.h"
+#include "ruby/internal/attr/noalias.h"
+#include "ruby/internal/attr/pure.h"
+#include "ruby/internal/attr/returns_nonnull.h"
+#include "ruby/internal/dllexport.h"
+#include "ruby/internal/value.h"
+#include "ruby/internal/core/rbasic.h"
+#include "ruby/internal/fl_type.h"
+
+RBIMPL_SYMBOL_EXPORT_BEGIN()
+
+/**
+ * `Encoding` class.
+ *
+ * @ingroup object
+ */
+RUBY_EXTERN VALUE rb_cEncoding;
+
+/**
+ * @private
+ *
+ * Bit constants used when embedding encodings into ::RBasic::flags. Extension
+ * libraries must not bother such things.
+ */
+enum ruby_encoding_consts {
+
+ /** Max possible number of embeddable encodings. */
+ RUBY_ENCODING_INLINE_MAX = 127,
+
+ /** Where inline encodings reside. */
+ RUBY_ENCODING_SHIFT = (RUBY_FL_USHIFT+10),
+
+ /** Bits we use to store inline encodings. */
+ RUBY_ENCODING_MASK = (RUBY_ENCODING_INLINE_MAX<<RUBY_ENCODING_SHIFT
+ /* RUBY_FL_USER10..RUBY_FL_USER16 */),
+
+ /** Max possible length of an encoding name. */
+ RUBY_ENCODING_MAXNAMELEN = 42
+};
+
+#define ENCODING_INLINE_MAX RUBY_ENCODING_INLINE_MAX /**< @old{RUBY_ENCODING_INLINE_MAX} */
+#define ENCODING_SHIFT RUBY_ENCODING_SHIFT /**< @old{RUBY_ENCODING_SHIFT} */
+#define ENCODING_MASK RUBY_ENCODING_MASK /**< @old{RUBY_ENCODING_MASK} */
+
+/**
+ * Destructively assigns the passed encoding to the passed object. The object
+ * must be capable of having inline encoding. Using this macro needs deep
+ * understanding of bit level object binary layout.
+ *
+ * @param[out] obj Target object to modify.
+ * @param[in] ecindex Encoding in encindex format.
+ * @post `obj`'s encoding is `encindex`.
+ */
+static inline void
+RB_ENCODING_SET_INLINED(VALUE obj, int encindex)
+{
+ VALUE f = /* upcast */ encindex;
+
+ f <<= RUBY_ENCODING_SHIFT;
+ RB_FL_UNSET_RAW(obj, RUBY_ENCODING_MASK);
+ RB_FL_SET_RAW(obj, f);
+}
+
+/**
+ * Queries the encoding of the passed object. The encoding must be smaller
+ * than ::RUBY_ENCODING_INLINE_MAX, which means you have some assumption on the
+ * return value. This means the API is for internal use only.
+ *
+ * @param[in] obj Target object.
+ * @return `obj`'s encoding index.
+ */
+static inline int
+RB_ENCODING_GET_INLINED(VALUE obj)
+{
+ VALUE ret = RB_FL_TEST_RAW(obj, RUBY_ENCODING_MASK) >> RUBY_ENCODING_SHIFT;
+
+ return RBIMPL_CAST((int)ret);
+}
+
+#define ENCODING_SET_INLINED(obj,i) RB_ENCODING_SET_INLINED(obj,i) /**< @old{RB_ENCODING_SET_INLINED} */
+#define ENCODING_SET(obj,i) RB_ENCODING_SET(obj,i) /**< @old{RB_ENCODING_SET} */
+#define ENCODING_GET_INLINED(obj) RB_ENCODING_GET_INLINED(obj) /**< @old{RB_ENCODING_GET_INLINED} */
+#define ENCODING_GET(obj) RB_ENCODING_GET(obj) /**< @old{RB_ENCODING_GET} */
+#define ENCODING_IS_ASCII8BIT(obj) RB_ENCODING_IS_ASCII8BIT(obj) /**< @old{RB_ENCODING_IS_ASCII8BIT} */
+#define ENCODING_MAXNAMELEN RUBY_ENCODING_MAXNAMELEN /**< @old{RUBY_ENCODING_MAXNAMELEN} */
+
+/**
+ * The type of encoding. Our design here is we take Oniguruma/Onigmo's
+ * multilingualisation schema as our base data structure.
+ */
+typedef const OnigEncodingType rb_encoding;
+
+RBIMPL_ATTR_NOALIAS()
+/**
+ * Converts a character option to its encoding. It only supports a very
+ * limited set of Japanese encodings due to its Japanese origin. Ruby still
+ * has this in-core for backwards compatibility. But new codes must not bother
+ * such concept like one-character encoding option. Consider deprecated in
+ * practice.
+ *
+ * @param[in] c One of `['n', 'e', 's', 'u', 'i', 'x', 'm']`.
+ * @param[out] option Return buffer.
+ * @param[out] kcode Return buffer.
+ * @retval 1 `c` understood properly.
+ * @retval 0 `c` is not understood.
+ * @post `option` is a ::OnigOptionType.
+ * @post `kcode` is an enum `ruby_preserved_encindex`.
+ *
+ * @internal
+ *
+ * `kcode` is opaque because `ruby_preserved_encindex` is not visible from
+ * extension libraries. But who cares?
+ */
+int rb_char_to_option_kcode(int c, int *option, int *kcode);
+
+/**
+ * Creates a new encoding, using the passed one as a template.
+ *
+ * @param[in] name Name of the creating encoding.
+ * @param[in] src Template.
+ * @exception rb_eArgError Duplicated or malformed `name`.
+ * @return Replicated new encoding's index.
+ * @post Encoding named `name` is created as a copy of `src`, whose index
+ * is the return value.
+ *
+ * @internal
+ *
+ * `name` can be `NULL`, but that just raises an exception. OTOH it seems no
+ * sanity check is done against `src`...?
+ */
+int rb_enc_replicate(const char *name, rb_encoding *src);
+
+/**
+ * Creates a new "dummy" encoding. Roughly speaking, an encoding is dummy when
+ * it is stateful. Notable example of dummy encoding are those defined in
+ * ISO/IEC 2022
+ *
+ * @param[in] name Name of the creating encoding.
+ * @exception rb_eArgError Duplicated or malformed `name`.
+ * @return New dummy encoding's index.
+ * @post Encoding named `name` is created, whose index is the return
+ * value.
+ */
+int rb_define_dummy_encoding(const char *name);
+
+RBIMPL_ATTR_PURE()
+/**
+ * Queries if the passed encoding is dummy.
+ *
+ * @param[in] enc Encoding in question.
+ * @retval 1 It is.
+ * @retval 0 It isn't.
+ */
+int rb_enc_dummy_p(rb_encoding *enc);
+
+RBIMPL_ATTR_PURE()
+/**
+ * Queries the index of the encoding. An encoding's index is a Ruby-local
+ * concept. It is a (sequential) number assigned to each encoding.
+ *
+ * @param[in] enc Encoding in question.
+ * @return Its index.
+ * @note You can pass null pointers to this function. It is equivalent
+ * to rb_usascii_encindex() then.
+ */
+int rb_enc_to_index(rb_encoding *enc);
+
+/**
+ * Queries the index of the encoding of the passed object, if any.
+ *
+ * @param[in] obj Object in question.
+ * @retval -1 `obj` is incapable of having an encoding.
+ * @retval otherwise `obj`'s encoding's index.
+ */
+int rb_enc_get_index(VALUE obj);
+
+/**
+ * @alias{rb_enc_get_index}
+ *
+ * @internal
+ *
+ * Implementation wise this is not a verbatim alias of rb_enc_get_index(). But
+ * the API is consistent. Don't bother.
+ */
+static inline int
+RB_ENCODING_GET(VALUE obj)
+{
+ int encindex = RB_ENCODING_GET_INLINED(obj);
+
+ if (encindex == RUBY_ENCODING_INLINE_MAX) {
+ return rb_enc_get_index(obj);
+ }
+ else {
+ return encindex;
+ }
+}
+
+/**
+ * Destructively assigns an encoding (via its index) to an object.
+ *
+ * @param[out] obj Object in question.
+ * @param[in] encindex An encoding index.
+ * @exception rb_eFrozenError `obj` is frozen.
+ * @exception rb_eArgError `obj` is incapable of having an encoding.
+ * @exception rb_eEncodingError `encindex` is out of bounds.
+ * @exception rb_eLoadError Failed to load the encoding.
+ */
+void rb_enc_set_index(VALUE obj, int encindex);
+
+/** @alias{rb_enc_set_index} */
+static inline void
+RB_ENCODING_SET(VALUE obj, int encindex)
+{
+ rb_enc_set_index(obj, encindex);
+}
+
+/**
+ * This is #RB_ENCODING_SET + RB_ENC_CODERANGE_SET combo. The object must be
+ * capable of having inline encoding. Using this macro needs deep
+ * understanding of bit level object binary layout.
+ *
+ * @param[out] obj Target object.
+ * @param[in] encindex Encoding in encindex format.
+ * @param[in] cr An enum ::ruby_coderange_type.
+ * @post `obj`'s encoding is `encindex`.
+ * @post `obj`'s code range is `cr`.
+ */
+static inline void
+RB_ENCODING_CODERANGE_SET(VALUE obj, int encindex, enum ruby_coderange_type cr)
+{
+ RB_ENCODING_SET(obj, encindex);
+ RB_ENC_CODERANGE_SET(obj, cr);
+}
+
+RBIMPL_ATTR_PURE()
+/**
+ * Queries if the passed object can have its encoding.
+ *
+ * @param[in] obj Object in question.
+ * @retval 1 It can.
+ * @retval 0 It cannot.
+ */
+int rb_enc_capable(VALUE obj);
+
+/**
+ * Queries the index of the encoding.
+ *
+ * @param[in] name Name of the encoding to find.
+ * @exception rb_eArgError No such encoding named `name`.
+ * @retval -1 `name` exists, but unable to load.
+ * @retval otherwise Index of encoding named `name`.
+ */
+int rb_enc_find_index(const char *name);
+
+/**
+ * Registers an "alias" name. In the wild, an encoding can be called using
+ * multiple names. For instance an encoding known as `"CP932"` is also called
+ * `"SJIS"` on occasions. This API registers such relationships.
+ *
+ * @param[in] alias New name.
+ * @param[in] orig Old name.
+ * @exception rb_eArgError `alias` is duplicated or malformed.
+ * @retval -1 Failed to load `orig`.
+ * @retval otherwise The index of `orig` and `alias`.
+ * @post `alias` is a synonym of `orig`. They refer to the identical
+ * encoding.
+ */
+int rb_enc_alias(const char *alias, const char *orig);
+
+/**
+ * Obtains a encoding index from a wider range of objects (than
+ * rb_enc_find_index()).
+ *
+ * @param[in] obj An ::rb_cEncoding, or its name in ::rb_cString.
+ * @retval -1 `obj` is unexpected type/contents.
+ * @retval otherwise Index corresponding to `obj`.
+ */
+int rb_to_encoding_index(VALUE obj);
+
+/**
+ * Identical to rb_find_encoding(), except it raises an exception instead of
+ * returning NULL.
+ *
+ * @param[in] obj An ::rb_cEncoding, or its name in ::rb_cString.
+ * @exception rb_eTypeError `obj` is neither ::rb_cEncoding nor ::rb_cString.
+ * @exception rb_eArgError `obj` is an unknown encoding name.
+ * @return Encoding of `obj`.
+ */
+rb_encoding *rb_to_encoding(VALUE obj);
+
+/**
+ * Identical to rb_to_encoding_index(), except the return type.
+ *
+ * @param[in] obj An ::rb_cEncoding, or its name in ::rb_cString.
+ * @exception rb_eTypeError `obj` is neither ::rb_cEncoding nor ::rb_cString.
+ * @retval NULL No such encoding.
+ * @return otherwise Encoding of `obj`.
+ */
+rb_encoding *rb_find_encoding(VALUE obj);
+
+/**
+ * Identical to rb_enc_get_index(), except the return type.
+ *
+ * @param[in] obj Object in question.
+ * @retval NULL Obj is incapable of having an encoding.
+ * @retval otherwise `obj`'s encoding.
+ */
+rb_encoding *rb_enc_get(VALUE obj);
+
+/**
+ * Look for the "common" encoding between the two. One character can or cannot
+ * be expressed depending on an encoding. This function finds the super-set of
+ * encodings that satisfy contents of both arguments. If that is impossible
+ * returns NULL.
+ *
+ * @param[in] str1 An object.
+ * @param[in] str2 Another object.
+ * @retval NULL No encoding can satisfy both at once.
+ * @retval otherwise Common encoding between the two.
+ * @note Arguments can be non-string, e.g. Regexp.
+ */
+rb_encoding *rb_enc_compatible(VALUE str1, VALUE str2);
+
+/**
+ * Identical to rb_enc_compatible(), except it raises an exception instead of
+ * returning NULL.
+ *
+ * @param[in] str1 An object.
+ * @param[in] str2 Another object.
+ * @exception rb_eEncCompatError No encoding can satisfy both.
+ * @return Common encoding between the two.
+ * @note Arguments can be non-string, e.g. Regexp.
+ */
+rb_encoding *rb_enc_check(VALUE str1,VALUE str2);
+
+/**
+ * Identical to rb_enc_set_index(), except it additionally does contents fix-up
+ * depending on the passed object. It for instance changes the byte length of
+ * terminating `U+0000` according to the passed encoding.
+ *
+ * @param[out] obj Object in question.
+ * @param[in] encindex An encoding index.
+ * @exception rb_eFrozenError `obj` is frozen.
+ * @exception rb_eArgError `obj` is incapable of having an encoding.
+ * @exception rb_eEncodingError `encindex` is out of bounds.
+ * @exception rb_eLoadError Failed to load the encoding.
+ * @return The passed `obj`.
+ * @post `obj`'s contents might be fixed according to `encindex`.
+ */
+VALUE rb_enc_associate_index(VALUE obj, int encindex);
+
+/**
+ * Identical to rb_enc_associate(), except it takes an encoding itself instead
+ * of its index.
+ *
+ * @param[out] obj Object in question.
+ * @param[in] enc An encoding.
+ * @exception rb_eFrozenError `obj` is frozen.
+ * @exception rb_eArgError `obj` is incapable of having an encoding.
+ * @return The passed `obj`.
+ * @post `obj`'s contents might be fixed according to `enc`.
+ */
+VALUE rb_enc_associate(VALUE obj, rb_encoding *enc);
+
+/**
+ * Destructively copies the encoding of the latter object to that of former
+ * one. It can also be seen as a routine identical to
+ * rb_enc_associate_index(), except it takes an object's encoding instead of an
+ * encoding's index.
+ *
+ * @param[out] dst Object to modify.
+ * @param[in] src Object to reference.
+ * @exception rb_eFrozenError `dst` is frozen.
+ * @exception rb_eArgError `dst` is incapable of having an encoding.
+ * @exception rb_eEncodingError `src` is incapable of having an encoding.
+ * @post `dst`'s encoding is that of `src`'s.
+ */
+void rb_enc_copy(VALUE dst, VALUE src);
+
+
+/**
+ * Identical to rb_find_encoding(), except it takes an encoding index instead
+ * of a Ruby object.
+ *
+ * @param[in] idx An encoding index.
+ * @retval NULL No such encoding.
+ * @retval otherwise An encoding whose index is `idx`.
+ */
+rb_encoding *rb_enc_from_index(int idx);
+
+/**
+ * Identical to rb_find_encoding(), except it takes a C's string instead of
+ * Ruby's.
+ *
+ * @param[in] name Name of the encoding to query.
+ * @retval NULL No such encoding.
+ * @retval otherwise An encoding whose index is `idx`.
+ */
+rb_encoding *rb_enc_find(const char *name);
+
+/**
+ * Queries the (canonical) name of the passed encoding.
+ *
+ * @param[in] enc An encoding.
+ * @return Its name.
+ */
+static inline const char *
+rb_enc_name(rb_encoding *enc)
+{
+ return enc->name;
+}
+
+/**
+ * Queries the minimum number of bytes that the passed encoding needs to
+ * represent a character. For ASCII and compatible encodings this is typically
+ * 1. There are however encodings whose minimum is not 1; they are
+ * historically called wide characters.
+ *
+ * @param[in] enc An encoding.
+ * @return Its least possible number of bytes except 0.
+ */
+static inline int
+rb_enc_mbminlen(rb_encoding *enc)
+{
+ return enc->min_enc_len;
+}
+
+/**
+ * Queries the maximum number of bytes that the passed encoding needs to
+ * represent a character. Fixed-width encodings have the same value for this
+ * one and #rb_enc_mbminlen. However there are variable-width encodings.
+ * UTF-8, for instance, takes from 1 up to 6 bytes.
+ *
+ * @param[in] enc An encoding.
+ * @return Its maximum possible number of bytes of a character.
+ */
+static inline int
+rb_enc_mbmaxlen(rb_encoding *enc)
+{
+ return enc->max_enc_len;
+}
+
+/**
+ * Queries the number of bytes of the character at the passed pointer.
+ *
+ * @param[in] p Pointer to a character's first byte.
+ * @param[in] e End of the string that has `p`.
+ * @param[in] enc Encoding of the string.
+ * @return If the character at `p` does not end until `e`, number of bytes
+ * between `p` and `e`. Otherwise the number of bytes that the
+ * character at `p` is encoded.
+ *
+ * @internal
+ *
+ * Strictly speaking there are chances when `p` points to a middle byte of a
+ * wide character. This function returns "the number of bytes from `p` to
+ * nearest of either `e` or the next character boundary", if you go strict.
+ */
+int rb_enc_mbclen(const char *p, const char *e, rb_encoding *enc);
+
+/**
+ * Identical to rb_enc_mbclen() unless the character at `p` overruns `e`. That
+ * can happen for instance when you read from a socket and its partial read
+ * cuts a wide character in-between. In those situations this function
+ * "estimates" theoretical length of the character in question. Typically it
+ * tends to be possible to know how many bytes a character needs before
+ * actually reaching its end; for instance UTF-8 encodes a character's length
+ * in the first byte of it. This function returns that info.
+ *
+ * @note This implies that the string is not broken.
+ *
+ * @param[in] p Pointer to the character's first byte.
+ * @param[in] e End of the string that has `p`.
+ * @param[in] enc Encoding of the string.
+ * @return Number of bytes of character at `p`, measured or estimated.
+ */
+int rb_enc_fast_mbclen(const char *p, const char *e, rb_encoding *enc);
+
+/**
+ * Queries the number of bytes of the character at the passed pointer. This
+ * function returns 3 different types of information:
+ *
+ * ```CXX
+ * auto n = rb_enc_precise_mbclen(p, q, r);
+ *
+ * if (ONIGENC_MBCLEN_CHARFOUND_P(n)) {
+ * // Character found. Normal return.
+ * auto found_length = ONIGENC_MBCLEN_CHARFOUND_LEN(n);
+ * }
+ * else if (ONIGENC_MBCLEN_NEEDMORE_P(n)) {
+ * // Character overruns past `q`; needs more.
+ * auto requested_length = ONIGENC_MBCLEN_NEEDMORE_LEN(n);
+ * }
+ * else {
+ * // `p` is broken.
+ * assert(ONIGENC_MBCLEN_INVALID_P(n));
+ * }
+ * ```
+ *
+ * @param[in] p Pointer to the character's first byte.
+ * @param[in] e End of the string that has `p`.
+ * @param[in] enc Encoding of the string.
+ * @return Encoded read/needed number of bytes (see above).
+ */
+int rb_enc_precise_mbclen(const char *p, const char *e, rb_encoding *enc);
+
+#define MBCLEN_CHARFOUND_P(ret) ONIGENC_MBCLEN_CHARFOUND_P(ret) /**< @old{ONIGENC_MBCLEN_CHARFOUND_P} */
+#define MBCLEN_CHARFOUND_LEN(ret) ONIGENC_MBCLEN_CHARFOUND_LEN(ret) /**< @old{ONIGENC_MBCLEN_CHARFOUND_LEN} */
+#define MBCLEN_INVALID_P(ret) ONIGENC_MBCLEN_INVALID_P(ret) /**< @old{ONIGENC_MBCLEN_INVALID_P} */
+#define MBCLEN_NEEDMORE_P(ret) ONIGENC_MBCLEN_NEEDMORE_P(ret) /**< @old{ONIGENC_MBCLEN_NEEDMORE_P} */
+#define MBCLEN_NEEDMORE_LEN(ret) ONIGENC_MBCLEN_NEEDMORE_LEN(ret) /**< @old{ONIGENC_MBCLEN_NEEDMORE_LEN} */
+
+/**
+ * Queries the code point of character pointed by the passed pointer. If that
+ * code point is included in ASCII that code point is returned. Otherwise -1.
+ * This can be different from just looking at the first byte. For instance it
+ * reads 2 bytes in case of UTF-16BE.
+ *
+ * @param[in] p Pointer to the character's first byte.
+ * @param[in] e End of the string that has `p`.
+ * @param[in] len Return buffer.
+ * @param[in] enc Encoding of the string.
+ * @retval -1 The character at `p` is not i ASCII.
+ * @retval otherwise A code point of the character at `p`.
+ * @post `len` (if set) is the number of bytes of `p`.
+ */
+int rb_enc_ascget(const char *p, const char *e, int *len, rb_encoding *enc);
+
+/**
+ * Queries the code point of character pointed by the passed pointer.
+ * Exceptions happen in case of broken input.
+ *
+ * @param[in] p Pointer to the character's first byte.
+ * @param[in] e End of the string that has `p`.
+ * @param[in] len Return buffer.
+ * @param[in] enc Encoding of the string.
+ * @exception rb_eArgError `p` is broken.
+ * @return Code point of the character pointed by `p`.
+ * @post `len` (if set) is the number of bytes of `p`.
+ */
+unsigned int rb_enc_codepoint_len(const char *p, const char *e, int *len, rb_encoding *enc);
+
+/**
+ * Queries the code point of character pointed by the passed pointer.
+ * Exceptions happen in case of broken input.
+ *
+ * @deprecated Use rb_enc_codepoint_len() instead.
+ * @param[in] p Pointer to the character's first byte.
+ * @param[in] e End of the string that has `p`.
+ * @param[in] enc Encoding of the string.
+ * @exception rb_eArgError `p` is broken.
+ * @return Code point of the character pointed by `p`.
+ *
+ * @internal
+ *
+ * @matz says in commit 91e5ba1cb865a2385d3e1cbfacd824496898e098 that the line
+ * below is a "prototype for obsolete function". However even today there
+ * still are some use cases of it throughout our repository. It seems it has
+ * its own niche.
+ */
+static inline unsigned int
+rb_enc_codepoint(const char *p, const char *e, rb_encoding *enc)
+{
+ return rb_enc_codepoint_len(p, e, 0, enc);
+ /* ^^^
+ * This can be `NULL` in C, `nullptr` in C++, and `0` for both.
+ * We choose the most portable one here.
+ */
+}
+
+
+/**
+ * Identical to rb_enc_codepoint(), except it assumes the passed character is
+ * not broken.
+ *
+ * @param[in] p Pointer to the character's first byte.
+ * @param[in] e End of the string that has `p`.
+ * @param[in] enc Encoding of the string.
+ * @return Code point of the character pointed by `p`.
+ */
+static inline OnigCodePoint
+rb_enc_mbc_to_codepoint(const char *p, const char *e, rb_encoding *enc)
+{
+ const OnigUChar *up = RBIMPL_CAST((const OnigUChar *)p);
+ const OnigUChar *ue = RBIMPL_CAST((const OnigUChar *)e);
+
+ return ONIGENC_MBC_TO_CODE(enc, up, ue);
+}
+
+/**
+ * Queries the number of bytes requested to represent the passed code point
+ * using the passed encoding.
+ *
+ * @param[in] code Code point in question.
+ * @param[in] enc Encoding to convert the code into a byte sequence.
+ * @exception rb_eArgError `enc` does not glean `code`.
+ * @return Number of bytes requested to represent `code` using `enc`.
+ */
+int rb_enc_codelen(int code, rb_encoding *enc);
+
+/**
+ * Identical to rb_enc_codelen(), except it returns 0 for invalid code points.
+ *
+ * @param[in] c Code point in question.
+ * @param[in] enc Encoding to convert `c` into a byte sequence.
+ * @retval 0 `c` is invalid.
+ * @return otherwise Number of bytes needed for `enc` to encode `c`.
+ */
+static inline int
+rb_enc_code_to_mbclen(int c, rb_encoding *enc)
+{
+ OnigCodePoint uc = RBIMPL_CAST((OnigCodePoint)c);
+
+ return ONIGENC_CODE_TO_MBCLEN(enc, uc);
+}
+
+/**
+ * Identical to rb_enc_uint_chr(), except it writes back to the passed buffer
+ * instead of allocating one.
+ *
+ * @param[in] c Code point.
+ * @param[out] buf Return buffer.
+ * @param[in] enc Target encoding scheme.
+ * @post `c` is encoded according to `enc`, then written to `buf`.
+ *
+ * @internal
+ *
+ * The second argument must be typed. But its current usages prevent us from
+ * being any stricter than this. :FIXME:
+ */
+static inline int
+rb_enc_mbcput(unsigned int c, void *buf, rb_encoding *enc)
+{
+ OnigCodePoint uc = RBIMPL_CAST((OnigCodePoint)c);
+ OnigUChar *ubuf = RBIMPL_CAST((OnigUChar *)buf);
+
+ return ONIGENC_CODE_TO_MBC(enc, uc, ubuf);
+}
+
+/**
+ * Queries the previous (left) character.
+ *
+ * @param[in] s Start of the string.
+ * @param[in] p Pointer to a character.
+ * @param[in] e End of the string.
+ * @param[in] enc Encoding.
+ * @retval NULL No previous character.
+ * @retval otherwise Pointer to the head of the previous character.
+ */
+static inline char *
+rb_enc_prev_char(const char *s, const char *p, const char *e, rb_encoding *enc)
+{
+ const OnigUChar *us = RBIMPL_CAST((const OnigUChar *)s);
+ const OnigUChar *up = RBIMPL_CAST((const OnigUChar *)p);
+ const OnigUChar *ue = RBIMPL_CAST((const OnigUChar *)e);
+ OnigUChar *ur = onigenc_get_prev_char_head(enc, us, up, ue);
+
+ return RBIMPL_CAST((char *)ur);
+}
+
+/**
+ * Queries the left boundary of a character. This function takes a pointer
+ * that is not necessarily a head of a character, and searches for its head.
+ *
+ * @param[in] s Start of the string.
+ * @param[in] p Pointer to a possibly-middle of a character.
+ * @param[in] e End of the string.
+ * @param[in] enc Encoding.
+ * @return Pointer to the head of the character that contains `p`.
+ */
+static inline char *
+rb_enc_left_char_head(const char *s, const char *p, const char *e, rb_encoding *enc)
+{
+ const OnigUChar *us = RBIMPL_CAST((const OnigUChar *)s);
+ const OnigUChar *up = RBIMPL_CAST((const OnigUChar *)p);
+ const OnigUChar *ue = RBIMPL_CAST((const OnigUChar *)e);
+ OnigUChar *ur = onigenc_get_left_adjust_char_head(enc, us, up, ue);
+
+ return RBIMPL_CAST((char *)ur);
+}
+
+/**
+ * Queries the right boundary of a character. This function takes a pointer
+ * that is not necessarily a head of a character, and searches for its tail.
+ *
+ * @param[in] s Start of the string.
+ * @param[in] p Pointer to a possibly-middle of a character.
+ * @param[in] e End of the string.
+ * @param[in] enc Encoding.
+ * @return Pointer to the end of the character that contains `p`.
+ */
+static inline char *
+rb_enc_right_char_head(const char *s, const char *p, const char *e, rb_encoding *enc)
+{
+ const OnigUChar *us = RBIMPL_CAST((const OnigUChar *)s);
+ const OnigUChar *up = RBIMPL_CAST((const OnigUChar *)p);
+ const OnigUChar *ue = RBIMPL_CAST((const OnigUChar *)e);
+ OnigUChar *ur = onigenc_get_right_adjust_char_head(enc, us, up, ue);
+
+ return RBIMPL_CAST((char *)ur);
+}
+
+/**
+ * Scans the string backwards for n characters.
+ *
+ * @param[in] s Start of the string.
+ * @param[in] p Pointer to a character.
+ * @param[in] e End of the string.
+ * @param[in] n Steps.
+ * @param[in] enc Encoding.
+ * @retval NULL There are no `n` characters left.
+ * @retval otherwise Pointer to `n` character before `p`.
+ */
+static inline char *
+rb_enc_step_back(const char *s, const char *p, const char *e, int n, rb_encoding *enc)
+{
+ const OnigUChar *us = RBIMPL_CAST((const OnigUChar *)s);
+ const OnigUChar *up = RBIMPL_CAST((const OnigUChar *)p);
+ const OnigUChar *ue = RBIMPL_CAST((const OnigUChar *)e);
+ const OnigUChar *ur = onigenc_step_back(enc, us, up, ue, n);
+
+ return RBIMPL_CAST((char *)ur);
+}
+
+/**
+ * @private
+ *
+ * This is an implementation detail of rb_enc_asciicompat(). People don't use
+ * it directly. Just always use rb_enc_asciicompat().
+ *
+ * @param[in] enc Encoding in question.
+ * @retval 1 It is ASCII compatible.
+ * @retval 0 It isn't.
+ */
+static inline int
+rb_enc_asciicompat_inline(rb_encoding *enc)
+{
+ return rb_enc_mbminlen(enc)==1 && !rb_enc_dummy_p(enc);
+}
+
+/**
+ * Queries if the passed encoding is _in some sense_ compatible with ASCII.
+ * The concept of ASCII compatibility is nuanced, and private to our
+ * implementation. For instance SJIS is ASCII compatible to us, despite their
+ * having different characters at code point `0x5C`. This is based on some
+ * practical consideration that Japanese people confuses SJIS to be "upper
+ * compatible" with ASCII (which is in fact a wrong idea, but we just don't go
+ * strict here). An example of ASCII incompatible encoding is UTF-16. UTF-16
+ * shares code points with ASCII, but employs a completely different encoding
+ * scheme.
+ *
+ * @param[in] enc Encoding in question.
+ * @retval 0 It is incompatible.
+ * @retval 1 It is compatible.
+ */
+static inline bool
+rb_enc_asciicompat(rb_encoding *enc)
+{
+ if (rb_enc_mbminlen(enc) != 1) {
+ return false;
+ }
+ else if (rb_enc_dummy_p(enc)) {
+ return false;
+ }
+ else {
+ return true;
+ }
+}
+
+/**
+ * Queries if the passed string is in an ASCII-compatible encoding.
+ *
+ * @param[in] str A Ruby's string to query.
+ * @retval 0 `str` is not a String, or an ASCII-incompatible string.
+ * @retval 1 Otherwise.
+ */
+static inline bool
+rb_enc_str_asciicompat_p(VALUE str)
+{
+ rb_encoding *enc = rb_enc_get(str);
+
+ return rb_enc_asciicompat(enc);
+}
+
+/**
+ * Queries the Ruby-level counterpart instance of ::rb_cEncoding that
+ * corresponds to the passed encoding.
+ *
+ * @param[in] enc An encoding
+ * @retval RUBY_Qnil `enc` is a null pointer.
+ * @retval otherwise An instance of ::rb_cEncoding.
+ */
+VALUE rb_enc_from_encoding(rb_encoding *enc);
+
+RBIMPL_ATTR_PURE()
+/**
+ * Queries if the passed encoding is either one of UTF-8/16/32.
+ *
+ * @note It does not take UTF-7, which we actually support, into account.
+ *
+ * @param[in] enc Encoding in question.
+ * @retval 0 It is not a Unicode variant.
+ * @retval otherwise It is.
+ *
+ * @internal
+ *
+ * In reality it returns 1/0, but the value is abstracted as
+ * `ONIGENC_FLAG_UNICODE`.
+ */
+int rb_enc_unicode_p(rb_encoding *enc);
+
+RBIMPL_ATTR_RETURNS_NONNULL()
+/**
+ * Queries the encoding that represents ASCII-8BIT a.k.a. binary.
+ *
+ * @return The encoding that represents ASCII-8BIT.
+ *
+ * @internal
+ *
+ * This can not return NULL once the process properly boots up.
+ */
+rb_encoding *rb_ascii8bit_encoding(void);
+
+RBIMPL_ATTR_RETURNS_NONNULL()
+/**
+ * Queries the encoding that represents UTF-8.
+ *
+ * @return The encoding that represents UTF-8.
+ *
+ * @internal
+ *
+ * This can not return NULL once the process properly boots up.
+ */
+rb_encoding *rb_utf8_encoding(void);
+
+RBIMPL_ATTR_RETURNS_NONNULL()
+/**
+ * Queries the encoding that represents US-ASCII.
+ *
+ * @return The encoding that represents US-ASCII.
+ *
+ * @internal
+ *
+ * This can not return NULL once the process properly boots up.
+ */
+rb_encoding *rb_usascii_encoding(void);
+
+/**
+ * Queries the encoding that represents the current locale.
+ *
+ * @return The encoding that represents the process' locale.
+ *
+ * @internal
+ *
+ * This is dynamic. If you change the process' locale by e.g. calling
+ * `setlocale(3)`, that should also change the return value of this function.
+ *
+ * There is no official way for Ruby scripts to manipulate locales, though.
+ */
+rb_encoding *rb_locale_encoding(void);
+
+/**
+ * Queries the "filesystem" encoding. This is the encoding that ruby expects
+ * info from the OS' file system are in. This affects for instance return
+ * value of rb_dir_getwd(). Most notably on Windows it can be an alias of OS
+ * codepage. Most notably on Linux users can set this via default external
+ * encoding.
+ *
+ * @return The "filesystem" encoding.
+ */
+rb_encoding *rb_filesystem_encoding(void);
+
+/**
+ * Queries the "default external" encoding. This is used to interact with
+ * outer-process things such as File. Though not recommended, you can set this
+ * using rb_enc_set_default_external().
+ *
+ * @return The "default external" encoding.
+ */
+rb_encoding *rb_default_external_encoding(void);
+
+/**
+ * Queries the "default internal" encoding. This could be a null pointer.
+ * Otherwise, outer-process info are transcoded from default external encoding
+ * to this one during reading from an IO.
+ *
+ * @return The "default internal" encoding (if any).
+ */
+rb_encoding *rb_default_internal_encoding(void);
+
+#ifndef rb_ascii8bit_encindex
+RBIMPL_ATTR_CONST()
+/**
+ * Identical to rb_ascii8bit_encoding(), except it returns the encoding's index
+ * instead of the encoding itself.
+ *
+ * @return The index of encoding of ASCII-8BIT.
+ *
+ * @internal
+ *
+ * This happens to be 0.
+ */
+int rb_ascii8bit_encindex(void);
+#endif
+
+/**
+ * Queries if the passed object is in ascii 8bit (== binary) encoding. The
+ * object must be capable of having inline encoding. Using this macro needs
+ * deep understanding of bit level object binary layout.
+ *
+ * @param[in] obj An object to check.
+ * @retval 1 It is.
+ * @retval 0 It isn't.
+ */
+static inline bool
+RB_ENCODING_IS_ASCII8BIT(VALUE obj)
+{
+ return RB_ENCODING_GET_INLINED(obj) == rb_ascii8bit_encindex();
+}
+
+#ifndef rb_utf8_encindex
+RBIMPL_ATTR_CONST()
+/**
+ * Identical to rb_utf8_encoding(), except it returns the encoding's index
+ * instead of the encoding itself.
+ *
+ * @return The index of encoding of UTF-8.
+ */
+int rb_utf8_encindex(void);
+#endif
+
+#ifndef rb_usascii_encindex
+RBIMPL_ATTR_CONST()
+/**
+ * Identical to rb_usascii_encoding(), except it returns the encoding's index
+ * instead of the encoding itself.
+ *
+ * @return The index of encoding of UTF-8.
+ */
+int rb_usascii_encindex(void);
+#endif
+
+/**
+ * Identical to rb_locale_encoding(), except it returns the encoding's index
+ * instead of the encoding itself.
+ *
+ * @return The index of the locale encoding.
+ */
+int rb_locale_encindex(void);
+
+/**
+ * Identical to rb_filesystem_encoding(), except it returns the encoding's
+ * index instead of the encoding itself.
+ *
+ * @return The index of the filesystem encoding.
+ */
+int rb_filesystem_encindex(void);
+
+/**
+ * Identical to rb_default_external_encoding(), except it returns the
+ * Ruby-level counterpart instance of ::rb_cEncoding that corresponds to the
+ * default external encoding.
+ *
+ * @return An instance of ::rb_cEncoding of default external.
+ */
+VALUE rb_enc_default_external(void);
+
+/**
+ * Identical to rb_default_internal_encoding(), except it returns the
+ * Ruby-level counterpart instance of ::rb_cEncoding that corresponds to the
+ * default internal encoding.
+ *
+ * @return An instance of ::rb_cEncoding of default internal.
+ */
+VALUE rb_enc_default_internal(void);
+
+/**
+ * Destructively assigns the passed encoding as the default external encoding.
+ * You should not use this API. It has process-global side effects. Also it
+ * doesn't change encodings of strings that have already been read.
+ *
+ * @param[in] encoding Ruby level encoding.
+ * @exception rb_eArgError `encoding` is ::RUBY_Qnil.
+ * @post The default external encoding is `encoding`.
+ */
+void rb_enc_set_default_external(VALUE encoding);
+
+/**
+ * Destructively assigns the passed encoding as the default internal encoding.
+ * You should not use this API. It has process-global side effects. Also it
+ * doesn't change encodings of strings that have already been read.
+ *
+ * @param[in] encoding Ruby level encoding.
+ * @post The default internal encoding is `encoding`.
+ * @note Unlike rb_enc_set_default_external() you can pass ::RUBY_Qnil.
+ */
+void rb_enc_set_default_internal(VALUE encoding);
+
+/**
+ * Returns a platform-depended "charmap" of the current locale. This
+ * information is called a "Codeset name" in IEEE 1003.1 section 13
+ * (`<langinfo.h>`). This is a very low-level API. The return value can have
+ * no corresponding encoding when passed to rb_find_encoding().
+ *
+ * @param[in] klass Ignored for no reason (why...)
+ * @return The low-level locale charmap, in Ruby's String.
+ */
+VALUE rb_locale_charmap(VALUE klass);
+
+RBIMPL_SYMBOL_EXPORT_END()
+
+/** @cond INTERNAL_MACRO */
+#define RB_ENCODING_GET RB_ENCODING_GET
+#define RB_ENCODING_GET_INLINED RB_ENCODING_GET_INLINED
+#define RB_ENCODING_IS_ASCII8BIT RB_ENCODING_IS_ASCII8BIT
+#define RB_ENCODING_SET RB_ENCODING_SET
+#define RB_ENCODING_SET_INLINED RB_ENCODING_SET_INLINED
+#define rb_enc_asciicompat rb_enc_asciicompat
+#define rb_enc_code_to_mbclen rb_enc_code_to_mbclen
+#define rb_enc_codepoint rb_enc_codepoint
+#define rb_enc_left_char_head rb_enc_left_char_head
+#define rb_enc_mbc_to_codepoint rb_enc_mbc_to_codepoint
+#define rb_enc_mbcput rb_enc_mbcput
+#define rb_enc_mbmaxlen rb_enc_mbmaxlen
+#define rb_enc_mbminlen rb_enc_mbminlen
+#define rb_enc_name rb_enc_name
+#define rb_enc_prev_char rb_enc_prev_char
+#define rb_enc_right_char_head rb_enc_right_char_head
+#define rb_enc_step_back rb_enc_step_back
+#define rb_enc_str_asciicompat_p rb_enc_str_asciicompat_p
+/** @endcond */
+
+#endif /* RUBY_INTERNAL_ENCODING_ENCODING_H */
diff --git a/include/ruby/internal/encoding/pathname.h b/include/ruby/internal/encoding/pathname.h
new file mode 100644
index 0000000000..0b5e85a524
--- /dev/null
+++ b/include/ruby/internal/encoding/pathname.h
@@ -0,0 +1,184 @@
+#ifndef RUBY_INTERNAL_ENCODING_PATHNAME_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RUBY_INTERNAL_ENCODING_PATHNAME_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Routines to manipulate encodings of pathnames.
+ */
+
+#include "ruby/internal/attr/nonnull.h"
+#include "ruby/internal/dllexport.h"
+#include "ruby/internal/encoding/encoding.h"
+#include "ruby/internal/value.h"
+
+RBIMPL_SYMBOL_EXPORT_BEGIN()
+RBIMPL_ATTR_NONNULL(())
+/**
+ * Returns a path component directly adjacent to the passed pointer.
+ *
+ * ```
+ * "/multi/byte/encoded/pathname.txt"
+ * ^ ^ ^
+ * | | +--- end
+ * | +--- @return
+ * +--- path
+ * ```
+ *
+ * @param[in] path Where to start scanning.
+ * @param[in] end End of the path string.
+ * @param[in] enc Encoding of the string.
+ * @return A pointer in the passed string where the next path component
+ * resides, or `end` if there is no next path component.
+ */
+char *rb_enc_path_next(const char *path, const char *end, rb_encoding *enc);
+
+RBIMPL_ATTR_NONNULL(())
+/**
+ * Seeks for non-prefix part of a pathname. This can be a no-op when the OS
+ * has no such concept like a path prefix. But there are OSes where path
+ * prefixes do exist.
+ *
+ * ```
+ * "C:\multi\byte\encoded\pathname.txt"
+ * ^ ^ ^
+ * | | +--- end
+ * | +--- @return
+ * +--- path
+ * ```
+ *
+ * @param[in] path Where to start scanning.
+ * @param[in] end End of the path string.
+ * @param[in] enc Encoding of the string.
+ * @return A pointer in the passed string where non-prefix part starts, or
+ * `path` if the OS does not have path prefix.
+ */
+char *rb_enc_path_skip_prefix(const char *path, const char *end, rb_encoding *enc);
+
+RBIMPL_ATTR_NONNULL(())
+/**
+ * Returns the last path component.
+ *
+ * ```
+ * "/multi/byte/encoded/pathname.txt"
+ * ^ ^ ^
+ * | | +--- end
+ * | +--- @return
+ * +--- path
+ * ```
+ *
+ * @param[in] path Where to start scanning.
+ * @param[in] end End of the path string.
+ * @param[in] enc Encoding of the string.
+ * @return A pointer in the passed string where the last path component
+ * resides, or `end` if there is no more path component.
+ */
+char *rb_enc_path_last_separator(const char *path, const char *end, rb_encoding *enc);
+
+RBIMPL_ATTR_NONNULL(())
+/**
+ * This just returns the passed end basically. It makes difference in case the
+ * passed string ends with tons of path separators like the following:
+ *
+ * ```
+ * "/path/that/ends/with/lots/of/slashes//////////////"
+ * ^ ^ ^
+ * | | +--- end
+ * | +--- @return
+ * +--- path
+ * ```
+ *
+ * @param[in] path Where to start scanning.
+ * @param[in] end End of the path string.
+ * @param[in] enc Encoding of the string.
+ * @return A pointer in the passed string where the trailing path
+ * separators start, or `end` if there is no trailing path
+ * separators.
+ *
+ * @internal
+ *
+ * It seems this function was introduced to mimic what POSIX says about
+ * `basename(3)`.
+ */
+char *rb_enc_path_end(const char *path, const char *end, rb_encoding *enc);
+
+RBIMPL_ATTR_NONNULL((1, 4))
+/**
+ * Our own encoding-aware version of `basename(3)`. Normally, this function
+ * returns the last path component of the given name. However in case the
+ * passed name ends with a path separator, it returns the name of the
+ * directory, not the last (empty) component. Also if the passed name is a
+ * root directory, it returns that root directory. Note however that Windows
+ * filesystem have drive letters, which this function does not return.
+ *
+ * @param[in] name Target path.
+ * @param[out] baselen Return buffer.
+ * @param[in,out] alllen Number of bytes of `name`.
+ * @param[enc] enc Encoding of `name`.
+ * @return The rightmost component of `name`.
+ * @post `baselen`, if passed, is updated to be the number of bytes
+ * of the returned basename.
+ * @post `alllen`, if passed, is updated to be the number of bytes of
+ * strings not considered as the basename.
+ */
+const char *ruby_enc_find_basename(const char *name, long *baselen, long *alllen, rb_encoding *enc);
+
+RBIMPL_ATTR_NONNULL((1, 3))
+/**
+ * Our own encoding-aware version of `extname`. This function first applies
+ * rb_enc_path_last_separator() to the passed name and only concerns its return
+ * value (ignores any parent directories). This function returns complicated
+ * results:
+ *
+ * ```CXX
+ * auto path = "...";
+ * auto len = strlen(path);
+ * auto ret = ruby_enc_find_extname(path, &len, rb_ascii8bit_encoding());
+ *
+ * switch(len) {
+ * case 0:
+ * if (ret == 0) {
+ * // `path` is a file without extensions.
+ * }
+ * else {
+ * // `path` is a dotfile.
+ * // `ret` is the file's name.
+ * }
+ * break;
+ *
+ * case 1:
+ * // `path` _ends_ with a dot.
+ * // `ret` is that dot.
+ * break;
+ *
+ * default:
+ * // `path` has an extension.
+ * // `ret` is that extension.
+ * }
+ * ```
+ *
+ * @param[in] name Target path.
+ * @param[in,out] len Number of bytes of `name`.
+ * @param[in] enc Encoding of `name`.
+ * @return See above.
+ * @post `len`, if passed, is updated (see above).
+ */
+const char *ruby_enc_find_extname(const char *name, long *len, rb_encoding *enc);
+
+RBIMPL_SYMBOL_EXPORT_END()
+
+#endif /* RUBY_INTERNAL_ENCODING_PATHNAME_H */
diff --git a/include/ruby/internal/encoding/re.h b/include/ruby/internal/encoding/re.h
new file mode 100644
index 0000000000..d0de23bc83
--- /dev/null
+++ b/include/ruby/internal/encoding/re.h
@@ -0,0 +1,46 @@
+#ifndef RUBY_INTERNAL_ENCODING_RE_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RUBY_INTERNAL_ENCODING_RE_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Routines to manipulate encodings of symbols.
+ */
+
+#include "ruby/internal/dllexport.h"
+#include "ruby/internal/encoding/encoding.h"
+#include "ruby/internal/value.h"
+
+RBIMPL_SYMBOL_EXPORT_BEGIN()
+
+/**
+ * Identical to rb_reg_new(), except it additionally takes an encoding.
+ *
+ * @param[in] ptr A memory region of `len` bytes length.
+ * @param[in] len Length of `ptr`, in bytes, not including the
+ * terminating NUL character.
+ * @param[in] enc Encoding of `ptr`.
+ * @param[in] opts Options e.g. ONIG_OPTION_MULTILINE.
+ * @exception rb_eRegexpError Failed to compile `ptr`.
+ * @return An allocated new instance of ::rb_cRegexp, of `enc` encoding,
+ * whose expression is compiled according to `ptr`.
+ */
+VALUE rb_enc_reg_new(const char *ptr, long len, rb_encoding *enc, int opts);
+
+RBIMPL_SYMBOL_EXPORT_END()
+
+#endif /* RUBY_INTERNAL_ENCODING_RE_H */
diff --git a/include/ruby/internal/encoding/sprintf.h b/include/ruby/internal/encoding/sprintf.h
new file mode 100644
index 0000000000..cb8737b414
--- /dev/null
+++ b/include/ruby/internal/encoding/sprintf.h
@@ -0,0 +1,78 @@
+#ifndef RUBY_INTERNAL_ENCODING_SPRINTF_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RUBY_INTERNAL_ENCODING_SPRINTF_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Routines to manipulate encodings of symbols.
+ */
+#include "ruby/internal/config.h"
+#include <stdarg.h>
+#include "ruby/internal/attr/format.h"
+#include "ruby/internal/attr/nonnull.h"
+#include "ruby/internal/attr/noreturn.h"
+#include "ruby/internal/dllexport.h"
+#include "ruby/internal/encoding/encoding.h"
+#include "ruby/internal/value.h"
+
+RBIMPL_SYMBOL_EXPORT_BEGIN()
+RBIMPL_ATTR_NONNULL((2))
+RBIMPL_ATTR_FORMAT(RBIMPL_PRINTF_FORMAT, 2, 3)
+/**
+ * Identical to rb_sprintf(), except it additionally takes an encoding. The
+ * passed encoding rules both the incoming format specifier and the resulting
+ * string.
+ *
+ * @param[in] enc Encoding of `fmt`.
+ * @param[in] fmt A `printf`-like format specifier.
+ * @param[in] ... Variadic number of contents to format.
+ * @return A rendered new instance of ::rb_cString, of `enc` encoding.
+ */
+VALUE rb_enc_sprintf(rb_encoding *enc, const char *fmt, ...);
+
+RBIMPL_ATTR_NONNULL((2))
+RBIMPL_ATTR_FORMAT(RBIMPL_PRINTF_FORMAT, 2, 0)
+/**
+ * Identical to rb_enc_sprintf(), except it takes a `va_list` instead of
+ * variadic arguments. It can also be seen as a routine identical to
+ * rb_vsprintf(), except it additionally takes an encoding.
+ *
+ * @param[in] enc Encoding of `fmt`.
+ * @param[in] fmt A `printf`-like format specifier.
+ * @param[in] ap Contents to format.
+ * @return A rendered new instance of ::rb_cString, of `enc` encoding.
+ */
+VALUE rb_enc_vsprintf(rb_encoding *enc, const char *fmt, va_list ap);
+
+RBIMPL_ATTR_NORETURN()
+RBIMPL_ATTR_NONNULL((3))
+RBIMPL_ATTR_FORMAT(RBIMPL_PRINTF_FORMAT, 3, 4)
+/**
+ * Identical to rb_raise(), except it additionally takes an encoding.
+ *
+ * @param[in] enc Encoding of the generating exception.
+ * @param[in] exc A subclass of ::rb_eException.
+ * @param[in] fmt Format specifier string compatible with rb_sprintf().
+ * @param[in] ... Contents of the message.
+ * @exception exc The specified exception.
+ * @note It never returns.
+ */
+void rb_enc_raise(rb_encoding *enc, VALUE exc, const char *fmt, ...);
+
+RBIMPL_SYMBOL_EXPORT_END()
+
+#endif /* RUBY_INTERNAL_ENCODING_SPRINTF_H */
diff --git a/include/ruby/internal/encoding/string.h b/include/ruby/internal/encoding/string.h
new file mode 100644
index 0000000000..6ed7ca1c90
--- /dev/null
+++ b/include/ruby/internal/encoding/string.h
@@ -0,0 +1,346 @@
+#ifndef RUBY_INTERNAL_ENCODING_STRING_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RUBY_INTERNAL_ENCODING_STRING_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Routines to manipulate encodings of strings.
+ */
+
+#include "ruby/internal/dllexport.h"
+#include "ruby/internal/value.h"
+#include "ruby/internal/encoding/encoding.h"
+#include "ruby/internal/attr/nonnull.h"
+#include "ruby/internal/intern/string.h" /* rbimpl_strlen */
+
+RBIMPL_SYMBOL_EXPORT_BEGIN()
+
+/**
+ * Identical to rb_enc_str_new(), except it additionally takes an encoding.
+ *
+ * @param[in] ptr A memory region of `len` bytes length.
+ * @param[in] len Length of `ptr`, in bytes, not including the
+ * terminating NUL character.
+ * @param[in] enc Encoding of `ptr`.
+ * @exception rb_eNoMemError Failed to allocate `len+1` bytes.
+ * @exception rb_eArgError `len` is negative.
+ * @return An instance of ::rb_cString, of `len` bytes length, of `enc`
+ * encoding, whose contents are verbatim copy of `ptr`.
+ * @pre At least `len` bytes of continuous memory region shall be
+ * accessible via `ptr`.
+ * @note `enc` can be a null pointer. It can also be seen as a routine
+ * identical to rb_usascii_str_new() then.
+ */
+VALUE rb_enc_str_new(const char *ptr, long len, rb_encoding *enc);
+
+RBIMPL_ATTR_NONNULL((1))
+/**
+ * Identical to rb_enc_str_new(), except it assumes the passed pointer is a
+ * pointer to a C string. It can also be seen as a routine identical to
+ * rb_str_new_cstr(), except it additionally takes an encoding.
+ *
+ * @param[in] ptr A C string.
+ * @param[in] enc Encoding of `ptr`.
+ * @exception rb_eNoMemError Failed to allocate memory.
+ * @return An instance of ::rb_cString, of `enc` encoding, whose contents
+ * are verbatim copy of `ptr`.
+ * @pre `ptr` must not be a null pointer.
+ * @pre Because `ptr` is a C string it makes no sense for `enc` to be
+ * something like UTF-32.
+ * @note `enc` can be a null pointer. It can also be seen as a routine
+ * identical to rb_usascii_str_new_cstr() then.
+ */
+VALUE rb_enc_str_new_cstr(const char *ptr, rb_encoding *enc);
+
+/**
+ * Identical to rb_enc_str_new(), except it takes a C string literal. It can
+ * also be seen as a routine identical to rb_str_new_static(), except it
+ * additionally takes an encoding.
+ *
+ * @param[in] ptr A C string literal.
+ * @param[in] len `strlen(ptr)`.
+ * @param[in] enc Encoding of `ptr`.
+ * @exception rb_eArgError `len` out of range of `size_t`.
+ * @pre `ptr` must be a C string constant.
+ * @return An instance of ::rb_cString, of `enc` encoding, whose backend
+ * storage is the passed C string literal.
+ * @warning It is a very bad idea to write to a C string literal (often
+ * immediate SEGV shall occur). Consider return values of this
+ * function be read-only.
+ * @note `enc` can be a null pointer. It can also be seen as a routine
+ * identical to rb_usascii_str_new_static() then.
+ */
+VALUE rb_enc_str_new_static(const char *ptr, long len, rb_encoding *enc);
+
+/**
+ * Identical to rb_enc_str_new(), except it returns a "f"string. It can also
+ * be seen as a routine identical to rb_interned_str(), except it additionally
+ * takes an encoding.
+ *
+ * @param[in] ptr A memory region of `len` bytes length.
+ * @param[in] len Length of `ptr`, in bytes, not including the
+ * terminating NUL character.
+ * @param[in] enc Encoding of `ptr`.
+ * @exception rb_eArgError `len` is negative.
+ * @return A found or created instance of ::rb_cString, of `len` bytes
+ * length, of `enc` encoding, whose contents are identical to that
+ * of `ptr`.
+ * @pre At least `len` bytes of continuous memory region shall be
+ * accessible via `ptr`.
+ * @note `enc` can be a null pointer.
+ */
+VALUE rb_enc_interned_str(const char *ptr, long len, rb_encoding *enc);
+
+RBIMPL_ATTR_NONNULL((1))
+/**
+ * Identical to rb_enc_str_new_cstr(), except it returns a "f"string. It can
+ * also be seen as a routine identical to rb_interned_str_cstr(), except it
+ * additionally takes an encoding.
+ *
+ * @param[in] ptr A memory region of `len` bytes length.
+ * @param[in] enc Encoding of `ptr`.
+ * @return A found or created instance of ::rb_cString of `enc` encoding,
+ * whose contents are identical to that of `ptr`.
+ * @pre At least `len` bytes of continuous memory region shall be
+ * accessible via `ptr`.
+ * @note `enc` can be a null pointer.
+ */
+VALUE rb_enc_interned_str_cstr(const char *ptr, rb_encoding *enc);
+
+/**
+ * Counts the number of characters of the passed string, according to the
+ * passed encoding. This has to be complicated. The passed string could be
+ * invalid and/or broken. This routine would scan from the beginning til the
+ * end, byte by byte, to seek out character boundaries. Could be super slow.
+ *
+ * @param[in] head Leftmost pointer to the string.
+ * @param[in] tail Rightmost pointer to the string.
+ * @param[in] enc Encoding of the string.
+ * @return Number of characters exist in `head` .. `tail`. The definition
+ * of "character" depends on the passed `enc`.
+ */
+long rb_enc_strlen(const char *head, const char *tail, rb_encoding *enc);
+
+/**
+ * Queries the n-th character. Like rb_enc_strlen() this function can be fast
+ * or slow depending on the contents. Don't expect characters to be uniformly
+ * distributed across the entire string.
+ *
+ * @param[in] head Leftmost pointer to the string.
+ * @param[in] tail Rightmost pointer to the string.
+ * @param[in] nth Requested index of characters.
+ * @param[in] enc Encoding of the string.
+ * @return Pointer to the first byte of the character that is `nth`
+ * character ahead of `head`, or `tail` if there is no such
+ * character (OOB etc). The definition of "character" depends on
+ * the passed `enc`.
+ */
+char *rb_enc_nth(const char *head, const char *tail, long nth, rb_encoding *enc);
+
+/**
+ * Identical to rb_enc_get_index(), except the return type.
+ *
+ * @param[in] obj Object in question.
+ * @exception rb_eTypeError `obj` is incapable of having an encoding.
+ * @return `obj`'s encoding.
+ */
+VALUE rb_obj_encoding(VALUE obj);
+
+/**
+ * Identical to rb_str_cat(), except it additionally takes an encoding.
+ *
+ * @param[out] str Destination object.
+ * @param[in] ptr Contents to append.
+ * @param[in] len Length of `src`, in bytes.
+ * @param[in] enc Encoding of `ptr`.
+ * @exception rb_eArgError `len` is negative.
+ * @exception rb_eEncCompatError `enc` is not compatible with `str`.
+ * @return The passed `dst`.
+ * @post The contents of `ptr` is copied, transcoded into `dst`'s
+ * encoding, then pasted into `dst`'s end.
+ */
+VALUE rb_enc_str_buf_cat(VALUE str, const char *ptr, long len, rb_encoding *enc);
+
+/**
+ * Encodes the passed code point into a series of bytes.
+ *
+ * @param[in] code Code point.
+ * @param[in] enc Target encoding scheme.
+ * @exception rb_eRangeError `enc` does not glean `code`.
+ * @return An instance of ::rb_cString, of `enc` encoding, whose sole
+ * contents is `code` represented in `enc`.
+ * @note No way to encode code points bigger than UINT_MAX.
+ *
+ * @internal
+ *
+ * In other languages, APIs like this one could be seen as the primitive
+ * routines where encodings' "encode" feature are implemented. However in case
+ * of Ruby this is not the primitive one. We directly manipulate encoded
+ * strings. Encoding conversion routines transcode an encoded string directly
+ * to another one; not via a code point array.
+ */
+VALUE rb_enc_uint_chr(unsigned int code, rb_encoding *enc);
+
+/**
+ * Identical to rb_external_str_new(), except it additionally takes an
+ * encoding. However the whole point of rb_external_str_new() is to encode a
+ * string into default external encoding. Being able to specify arbitrary
+ * encoding just ruins the designed purpose the function meseems.
+ *
+ * @param[in] ptr A memory region of `len` bytes length.
+ * @param[in] len Length of `ptr`, in bytes, not including the
+ * terminating NUL character.
+ * @param[in] enc Target encoding scheme.
+ * @exception rb_eArgError `len` is negative.
+ * @return An instance of ::rb_cString. In case encoding conversion from
+ * "default internal" to `enc` is fully defined over the given
+ * contents, then the return value is a string of `enc` encoding,
+ * whose contents are the converted ones. Otherwise the string is
+ * a junk.
+ * @warning It doesn't raise on a conversion failure and silently ends up in
+ * a corrupted output. You can know the failure by querying
+ * `valid_encoding?` of the result object.
+ *
+ * @internal
+ *
+ * @shyouhei has no idea why this one does not follow the naming convention
+ * that others obey. It seems to him that this should have been called
+ * `rb_enc_external_str_new`.
+ */
+VALUE rb_external_str_new_with_enc(const char *ptr, long len, rb_encoding *enc);
+
+/**
+ * Identical to rb_str_export(), except it additionally takes an encoding.
+ *
+ * @param[in] obj Target object.
+ * @param[in] enc Target encoding.
+ * @exception rb_eTypeError No implicit conversion to String.
+ * @return Converted ruby string of `enc` encoding.
+ */
+VALUE rb_str_export_to_enc(VALUE obj, rb_encoding *enc);
+
+/**
+ * Encoding conversion main routine.
+ *
+ * @param[in] str String to convert.
+ * @param[in] from Source encoding.
+ * @param[in] to Destination encoding.
+ * @return A copy of `str`, with conversion from `from` to `to` applied.
+ * @note `from` can be a null pointer. `str`'s encoding is taken then.
+ * @note `to` can be a null pointer. No-op then.
+ */
+VALUE rb_str_conv_enc(VALUE str, rb_encoding *from, rb_encoding *to);
+
+/**
+ * Identical to rb_str_conv_enc(), except it additionally takes IO encoder
+ * options. The extra arguments can be constructed using io_extract_modeenc()
+ * etc.
+ *
+ * @param[in] str String to convert.
+ * @param[in] from Source encoding.
+ * @param[in] to Destination encoding.
+ * @param[in] ecflags A set of enum ::ruby_econv_flag_type.
+ * @param[in] ecopts Optional hash.
+ * @return A copy of `str`, with conversion from `from` to `to` applied.
+ * @note `from` can be a null pointer. `str`'s encoding is taken then.
+ * @note `to` can be a null pointer. No-op then.
+ * @note `ecopts` can be ::RUBY_Qnil, which is equivalent to passing an
+ * empty hash.
+ */
+VALUE rb_str_conv_enc_opts(VALUE str, rb_encoding *from, rb_encoding *to, int ecflags, VALUE ecopts);
+
+/**
+ * Scans the passed string to collect its code range. Because a Ruby's string
+ * is mutable, its contents change from time to time; so does its code range.
+ * A long-lived string tends to fall back to ::RUBY_ENC_CODERANGE_UNKNOWN.
+ * This API scans it and re-assigns a fine-grained code range constant.
+ *
+ * @param[out] str A string.
+ * @return An enum ::ruby_coderange_type.
+ */
+int rb_enc_str_coderange(VALUE str);
+
+/**
+ * Scans the passed string until it finds something odd. Returns the number of
+ * bytes scanned. As the name implies this is suitable for repeated call. One
+ * of its application is `IO#readlines`. The method reads from its receiver's
+ * read buffer, maybe more than once, looking for newlines. But "newline" can
+ * be different among encodings. This API is used to detect broken contents to
+ * properly mark them as such.
+ *
+ * @param[in] str String to scan.
+ * @param[in] end End of `str`.
+ * @param[in] enc `str`'s encoding.
+ * @param[out] cr Return buffer.
+ * @return Distance between `str` and first such byte where broken.
+ * @post `cr` has the code range type.
+ */
+long rb_str_coderange_scan_restartable(const char *str, const char *end, rb_encoding *enc, int *cr);
+
+/**
+ * Queries if the passed string is "ASCII only". An ASCII only string is a
+ * string who doesn't have any non-ASCII characters at all. This doesn't
+ * necessarily mean the string is in ASCII encoding. For instance a String of
+ * CP932 encoding can quite much be ASCII only, depending on its contents.
+ *
+ * @param[in] str String in question.
+ * @retval 1 It doesn't have non-ASCII characters.
+ * @retval 0 It has characters that are out of ASCII.
+ */
+int rb_enc_str_asciionly_p(VALUE str);
+
+RBIMPL_ATTR_NONNULL(())
+/**
+ * Looks for the passed string in the passed buffer.
+ *
+ * @param[in] x Buffer that potentially includes `y`.
+ * @param[in] m Number of bytes of `x`.
+ * @param[in] y Query string.
+ * @param[in] n Number of bytes of `y`.
+ * @param[in] enc Encoding of both `x` and `y`.
+ * @retval -1 Not found.
+ * @retval otherwise Found index in `x`.
+ * @note This API can match at a non-character-boundary.
+ */
+long rb_memsearch(const void *x, long m, const void *y, long n, rb_encoding *enc);
+
+/** @cond INTERNAL_MACRO */
+RBIMPL_ATTR_NONNULL(())
+static inline VALUE
+rbimpl_enc_str_new_cstr(const char *str, rb_encoding *enc)
+{
+ long len = rbimpl_strlen(str);
+
+ return rb_enc_str_new_static(str, len, enc);
+}
+
+#define rb_enc_str_new(str, len, enc) \
+ ((RBIMPL_CONSTANT_P(str) && \
+ RBIMPL_CONSTANT_P(len) ? \
+ rb_enc_str_new_static: \
+ rb_enc_str_new) ((str), (len), (enc)))
+
+#define rb_enc_str_new_cstr(str, enc) \
+ ((RBIMPL_CONSTANT_P(str) ? \
+ rbimpl_enc_str_new_cstr : \
+ rb_enc_str_new_cstr) ((str), (enc)))
+
+/** @endcond */
+
+RBIMPL_SYMBOL_EXPORT_END()
+
+#endif /* RUBY_INTERNAL_ENCODING_STRING_H */
diff --git a/include/ruby/internal/encoding/symbol.h b/include/ruby/internal/encoding/symbol.h
new file mode 100644
index 0000000000..9cd1b0dbf4
--- /dev/null
+++ b/include/ruby/internal/encoding/symbol.h
@@ -0,0 +1,100 @@
+#ifndef RUBY_INTERNAL_ENCODING_SYMBOL_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RUBY_INTERNAL_ENCODING_SYMBOL_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Routines to manipulate encodings of symbols.
+ */
+
+#include "ruby/internal/attr/nonnull.h"
+#include "ruby/internal/dllexport.h"
+#include "ruby/internal/encoding/encoding.h"
+#include "ruby/internal/value.h"
+
+RBIMPL_SYMBOL_EXPORT_BEGIN()
+
+/**
+ * Identical to rb_intern2(), except it additionally takes an encoding.
+ *
+ * @param[in] name The name of the id.
+ * @param[in] len Length of `name`.
+ * @param[in] enc `name`'s encoding.
+ * @exception rb_eRuntimeError Too many symbols.
+ * @return A (possibly new) id whose value is the given name.
+ * @note These days Ruby internally has two kinds of symbols
+ * (static/dynamic). Symbols created using this function would
+ * become static ones; i.e. would never be garbage collected. It
+ * is up to you to avoid memory leaks. Think twice before using
+ * it.
+ */
+ID rb_intern3(const char *name, long len, rb_encoding *enc);
+
+RBIMPL_ATTR_NONNULL(())
+/**
+ * Identical to rb_symname_p(), except it additionally takes an encoding.
+ *
+ * @param[in] str A C string to check.
+ * @param[in] enc `str`'s encoding.
+ * @retval 1 It is a valid symbol name.
+ * @retval 0 It is invalid as a symbol name.
+ */
+int rb_enc_symname_p(const char *str, rb_encoding *enc);
+
+/**
+ * Identical to rb_enc_symname_p(), except it additionally takes the passed
+ * string's length. This is needed for strings containing NUL bytes, like in
+ * case of UTF-32.
+ *
+ * @param[in] name A C string to check.
+ * @param[in] len Number of bytes of `str`.
+ * @param[in] enc `str`'s encoding.
+ * @retval 1 It is a valid symbol name.
+ * @retval 0 It is invalid as a symbol name.
+ */
+int rb_enc_symname2_p(const char *name, long len, rb_encoding *enc);
+
+/**
+ * Identical to rb_check_id(), except it takes a pointer to a memory region
+ * instead of Ruby's string.
+ *
+ * @param[in] ptr A pointer to a memory region.
+ * @param[in] len Number of bytes of `ptr`.
+ * @param[in] enc Encoding of `ptr`.
+ * @exception rb_eEncodingError `ptr` contains non-ASCII according to `enc`.
+ * @retval 0 No such id ever existed in the history.
+ * @retval otherwise The id that represents the given name.
+ */
+ID rb_check_id_cstr(const char *ptr, long len, rb_encoding *enc);
+
+/**
+ * Identical to rb_check_id_cstr(), except for the return type. It can also be
+ * seen as a routine identical to rb_check_symbol(), except it takes a pointer
+ * to a memory region instead of Ruby's string.
+ *
+ * @param[in] ptr A pointer to a memory region.
+ * @param[in] len Number of bytes of `ptr`.
+ * @param[in] enc Encoding of `ptr`.
+ * @exception rb_eEncodingError `ptr` contains non-ASCII according to `enc`.
+ * @retval RUBY_Qnil No such id ever existed in the history.
+ * @retval otherwise The id that represents the given name.
+ */
+VALUE rb_check_symbol_cstr(const char *ptr, long len, rb_encoding *enc);
+
+RBIMPL_SYMBOL_EXPORT_END()
+
+#endif /* RUBY_INTERNAL_ENCODING_SYMBOL_H */
diff --git a/include/ruby/internal/encoding/transcode.h b/include/ruby/internal/encoding/transcode.h
new file mode 100644
index 0000000000..60c96a41c9
--- /dev/null
+++ b/include/ruby/internal/encoding/transcode.h
@@ -0,0 +1,558 @@
+#ifndef RUBY_INTERNAL_ENCODING_TRANSCODE_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RUBY_INTERNAL_ENCODING_TRANSCODE_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief econv stuff
+ */
+
+#include "ruby/internal/dllexport.h"
+#include "ruby/internal/value.h"
+
+RBIMPL_SYMBOL_EXPORT_BEGIN()
+
+/** return value of rb_econv_convert() */
+typedef enum {
+
+ /**
+ * The conversion stopped when it found an invalid sequence.
+ */
+ econv_invalid_byte_sequence,
+
+ /**
+ * The conversion stopped when it found a character in the input which
+ * cannot be representable in the output.
+ */
+ econv_undefined_conversion,
+
+ /**
+ * The conversion stopped because there is no destination.
+ */
+ econv_destination_buffer_full,
+
+ /**
+ * The conversion stopped because there is no input.
+ */
+ econv_source_buffer_empty,
+
+ /**
+ * The conversion stopped after converting everything. This is arguably
+ * the expected normal end of conversion.
+ */
+ econv_finished,
+
+ /**
+ * The conversion stopped after writing something to somewhere, before
+ * reading everything.
+ */
+ econv_after_output,
+
+ /**
+ * The conversion stopped in middle of reading a character, possibly due to
+ * a partial read of a socket etc.
+ */
+ econv_incomplete_input
+} rb_econv_result_t;
+
+/** An opaque struct that represents a lowest level of encoding conversion. */
+typedef struct rb_econv_t rb_econv_t;
+
+/**
+ * Converts the contents of the passed string from its encoding to the passed
+ * one.
+ *
+ * @param[in] str Target string.
+ * @param[in] to Destination encoding.
+ * @param[in] ecflags A set of enum
+ * ::ruby_econv_flag_type.
+ * @param[in] ecopts A keyword hash, like
+ * ::rb_io_t::rb_io_enc_t::ecopts.
+ * @exception rb_eArgError Not fully converted.
+ * @exception rb_eInvalidByteSequenceError `str` is malformed.
+ * @exception rb_eUndefinedConversionError `str` has a character not
+ * representable using `to`.
+ * @exception rb_eConversionNotFoundError There is no known conversion from
+ * `str`'s encoding to `to`.
+ * @return A string whose encoding is `to`, and whose contents is converted
+ * contents of `str`.
+ * @note Use rb_econv_prepare_options() to generate `ecopts`.
+ */
+VALUE rb_str_encode(VALUE str, VALUE to, int ecflags, VALUE ecopts);
+
+/**
+ * Queries if there is more than one way to convert between the passed two
+ * encodings. Encoding conversion are has_and_belongs_to_many relationships.
+ * There could be no direct conversion defined for the passed pair. Ruby tries
+ * to find an indirect way to do so then. For instance ISO-8859-1 has no
+ * direct conversion to ISO-2022-JP. But there is ISO-8859-1 to UTF-8
+ * conversion; then there is UTF-8 to EUC-JP conversion; finally there also is
+ * EUC-JP to ISO-2022-JP conversion. So in short ISO-8859-1 can be converted
+ * to ISO-2022-JP using that path. This function returns true. Obviously not
+ * everything that can be represented using UTF-8 can also be represented using
+ * EUC-JP. Conversions in practice can fail depending on the actual input, and
+ * that renders exceptions in case of rb_str_encode().
+ *
+ * @param[in] from_encoding One encoding.
+ * @param[in] to_encoding Another encoding.
+ * @retval 0 No way to convert the two.
+ * @retval 1 At least one way to convert the two.
+ *
+ * @internal
+ *
+ * Practically @shyouhei knows no way for this function to return 0. It seems
+ * everything can eventually be converted to/from UTF-8, which connects
+ * everything.
+ */
+int rb_econv_has_convpath_p(const char* from_encoding, const char* to_encoding);
+
+/**
+ * Identical to rb_econv_prepare_opts(), except it additionally takes the
+ * initial value of flags. The extra bits are bitwise-ORed to the return
+ * value.
+ *
+ * @param[in] opthash Keyword arguments.
+ * @param[out] ecopts Return buffer.
+ * @param[in] ecflags Default set of enum ::ruby_econv_flag_type.
+ * @exception rb_eArgError Unknown/Broken values passed.
+ * @return Calculated set of enum ::ruby_econv_flag_type.
+ * @post `ecopts` holds a hash object suitable for
+ * ::rb_io_t::rb_io_enc_t::ecopts.
+ */
+int rb_econv_prepare_options(VALUE opthash, VALUE *ecopts, int ecflags);
+
+/**
+ * Splits a keyword arguments hash (that for instance `String#encode` took)
+ * into a set of enum ::ruby_econv_flag_type and a hash storing replacement
+ * characters etc.
+ *
+ * @param[in] opthash Keyword arguments.
+ * @param[out] ecopts Return buffer.
+ * @exception rb_eArgError Unknown/Broken values passed.
+ * @return Calculated set of enum ::ruby_econv_flag_type.
+ * @post `ecopts` holds a hash object suitable for
+ * ::rb_io_t::rb_io_enc_t::ecopts.
+ */
+int rb_econv_prepare_opts(VALUE opthash, VALUE *ecopts);
+
+/**
+ * Creates a new instance of struct ::rb_econv_t.
+ *
+ * @param[in] source_encoding Name of an encoding.
+ * @param[in] destination_encoding Name of another encoding.
+ * @param[in] ecflags A set of enum ::ruby_econv_flag_type.
+ * @exception rb_eArgError No such encoding.
+ * @retval NULL Failed to create a struct ::rb_econv_t.
+ * @retval otherwise Allocated struct ::rb_econv_t.
+ * @warning Return value must be passed to rb_econv_close() exactly once.
+ */
+rb_econv_t *rb_econv_open(const char *source_encoding, const char *destination_encoding, int ecflags);
+
+/**
+ * Identical to rb_econv_open(), except it additionally takes a hash of
+ * optional strings.
+ *
+ *
+ * @param[in] source_encoding Name of an encoding.
+ * @param[in] destination_encoding Name of another encoding.
+ * @param[in] ecflags A set of enum ::ruby_econv_flag_type.
+ * @param[in] ecopts Optional set of strings.
+ * @exception rb_eArgError No such encoding.
+ * @retval NULL Failed to create a struct ::rb_econv_t.
+ * @retval otherwise Allocated struct ::rb_econv_t.
+ * @warning Return value must be passed to rb_econv_close() exactly once.
+ */
+rb_econv_t *rb_econv_open_opts(const char *source_encoding, const char *destination_encoding, int ecflags, VALUE ecopts);
+
+/**
+ * Converts a string from an encoding to another.
+ *
+ * Possible flags are either ::RUBY_ECONV_PARTIAL_INPUT (means the source
+ * buffer is a part of much larger one), ::RUBY_ECONV_AFTER_OUTPUT (instructs
+ * the converter to stop after output before input), or both of them.
+ *
+ * @param[in,out] ec Conversion specification/state etc.
+ * @param[in] source_buffer_ptr Target string.
+ * @param[in] source_buffer_end End of target string.
+ * @param[out] destination_buffer_ptr Return buffer.
+ * @param[out] destination_buffer_end End of return buffer.
+ * @param[in] flags Flags (see above).
+ * @return The status of the conversion.
+ * @post `destination_buffer_ptr` holds conversion results.
+ */
+rb_econv_result_t rb_econv_convert(rb_econv_t *ec,
+ const unsigned char **source_buffer_ptr, const unsigned char *source_buffer_end,
+ unsigned char **destination_buffer_ptr, unsigned char *destination_buffer_end,
+ int flags);
+
+/**
+ * Destructs a converter. Note that a converter can have a buffer, and can be
+ * non-empty. Calling this would lose your data then.
+ *
+ * @param[out] ec The converter to destroy.
+ * @post `ec` is no longer a valid pointer.
+ */
+void rb_econv_close(rb_econv_t *ec);
+
+/**
+ * Assigns the replacement string. The string passed here would appear in
+ * converted string when it cannot represent its source counterpart. This can
+ * happen for instance you convert an emoji to ISO-8859-1.
+ *
+ * @param[out] ec Target converter.
+ * @param[in] str Replacement string.
+ * @param[in] len Number of bytes of `str`.
+ * @param[in] encname Name of encoding of `str`.
+ * @retval 0 Success.
+ * @retval -1 Failure (ENOMEM etc.).
+ * @post `ec`'s replacement string is set to `str`.
+ */
+int rb_econv_set_replacement(rb_econv_t *ec, const unsigned char *str, size_t len, const char *encname);
+
+/**
+ * "Decorate"s a converter. There are special kind of converters that
+ * transforms the contents, like replacing CR into CRLF. You can add such
+ * decorators to a converter using this API. By using this function a
+ * decorator is prepended at the beginning of a conversion sequence: in case of
+ * CRLF conversion, newlines are converted before encodings are converted.
+ *
+ * @param[out] ec Target converter to decorate.
+ * @param[in] decorator_name Name of decorator to prepend.
+ * @retval 0 Success.
+ * @retval -1 Failure (no such decorator etc.).
+ * @post Decorator works before encoding conversion happens.
+ *
+ * @internal
+ *
+ * What is the possible value of the `decorator_name` is not public. You have
+ * to read through `transcode.c` carefully.
+ */
+int rb_econv_decorate_at_first(rb_econv_t *ec, const char *decorator_name);
+
+/**
+ * Identical to rb_econv_decorate_at_first(), except it adds to the opposite
+ * direction. For instance CRLF conversion would run _after_ encodings are
+ * converted.
+ *
+ * @param[out] ec Target converter to decorate.
+ * @param[in] decorator_name Name of decorator to prepend.
+ * @retval 0 Success.
+ * @retval -1 Failure (no such decorator etc.).
+ * @post Decorator works after encoding conversion happens.
+ */
+int rb_econv_decorate_at_last(rb_econv_t *ec, const char *decorator_name);
+
+/**
+ * Creates a `rb_eConverterNotFoundError` exception object (but does not
+ * raise).
+ *
+ * @param[in] senc Name of source encoding.
+ * @param[in] denc Name of destination encoding.
+ * @param[in] ecflags A set of enum ::ruby_econv_flag_type.
+ * @return An instance of `rb_eConverterNotFoundError`.
+ */
+VALUE rb_econv_open_exc(const char *senc, const char *denc, int ecflags);
+
+/**
+ * Appends the passed string to the passed converter's output buffer. This can
+ * be handy when an encoding needs bytes out of thin air; for instance
+ * ISO-2022-JP has "shift function" which does not correspond to any
+ * characters.
+ *
+ * @param[out] ec Target converter.
+ * @param[in] str String to insert.
+ * @param[in] len Number of bytes of `str`.
+ * @param[in] str_encoding Encoding of `str`.
+ * @retval 0 Success.
+ * @retval -1 Failure (conversion error etc.).
+ * @note `str_encoding` can be anything, and `str` itself is converted
+ * when necessary.
+ */
+int rb_econv_insert_output(rb_econv_t *ec,
+ const unsigned char *str, size_t len, const char *str_encoding);
+
+/**
+ * Queries an encoding name which best suits for rb_econv_insert_output()'s
+ * last parameter. Strings in this encoding need no conversion when inserted;
+ * can be both time/space efficient.
+ *
+ * @param[in] ec Target converter.
+ * @return Its encoding for insertion.
+ */
+const char *rb_econv_encoding_to_insert_output(rb_econv_t *ec);
+
+/**
+ * This is a rb_econv_make_exception() + rb_exc_raise() combo.
+ *
+ * @param[in] ec (Possibly failed) conversion.
+ * @exception rb_eInvalidByteSequenceError Invalid byte sequence.
+ * @exception rb_eUndefinedConversionError Conversion undefined.
+ * @note This function can return when no error.
+ */
+void rb_econv_check_error(rb_econv_t *ec);
+
+/**
+ * This function makes sense right after rb_econv_convert() returns. As listed
+ * in ::rb_econv_result_t, rb_econv_convert() can bail out for various reasons.
+ * This function checks the passed converter's internal state and convert it to
+ * an appropriate exception object.
+ *
+ * @param[in] ec Target converter.
+ * @retval RUBY_Qnil The converter has no error.
+ * @retval otherwise Conversion error turned into an exception.
+ */
+VALUE rb_econv_make_exception(rb_econv_t *ec);
+
+/**
+ * Queries if rb_econv_putback() makes sense, i.e. there are invalid byte
+ * sequences remain in the buffer.
+ *
+ * @param[in] ec Target converter.
+ * @return Number of bytes that can be pushed back.
+ */
+int rb_econv_putbackable(rb_econv_t *ec);
+
+/**
+ * Puts back the bytes. In case of ::econv_invalid_byte_sequence, some of
+ * those invalid bytes are discarded and the others are buffered to be
+ * converted later. The latter bytes can be put back using this API.
+ *
+ * @param[out] ec Target converter (invalid byte sequence).
+ * @param[out] p Return buffer.
+ * @param[in] n Max number of bytes to put back.
+ * @post At most `n` bytes of what was put back is written to `p`.
+ */
+void rb_econv_putback(rb_econv_t *ec, unsigned char *p, int n);
+
+/**
+ * Queries the passed encoding's corresponding ASCII compatible encoding. "The
+ * corresponding ASCII compatible encoding" in this context is an ASCII
+ * compatible encoding which can represent exactly the same character sets as
+ * the given ASCII incompatible encoding. For instance that of UTF-16LE is
+ * UTF-8.
+ *
+ * @param[in] encname Name of an ASCII incompatible encoding.
+ * @retval NULL `encname` is already ASCII compatible.
+ * @retval otherwise The corresponding ASCII compatible encoding.
+ */
+const char *rb_econv_asciicompat_encoding(const char *encname);
+
+/**
+ * Identical to rb_econv_convert(), except it takes Ruby's string instead of
+ * C's pointer.
+ *
+ * @param[in,out] ec Target converter.
+ * @param[in] src Source string.
+ * @param[in] flags Flags (see rb_econv_convert).
+ * @exception rb_eArgError Converted string is too long.
+ * @exception rb_eInvalidByteSequenceError Invalid byte sequence.
+ * @exception rb_eUndefinedConversionError Conversion undefined.
+ * @return The conversion result.
+ */
+VALUE rb_econv_str_convert(rb_econv_t *ec, VALUE src, int flags);
+
+/**
+ * Identical to rb_econv_str_convert(), except it converts only a part of the
+ * passed string. Can be handy when you for instance want to do line-buffered
+ * conversion.
+ *
+ * @param[in,out] ec Target converter.
+ * @param[in] src Source string.
+ * @param[in] byteoff Number of bytes to seek.
+ * @param[in] bytesize Number of bytes to read.
+ * @param[in] flags Flags (see rb_econv_convert).
+ * @exception rb_eArgError Converted string is too long.
+ * @exception rb_eInvalidByteSequenceError Invalid byte sequence.
+ * @exception rb_eUndefinedConversionError Conversion undefined.
+ * @return The conversion result.
+ */
+VALUE rb_econv_substr_convert(rb_econv_t *ec, VALUE src, long byteoff, long bytesize, int flags);
+
+/**
+ * Identical to rb_econv_str_convert(), except it appends the conversion result
+ * to the additionally passed string instead of creating a new string. It can
+ * also be seen as a routine identical to rb_econv_append(), except it takes a
+ * Ruby's string instead of C's pointer.
+ *
+ * @param[in,out] ec Target converter.
+ * @param[in] src Source string.
+ * @param[in] dst Return buffer.
+ * @param[in] flags Flags (see rb_econv_convert).
+ * @exception rb_eArgError Converted string is too long.
+ * @exception rb_eInvalidByteSequenceError Invalid byte sequence.
+ * @exception rb_eUndefinedConversionError Conversion undefined.
+ * @return The conversion result.
+ */
+VALUE rb_econv_str_append(rb_econv_t *ec, VALUE src, VALUE dst, int flags);
+
+/**
+ * Identical to rb_econv_str_append(), except it appends only a part of the
+ * passed string with conversion. It can also be seen as a routine identical
+ * to rb_econv_substr_convert(), except it appends the conversion result to the
+ * additionally passed string instead of creating a new string.
+ *
+ * @param[in,out] ec Target converter.
+ * @param[in] src Source string.
+ * @param[in] byteoff Number of bytes to seek.
+ * @param[in] bytesize Number of bytes to read.
+ * @param[in] dst Return buffer.
+ * @param[in] flags Flags (see rb_econv_convert).
+ * @exception rb_eArgError Converted string is too long.
+ * @exception rb_eInvalidByteSequenceError Invalid byte sequence.
+ * @exception rb_eUndefinedConversionError Conversion undefined.
+ * @return The conversion result.
+ */
+VALUE rb_econv_substr_append(rb_econv_t *ec, VALUE src, long byteoff, long bytesize, VALUE dst, int flags);
+
+/**
+ * Converts the passed C's pointer according to the passed converter, then
+ * append the conversion result to the passed Ruby's string. This way buffer
+ * overflow is properly avoided to resize the destination properly.
+ *
+ * @param[in,out] ec Target converter.
+ * @param[in] bytesrc Target string.
+ * @param[in] bytesize Number of bytes of `bytesrc`.
+ * @param[in] dst Return buffer.
+ * @param[in] flags Flags (see rb_econv_convert).
+ * @exception rb_eArgError Converted string is too long.
+ * @exception rb_eInvalidByteSequenceError Invalid byte sequence.
+ * @exception rb_eUndefinedConversionError Conversion undefined.
+ * @return The conversion result.
+ */
+VALUE rb_econv_append(rb_econv_t *ec, const char *bytesrc, long bytesize, VALUE dst, int flags);
+
+/**
+ * This badly named function does not set the destination encoding to binary,
+ * but instead just nullifies newline conversion decorators if any. Other
+ * ordinal character conversions still happen after this; something non-binary
+ * would still be generated.
+ *
+ * @param[out] ec Target converter to modify.
+ * @post Any newline conversions, if any, would be killed.
+ */
+void rb_econv_binmode(rb_econv_t *ec);
+
+/**
+ * This enum is kind of omnibus. Gathers various constants.
+ */
+enum ruby_econv_flag_type {
+
+ /**
+ * @name Flags for rb_econv_open()
+ *
+ * @{
+ */
+
+ /** Mask for error handling related bits. */
+ RUBY_ECONV_ERROR_HANDLER_MASK = 0x000000ff,
+
+ /** Special handling of invalid sequences are there. */
+ RUBY_ECONV_INVALID_MASK = 0x0000000f,
+
+ /** Invalid sequences shall be replaced. */
+ RUBY_ECONV_INVALID_REPLACE = 0x00000002,
+
+ /** Special handling of undefined conversion are there. */
+ RUBY_ECONV_UNDEF_MASK = 0x000000f0,
+
+ /** Undefined characters shall be replaced. */
+ RUBY_ECONV_UNDEF_REPLACE = 0x00000020,
+
+ /** Undefined characters shall be escaped. */
+ RUBY_ECONV_UNDEF_HEX_CHARREF = 0x00000030,
+
+ /** Decorators are there. */
+ RUBY_ECONV_DECORATOR_MASK = 0x0000ff00,
+
+ /** Newline converters are there. */
+ RUBY_ECONV_NEWLINE_DECORATOR_MASK = 0x00003f00,
+
+ /** (Unclear; seems unused). */
+ RUBY_ECONV_NEWLINE_DECORATOR_READ_MASK = 0x00000f00,
+
+ /** (Unclear; seems unused). */
+ RUBY_ECONV_NEWLINE_DECORATOR_WRITE_MASK = 0x00003000,
+
+ /** Universal newline mode. */
+ RUBY_ECONV_UNIVERSAL_NEWLINE_DECORATOR = 0x00000100,
+
+ /** CR to CRLF conversion shall happen. */
+ RUBY_ECONV_CRLF_NEWLINE_DECORATOR = 0x00001000,
+
+ /** CRLF to CR conversion shall happen. */
+ RUBY_ECONV_CR_NEWLINE_DECORATOR = 0x00002000,
+
+ /** Texts shall be XML-escaped. */
+ RUBY_ECONV_XML_TEXT_DECORATOR = 0x00004000,
+
+ /** Texts shall be AttrValue escaped */
+ RUBY_ECONV_XML_ATTR_CONTENT_DECORATOR = 0x00008000,
+
+ /** (Unclear; seems unused). */
+ RUBY_ECONV_STATEFUL_DECORATOR_MASK = 0x00f00000,
+
+ /** Texts shall be AttrValue escaped. */
+ RUBY_ECONV_XML_ATTR_QUOTE_DECORATOR = 0x00100000,
+
+ /** Newline decorator's default. */
+ RUBY_ECONV_DEFAULT_NEWLINE_DECORATOR =
+#if defined(RUBY_TEST_CRLF_ENVIRONMENT) || defined(_WIN32)
+ RUBY_ECONV_CRLF_NEWLINE_DECORATOR,
+#else
+ 0,
+#endif
+
+#define ECONV_ERROR_HANDLER_MASK RUBY_ECONV_ERROR_HANDLER_MASK /**< @old{RUBY_ECONV_ERROR_HANDLER_MASK} */
+#define ECONV_INVALID_MASK RUBY_ECONV_INVALID_MASK /**< @old{RUBY_ECONV_INVALID_MASK} */
+#define ECONV_INVALID_REPLACE RUBY_ECONV_INVALID_REPLACE /**< @old{RUBY_ECONV_INVALID_REPLACE} */
+#define ECONV_UNDEF_MASK RUBY_ECONV_UNDEF_MASK /**< @old{RUBY_ECONV_UNDEF_MASK} */
+#define ECONV_UNDEF_REPLACE RUBY_ECONV_UNDEF_REPLACE /**< @old{RUBY_ECONV_UNDEF_REPLACE} */
+#define ECONV_UNDEF_HEX_CHARREF RUBY_ECONV_UNDEF_HEX_CHARREF /**< @old{RUBY_ECONV_UNDEF_HEX_CHARREF} */
+#define ECONV_DECORATOR_MASK RUBY_ECONV_DECORATOR_MASK /**< @old{RUBY_ECONV_DECORATOR_MASK} */
+#define ECONV_NEWLINE_DECORATOR_MASK RUBY_ECONV_NEWLINE_DECORATOR_MASK /**< @old{RUBY_ECONV_NEWLINE_DECORATOR_MASK} */
+#define ECONV_NEWLINE_DECORATOR_READ_MASK RUBY_ECONV_NEWLINE_DECORATOR_READ_MASK /**< @old{RUBY_ECONV_NEWLINE_DECORATOR_READ_MASK} */
+#define ECONV_NEWLINE_DECORATOR_WRITE_MASK RUBY_ECONV_NEWLINE_DECORATOR_WRITE_MASK /**< @old{RUBY_ECONV_NEWLINE_DECORATOR_WRITE_MASK} */
+#define ECONV_UNIVERSAL_NEWLINE_DECORATOR RUBY_ECONV_UNIVERSAL_NEWLINE_DECORATOR /**< @old{RUBY_ECONV_UNIVERSAL_NEWLINE_DECORATOR} */
+#define ECONV_CRLF_NEWLINE_DECORATOR RUBY_ECONV_CRLF_NEWLINE_DECORATOR /**< @old{RUBY_ECONV_CRLF_NEWLINE_DECORATOR} */
+#define ECONV_CR_NEWLINE_DECORATOR RUBY_ECONV_CR_NEWLINE_DECORATOR /**< @old{RUBY_ECONV_CR_NEWLINE_DECORATOR} */
+#define ECONV_XML_TEXT_DECORATOR RUBY_ECONV_XML_TEXT_DECORATOR /**< @old{RUBY_ECONV_XML_TEXT_DECORATOR} */
+#define ECONV_XML_ATTR_CONTENT_DECORATOR RUBY_ECONV_XML_ATTR_CONTENT_DECORATOR /**< @old{RUBY_ECONV_XML_ATTR_CONTENT_DECORATOR} */
+#define ECONV_STATEFUL_DECORATOR_MASK RUBY_ECONV_STATEFUL_DECORATOR_MASK /**< @old{RUBY_ECONV_STATEFUL_DECORATOR_MASK} */
+#define ECONV_XML_ATTR_QUOTE_DECORATOR RUBY_ECONV_XML_ATTR_QUOTE_DECORATOR /**< @old{RUBY_ECONV_XML_ATTR_QUOTE_DECORATOR} */
+#define ECONV_DEFAULT_NEWLINE_DECORATOR RUBY_ECONV_DEFAULT_NEWLINE_DECORATOR /**< @old{RUBY_ECONV_DEFAULT_NEWLINE_DECORATOR} */
+ /** @} */
+
+ /**
+ * @name Flags for rb_econv_convert()
+ *
+ * @{
+ */
+
+ /** Indicates the input is a part of much larger one. */
+ RUBY_ECONV_PARTIAL_INPUT = 0x00010000,
+
+ /** Instructs the converter to stop after output. */
+ RUBY_ECONV_AFTER_OUTPUT = 0x00020000,
+#define ECONV_PARTIAL_INPUT RUBY_ECONV_PARTIAL_INPUT /**< @old{RUBY_ECONV_PARTIAL_INPUT} */
+#define ECONV_AFTER_OUTPUT RUBY_ECONV_AFTER_OUTPUT /**< @old{RUBY_ECONV_AFTER_OUTPUT} */
+
+ RUBY_ECONV_FLAGS_PLACEHOLDER /**< Placeholder (not used) */
+};
+
+RBIMPL_SYMBOL_EXPORT_END()
+
+#endif /* RUBY_INTERNAL_ENCODING_TRANSCODE_H */
diff --git a/include/ruby/internal/error.h b/include/ruby/internal/error.h
new file mode 100644
index 0000000000..49e2276cb9
--- /dev/null
+++ b/include/ruby/internal/error.h
@@ -0,0 +1,582 @@
+#ifndef RBIMPL_ERROR_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_ERROR_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Declares ::rb_raise().
+ */
+#include "ruby/internal/attr/cold.h"
+#include "ruby/internal/attr/format.h"
+#include "ruby/internal/attr/noreturn.h"
+#include "ruby/internal/attr/nonnull.h"
+#include "ruby/internal/dllexport.h"
+#include "ruby/internal/value.h"
+
+/**
+ * @defgroup exception Exception handlings
+ * @{
+ */
+
+/**
+ * Warning categories. A warning issued using this API can be selectively
+ * requested / suppressed by the end-users. For instance passing
+ * `-W:no-deprecated` to the ruby process would suppress those warnings in
+ * deprecated category.
+ *
+ * @warning There is no way to declare a new category (for now).
+ */
+typedef enum {
+ /** Category unspecified. */
+ RB_WARN_CATEGORY_NONE,
+
+ /** Warning is for deprecated features. */
+ RB_WARN_CATEGORY_DEPRECATED,
+
+ /** Warning is for experimental features. */
+ RB_WARN_CATEGORY_EXPERIMENTAL,
+
+ RB_WARN_CATEGORY_ALL_BITS = 0x6 /* no RB_WARN_CATEGORY_NONE bit */
+} rb_warning_category_t;
+
+/** for rb_readwrite_sys_fail first argument */
+enum rb_io_wait_readwrite {RB_IO_WAIT_READABLE, RB_IO_WAIT_WRITABLE};
+/** @cond INTERNAL_MACRO */
+#define RB_IO_WAIT_READABLE RB_IO_WAIT_READABLE
+#define RB_IO_WAIT_WRITABLE RB_IO_WAIT_WRITABLE
+/** @endcond */
+
+RBIMPL_SYMBOL_EXPORT_BEGIN()
+
+/**
+ * This is the same as `$!` in Ruby.
+ *
+ * @retval RUBY_Qnil Not handling exceptions at the moment.
+ * @retval otherwise The current exception in the current thread.
+ * @ingroup exception
+ */
+VALUE rb_errinfo(void);
+
+/**
+ * Sets the current exception (`$!`) to the given value.
+ *
+ * @param[in] err An instance of ::rb_eException, or ::RUBY_Qnil.
+ * @exception rb_eTypeError What is given was neither ::rb_eException nor
+ * ::RUBY_Qnil.
+ * @note Use rb_raise() instead to raise `err`. This function just
+ * assigns the given object to the global variable.
+ * @ingroup exception
+ */
+void rb_set_errinfo(VALUE err);
+
+RBIMPL_ATTR_NORETURN()
+RBIMPL_ATTR_NONNULL((2))
+RBIMPL_ATTR_FORMAT(RBIMPL_PRINTF_FORMAT, 2, 3)
+/**
+ * Exception entry point. By calling this function the execution of your
+ * program gets interrupted to "raise" an exception up to the callee entities.
+ * Programs could "rescue" that exception, or could "ensure" some part of them.
+ * If nobody cares about such things, the raised exception reaches at the top
+ * of execution. This yields abnormal end of the process.
+ *
+ * @param[in] exc A subclass of ::rb_eException.
+ * @param[in] fmt Format specifier string compatible with rb_sprintf().
+ * @exception exc The specified exception.
+ * @note It never returns.
+ */
+void rb_raise(VALUE exc, const char *fmt, ...);
+
+RBIMPL_ATTR_NORETURN()
+RBIMPL_ATTR_NONNULL((1))
+RBIMPL_ATTR_FORMAT(RBIMPL_PRINTF_FORMAT, 1, 2)
+/**
+ * Raises the unsung "fatal" exception. This is considered severe. Nobody can
+ * rescue the exception. Once raised, process termination is inevitable.
+ * However ensure clauses still run, so that resources are properly cleaned up.
+ *
+ * @param[in] fmt Format specifier string compatible with rb_sprintf().
+ * @exception rb_eFatal An exception that you cannot rescue.
+ * @note It never returns.
+ */
+void rb_fatal(const char *fmt, ...);
+
+RBIMPL_ATTR_COLD()
+RBIMPL_ATTR_NORETURN()
+RBIMPL_ATTR_NONNULL((1))
+RBIMPL_ATTR_FORMAT(RBIMPL_PRINTF_FORMAT, 1, 2)
+/**
+ * Interpreter panic switch. Immediate process termination without any
+ * synchronisations shall occur. LOTS of internal states, stack traces, and
+ * even machine registers are displayed if possible for debugging purposes
+ * then.
+ *
+ * @warning Do not use this API.
+ * @warning You are not expected to use this API.
+ * @warning Why not just fix your code instead of calling this API?
+ * @warning It was a bad idea to expose this API to extension libraries at
+ * the first place. We just cannot delete it at this point for
+ * backwards compatibility. That doesn't mean everyone are
+ * welcomed to call this function at will.
+ * @param[in] fmt Format specifier string compatible with rb_sprintf().
+ * @note It never returns.
+ */
+void rb_bug(const char *fmt, ...);
+
+RBIMPL_ATTR_NORETURN()
+RBIMPL_ATTR_NONNULL(())
+/**
+ * This is a wrapper of rb_bug() which automatically constructs appropriate
+ * message from the passed errno.
+ *
+ * @param[in] msg Additional message to display.
+ * @exception err C level errno.
+ * @note It never returns.
+ */
+void rb_bug_errno(const char *msg, int err);
+
+RBIMPL_ATTR_NORETURN()
+/**
+ * Converts a C errno into a Ruby exception, then raises it. For instance:
+ *
+ * ```CXX
+ * static VALUE
+ * foo(VALUE argv)
+ * {
+ * const auto cmd = StringValueCStr(argv);
+ * const auto waitr = system(cmd);
+ * if (waitr == -1) {
+ * rb_sys_fail("system(3posix)"); // <-------------- this
+ * }
+ * else {
+ * return INT2FIX(fd);
+ * }
+ * }
+ * ```
+ *
+ * @param[in] msg Additional message to raise.
+ * @exception rb_eSystemCallError An exception representing errno.
+ * @note It never returns.
+ */
+void rb_sys_fail(const char *msg);
+
+RBIMPL_ATTR_NORETURN()
+/**
+ * Identical to rb_sys_fail(), except it takes the message in Ruby's String
+ * instead of C's.
+ *
+ * @param[in] msg Additional message to raise.
+ * @exception rb_eSystemCallError An exception representing errno.
+ * @note It never returns.
+ */
+void rb_sys_fail_str(VALUE msg);
+
+RBIMPL_ATTR_NORETURN()
+RBIMPL_ATTR_NONNULL((2))
+/**
+ * Identical to rb_sys_fail(), except it takes additional module to extend the
+ * exception object before raising.
+ *
+ * @param[in] mod A ::rb_cModule instance.
+ * @param[in] msg Additional message to raise.
+ * @exception rb_eSystemCallError An exception representing errno.
+ * @note It never returns.
+ *
+ * @internal
+ *
+ * Does anybody use it?
+ */
+void rb_mod_sys_fail(VALUE mod, const char *msg);
+
+RBIMPL_ATTR_NORETURN()
+/**
+ * Identical to rb_mod_sys_fail(), except it takes the message in Ruby's String
+ * instead of C's.
+ *
+ * @param[in] mod A ::rb_cModule instance.
+ * @param[in] msg Additional message to raise.
+ * @exception rb_eSystemCallError An exception representing errno.
+ * @note It never returns.
+ */
+void rb_mod_sys_fail_str(VALUE mod, VALUE msg);
+
+RBIMPL_ATTR_NORETURN()
+/**
+ * Raises appropriate exception using the parameters.
+ *
+ * In Ruby level there are rb_eEAGAINWaitReadable etc. This function maps the
+ * given parameter to an appropriate exception class, then raises it.
+ *
+ * @param[in] waiting Reason for the IO to wait.
+ * @param[in] msg Additional message to raise.
+ * @exception rb_eEAGAINWaitWritable
+ * @exception rb_eEWOULDBLOCKWaitWritable
+ * @exception rb_eEINPROGRESSWaitWritable
+ * @exception rb_eEAGAINWaitReadable
+ * @exception rb_eEWOULDBLOCKWaitReadable
+ * @exception rb_eEINPROGRESSWaitReadable
+ * @exception rb_eSystemCallError
+ * @note It never returns.
+ */
+void rb_readwrite_sys_fail(enum rb_io_wait_readwrite waiting, const char *msg);
+
+RBIMPL_ATTR_NORETURN()
+/**
+ * Breaks from a block. Because you are using a CAPI this is not as intuitive
+ * as it sounds. In order for this function to properly work, make a
+ * ::rb_block_call_func_t function that calls it internally, and pass that
+ * function to rb_block_call().
+ *
+ * @exception rb_eLocalJumpError Called from outside of a block.
+ * @note It never returns.
+ */
+void rb_iter_break(void);
+
+RBIMPL_ATTR_NORETURN()
+/**
+ * Identical to rb_iter_break(), except it additionally takes the "value" of
+ * this breakage. It will be the evaluation result of the iterator. This is
+ * kind of complicated; you cannot see this as a "return from a block"
+ * behaviour. Take a look at this example:
+ *
+ * ```ruby
+ * def foo(q)
+ * puts(w = yield(q))
+ * puts(e = yield(w))
+ * puts(r = yield(e))
+ * puts(t = yield(r))
+ * puts(y = yield(t))
+ * return "howdy!"
+ * end
+ *
+ * x = foo(0) {|i|
+ * if i > 2
+ * break "hello!"
+ * else
+ * next i + 1
+ * end
+ * }
+ *
+ * puts x
+ * ```
+ *
+ * This script outputs 1, 2, 3, and hello. Note that the value passed to break
+ * becomes the return value of foo method, not the value of yield. This is
+ * confusing, but can be handy on occasions e.g. when you want to bring a
+ * local variable out of a block.
+ *
+ * @param[in] val The value of the iterator.
+ * @exception rb_eLocalJumpError Called from outside of a block.
+ * @note It never returns.
+ */
+void rb_iter_break_value(VALUE val);
+
+RBIMPL_ATTR_NORETURN()
+/**
+ * Terminates the current execution context. This API is the entry point of a
+ * "well-mannered" termination sequence. When called from an extension
+ * library, it raises ::rb_eSystemExit exception. Programs could rescue that
+ * exception. Can cancel process exit then. Otherwise, that exception results
+ * in a process termination with the status passed to this function.
+ *
+ * @param[in] status Exit status, see also exit(3).
+ * @exception rb_eSystemExit Exception representing the exit status.
+ * @note It never returns.
+ *
+ * @internal
+ *
+ * "When called from an extension library"? You might wonder. In fact there
+ * are chances for this function to be called from outside of it, for instance
+ * when dlopen(3) failed. In case it is not possible for this function to
+ * raise an exception, it does not (silently enters to process cleanup). But
+ * that is a kind of implementation detail which extension library authors
+ * should not bother.
+ */
+void rb_exit(int status);
+
+RBIMPL_ATTR_NORETURN()
+/**
+ * @exception rb_eNotImpError
+ * @note It never returns.
+ */
+void rb_notimplement(void);
+
+/**
+ * Creates an exception object that represents the given C errno.
+ *
+ * @param[in] err C level errno.
+ * @param[in] msg Additional message.
+ * @retval rb_eSystemCallError An exception for the errno.
+ */
+VALUE rb_syserr_new(int err, const char * msg);
+
+/**
+ * Identical to rb_syserr_new(), except it takes the message in Ruby's String
+ * instead of C's.
+ *
+ * @param[in] n C level errno.
+ * @param[in] arg Additional message.
+ * @retval rb_eSystemCallError An exception for the errno.
+ */
+VALUE rb_syserr_new_str(int n, VALUE arg);
+
+RBIMPL_ATTR_NORETURN()
+/**
+ * Raises appropriate exception that represents a C errno.
+ *
+ * @param[in] err C level errno.
+ * @param[in] msg Additional message to raise.
+ * @exception rb_eSystemCallError An exception representing `err`.
+ * @note It never returns.
+ */
+void rb_syserr_fail(int err, const char *msg);
+
+RBIMPL_ATTR_NORETURN()
+/**
+ * Identical to rb_syserr_fail(), except it takes the message in Ruby's String
+ * instead of C's.
+ *
+ * @param[in] err C level errno.
+ * @param[in] msg Additional message to raise.
+ * @exception rb_eSystemCallError An exception representing `err`.
+ * @note It never returns.
+ */
+void rb_syserr_fail_str(int err, VALUE msg);
+
+RBIMPL_ATTR_NORETURN()
+RBIMPL_ATTR_NONNULL(())
+/**
+ * Identical to rb_mod_sys_fail(), except it does not depend on C global
+ * variable errno. Pass it explicitly.
+ *
+ * @param[in] mod A ::rb_cModule instance.
+ * @param[in] err C level errno.
+ * @param[in] msg Additional message to raise.
+ * @exception rb_eSystemCallError An exception representing `err`.
+ * @note It never returns.
+ */
+void rb_mod_syserr_fail(VALUE mod, int err, const char *msg);
+
+RBIMPL_ATTR_NORETURN()
+/**
+ * Identical to rb_mod_syserr_fail(), except it takes the message in Ruby's
+ * String instead of C's.
+ *
+ * @param[in] mod A ::rb_cModule instance.
+ * @param[in] err C level errno.
+ * @param[in] msg Additional message to raise.
+ * @exception rb_eSystemCallError An exception representing `err`.
+ * @note It never returns.
+ */
+void rb_mod_syserr_fail_str(VALUE mod, int err, VALUE msg);
+
+RBIMPL_ATTR_NORETURN()
+/**
+ * Identical to rb_readwrite_sys_fail(), except it does not depend on C global
+ * variable errno. Pass it explicitly.
+ *
+ * @param[in] waiting Reason for the IO to wait.
+ * @param[in] err C level errno.
+ * @param[in] msg Additional message to raise.
+ * @exception rb_eEAGAINWaitWritable
+ * @exception rb_eEWOULDBLOCKWaitWritable
+ * @exception rb_eEINPROGRESSWaitWritable
+ * @exception rb_eEAGAINWaitReadable
+ * @exception rb_eEWOULDBLOCKWaitReadable
+ * @exception rb_eEINPROGRESSWaitReadable
+ * @exception rb_eSystemCallError
+ * @note It never returns.
+ */
+void rb_readwrite_syserr_fail(enum rb_io_wait_readwrite waiting, int err, const char *msg);
+
+RBIMPL_ATTR_COLD()
+RBIMPL_ATTR_NORETURN()
+/**
+ * Fails with the given object's type incompatibility to the type.
+ *
+ * It seems this function is visible from extension libraries only because
+ * RTYPEDDATA_TYPE() uses it on RUBY_DEBUG. So you can basically ignore it;
+ * use some other fine-grained method instead.
+ *
+ * @param[in] self The object in question.
+ * @param[in] t Expected type of the object.
+ * @exception rb_eTypeError `self` not in type `t`.
+ * @note It never returns.
+ * @note The second argument must have been an enum ::ruby_value_type,
+ * but for historical reasons it remains to be an int (in other
+ * words we see no benefits fixing this bug).
+ */
+void rb_unexpected_type(VALUE self, int t);
+
+/**
+ * @private
+ *
+ * This is an implementation detail of #ruby_verbose. Please don't use it
+ * directly.
+ *
+ * @retval Qnil Interpreter is quiet.
+ * @retval Qfalse Interpreter is kind of chatty.
+ * @retval otherwise Interpreter is very verbose.
+ */
+VALUE *rb_ruby_verbose_ptr(void);
+
+/**
+ * @private
+ *
+ * This is an implementation detail of #ruby_debug. Please don't use it
+ * directly.
+ *
+ * @retval Qnil Interpreter not in debug mode.
+ * @retval Qfalse Interpreter not in debug mode.
+ * @retval otherwise Interpreter is in debug mode.
+ */
+VALUE *rb_ruby_debug_ptr(void);
+
+/**
+ * This variable controls whether the interpreter is in debug mode. Setting
+ * this to some truthy value is equivalent to passing `-W` flag to the
+ * interpreter. Setting this to ::Qfalse is equivalent to passing `-W1` flag
+ * to the interpreter. Setting this to ::Qnil is equivalent to passing `-W0`
+ * flag to the interpreter.
+ *
+ * @retval Qnil Interpreter is quiet.
+ * @retval Qfalse Interpreter is kind of chatty.
+ * @retval otherwise Interpreter is very verbose.
+ */
+#define ruby_verbose (*rb_ruby_verbose_ptr())
+
+/**
+ * This variable controls whether the interpreter is in debug mode. Setting
+ * this to some truthy value is equivalent to passing `-d` flag to the
+ * interpreter.
+ *
+ * @retval Qnil Interpreter not in debug mode.
+ * @retval Qfalse Interpreter not in debug mode.
+ * @retval otherwise Interpreter is in debug mode.
+ */
+#define ruby_debug (*rb_ruby_debug_ptr())
+
+/* reports if `-W' specified */
+RBIMPL_ATTR_NONNULL((1))
+RBIMPL_ATTR_FORMAT(RBIMPL_PRINTF_FORMAT, 1, 2)
+/**
+ * Issues a warning.
+ *
+ * In ruby, warnings these days are tightly coupled with the rb_mWarning
+ * constant and its `warn` singleton method. This CAPI is just a thin wrapper
+ * of it; everything passed are formatted like what rb_sprintf() does, then
+ * passed through to the method. Programs can have their own `def
+ * Warning.warn` at will to do whatever they want, from ignoring the warnings
+ * at all to sinking them to some BigQuery data set via a Fluentd cluster. By
+ * default, the method just emits its passed contents to ::rb_stderr using
+ * rb_io_write().
+ *
+ * @note This function is affected by the `-W` flag.
+ * @param[in] fmt Format specifier string compatible with rb_sprintf().
+ *
+ * @internal
+ *
+ * Above description is in fact inaccurate. This API interfaces with Ractors.
+ */
+void rb_warning(const char *fmt, ...);
+
+RBIMPL_ATTR_NONNULL((2))
+RBIMPL_ATTR_FORMAT(RBIMPL_PRINTF_FORMAT, 2, 3)
+/**
+ * Identical to rb_warning(), except it takes additional "category" parameter.
+ *
+ * @param[in] cat Name of a known category.
+ * @param[in] fmt Format specifier string compatible with rb_sprintf().
+ */
+void rb_category_warning(rb_warning_category_t cat, const char *fmt, ...);
+
+RBIMPL_ATTR_NONNULL((1, 3))
+RBIMPL_ATTR_FORMAT(RBIMPL_PRINTF_FORMAT, 3, 4)
+/**
+ * Issues a compile-time warning that happens at `__file__:__line__`. Purpose
+ * of this function being exposed to CAPI is unclear.
+ *
+ * @note This function is affected by the `-W` flag.
+ * @param[in] file The path corresponding to Ruby level `__FILE__`.
+ * @param[in] line The number corresponding to Ruby level `__LINE__`.
+ * @param[in] fmt Format specifier string compatible with rb_sprintf().
+ */
+void rb_compile_warning(const char *file, int line, const char *fmt, ...);
+
+RBIMPL_ATTR_NONNULL((1))
+RBIMPL_ATTR_FORMAT(RBIMPL_PRINTF_FORMAT, 1, 2)
+/**
+ * Identical to rb_sys_fail(), except it does not raise an exception to render
+ * a warning instead.
+ *
+ * @note This function is affected by the `-W` flag.
+ * @param[in] fmt Format specifier string compatible with rb_sprintf().
+ */
+void rb_sys_warning(const char *fmt, ...);
+
+/* reports always */
+RBIMPL_ATTR_COLD()
+RBIMPL_ATTR_NONNULL((1))
+RBIMPL_ATTR_FORMAT(RBIMPL_PRINTF_FORMAT, 1, 2)
+/**
+ * Identical to rb_warning(), except it reports always regardless of runtime
+ * `-W` flag.
+ *
+ * @param[in] fmt Format specifier string compatible with rb_sprintf().
+ */
+void rb_warn(const char *fmt, ...);
+
+RBIMPL_ATTR_COLD()
+RBIMPL_ATTR_NONNULL((2))
+RBIMPL_ATTR_FORMAT(RBIMPL_PRINTF_FORMAT, 2, 3)
+/**
+ * Identical to rb_category_warning(), except it reports always regardless of
+ * runtime `-W` flag.
+ *
+ * @param[in] cat Category e.g. deprecated.
+ * @param[in] fmt Format specifier string compatible with rb_sprintf().
+ */
+void rb_category_warn(rb_warning_category_t cat, const char *fmt, ...);
+
+RBIMPL_ATTR_NONNULL((1, 3))
+RBIMPL_ATTR_FORMAT(RBIMPL_PRINTF_FORMAT, 3, 4)
+/**
+ * Identical to rb_compile_warning(), except it reports always regardless of
+ * runtime `-W` flag.
+ *
+ * @param[in] file The path corresponding to Ruby level `__FILE__`.
+ * @param[in] line The number corresponding to Ruby level `__LINE__`.
+ * @param[in] fmt Format specifier string compatible with rb_sprintf().
+ */
+void rb_compile_warn(const char *file, int line, const char *fmt, ...);
+
+RBIMPL_ATTR_NONNULL((2, 4))
+RBIMPL_ATTR_FORMAT(RBIMPL_PRINTF_FORMAT, 4, 5)
+/**
+ * Identical to rb_compile_warn(), except it also accepts category.
+ *
+ * @param[in] cat Category e.g. deprecated.
+ * @param[in] file The path corresponding to Ruby level `__FILE__`.
+ * @param[in] line The number corresponding to Ruby level `__LINE__`.
+ * @param[in] fmt Format specifier string compatible with rb_sprintf().
+ */
+void rb_category_compile_warn(rb_warning_category_t cat, const char *file, int line, const char *fmt, ...);
+
+/** @} */
+
+RBIMPL_SYMBOL_EXPORT_END()
+
+#endif /* RBIMPL_ERROR_H */
diff --git a/include/ruby/internal/eval.h b/include/ruby/internal/eval.h
new file mode 100644
index 0000000000..34a53849da
--- /dev/null
+++ b/include/ruby/internal/eval.h
@@ -0,0 +1,373 @@
+#ifndef RBIMPL_EVAL_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_EVAL_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Declares ::rb_eval_string().
+ */
+#include "ruby/internal/dllexport.h"
+#include "ruby/internal/attr/nonnull.h"
+#include "ruby/internal/value.h"
+
+RBIMPL_SYMBOL_EXPORT_BEGIN()
+
+RBIMPL_ATTR_NONNULL(())
+/**
+ * Evaluates the given string in an isolated binding.
+ *
+ * Here "isolated" means that the binding does not inherit any other
+ * bindings. This behaves same as the binding for required libraries.
+ *
+ * `__FILE__` will be `"(eval)"`, and `__LINE__` starts from 1 in the
+ * evaluation.
+ *
+ * @param[in] str Ruby code to evaluate.
+ * @exception rb_eException Raises an exception on error.
+ * @return The evaluated result.
+ */
+VALUE rb_eval_string(const char *str);
+
+RBIMPL_ATTR_NONNULL((1))
+/**
+ * Identical to rb_eval_string(), except it avoids potential global escapes.
+ * Such global escapes include exceptions, `throw`, `break`, for example.
+ *
+ * It first evaluates the given string as rb_eval_string() does. If no global
+ * escape occurred during the evaluation, it returns the result and `*state` is
+ * zero. Otherwise, it returns some undefined value and sets `*state` to
+ * nonzero. If state is `NULL`, it is not set in both cases.
+ *
+ * @param[in] str Ruby code to evaluate.
+ * @param[out] state State of execution.
+ * @return The evaluated result if succeeded, an undefined value if
+ * otherwise.
+ * @post `*state` is set to zero if succeeded. Nonzero otherwise.
+ * @warning You have to clear the error info with `rb_set_errinfo(Qnil)` if
+ * you decide to ignore the caught exception.
+ * @see rb_eval_string
+ * @see rb_protect
+ *
+ * @internal
+ *
+ * The "undefined value" described above is in fact ::RUBY_Qnil for now. But
+ * @shyouhei doesn't think that we would never change that.
+ *
+ * Though not a part of our public API, `state` is in fact an
+ * enum ruby_tag_type. You can see the potential "nonzero" values by looking
+ * at vm_core.h.
+ */
+VALUE rb_eval_string_protect(const char *str, int *state);
+
+RBIMPL_ATTR_NONNULL((1))
+/**
+ * Identical to rb_eval_string_protect(), except it evaluates the given string
+ * under a module binding in an isolated binding. This is the same as a
+ * binding for loaded libraries on `rb_load(something, true)`.
+ *
+ * @param[in] str Ruby code to evaluate.
+ * @param[out] state State of execution.
+ * @return The evaluated result if succeeded, an undefined value if
+ * otherwise.
+ * @post `*state` is set to zero if succeeded. Nonzero otherwise.
+ * @warning You have to clear the error info with `rb_set_errinfo(Qnil)` if
+ * you decide to ignore the caught exception.
+ * @see rb_eval_string
+ */
+VALUE rb_eval_string_wrap(const char *str, int *state);
+
+/**
+ * Calls a method. Can call both public and private methods.
+ *
+ * @param[in,out] recv Receiver of the method.
+ * @param[in] mid Name of the method to call.
+ * @param[in] n Number of arguments that follow.
+ * @param[in] ... Arbitrary number of method arguments.
+ * @exception rb_eNoMethodError No such method.
+ * @exception rb_eException Any exceptions happen inside.
+ * @return What the method evaluates to.
+ */
+VALUE rb_funcall(VALUE recv, ID mid, int n, ...);
+
+/**
+ * Identical to rb_funcall(), except it takes the method arguments as a C
+ * array.
+ *
+ * @param[in,out] recv Receiver of the method.
+ * @param[in] mid Name of the method to call.
+ * @param[in] argc Number of arguments.
+ * @param[in] argv Arbitrary number of method arguments.
+ * @exception rb_eNoMethodError No such method.
+ * @exception rb_eException Any exceptions happen inside.
+ * @return What the method evaluates to.
+ */
+VALUE rb_funcallv(VALUE recv, ID mid, int argc, const VALUE *argv);
+
+/**
+ * Identical to rb_funcallv(), except you can specify how to handle the last
+ * element of the given array.
+ *
+ * @param[in,out] recv Receiver of the method.
+ * @param[in] mid Name of the method to call.
+ * @param[in] argc Number of arguments.
+ * @param[in] argv Arbitrary number of method arguments.
+ * @param[in] kw_splat Handling of keyword parameters:
+ * - RB_NO_KEYWORDS `argv`'s last is not a keyword argument.
+ * - RB_PASS_KEYWORDS `argv`'s last is a keyword argument.
+ * - RB_PASS_CALLED_KEYWORDS it depends if there is a passed block.
+ * @exception rb_eNoMethodError No such method.
+ * @exception rb_eException Any exceptions happen inside.
+ * @return What the method evaluates to.
+ */
+VALUE rb_funcallv_kw(VALUE recv, ID mid, int argc, const VALUE *argv, int kw_splat);
+
+/**
+ * Identical to rb_funcallv(), except it only takes public methods into
+ * account. This is roughly Ruby's `Object#public_send`.
+ *
+ * @param[in,out] recv Receiver of the method.
+ * @param[in] mid Name of the method to call.
+ * @param[in] argc Number of arguments.
+ * @param[in] argv Arbitrary number of method arguments.
+ * @exception rb_eNoMethodError No such method.
+ * @exception rb_eNoMethodError The method is private or protected.
+ * @exception rb_eException Any exceptions happen inside.
+ * @return What the method evaluates to.
+ */
+VALUE rb_funcallv_public(VALUE recv, ID mid, int argc, const VALUE *argv);
+
+/**
+ * Identical to rb_funcallv_public(), except you can specify how to handle the
+ * last element of the given array. It can also be seen as a routine identical
+ * to rb_funcallv_kw(), except it only takes public methods into account.
+ *
+ * @param[in,out] recv Receiver of the method.
+ * @param[in] mid Name of the method to call.
+ * @param[in] argc Number of arguments.
+ * @param[in] argv Arbitrary number of method arguments.
+ * @param[in] kw_splat Handling of keyword parameters:
+ * - RB_NO_KEYWORDS `argv`'s last is not a keyword argument.
+ * - RB_PASS_KEYWORDS `argv`'s last is a keyword argument.
+ * - RB_PASS_CALLED_KEYWORDS it depends if there is a passed block.
+ * @exception rb_eNoMethodError No such method.
+ * @exception rb_eNoMethodError The method is private or protected.
+ * @exception rb_eException Any exceptions happen inside.
+ * @return What the method evaluates to.
+ */
+VALUE rb_funcallv_public_kw(VALUE recv, ID mid, int argc, const VALUE *argv, int kw_splat);
+
+/**
+ * @deprecated This is an old name of rb_funcallv(). Provided here for
+ * backwards compatibility to 2.x programs (introduced in 2.1).
+ * It is not a good name. Please don't use it any longer.
+ */
+#define rb_funcall2 rb_funcallv
+
+/**
+ * @deprecated This is an old name of rb_funcallv_public(). Provided here
+ * for backwards compatibility to 2.x programs (introduced in
+ * 2.1). It is not a good name. Please don't use it any longer.
+ */
+#define rb_funcall3 rb_funcallv_public
+
+/**
+ * Identical to rb_funcallv_public(), except you can pass the passed block.
+ *
+ * Sometimes you want to "pass" a block parameter form one method to another.
+ * Suppose you have this Ruby method `foo`:
+ *
+ * ```ruby
+ * def foo(x, y, &z)
+ * x.open(y, &z)
+ * end
+ * ```
+ *
+ * And suppose you want to translate this into C. Then
+ * rb_funcall_passing_block() function is usable in this situation.
+ *
+ * ```CXX
+ * VALUE
+ * foo_translated_into_C(VALUE self, VALUE x, VALUE y)
+ * {
+ * const auto open = rb_intern("open");
+ *
+ * return rb_funcall_passing_block(x, open, 1, &y);
+ * }
+ * ```
+ *
+ * @see rb_yield_block
+ * @param[in,out] recv Receiver of the method.
+ * @param[in] mid Name of the method to call.
+ * @param[in] argc Number of arguments.
+ * @param[in] argv Arbitrary number of method arguments.
+ * @exception rb_eNoMethodError No such method.
+ * @exception rb_eNoMethodError The method is private or protected.
+ * @exception rb_eException Any exceptions happen inside.
+ * @return What the method evaluates to.
+ */
+VALUE rb_funcall_passing_block(VALUE recv, ID mid, int argc, const VALUE *argv);
+
+/**
+ * Identical to rb_funcallv_passing_block(), except you can specify how to
+ * handle the last element of the given array. It can also be seen as a
+ * routine identical to rb_funcallv_public_kw(), except you can pass the passed
+ * block.
+ *
+ * @param[in,out] recv Receiver of the method.
+ * @param[in] mid Name of the method to call.
+ * @param[in] argc Number of arguments.
+ * @param[in] argv Arbitrary number of method arguments.
+ * @param[in] kw_splat Handling of keyword parameters:
+ * - RB_NO_KEYWORDS `argv`'s last is not a keyword argument.
+ * - RB_PASS_KEYWORDS `argv`'s last is a keyword argument.
+ * - RB_PASS_CALLED_KEYWORDS it depends if there is a passed block.
+ * @exception rb_eNoMethodError No such method.
+ * @exception rb_eNoMethodError The method is private or protected.
+ * @exception rb_eException Any exceptions happen inside.
+ * @return What the method evaluates to.
+ */
+VALUE rb_funcall_passing_block_kw(VALUE recv, ID mid, int argc, const VALUE *argv, int kw_splat);
+
+/**
+ * Identical to rb_funcallv_public(), except you can pass a block. A block
+ * here basically is an instance of ::rb_cProc. If you want to exercise
+ * `to_proc` conversion, do so before passing it here. However nil and symbols
+ * are special-case allowed.
+ *
+ * @param[in,out] recv Receiver of the method.
+ * @param[in] mid Name of the method to call.
+ * @param[in] argc Number of arguments.
+ * @param[in] argv Arbitrary number of method arguments.
+ * @param[in] procval An instance of Proc, Symbol, or NilClass.
+ * @exception rb_eNoMethodError No such method.
+ * @exception rb_eNoMethodError The method is private or protected.
+ * @exception rb_eException Any exceptions happen inside.
+ * @return What the method evaluates to.
+ *
+ * @internal
+ *
+ * Implementation-wise, `procval` is in fact a "block handler" object. You
+ * could also pass an IFUNC (block_handler_ifunc) here to say precise. --- But
+ * AFAIK there is no 3rd party way to even know that there are objects called
+ * IFUNC behind-the-scene.
+ */
+VALUE rb_funcall_with_block(VALUE recv, ID mid, int argc, const VALUE *argv, VALUE procval);
+
+/**
+ * Identical to rb_funcallv_with_block(), except you can specify how to handle
+ * the last element of the given array. It can also be seen as a routine
+ * identical to rb_funcallv_public_kw(), except you can pass a block.
+ *
+ * @param[in,out] recv Receiver of the method.
+ * @param[in] mid Name of the method to call.
+ * @param[in] argc Number of arguments.
+ * @param[in] argv Arbitrary number of method arguments.
+ * @param[in] procval An instance of Proc, Symbol, or NilClass.
+ * @param[in] kw_splat Handling of keyword parameters:
+ * - RB_NO_KEYWORDS `argv`'s last is not a keyword argument.
+ * - RB_PASS_KEYWORDS `argv`'s last is a keyword argument.
+ * - RB_PASS_CALLED_KEYWORDS it depends if there is a passed block.
+ * @exception rb_eNoMethodError No such method.
+ * @exception rb_eNoMethodError The method is private or protected.
+ * @exception rb_eException Any exceptions happen inside.
+ * @return What the method evaluates to.
+ */
+VALUE rb_funcall_with_block_kw(VALUE recv, ID mid, int argc, const VALUE *argv, VALUE procval, int kw_splat);
+
+/**
+ * This resembles ruby's `super`.
+ *
+ * @param[in] argc Number of arguments.
+ * @param[in] argv Arbitrary number of method arguments.
+ * @exception rb_eNoMethodError No super method are there.
+ * @exception rb_eException Any exceptions happen inside.
+ * @return What the super method evaluates to.
+ */
+VALUE rb_call_super(int argc, const VALUE *argv);
+
+/**
+ * Identical to rb_call_super(), except you can specify how to handle the last
+ * element of the given array.
+ *
+ * @param[in] argc Number of arguments.
+ * @param[in] argv Arbitrary number of method arguments.
+ * @param[in] kw_splat Handling of keyword parameters:
+ * - RB_NO_KEYWORDS `argv`'s last is not a keyword argument.
+ * - RB_PASS_KEYWORDS `argv`'s last is a keyword argument.
+ * - RB_PASS_CALLED_KEYWORDS it depends if there is a passed block.
+ * @exception rb_eNoMethodError No super method are there.
+ * @exception rb_eException Any exceptions happen inside.
+ * @return What the super method evaluates to.
+ */
+VALUE rb_call_super_kw(int argc, const VALUE *argv, int kw_splat);
+
+/**
+ * This resembles ruby's `self`.
+ *
+ * @exception rb_eRuntimeError Called from outside of method context.
+ * @return Current receiver.
+ */
+VALUE rb_current_receiver(void);
+
+RBIMPL_ATTR_NONNULL((2))
+/**
+ * Keyword argument deconstructor.
+ *
+ * Retrieves argument values bound to keywords, which directed by `table` into
+ * `values`, deleting retrieved entries from `keyword_hash` along the way.
+ * First `required` number of IDs referred by `table` are mandatory, and
+ * succeeding `optional` (`-optional-1` if `optional` is negative) number of
+ * IDs are optional. If a mandatory key is not contained in `keyword_hash`,
+ * raises ::rb_eArgError. If an optional key is not present in `keyword_hash`,
+ * the corresponding element in `values` is set to ::RUBY_Qundef. If
+ * `optional` is negative, rest of `keyword_hash` are ignored, otherwise raises
+ * ::rb_eArgError.
+ *
+ * @warning Handling keyword arguments in the C API is less efficient than
+ * handling them in Ruby. Consider using a Ruby wrapper method
+ * around a non-keyword C function.
+ * @see https://bugs.ruby-lang.org/issues/11339
+ * @param[out] keyword_hash Target hash to deconstruct.
+ * @param[in] table List of keywords that you are interested in.
+ * @param[in] required Number of mandatory keywords.
+ * @param[in] optional Number of optional keywords (can be negative).
+ * @param[out] values Buffer to be filled.
+ * @exception rb_eArgError Absence of a mandatory keyword.
+ * @exception rb_eArgError Found an unknown keyword.
+ * @return Number of found values that are stored into `values`.
+ */
+int rb_get_kwargs(VALUE keyword_hash, const ID *table, int required, int optional, VALUE *values);
+
+RBIMPL_ATTR_NONNULL(())
+/**
+ * Splits a hash into two.
+ *
+ * Takes a hash of various keys, and split it into symbol-keyed parts and
+ * others. Symbol-keyed part becomes the return value. What remains are
+ * returned as a new hash object stored at the argument pointer.
+ *
+ * @param[in,out] orighash Pointer to a target hash to split.
+ * @return An extracted keyword hash.
+ * @post Upon successful return `orighash` points to another hash
+ * object, whose contents are the remainder of the operation.
+ * @note The argument hash object is not modified.
+ */
+VALUE rb_extract_keywords(VALUE *orighash);
+
+RBIMPL_SYMBOL_EXPORT_END()
+
+#endif /* RBIMPL_EVAL_H */
diff --git a/include/ruby/internal/event.h b/include/ruby/internal/event.h
new file mode 100644
index 0000000000..04b137a193
--- /dev/null
+++ b/include/ruby/internal/event.h
@@ -0,0 +1,154 @@
+#ifndef RBIMPL_EVENT_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_EVENT_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Debugging and tracing APIs.
+ */
+#include "ruby/internal/dllexport.h"
+#include "ruby/internal/value.h"
+
+/* These macros are not enums because they are wider than int.*/
+
+/**
+ * @name Traditional set_trace_func events
+ *
+ * @{
+ */
+#define RUBY_EVENT_NONE 0x0000 /**< No events. */
+#define RUBY_EVENT_LINE 0x0001 /**< Encountered a new line. */
+#define RUBY_EVENT_CLASS 0x0002 /**< Encountered a new class. */
+#define RUBY_EVENT_END 0x0004 /**< Encountered an end of a class clause. */
+#define RUBY_EVENT_CALL 0x0008 /**< A method, written in Ruby, is called. */
+#define RUBY_EVENT_RETURN 0x0010 /**< Encountered a `return` statement. */
+#define RUBY_EVENT_C_CALL 0x0020 /**< A method, written in C, is called. */
+#define RUBY_EVENT_C_RETURN 0x0040 /**< Return from a method, written in C. */
+#define RUBY_EVENT_RAISE 0x0080 /**< Encountered a `raise` statement. */
+#define RUBY_EVENT_ALL 0x00ff /**< Bitmask of traditional events. */
+
+/** @} */
+
+/**
+ * @name TracePoint extended events
+ *
+ * @{
+ */
+#define RUBY_EVENT_B_CALL 0x0100 /**< Encountered an `yield` statement. */
+#define RUBY_EVENT_B_RETURN 0x0200 /**< Encountered a `next` statement. */
+#define RUBY_EVENT_THREAD_BEGIN 0x0400 /**< Encountered a new thread. */
+#define RUBY_EVENT_THREAD_END 0x0800 /**< Encountered an end of a thread. */
+#define RUBY_EVENT_FIBER_SWITCH 0x1000 /**< Encountered a `Fiber#yield`. */
+#define RUBY_EVENT_SCRIPT_COMPILED 0x2000 /**< Encountered an `eval`. */
+#define RUBY_EVENT_TRACEPOINT_ALL 0xffff /**< Bitmask of extended events. */
+
+/** @} */
+
+/**
+ * @name Special events
+ *
+ * @internal
+ *
+ * These bits are actually used internally. See vm_core.h if you are curious.
+ *
+ * @endinternal
+ *
+ * @{
+ */
+#define RUBY_EVENT_RESERVED_FOR_INTERNAL_USE 0x030000 /**< Opaque bits. */
+
+/** @} */
+
+/**
+ * @name Internal events
+ *
+ * @shyouhei's understanding is that some of them are visible from extension
+ * libraries because of `ext/objspace`. But it seems that doesn't describe
+ * everything? The ultimate reason why they are here remains unclear.
+ *
+ * @{
+ */
+#define RUBY_INTERNAL_EVENT_SWITCH 0x040000 /**< Thread switched. */
+#define RUBY_EVENT_SWITCH 0x040000 /**< @old{RUBY_INTERNAL_EVENT_SWITCH} */
+ /* 0x080000 */
+#define RUBY_INTERNAL_EVENT_NEWOBJ 0x100000 /**< Object allocated. */
+#define RUBY_INTERNAL_EVENT_FREEOBJ 0x200000 /**< Object swept. */
+#define RUBY_INTERNAL_EVENT_GC_START 0x400000 /**< GC started. */
+#define RUBY_INTERNAL_EVENT_GC_END_MARK 0x800000 /**< GC ended mark phase. */
+#define RUBY_INTERNAL_EVENT_GC_END_SWEEP 0x1000000 /**< GC ended sweep phase. */
+#define RUBY_INTERNAL_EVENT_GC_ENTER 0x2000000 /**< `gc_enter()` is called. */
+#define RUBY_INTERNAL_EVENT_GC_EXIT 0x4000000 /**< `gc_exit()` is called. */
+#define RUBY_INTERNAL_EVENT_OBJSPACE_MASK 0x7f00000 /**< Bitmask of GC events. */
+#define RUBY_INTERNAL_EVENT_MASK 0xffff0000 /**< Bitmask of internal events. */
+
+/** @} */
+
+/**
+ * Represents event(s). As the name implies events are bit flags.
+ */
+typedef uint32_t rb_event_flag_t;
+
+/**
+ * Type of event hooks. When an event happens registered functions are kicked
+ * with appropriate parameters.
+ *
+ * @param[in] evflag The kind of event that happened.
+ * @param[in] data The `data` passed to rb_add_event_hook().
+ * @param[in] self Current receiver.
+ * @param[in] mid Name of the current method.
+ * @param[in] klass Current class.
+ */
+typedef void (*rb_event_hook_func_t)(rb_event_flag_t evflag, VALUE data, VALUE self, ID mid, VALUE klass);
+
+/**
+ * @private
+ *
+ * @deprecated This macro once was a thing in the old days, but makes no sense
+ * any longer today. Exists here for backwards compatibility
+ * only. You can safely forget about it.
+ */
+#define RB_EVENT_HOOKS_HAVE_CALLBACK_DATA 1
+
+RBIMPL_SYMBOL_EXPORT_BEGIN()
+
+/**
+ * Registers an event hook function.
+ *
+ * @param[in] func A callback.
+ * @param[in] events A set of events that `func` should run.
+ * @param[in] data Passed as-is to `func`.
+ */
+void rb_add_event_hook(rb_event_hook_func_t func, rb_event_flag_t events, VALUE data);
+
+/**
+ * Removes the passed function from the list of event hooks.
+ *
+ * @param[in] func A callback.
+ * @return Number of deleted event hooks.
+ * @note As multiple events can share the same `func` it is quite
+ * possible for the return value to become more than one.
+ *
+ * @internal
+ *
+ * @shyouhei doesn't know if this is an Easter egg or an official feature, but
+ * you can pass 0 to the argument. That effectively swipes everything out from
+ * the hook list.
+ */
+int rb_remove_event_hook(rb_event_hook_func_t func);
+RBIMPL_SYMBOL_EXPORT_END()
+
+#endif /* RBIMPL_EVENT_H */
diff --git a/include/ruby/internal/fl_type.h b/include/ruby/internal/fl_type.h
new file mode 100644
index 0000000000..08405d6f30
--- /dev/null
+++ b/include/ruby/internal/fl_type.h
@@ -0,0 +1,967 @@
+#ifndef RBIMPL_FL_TYPE_H /*-*-C++-*-vi:se ft=cpp:*/
+#define RBIMPL_FL_TYPE_H
+/**
+ * @file
+ * @author Ruby developers <ruby-core@ruby-lang.org>
+ * @copyright This file is a part of the programming language Ruby.
+ * Permission is hereby granted, to either redistribute and/or
+ * modify this file, provided that the conditions mentioned in the
+ * file COPYING are met. Consult the file for details.
+ * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
+ * implementation details. Don't take them as canon. They could
+ * rapidly appear then vanish. The name (path) of this header file
+ * is also an implementation detail. Do not expect it to persist
+ * at the place it is now. Developers are free to move it anywhere
+ * anytime at will.
+ * @note To ruby-core: remember that this header can be possibly
+ * recursively included from extension libraries written in C++.
+ * Do not expect for instance `__VA_ARGS__` is always available.
+ * We assume C99 for ruby itself but we don't assume languages of
+ * extension libraries. They could be written in C++98.
+ * @brief Defines enum ::ruby_fl_type.
+ */
+#include "ruby/internal/config.h" /* for ENUM_OVER_INT */
+#include "ruby/internal/attr/artificial.h"
+#include "ruby/internal/attr/deprecated.h"
+#include "ruby/internal/attr/flag_enum.h"
+#include "ruby/internal/attr/forceinline.h"
+#include "ruby/internal/attr/noalias.h"
+#include "ruby/internal/attr/pure.h"
+#include "ruby/internal/cast.h"
+#include "ruby/internal/compiler_since.h"
+#include "ruby/internal/core/rbasic.h"
+#include "ruby/internal/dllexport.h"
+#include "ruby/internal/has/extension.h"
+#include "ruby/internal/special_consts.h"
+#include "ruby/internal/stdbool.h"
+#include "ruby/internal/value.h"
+#include "ruby/internal/value_type.h"
+#include "ruby/assert.h"
+#include "ruby/defines.h"
+
+/** @cond INTERNAL_MACRO */
+#if RBIMPL_HAS_EXTENSION(enumerator_attributes)
+# define RBIMPL_HAVE_ENUM_ATTRIBUTE 1
+#elif RBIMPL_COMPILER_SINCE(GCC, 6, 0, 0)
+# define RBIMPL_HAVE_ENUM_ATTRIBUTE 1
+#endif
+
+#ifdef ENUM_OVER_INT
+# define RBIMPL_WIDER_ENUM 1
+#elif SIZEOF_INT * CHAR_BIT > 12+19+1
+# define RBIMPL_WIDER_ENUM 1
+#else
+# define RBIMPL_WIDER_ENUM 0
+#endif
+/** @endcond */
+
+#define FL_SINGLETON RBIMPL_CAST((VALUE)RUBY_FL_SINGLETON) /**< @old{RUBY_FL_SINGLETON} */
+#define FL_WB_PROTECTED RBIMPL_CAST((VALUE)RUBY_FL_WB_PROTECTED) /**< @old{RUBY_FL_WB_PROTECTED} */
+#define FL_PROMOTED0 RBIMPL_CAST((VALUE)RUBY_FL_PROMOTED0) /**< @old{RUBY_FL_PROMOTED0} */
+#define FL_PROMOTED1 RBIMPL_CAST((VALUE)RUBY_FL_PROMOTED1) /**< @old{RUBY_FL_PROMOTED1} */
+#define FL_FINALIZE RBIMPL_CAST((VALUE)RUBY_FL_FINALIZE) /**< @old{RUBY_FL_FINALIZE} */
+#define FL_TAINT RBIMPL_CAST((VALUE)RUBY_FL_TAINT) /**< @old{RUBY_FL_TAINT} */
+#define FL_SHAREABLE RBIMPL_CAST((VALUE)RUBY_FL_SHAREABLE) /**< @old{RUBY_FL_SHAREABLE} */
+#define FL_UNTRUSTED RBIMPL_CAST((VALUE)RUBY_FL_UNTRUSTED) /**< @old{RUBY_FL_UNTRUSTED} */
+#define FL_SEEN_OBJ_ID RBIMPL_CAST((VALUE)RUBY_FL_SEEN_OBJ_ID) /**< @old{RUBY_FL_SEEN_OBJ_ID} */
+#define FL_EXIVAR RBIMPL_CAST((VALUE)RUBY_FL_EXIVAR) /**< @old{RUBY_FL_EXIVAR} */
+#define FL_FREEZE RBIMPL_CAST((VALUE)RUBY_FL_FREEZE) /**< @old{RUBY_FL_FREEZE} */
+
+#define FL_USHIFT RBIMPL_CAST((VALUE)RUBY_FL_USHIFT) /**< @old{RUBY_FL_USHIFT} */
+
+#define FL_USER0 RBIMPL_CAST((VALUE)RUBY_FL_USER0) /**< @old{RUBY_FL_USER0} */
+#define FL_USER1 RBIMPL_CAST((VALUE)RUBY_FL_USER1) /**< @old{RUBY_FL_USER1} */
+#define FL_USER2 RBIMPL_CAST((VALUE)RUBY_FL_USER2) /**< @old{RUBY_FL_USER2} */
+#define FL_USER3 RBIMPL_CAST((VALUE)RUBY_FL_USER3) /**< @old{RUBY_FL_USER3} */
+#define FL_USER4 RBIMPL_CAST((VALUE)RUBY_FL_USER4) /**< @old{RUBY_FL_USER4} */
+#define FL_USER5 RBIMPL_CAST((VALUE)RUBY_FL_USER5) /**< @old{RUBY_FL_USER5} */
+#define FL_USER6 RBIMPL_CAST((VALUE)RUBY_FL_USER6) /**< @old{RUBY_FL_USER6} */
+#define FL_USER7 RBIMPL_CAST((VALUE)RUBY_FL_USER7) /**< @old{RUBY_FL_USER7} */
+#define FL_USER8 RBIMPL_CAST((VALUE)RUBY_FL_USER8) /**< @old{RUBY_FL_USER8} */
+#define FL_USER9 RBIMPL_CAST((VALUE)RUBY_FL_USER9) /**< @old{RUBY_FL_USER9} */
+#define FL_USER10 RBIMPL_CAST((VALUE)RUBY_FL_USER10) /**< @old{RUBY_FL_USER10} */
+#define FL_USER11 RBIMPL_CAST((VALUE)RUBY_FL_USER11) /**< @old{RUBY_FL_USER11} */
+#define FL_USER12 RBIMPL_CAST((VALUE)RUBY_FL_USER12) /**< @old{RUBY_FL_USER12} */
+#define FL_USER13 RBIMPL_CAST((VALUE)RUBY_FL_USER13) /**< @old{RUBY_FL_USER13} */
+#define FL_USER14 RBIMPL_CAST((VALUE)RUBY_FL_USER14) /**< @old{RUBY_FL_USER14} */
+#define FL_USER15 RBIMPL_CAST((VALUE)RUBY_FL_USER15) /**< @old{RUBY_FL_USER15} */
+#define FL_USER16 RBIMPL_CAST((VALUE)RUBY_FL_USER16) /**< @old{RUBY_FL_USER16} */
+#define FL_USER17 RBIMPL_CAST((VALUE)RUBY_FL_USER17) /**< @old{RUBY_FL_USER17} */
+#define FL_USER18 RBIMPL_CAST((VALUE)RUBY_FL_USER18) /**< @old{RUBY_FL_USER18} */
+#define FL_USER19 RBIMPL_CAST((VALUE)(unsigned int)RUBY_FL_USER19) /**< @old{RUBY_FL_USER19} */
+
+#define ELTS_SHARED RUBY_ELTS_SHARED /**< @old{RUBY_ELTS_SHARED} */
+#define RB_OBJ_FREEZE rb_obj_freeze_inline /**< @alias{rb_obj_freeze_inline} */
+
+/** @cond INTERNAL_MACRO */
+#define RUBY_ELTS_SHARED RUBY_ELTS_SHARED
+#define RB_FL_ABLE RB_FL_ABLE
+#define RB_FL_ALL RB_FL_ALL
+#define RB_FL_ALL_RAW RB_FL_ALL_RAW
+#define RB_FL_ANY RB_FL_ANY
+#define RB_FL_ANY_RAW RB_FL_ANY_RAW
+#define RB_FL_REVERSE RB_FL_REVERSE
+#define RB_FL_REVERSE_RAW RB_FL_REVERSE_RAW
+#define RB_FL_SET RB_FL_SET
+#define RB_FL_SET_RAW RB_FL_SET_RAW
+#define RB_FL_TEST RB_FL_TEST
+#define RB_FL_TEST_RAW RB_FL_TEST_RAW
+#define RB_FL_UNSET RB_FL_UNSET
+#define RB_FL_UNSET_RAW RB_FL_UNSET_RAW
+#define RB_OBJ_FREEZE_RAW RB_OBJ_FREEZE_RAW
+#define RB_OBJ_FROZEN RB_OBJ_FROZEN
+#define RB_OBJ_FROZEN_RAW RB_OBJ_FROZEN_RAW
+#define RB_OBJ_INFECT RB_OBJ_INFECT
+#define RB_OBJ_INFECT_RAW RB_OBJ_INFECT_RAW
+#define RB_OBJ_TAINT RB_OBJ_TAINT
+#define RB_OBJ_TAINTABLE RB_OBJ_TAINTABLE
+#define RB_OBJ_TAINTED RB_OBJ_TAINTED
+#define RB_OBJ_TAINTED_RAW RB_OBJ_TAINTED_RAW
+#define RB_OBJ_TAINT_RAW RB_OBJ_TAINT_RAW
+#define RB_OBJ_UNTRUST RB_OBJ_TAINT
+#define RB_OBJ_UNTRUSTED RB_OBJ_TAINTED
+/** @endcond */
+
+/**
+ * @defgroup deprecated_macros Deprecated macro APIs
+ * @{
+ * These macros are deprecated. Prefer their `RB_`-prefixed versions.
+ */
+#define FL_ABLE RB_FL_ABLE /**< @old{RB_FL_ABLE} */
+#define FL_ALL RB_FL_ALL /**< @old{RB_FL_ALL} */
+#define FL_ALL_RAW RB_FL_ALL_RAW /**< @old{RB_FL_ALL_RAW} */
+#define FL_ANY RB_FL_ANY /**< @old{RB_FL_ANY} */
+#define FL_ANY_RAW RB_FL_ANY_RAW /**< @old{RB_FL_ANY_RAW} */
+#define FL_REVERSE RB_FL_REVERSE /**< @old{RB_FL_REVERSE} */
+#define FL_REVERSE_RAW RB_FL_REVERSE_RAW /**< @old{RB_FL_REVERSE_RAW} */
+#define FL_SET RB_FL_SET /**< @old{RB_FL_SET} */
+#define FL_SET_RAW RB_FL_SET_RAW /**< @old{RB_FL_SET_RAW} */
+#define FL_TEST RB_FL_TEST /**< @old{RB_FL_TEST} */
+#define FL_TEST_RAW RB_FL_TEST_RAW /**< @old{RB_FL_TEST_RAW} */
+#define FL_UNSET RB_FL_UNSET /**< @old{RB_FL_UNSET} */
+#define FL_UNSET_RAW RB_FL_UNSET_RAW /**< @old{RB_FL_UNSET_RAW} */
+#define OBJ_FREEZE RB_OBJ_FREEZE /**< @old{RB_OBJ_FREEZE} */
+#define OBJ_FREEZE_RAW RB_OBJ_FREEZE_RAW /**< @old{RB_OBJ_FREEZE_RAW} */
+#define OBJ_FROZEN RB_OBJ_FROZEN /**< @old{RB_OBJ_FROZEN} */
+#define OBJ_FROZEN_RAW RB_OBJ_FROZEN_RAW /**< @old{RB_OBJ_FROZEN_RAW} */
+#define OBJ_INFECT RB_OBJ_INFECT /**< @old{RB_OBJ_INFECT} */
+#define OBJ_INFECT_RAW RB_OBJ_INFECT_RAW /**< @old{RB_OBJ_INFECT_RAW} */
+#define OBJ_TAINT RB_OBJ_TAINT /**< @old{RB_OBJ_TAINT} */
+#define OBJ_TAINTABLE RB_OBJ_TAINTABLE /**< @old{RB_OBJ_TAINT_RAW} */
+#define OBJ_TAINTED RB_OBJ_TAINTED /**< @old{RB_OBJ_TAINTED} */
+#define OBJ_TAINTED_RAW RB_OBJ_TAINTED_RAW /**< @old{RB_OBJ_TAINTED_RAW} */
+#define OBJ_TAINT_RAW RB_OBJ_TAINT_RAW /**< @old{RB_OBJ_TAINT_RAW} */
+#define OBJ_UNTRUST RB_OBJ_UNTRUST /**< @old{RB_OBJ_TAINT} */
+#define OBJ_UNTRUSTED RB_OBJ_UNTRUSTED /**< @old{RB_OBJ_TAINTED} */
+/** @} */
+
+/**
+ * This is an enum because GDB wants it (rather than a macro). People need not
+ * bother.
+ */
+enum ruby_fl_ushift {
+ /**
+ * Number of bits in ::ruby_fl_type that are _not_ open to users. This is
+ * an implementation detail. Please ignore.
+ */
+ RUBY_FL_USHIFT = 12
+};
+
+/* > The expression that defines the value of an enumeration constant shall be
+ * > an integer constant expression that has a value representable as an `int`.
+ *
+ * -- ISO/IEC 9899:2018 section 6.7.2.2
+ *
+ * So ENUM_OVER_INT situation is an extension to the standard. Note however
+ * that we do not support 16 bit `int` environment. */
+RB_GNUC_EXTENSION
+/**
+ * The flags. Each ruby objects have their own characteristics apart from
+ * their classes. For instance whether an object is frozen or not is not
+ * controlled by its class. This is the type that represents such properties.
+ *
+ * @note About the `FL_USER` terminology: the "user" here does not necessarily
+ * mean only you. For instance struct ::RString instances use these
+ * bits to cache their encodings etc. Devs discussed about this topic,
+ * reached their consensus that ::RUBY_T_DATA is the only valid data
+ * structure that can use these bits; other data structures including
+ * ::RUBY_T_OBJECT use these bits for their own purpose. See also
+ * https://bugs.ruby-lang.org/issues/18059
+ */
+enum
+RBIMPL_ATTR_FLAG_ENUM()
+ruby_fl_type {
+
+ /**
+ * @deprecated This flag once was a thing back in the old days, but makes
+ * no sense any longer today. Exists here for backwards
+ * compatibility only. You can safely forget about it.
+ *
+ * @internal
+ *
+ * The reality is our GC no longer remembers write barriers inside of each
+ * objects, to use dedicated bitmap instead. But this flag is still used
+ * internally. The current usages of this flag should be something
+ * different, which is unclear to @shyouhei.
+ */
+ RUBY_FL_WB_PROTECTED = (1<<5),
+
+ /**
+ * This flag has something to do with our garbage collector. These days
+ * ruby objects are "generational". There are those who are young and
+ * those who are old. Young objects are prone to die; monitored relatively
+ * extensively by the garbage collector. OTOH old objects tend to live
+ * longer. They are relatively rarely considered. This flag is set when a
+ * object experienced promotion i.e. survived a garbage collection.
+ *
+ * @internal
+ *
+ * But honestly, @shyouhei doesn't think this flag should be visible from
+ * 3rd parties. It must be an implementation detail that they should never
+ * know. Might better be hidden.
+ */
+ RUBY_FL_PROMOTED0 = (1<<5),
+
+ /**
+ * This flag has something to do with our garbage collector. These days
+ * ruby objects are "generational". There are those who are young and
+ * those who are old. Young objects are prone to die; monitored relatively
+ * extensively by the garbage collector. OTOH old objects tend to live
+ * longer. They are relatively rarely considered. This flag is set when a
+ * object experienced two promotions i.e. survived garbage collections
+ * twice.
+ *
+ * @internal
+ *
+ * But honestly, @shyouhei doesn't think this flag should be visible from
+ * 3rd parties. It must be an implementation detail that they should never
+ * know. Might better be hidden.
+ */
+ RUBY_FL_PROMOTED1 = (1<<6),
+
+ /**
+ * This flag has something to do with our garbage collector. These days
+ * ruby objects are "generational". There are those who are young and
+ * those who are old. Young objects are prone to die; monitored relatively
+ * extensively by the garbage collector. OTOH old objects tend to live
+ * longer. They are relatively rarely considered. This flag is set when a
+ * object experienced promotions i.e. survived more than one garbage
+ * collections.
+ *
+ * @internal
+ *
+ * But honestly, @shyouhei doesn't think this flag should be visible from
+ * 3rd parties. It must be an implementation detail that they should never
+ * know. Might better be hidden.
+ */
+ RUBY_FL_PROMOTED = RUBY_FL_PROMOTED0 | RUBY_FL_PROMOTED1,
+
+ /**
+ * This flag has something to do with finalisers. A ruby object can have
+ * its finaliser, which is another object that evaluates when the target
+ * object is about to die. This flag is used to denote that there is an
+ * attached finaliser.
+ *
+ * @internal
+ *
+ * But honestly, @shyouhei doesn't think this flag should be visible from
+ * 3rd parties. It must be an implementation detail that they should never
+ * know. Might better be hidden.
+ */
+ RUBY_FL_FINALIZE = (1<<7),
+
+ /**
+ * @deprecated This flag once was a thing back in the old days, but makes
+ * no sense any longer today. Exists here for backwards
+ * compatibility only. You can safely forget about it.
+ */
+ RUBY_FL_TAINT
+
+#if defined(RBIMPL_HAVE_ENUM_ATTRIBUTE)
+ RBIMPL_ATTR_DEPRECATED(("taintedness turned out to be a wrong idea."))
+#elif defined(_MSC_VER)
+# pragma deprecated(RUBY_FL_TAINT)
+#endif
+
+ = (1<<8),
+
+ /**
+ * This flag has something to do with Ractor. Multiple Ractors run without
+ * protecting each other. Sharing an object among Ractors are basically
+ * dangerous, disabled by default. This flag is used to bypass that
+ * restriction. Of course, you have to manually prevent race conditions
+ * then.
+ *
+ * This flag needs deep understanding of multithreaded programming. You
+ * would better not use it.
+ */
+ RUBY_FL_SHAREABLE = (1<<8),
+
+ /**
+ * @deprecated This flag once was a thing back in the old days, but makes
+ * no sense any longer today. Exists here for backwards
+ * compatibility only. You can safely forget about it.
+ */
+ RUBY_FL_UNTRUSTED
+
+#if defined(RBIMPL_HAVE_ENUM_ATTRIBUTE)
+ RBIMPL_ATTR_DEPRECATED(("trustedness turned out to be a wrong idea."))
+#elif defined(_MSC_VER)
+# pragma deprecated(RUBY_FL_UNTRUSTED)
+#endif
+
+ = (1<<8),
+
+ /**
+ * This flag has something to do with object IDs. Unlike in the old days,
+ * an object's object ID (that a user can query using `Object#object_id`)
+ * is no longer its physical address represented using Ruby level integers.
+ * It is now a monotonic-increasing integer unrelated to the underlying
+ * memory arrangement. Object IDs are assigned when necessary; objects are
+ * born without one, and will eventually have such property when queried.
+ * The interpreter has to manage which one is which. This is the flag that
+ * helps the management. Objects with this flag set are the ones with
+ * object IDs assigned.
+ *
+ * @internal
+ *
+ * But honestly, @shyouhei doesn't think this flag should be visible from
+ * 3rd parties. It must be an implementation detail that they should never
+ * know. Might better be hidden.
+ */
+ RUBY_FL_SEEN_OBJ_ID = (1<<9),
+
+ /**
+ * This flag has something to do with instance variables. 3rd parties need
+ * not know, but there are several ways to store an object's instance
+ * variables. Objects with this flag use so-called "generic" backend
+ * storage. This distinction is purely an implementation detail. People
+ * need not be aware of this working behind-the-scene.
+ *
+ * @internal
+ *
+ * As of writing everything except ::RObject and RModule use this scheme.
+ */
+ RUBY_FL_EXIVAR = (1<<10),
+
+ /**
+ * This flag has something to do with data immutability. When this flag is
+ * set an object is considered "frozen". No modification are expected to
+ * happen beyond that point for the particular object. Immutability is
+ * basically considered to be a good property these days. Library authors
+ * are expected to obey. Test this bit before you touch a data structure.
+ *
+ * @see rb_check_frozen()
+ */
+ RUBY_FL_FREEZE = (1<<11),
+
+/** (@shyouhei doesn't know how to excude this macro from doxygen). */
+#define RBIMPL_FL_USER_N(n) RUBY_FL_USER##n = (1<<(RUBY_FL_USHIFT+n))
+ RBIMPL_FL_USER_N(0), /**< User-defined flag. */
+ RBIMPL_FL_USER_N(1), /**< User-defined flag. */
+ RBIMPL_FL_USER_N(2), /**< User-defined flag. */
+ RBIMPL_FL_USER_N(3), /**< User-defined flag. */
+ RBIMPL_FL_USER_N(4), /**< User-defined flag. */
+ RBIMPL_FL_USER_N(5), /**< User-defined flag. */
+ RBIMPL_FL_USER_N(6), /**< User-defined flag. */
+ RBIMPL_FL_USER_N(7), /**< User-defined flag. */
+ RBIMPL_FL_USER_N(8), /**< User-defined flag. */
+ RBIMPL_FL_USER_N(9), /**< User-defined flag. */
+ RBIMPL_FL_USER_N(10), /**< User-defined flag. */
+ RBIMPL_FL_USER_N(11), /**< User-defined flag. */
+ RBIMPL_FL_USER_N(12), /**< User-defined flag. */
+ RBIMPL_FL_USER_N(13), /**< User-defined flag. */
+ RBIMPL_FL_USER_N(14), /**< User-defined flag. */
+ RBIMPL_FL_USER_N(15), /**< User-defined flag. */
+ RBIMPL_FL_USER_N(16), /**< User-defined flag. */
+ RBIMPL_FL_USER_N(17), /**< User-defined flag. */
+ RBIMPL_FL_USER_N(18), /**< User-defined flag. */
+#ifdef ENUM_OVER_INT
+ RBIMPL_FL_USER_N(19), /**< User-defined flag. */
+#else
+# define RUBY_FL_USER19 (RBIMPL_VALUE_ONE<<(RUBY_FL_USHIFT+19))
+#endif
+#undef RBIMPL_FL_USER_N
+#undef RBIMPL_WIDER_ENUM
+
+ /**
+ * This flag has something to do with data structures. Over time, ruby
+ * evolved to reduce memory footprints. One of such attempt is so-called
+ * copy-on-write, which delays duplication of resources until ultimately
+ * necessary. Some data structures share this scheme. For example
+ * multiple instances of struct ::RArray could point identical memory
+ * region in common, as long as they don't differ. As people favour
+ * immutable style of programming than before, this situation is getting
+ * more and more common. Because such "shared" memory regions have nuanced
+ * ownership by nature, each structures need special care for them. This
+ * flag is used to distinguish such shared constructs.
+ *
+ * @internal
+ *
+ * But honestly, @shyouhei doesn't think this flag should be visible from
+ * 3rd parties. It must be an implementation detail that they should never
+ * know. Might better be hidden.
+ */
+ RUBY_ELTS_SHARED = RUBY_FL_USER2,
+
+ /**
+ * This flag has something to do with an object's class. There are kind of
+ * classes called "singleton class", each of which have exactly one
+ * instance. What is interesting about singleton classes is that they are
+ * created _after_ their instance were instantiated, like this:
+ *
+ * ```ruby
+ * foo = Object.new # foo is an instance of Object...
+ * bar = foo.singleton_class # foo is now an instance of bar.
+ * ```
+ *
+ * Here as you see `bar` is a singleton class of `foo`, which is injected
+ * into `foo`'s inheritance tree in a different statement (== distinct
+ * sequence point). In order to achieve this property singleton classes
+ * are special-cased in the interpreter. There is one bit flag that
+ * distinguishes if a class is a singleton class or not, and this is it.
+ *
+ * @internal
+ *
+ * But honestly, @shyouhei doesn't think this flag should be visible from
+ * 3rd parties. It must be an implementation detail that they should never
+ * know. Might better be hidden.
+ */
+ RUBY_FL_SINGLETON = RUBY_FL_USER0,
+};
+
+enum {
+ /**
+ * @deprecated This flag once was a thing back in the old days, but makes
+ * no sense any longer today. Exists here for backwards
+ * compatibility only. You can safely forget about it.
+ */
+ RUBY_FL_DUPPED
+
+#if defined(RBIMPL_HAVE_ENUM_ATTRIBUTE)
+ RBIMPL_ATTR_DEPRECATED(("It seems there is no actual usage of this enum."))
+#elif defined(_MSC_VER)
+# pragma deprecated(RUBY_FL_DUPPED)
+#endif
+
+ = (int)RUBY_T_MASK | (int)RUBY_FL_EXIVAR
+};
+
+#undef RBIMPL_HAVE_ENUM_ATTRIBUTE
+
+RBIMPL_SYMBOL_EXPORT_BEGIN()
+/**
+ * @deprecated Does nothing. This method is deprecated and will be removed in
+ * Ruby 3.2.
+ */
+void rb_obj_infect(VALUE victim, VALUE carrier);
+
+/**
+ * This is an implementation detail of #RB_OBJ_FREEZE(). People don't use it
+ * directly.
+ *
+ * @param[out] klass A singleton class.
+ * @post `klass` gets frozen.
+ */
+void rb_freeze_singleton_class(VALUE klass);
+RBIMPL_SYMBOL_EXPORT_END()
+
+RBIMPL_ATTR_PURE_UNLESS_DEBUG()
+RBIMPL_ATTR_ARTIFICIAL()
+RBIMPL_ATTR_FORCEINLINE()
+/**
+ * Checks if the object is flaggable. There are some special cases (most
+ * notably ::RUBY_Qfalse) where appending a flag to an object is not possible.
+ * This function can detect that.
+ *
+ * @param[in] obj Object in question
+ * @retval true It is flaggable.
+ * @retval false No it isn't.
+ */
+static bool
+RB_FL_ABLE(VALUE obj)
+{
+ if (RB_SPECIAL_CONST_P(obj)) {
+ return false;
+ }
+ else if (RB_TYPE_P(obj, RUBY_T_NODE)) {
+ return false;
+ }
+ else {
+ return true;
+ }
+}
+
+RBIMPL_ATTR_PURE_UNLESS_DEBUG()
+RBIMPL_ATTR_ARTIFICIAL()
+/**
+ * This is an implenentation detail of RB_FL_TEST(). 3rd parties need not use
+ * this. Just always use RB_FL_TEST().
+ *
+ * @param[in] obj Object in question.
+ * @param[in] flags A set of enum ::ruby_fl_type.
+ * @pre The object must not be an enum ::ruby_special_consts.
+ * @return `obj`'s flags, masked by `flags`.
+ */
+static inline VALUE
+RB_FL_TEST_RAW(VALUE obj, VALUE flags)
+{
+ RBIMPL_ASSERT_OR_ASSUME(RB_FL_ABLE(obj));
+ return RBASIC(obj)->flags & flags;
+}
+
+RBIMPL_ATTR_PURE_UNLESS_DEBUG()
+RBIMPL_ATTR_ARTIFICIAL()
+/**
+ * Tests if the given flag(s) are set or not. You can pass multiple flags at
+ * once:
+ *
+ * ```CXX
+ * auto obj = rb_eval_string("...");
+ * if (RB_FL_TEST(obj, RUBY_FL_FREEZE | RUBY_FL_SHAREABLE)) {
+ * printf("Ractor ready!\n");
+ * }
+ * ```
+ *
+ * @param[in] obj Object in question.
+ * @param[in] flags A set of enum ::ruby_fl_type.
+ * @return `obj`'s flags, masked by `flags`.
+ * @note It is intentional for this function to return ::VALUE. The
+ * return value could be passed to RB_FL_STE() etc.
+ */
+static inline VALUE
+RB_FL_TEST(VALUE obj, VALUE flags)
+{
+ if (RB_FL_ABLE(obj)) {
+ return RB_FL_TEST_RAW(obj, flags);
+ }
+ else {
+ return RBIMPL_VALUE_NULL;
+ }
+}
+
+RBIMPL_ATTR_PURE_UNLESS_DEBUG()
+RBIMPL_ATTR_ARTIFICIAL()
+/**
+ * This is an implenentation detail of RB_FL_ANY(). 3rd parties need not use
+ * this. Just always use RB_FL_ANY().
+ *
+ * @param[in] obj Object in question.
+ * @param[in] flags A set of enum ::ruby_fl_type.
+ * @retval true The object has any of the flags set.
+ * @retval false No it doesn't at all.
+ * @pre The object must not be an enum ::ruby_special_consts.
+ */
+static inline bool
+RB_FL_ANY_RAW(VALUE obj, VALUE flags)
+{
+ return RB_FL_TEST_RAW(obj, flags);
+}
+
+RBIMPL_ATTR_PURE_UNLESS_DEBUG()
+RBIMPL_ATTR_ARTIFICIAL()
+/**
+ * Identical to RB_FL_TEST(), except it returns bool.
+ *
+ * @param[in] obj Object in question.
+ * @param[in] flags A set of enum ::ruby_fl_type.
+ * @retval true The object has any of the flags set.
+ * @retval false No it doesn't at all.
+ */
+static inline bool
+RB_FL_ANY(VALUE obj, VALUE flags)
+{
+ return RB_FL_TEST(obj, flags);
+}
+
+RBIMPL_ATTR_PURE_UNLESS_DEBUG()
+RBIMPL_ATTR_ARTIFICIAL()
+/**
+ * This is an implenentation detail of RB_FL_ALL(). 3rd parties need not use
+ * this. Just always use RB_FL_ALL().
+ *
+ * @param[in] obj Object in question.
+ * @param[in] flags A set of enum ::ruby_fl_type.
+ * @retval true The object has all of the flags set.
+ * @retval false The object lacks any of the flags.
+ * @pre The object must not be an enum ::ruby_special_consts.
+ */
+static inline bool
+RB_FL_ALL_RAW(VALUE obj, VALUE flags)
+{
+ return RB_FL_TEST_RAW(obj, flags) == flags;
+}
+
+RBIMPL_ATTR_PURE_UNLESS_DEBUG()
+RBIMPL_ATTR_ARTIFICIAL()
+/**
+ * Identical to RB_FL_ANY(), except it mandates all passed flags be set.
+ *
+ * @param[in] obj Object in question.
+ * @param[in] flags A set of enum ::ruby_fl_type.
+ * @retval true The object has all of the flags set.
+ * @retval false The object lacks any of the flags.
+ */
+static inline bool
+RB_FL_ALL(VALUE obj, VALUE flags)
+{
+ return RB_FL_TEST(obj, flags) == flags;
+}
+
+RBIMPL_ATTR_NOALIAS()
+RBIMPL_ATTR_ARTIFICIAL()
+/**
+ * @private
+ *
+ * This is an implenentation detail of RB_FL_SET(). 3rd parties need not use
+ * this. Just always use RB_FL_SET().
+ *
+ * @param[out] obj Object in question.
+ * @param[in] flags A set of enum ::ruby_fl_type.
+ * @post `obj` has `flags` set.
+ *
+ * @internal
+ *
+ * This is function is here to annotate a part of RB_FL_SET_RAW() as
+ * `__declspec(noalias)`.
+ */
+static inline void
+rbimpl_fl_set_raw_raw(struct RBasic *obj, VALUE flags)
+{
+ obj->flags |= flags;
+}
+
+RBIMPL_ATTR_ARTIFICIAL()
+/**
+ * This is an implenentation detail of RB_FL_SET(). 3rd parties need not use
+ * this. Just always use RB_FL_SET().
+ *
+ * @param[out] obj Object in question.
+ * @param[in] flags A set of enum ::ruby_fl_type.
+ * @post `obj` has `flags` set.
+ */
+static inline void
+RB_FL_SET_RAW(VALUE obj, VALUE flags)
+{
+ RBIMPL_ASSERT_OR_ASSUME(RB_FL_ABLE(obj));
+ rbimpl_fl_set_raw_raw(RBASIC(obj), flags);
+}
+
+RBIMPL_ATTR_ARTIFICIAL()
+/**
+ * Sets the given flag(s).
+ *
+ * ```CXX
+ * auto v = rb_eval_string("...");
+ * RB_FL_SET(v, RUBY_FL_FREEZE);
+ * ```
+ *
+ * @param[out] obj Object in question.
+ * @param[in] flags A set of enum ::ruby_fl_type.
+ * @post `obj` has `flags` set.
+ */
+static inline void
+RB_FL_SET(VALUE obj, VALUE flags)
+{
+ if (RB_FL_ABLE(obj)) {
+ RB_FL_SET_RAW(obj, flags);
+ }
+}
+
+RBIMPL_ATTR_NOALIAS()
+RBIMPL_ATTR_ARTIFICIAL()
+/**
+ * @private
+ *
+ * This is an implenentation detail of RB_FL_UNSET(). 3rd parties need not use
+ * this. Just always use RB_FL_UNSET().
+ *
+ * @param[out] obj Object in question.
+ * @param[in] flags A set of enum ::ruby_fl_type.
+ * @post `obj` has `flags` cleared.
+ *
+ * @internal
+ *
+ * This is function is here to annotate a part of RB_FL_UNSET_RAW() as
+ * `__declspec(noalias)`.
+ */
+static inline void
+rbimpl_fl_unset_raw_raw(struct RBasic *obj, VALUE flags)
+{
+ obj->flags &= ~flags;
+}
+
+RBIMPL_ATTR_ARTIFICIAL()
+/**
+ * This is an implenentation detail of RB_FL_UNSET(). 3rd parties need not use
+ * this. Just always use RB_FL_UNSET().
+ *
+ * @param[out] obj Object in question.
+ * @param[in] flags A set of enum ::ruby_fl_type.
+ * @post `obj` has `flags` cleared.
+ */
+static inline void
+RB_FL_UNSET_RAW(VALUE obj, VALUE flags)
+{
+ RBIMPL_ASSERT_OR_ASSUME(RB_FL_ABLE(obj));
+ rbimpl_fl_unset_raw_raw(RBASIC(obj), flags);
+}
+
+RBIMPL_ATTR_ARTIFICIAL()
+/**
+ * Clears the given flag(s).
+ *
+ * @param[out] obj Object in question.
+ * @param[in] flags A set of enum ::ruby_fl_type.
+ * @post `obj` has `flags` cleard.
+ */
+static inline void
+RB_FL_UNSET(VALUE obj, VALUE flags)
+{
+ if (RB_FL_ABLE(obj)) {
+ RB_FL_UNSET_RAW(obj, flags);
+ }
+}
+
+RBIMPL_ATTR_NOALIAS()
+RBIMPL_ATTR_ARTIFICIAL()
+/**
+ * @private
+ *
+ * This is an implenentation detail of RB_FL_REVERSE(). 3rd parties need not
+ * use this. Just always use RB_FL_REVERSE().
+ *
+ * @param[out] obj Object in question.
+ * @param[in] flags A set of enum ::ruby_fl_type.
+ * @post `obj` has `flags` reversed.
+ *
+ * @internal
+ *
+ * This is function is here to annotate a part of RB_FL_REVERSE_RAW() as
+ * `__declspec(noalias)`.
+ */
+static inline void
+rbimpl_fl_reverse_raw_raw(struct RBasic *obj, VALUE flags)
+{
+ obj->flags ^= flags;
+}
+
+RBIMPL_ATTR_ARTIFICIAL()
+/**
+ * This is an implenentation detail of RB_FL_REVERSE(). 3rd parties need not
+ * use this. Just always use RB_FL_REVERSE().
+ *
+ * @param[out] obj Object in question.
+ * @param[in] flags A set of enum ::ruby_fl_type.
+ * @post `obj` has `flags` cleared.
+ */
+static inline void
+RB_FL_REVERSE_RAW(VALUE obj, VALUE flags)
+{
+ RBIMPL_ASSERT_OR_ASSUME(RB_FL_ABLE(obj));
+ rbimpl_fl_reverse_raw_raw(RBASIC(obj), flags);
+}
+
+RBIMPL_ATTR_ARTIFICIAL()
+/**
+ * Reverses the flags. This function is here mainly for symmetry on set/unset.
+ * Rarely used in practice.
+ *
+ * @param[out] obj Object in question.
+ * @param[in] flags A set of enum ::ruby_fl_type.
+ * @post `obj` has `flags` reversed.
+ */
+static inline void
+RB_FL_REVERSE(VALUE obj, VALUE flags)
+{
+ if (RB_FL_ABLE(obj)) {
+ RB_FL_REVERSE_RAW(obj, flags);
+ }
+}
+
+RBIMPL_ATTR_PURE_UNLESS_DEBUG()
+RBIMPL_ATTR_ARTIFICIAL()
+RBIMPL_ATTR_DEPRECATED(("taintedness turned out to be a wrong idea."))
+/**
+ * @deprecated This function once was a thing in the old days, but makes no
+ * sense any longer today. Exists here for backwards
+ * compatibility only. You can safely forget about it.
+ *
+ * @param[in] obj Object in question.
+ * @return false always.
+ */
+static inline bool
+RB_OBJ_TAINTABLE(VALUE obj)
+{
+ return false;
+}
+
+RBIMPL_ATTR_PURE_UNLESS_DEBUG()
+RBIMPL_ATTR_ARTIFICIAL()
+RBIMPL_ATTR_DEPRECATED(("taintedness turned out to be a wrong idea."))
+/**
+ * @deprecated This function once was a thing in the old days, but makes no
+ * sense any longer today. Exists here for backwards
+ * compatibility only. You can safely forget about it.
+ *
+ * @param[in] obj Object in question.
+ * @return false always.
+ */
+static inline VALUE
+RB_OBJ_TAINTED_RAW(VALUE obj)
+{
+ return false;
+}
+
+RBIMPL_ATTR_PURE_UNLESS_DEBUG()
+RBIMPL_ATTR_ARTIFICIAL()
+RBIMPL_ATTR_DEPRECATED(("taintedness turned out to be a wrong idea."))
+/**
+ * @deprecated This function once was a thing in the old days, but makes no
+ * sense any longer today. Exists here for backwards
+ * compatibility only. You can safely forget about it.
+ *
+ * @param[in] obj Object in question.
+ * @return false always.
+ */
+static inline bool
+RB_OBJ_TAINTED(VALUE obj)
+{
+ return false;
+}
+
+RBIMPL_ATTR_ARTIFICIAL()
+RBIMPL_ATTR_DEPRECATED(("taintedness turned out to be a wrong idea."))
+/**
+ * @deprecated This function once was a thing in the old days, but makes no
+ * sense any longer today. Exists here for backwards
+ * compatibility only. You can safely forget about it.
+ *
+ * @param[in] obj Object in question.
+ */
+static inline void
+RB_OBJ_TAINT_RAW(VALUE obj)
+{
+ return;
+}
+
+RBIMPL_ATTR_ARTIFICIAL()
+RBIMPL_ATTR_DEPRECATED(("taintedness turned out to be a wrong idea."))
+/**
+ * @deprecated This function once was a thing in the old days, but makes no
+ * sense any longer today. Exists here for backwards
+ * compatibility only. You can safely forget about it.
+ *
+ * @param[in] obj Object in question.
+ */
+static inline void
+RB_OBJ_TAINT(VALUE obj)
+{
+ return;
+}
+
+RBIMPL_ATTR_ARTIFICIAL()
+RBIMPL_ATTR_DEPRECATED(("taintedness turned out to be a wrong idea."))
+/**
+ * @deprecated This function once was a thing in the old days, but makes no
+ * sense any longer today. Exists here for backwards
+ * compatibility only. You can safely forget about it.
+ *
+ * @param[in] dst Victim object.
+ * @param[in] src Infectant object.
+ */
+static inline void
+RB_OBJ_INFECT_RAW(VALUE dst, VALUE src)
+{
+ return;
+}
+
+RBIMPL_ATTR_ARTIFICIAL()
+RBIMPL_ATTR_DEPRECATED(("taintedness turned out to be a wrong idea."))
+/**
+ * @deprecated This function once was a thing in the old days, but makes no
+ * sense any longer today. Exists here for backwards
+ * compatibility only. You can safely forget about it.
+ *
+ * @param[in] dst Victim object.
+ * @param[in] src Infectant object.
+ */
+static inline void
+RB_OBJ_INFECT(VALUE dst, VALUE src)
+{
+ return;
+}
+
+RBIMPL_ATTR_PURE_UNLESS_DEBUG()
+RBIMPL_ATTR_ARTIFICIAL()
+/**
+ * This is an implenentation detail of RB_OBJ_FROZEN(). 3rd parties need not
+ * use this. Just always use RB_OBJ_FROZEN().
+ *
+ * @param[in] obj Object in question.
+ * @retval RUBY_FL_FREEZE Yes it is.
+ * @retval 0 No it isn't.
+ *
+ * @internal
+ *
+ * It is intentional not to return bool here. There is a place in ruby core
+ * (namely `class.c:singleton_class_of()`) where return value of this function
+ * is passed to RB_FL_SET_RAW().
+ */
+static inline VALUE
+RB_OBJ_FROZEN_RAW(VALUE obj)
+{
+ return RB_FL_TEST_RAW(obj, RUBY_FL_FREEZE);
+}
+
+RBIMPL_ATTR_PURE_UNLESS_DEBUG()
+RBIMPL_ATTR_ARTIFICIAL()
+/**
+ * Checks if an object is frozen.
+ *
+ * @param[in] obj Object in question.
+ * @retval true Yes it is.
+ * @retval false No it isn't.
+ */
+static inline bool
+RB_OBJ_FROZEN(VALUE obj)
+{
+ if (! RB_FL_ABLE(obj)) {
+ return true;
+ }
+ else {
+ return RB_OBJ_FROZEN_RAW(obj);
+ }
+}
+
+RBIMPL_ATTR_ARTIFICIAL()
+/**
+ * This is an implenentation detail of RB_OBJ_FREEZE(). 3rd parties need not
+ * use this. Just always use RB_OBJ_FREEZE().
+ *
+ * @param[out] obj Object in question.
+ */
+static inline void
+RB_OBJ_FREEZE_RAW(VALUE obj)
+{
+ RB_FL_SET_RAW(obj, RUBY_FL_FREEZE);
+}
+
+/**
+ * Prevents further modifications to the given object. ::rb_eFrozenError shall
+ * be raised if modification is attempted.
+ *
+ * @param[out] x Object in question.
+ */
+static inline void
+rb_obj_freeze_inline(VALUE x)
+{
+ if (RB_FL_ABLE(x)) {
+ RB_OBJ_FREEZE_RAW(x);
+ if (RBASIC_CLASS(x) && !(RBASIC(x)->flags & RUBY_FL_SINGLETON)) {
+ rb_freeze_singleton_class(x);
+ }
+ }
+}
+
+#endif /* RBIMPL_FL_TYPE_H */
diff --git a/include/ruby/internal/gc.h b/include/ruby/internal/gc.h
new file mode 100644