Merge pull request #2991 from shyouhei/ruby.h

Split ruby.h

14 files changed, 740 insertions, 21 deletions

diff --git a/include/ruby/backward/2/assume.h b/include/ruby/backward/2/assume.h
new file mode 100644
index 0000000000..2be231093b
--- /dev/null
+++ b/include/ruby/backward/2/assume.h
@@ -0,0 +1,39 @@
+/**                                                     \noop-*-C++-*-vi:ft=cpp
+ * @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  `RUBY3`   or   `ruby3`   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 #ASSUME / #RB_LIKELY / #UNREACHABLE
+ */
+#include "ruby/3/config.h"
+#include "ruby/3/assume.h"
+#include "ruby/3/has/builtin.h"
+
+#undef  ASSUME             /* Kill config.h definition */
+#undef  UNREACHABLE        /* Kill config.h definition */
+#define ASSUME             RUBY3_ASSUME
+#define UNREACHABLE        RUBY3_UNREACHABLE()
+#define UNREACHABLE_RETURN RUBY3_UNREACHABLE_RETURN
+
+/* likely */
+#if RUBY3_HAS_BUILTIN(__builtin_expect)
+# define RB_LIKELY(x)   (__builtin_expect(!!(x), 1))
+# define RB_UNLIKELY(x) (__builtin_expect(!!(x), 0))
+
+#else
+# define RB_LIKELY(x)   (x)
+# define RB_UNLIKELY(x) (x)
+#endif
diff --git a/include/ruby/backward/2/attributes.h b/include/ruby/backward/2/attributes.h
new file mode 100644
index 0000000000..0735385292
--- /dev/null
+++ b/include/ruby/backward/2/attributes.h
@@ -0,0 +1,157 @@
+/**                                                     \noop-*-C++-*-vi:ft=cpp
+ * @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  `RUBY3`   or   `ruby3`   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      Various attribute-related macros.
+ *
+ * ### Q&A ###
+ *
+ * - Q: Why  are the  macros defined  in this  header file  so inconsistent  in
+ *      style?
+ *
+ * - A: Don't know.   Don't blame me.  Backward compatibility is  the key here.
+ *      I'm just preserving what they have been.
+ */
+#ifndef  RUBY_BACKWARD2_ATTRIBUTES_H
+#define  RUBY_BACKWARD2_ATTRIBUTES_H
+#include "ruby/3/config.h"
+#include "ruby/3/attr/alloc_size.h"
+#include "ruby/3/attr/cold.h"
+#include "ruby/3/attr/const.h"
+#include "ruby/3/attr/deprecated.h"
+#include "ruby/3/attr/error.h"
+#include "ruby/3/attr/forceinline.h"
+#include "ruby/3/attr/format.h"
+#include "ruby/3/attr/maybe_unused.h"
+#include "ruby/3/attr/noinline.h"
+#include "ruby/3/attr/nonnull.h"
+#include "ruby/3/attr/noreturn.h"
+#include "ruby/3/attr/pure.h"
+#include "ruby/3/attr/restrict.h"
+#include "ruby/3/attr/returns_nonnull.h"
+#include "ruby/3/attr/warning.h"
+#include "ruby/3/has/attribute.h"
+
+/* function attributes */
+#undef CONSTFUNC
+#define CONSTFUNC(x) RUBY3_ATTR_CONST() x
+
+#undef PUREFUNC
+#define PUREFUNC(x) RUBY3_ATTR_PURE() x
+
+#undef DEPRECATED
+#define DEPRECATED(x) RUBY3_ATTR_DEPRECATED(("")) x
+
+#undef DEPRECATED_BY
+#define DEPRECATED_BY(n,x) RUBY3_ATTR_DEPRECATED(("by: " # n)) x
+
+#undef DEPRECATED_TYPE
+#define DEPRECATED_TYPE(mseg, decl) decl RUBY3_ATTR_DEPRECATED(mseg)
+
+#undef RUBY_CXX_DEPRECATED
+#define RUBY_CXX_DEPRECATED(mseg) RUBY3_ATTR_DEPRECATED((mseg))
+
+#undef NOINLINE
+#define NOINLINE(x) RUBY3_ATTR_NOINLINE() x
+
+#ifndef MJIT_HEADER
+# undef ALWAYS_INLINE
+# define ALWAYS_INLINE(x) RUBY3_ATTR_FORCEINLINE() x
+#endif
+
+#undef ERRORFUNC
+#define ERRORFUNC(mesg, x) RUBY3_ATTR_ERROR(mesg) x
+#if RUBY3_HAS_ATTRIBUTE(error)
+# define HAVE_ATTRIBUTE_ERRORFUNC 1
+#else
+# define HAVE_ATTRIBUTE_ERRORFUNC 0
+#endif
+
+#undef WARNINGFUNC
+#define WARNINGFUNC(mesg, x) RUBY3_ATTR_WARNING(mesg) x
+#if RUBY3_HAS_ATTRIBUTE(warning)
+# define HAVE_ATTRIBUTE_WARNINGFUNC 1
+#else
+# define HAVE_ATTRIBUTE_WARNINGFUNC 0
+#endif
+
+/*
+  cold attribute for code layout improvements
+  RUBY_FUNC_ATTRIBUTE not used because MSVC does not like nested func macros
+ */
+#undef COLDFUNC
+#define COLDFUNC RUBY3_ATTR_COLD()
+
+#define PRINTF_ARGS(decl, string_index, first_to_check) \
+    RUBY3_ATTR_FORMAT(RUBY3_PRINTF_FORMAT, (string_index), (first_to_check)) \
+    decl
+
+#undef RUBY_ATTR_ALLOC_SIZE
+#define RUBY_ATTR_ALLOC_SIZE RUBY3_ATTR_ALLOC_SIZE
+
+#undef RUBY_ATTR_MALLOC
+#define RUBY_ATTR_MALLOC RUBY3_ATTR_RESTRICT()
+
+#undef RUBY_ATTR_RETURNS_NONNULL
+#define RUBY_ATTR_RETURNS_NONNULL RUBY3_ATTR_RETURNS_NONNULL()
+
+#ifndef FUNC_MINIMIZED
+#define FUNC_MINIMIZED(x) x
+#endif
+
+#ifndef FUNC_UNOPTIMIZED
+#define FUNC_UNOPTIMIZED(x) x
+#endif
+
+#ifndef RUBY_ALIAS_FUNCTION_TYPE
+#define RUBY_ALIAS_FUNCTION_TYPE(type, prot, name, args) \
+    FUNC_MINIMIZED(type prot) {return (type)name args;}
+#endif
+
+#ifndef RUBY_ALIAS_FUNCTION_VOID
+#define RUBY_ALIAS_FUNCTION_VOID(prot, name, args) \
+    FUNC_MINIMIZED(void prot) {name args;}
+#endif
+
+#ifndef RUBY_ALIAS_FUNCTION
+#define RUBY_ALIAS_FUNCTION(prot, name, args) \
+    RUBY_ALIAS_FUNCTION_TYPE(VALUE, prot, name, args)
+#endif
+
+#undef RUBY_FUNC_NONNULL
+#define RUBY_FUNC_NONNULL(n, x) RUBY3_ATTR_NONNULL(n) x
+
+#undef  NORETURN
+#define NORETURN(x) RUBY3_ATTR_NORETURN() x
+#define NORETURN_STYLE_NEW
+
+#ifndef PACKED_STRUCT
+# define PACKED_STRUCT(x) x
+#endif
+
+#ifndef PACKED_STRUCT_UNALIGNED
+# if UNALIGNED_WORD_ACCESS
+#   define PACKED_STRUCT_UNALIGNED(x) PACKED_STRUCT(x)
+# else
+#   define PACKED_STRUCT_UNALIGNED(x) x
+# endif
+#endif
+
+#undef RB_UNUSED_VAR
+#define RB_UNUSED_VAR(x) x RUBY3_ATTR_MAYBE_UNUSED()
+
+#endif /* RUBY_BACKWARD2_ATTRIBUTES_H */
diff --git a/include/ruby/backward/2/bool.h b/include/ruby/backward/2/bool.h
new file mode 100644
index 0000000000..8c619b8215
--- /dev/null
+++ b/include/ruby/backward/2/bool.h
@@ -0,0 +1,33 @@
+/**                                                     \noop-*-C++-*-vi:ft=cpp
+ * @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  `RUBY3`   or   `ruby3`   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 old #TRUE / #FALSE
+ */
+#include "ruby/3/stdbool.h"
+
+#ifndef FALSE
+# define FALSE false
+#elif FALSE
+# error FALSE must be false
+#endif
+
+#ifndef TRUE
+# define TRUE true
+#elif ! TRUE
+# error TRUE must be true
+#endif
diff --git a/include/ruby/backward/2/extern.h b/include/ruby/backward/2/extern.h
new file mode 100644
index 0000000000..e7018342ea
--- /dev/null
+++ b/include/ruby/backward/2/extern.h
@@ -0,0 +1,45 @@
+/**                                                     \noop-*-C++-*-vi:ft=cpp
+ * @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  `RUBY3`   or   `ruby3`   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 old #EXTERN
+ */
+#include "ruby/3/config.h"      /* for STRINGIZE */
+
+/**
+ * @brief      Synonym of #RUBY_EXTERN.
+ * @deprecated #EXTERN is deprecated, use #RUBY_EXTERN instead.
+ */
+#ifdef EXTERN
+# /* Stop bothering then. */
+
+#elif defined __GNUC__
+# define EXTERN \
+    _Pragma("message \"EXTERN is deprecated, use RUBY_EXTERN instead\""); \
+    RUBY_EXTERN
+
+#elif defined _MSC_VER
+# pragma deprecated(EXTERN)
+# define EXTERN \
+    __pragma(message(__FILE__"("STRINGIZE(__LINE__)"): warning: " \
+                     "EXTERN is deprecated, use RUBY_EXTERN instead")) \
+    RUBY_EXTERN
+
+#else
+# define EXTERN <-<-"EXTERN is deprecated, use RUBY_EXTERN instead"->->
+
+#endif
diff --git a/include/ruby/backward/2/gcc_version_since.h b/include/ruby/backward/2/gcc_version_since.h
new file mode 100644
index 0000000000..c3c7aca5e0
--- /dev/null
+++ b/include/ruby/backward/2/gcc_version_since.h
@@ -0,0 +1,34 @@
+/**                                                     \noop-*-C++-*-vi:ft=cpp
+ * @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  `RUBY3`   or   `ruby3`   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 old #GCC_VERSION_SINCE
+ */
+#include "ruby/3/compiler_since.h"
+
+#ifndef GCC_VERSION_SINCE
+#define GCC_VERSION_SINCE(x, y, z) RUBY3_COMPILER_SINCE(GCC, (x), (y), (z))
+#endif
+
+#ifndef GCC_VERSION_BEFORE
+#define GCC_VERSION_BEFORE(x, y, z) \
+     (RUBY3_COMPILER_BEFORE(GCC, (x), (y), (z)) || \
+     (RUBY3_COMPILER_IS(GCC)                    && \
+    ((RUBY3_COMPILER_VERSION_MAJOR == (x))      && \
+    ((RUBY3_COMPILER_VERSION_MINOR == (y))      && \
+     (RUBY3_COMPILER_VERSION_PATCH == (z))))))
+#endif
diff --git a/include/ruby/backward/2/inttypes.h b/include/ruby/backward/2/inttypes.h
new file mode 100644
index 0000000000..7e9b525a52
--- /dev/null
+++ b/include/ruby/backward/2/inttypes.h
@@ -0,0 +1,128 @@
+/**                                                     \noop-*-C++-*-vi:ft=cpp
+ * @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  `RUBY3`   or   `ruby3`   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      C99 shim for `<inttypes.h>`
+ */
+#include "ruby/3/config.h"      /* PRI_LL_PREFIX etc. are here */
+
+#ifdef HAVE_INTTYPES_H
+# include <inttypes.h>
+#endif
+
+#include "ruby/3/value.h"       /* PRI_VALUE_PREFIX is here. */
+
+#ifndef PRI_INT_PREFIX
+# define PRI_INT_PREFIX ""
+#endif
+
+#ifndef PRI_LONG_PREFIX
+# define PRI_LONG_PREFIX "l"
+#endif
+
+#ifndef PRI_SHORT_PREFIX
+# define PRI_SHORT_PREFIX "h"
+#endif
+
+#ifdef PRI_64_PREFIX
+# /* Take that. */
+#elif SIZEOF_LONG == 8
+# define PRI_64_PREFIX PRI_LONG_PREFIX
+#elif SIZEOF_LONG_LONG == 8
+# define PRI_64_PREFIX PRI_LL_PREFIX
+#endif
+
+#ifndef PRIdPTR
+# define PRIdPTR PRI_PTR_PREFIX"d"
+# define PRIiPTR PRI_PTR_PREFIX"i"
+# define PRIoPTR PRI_PTR_PREFIX"o"
+# define PRIuPTR PRI_PTR_PREFIX"u"
+# define PRIxPTR PRI_PTR_PREFIX"x"
+# define PRIXPTR PRI_PTR_PREFIX"X"
+#endif
+
+#ifndef RUBY_PRI_VALUE_MARK
+# define RUBY_PRI_VALUE_MARK "\v"
+#endif
+
+#if defined PRIdPTR && !defined PRI_VALUE_PREFIX
+# define PRIdVALUE PRIdPTR
+# define PRIoVALUE PRIoPTR
+# define PRIuVALUE PRIuPTR
+# define PRIxVALUE PRIxPTR
+# define PRIXVALUE PRIXPTR
+# define PRIsVALUE PRIiPTR"" RUBY_PRI_VALUE_MARK
+#else
+# define PRIdVALUE PRI_VALUE_PREFIX"d"
+# define PRIoVALUE PRI_VALUE_PREFIX"o"
+# define PRIuVALUE PRI_VALUE_PREFIX"u"
+# define PRIxVALUE PRI_VALUE_PREFIX"x"
+# define PRIXVALUE PRI_VALUE_PREFIX"X"
+# define PRIsVALUE PRI_VALUE_PREFIX"i" RUBY_PRI_VALUE_MARK
+#endif
+
+#ifndef PRI_VALUE_PREFIX
+# define PRI_VALUE_PREFIX ""
+#endif
+
+#ifdef PRI_TIMET_PREFIX
+# /* Take that. */
+#elif SIZEOF_TIME_T == SIZEOF_INT
+# define PRI_TIMET_PREFIX
+#elif SIZEOF_TIME_T == SIZEOF_LONG
+# define PRI_TIMET_PREFIX "l"
+#elif SIZEOF_TIME_T == SIZEOF_LONG_LONG
+# define PRI_TIMET_PREFIX PRI_LL_PREFIX
+#endif
+
+#ifdef PRI_PTRDIFF_PREFIX
+# /* Take that. */
+#elif SIZEOF_PTRDIFF_T == SIZEOF_INT
+# define PRI_PTRDIFF_PREFIX ""
+#elif SIZEOF_PTRDIFF_T == SIZEOF_LONG
+# define PRI_PTRDIFF_PREFIX "l"
+#elif SIZEOF_PTRDIFF_T == SIZEOF_LONG_LONG
+# define PRI_PTRDIFF_PREFIX PRI_LL_PREFIX
+#endif
+
+#ifndef PRIdPTRDIFF
+# define PRIdPTRDIFF PRI_PTRDIFF_PREFIX"d"
+# define PRIiPTRDIFF PRI_PTRDIFF_PREFIX"i"
+# define PRIoPTRDIFF PRI_PTRDIFF_PREFIX"o"
+# define PRIuPTRDIFF PRI_PTRDIFF_PREFIX"u"
+# define PRIxPTRDIFF PRI_PTRDIFF_PREFIX"x"
+# define PRIXPTRDIFF PRI_PTRDIFF_PREFIX"X"
+#endif
+
+#ifdef PRI_SIZE_PREFIX
+# /* Take that. */
+#elif SIZEOF_SIZE_T == SIZEOF_INT
+# define PRI_SIZE_PREFIX ""
+#elif SIZEOF_SIZE_T == SIZEOF_LONG
+# define PRI_SIZE_PREFIX "l"
+#elif SIZEOF_SIZE_T == SIZEOF_LONG_LONG
+# define PRI_SIZE_PREFIX PRI_LL_PREFIX
+#endif
+
+#ifndef PRIdSIZE
+# define PRIdSIZE PRI_SIZE_PREFIX"d"
+# define PRIiSIZE PRI_SIZE_PREFIX"i"
+# define PRIoSIZE PRI_SIZE_PREFIX"o"
+# define PRIuSIZE PRI_SIZE_PREFIX"u"
+# define PRIxSIZE PRI_SIZE_PREFIX"x"
+# define PRIXSIZE PRI_SIZE_PREFIX"X"
+#endif
diff --git a/include/ruby/backward/2/limits.h b/include/ruby/backward/2/limits.h
new file mode 100644
index 0000000000..28eb1596a9
--- /dev/null
+++ b/include/ruby/backward/2/limits.h
@@ -0,0 +1,96 @@
+/**                                                     \noop-*-C++-*-vi:ft=cpp
+ * @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  `RUBY3`   or   `ruby3`   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      Historical shim for `<limits.h>`.
+ *
+ * The macros in this header file are obsolescent.  Does anyone really need our
+ * own definition of #CHAR_BIT today?
+ */
+#include "ruby/3/config.h"
+
+#ifdef HAVE_LIMITS_H
+# include <limits.h>
+#endif
+
+#include "ruby/backward/2/long_long.h"
+
+#ifndef LONG_MAX
+# /* assuming 32bit(2's complement) long */
+# define LONG_MAX 2147483647L
+#endif
+
+#ifndef LONG_MIN
+# define LONG_MIN (-LONG_MAX-1)
+#endif
+
+#ifndef CHAR_BIT
+# define CHAR_BIT 8
+#endif
+
+#ifdef LLONG_MAX
+# /* Take that. */
+#elif defined(LONG_LONG_MAX)
+# define LLONG_MAX  LONG_LONG_MAX
+#elif defined(_I64_MAX)
+# define LLONG_MAX _I64_MAX
+#else
+# /* assuming 64bit(2's complement) long long */
+# define LLONG_MAX 9223372036854775807LL
+#endif
+
+#ifdef LLONG_MIN
+# /* Take that. */
+#elif defined(LONG_LONG_MIN)
+# define LLONG_MIN  LONG_LONG_MIN
+#elif defined(_I64_MAX)
+# define LLONG_MIN _I64_MIN
+#else
+# define LLONG_MIN (-LLONG_MAX-1)
+#endif
+
+#ifdef SIZE_MAX
+# /* Take that. */
+#elif SIZEOF_SIZE_T == SIZEOF_LONG_LONG
+# define SIZE_MAX ULLONG_MAX
+# define SIZE_MIN ULLONG_MIN
+#elif SIZEOF_SIZE_T == SIZEOF_LONG
+# define SIZE_MAX ULONG_MAX
+# define SIZE_MIN ULONG_MIN
+#elif SIZEOF_SIZE_T == SIZEOF_INT
+# define SIZE_MAX UINT_MAX
+# define SIZE_MIN UINT_MIN
+#else
+# define SIZE_MAX USHRT_MAX
+# define SIZE_MIN USHRT_MIN
+#endif
+
+#ifdef SSIZE_MAX
+# /* Take that. */
+#elif SIZEOF_SIZE_T == SIZEOF_LONG_LONG
+# define SSIZE_MAX LLONG_MAX
+# define SSIZE_MIN LLONG_MIN
+#elif SIZEOF_SIZE_T == SIZEOF_LONG
+# define SSIZE_MAX LONG_MAX
+# define SSIZE_MIN LONG_MIN
+#elif SIZEOF_SIZE_T == SIZEOF_INT
+# define SSIZE_MAX INT_MAX
+# define SSIZE_MIN INT_MIN
+#else
+# define SSIZE_MAX SHRT_MAX
+# define SSIZE_MIN SHRT_MIN
+#endif
diff --git a/include/ruby/backward/2/long_long.h b/include/ruby/backward/2/long_long.h
new file mode 100644
index 0000000000..8669d42cd6
--- /dev/null
+++ b/include/ruby/backward/2/long_long.h
@@ -0,0 +1,64 @@
+/**                                                     \noop-*-C++-*-vi:ft=cpp
+ * @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  `RUBY3`   or   `ruby3`   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 old #LONG_LONG
+ *
+ * No  known  compiler   that  can  compile  today's  ruby   lacks  long  long.
+ * Historically MSVC was  one of such compiler, but it  implemented long long a
+ * while  ago  (some  time  back  in  2013).   The  macros  are  for  backwards
+ * compatibility only.
+ */
+#include "ruby/3/config.h"
+#include "ruby/3/has/warning.h"
+#include "ruby/3/warning_push.h"
+
+#if defined(LONG_LONG)
+# /* Take that. */
+
+#elif RUBY3_HAS_WARNING("-Wc++11-long-long")
+# define HAVE_TRUE_LONG_LONG 1
+# define LONG_LONG                           \
+    RUBY3_WARNING_PUSH()                     \
+    RUBY3_WARNING_IGNORED(-Wc++11-long-long) \
+    long long                                \
+    RUBY3_WARNING_POP()
+
+#elif RUBY3_HAS_WARNING("-Wlong-long")
+# define HAVE_TRUE_LONG_LONG 1
+# define LONG_LONG                     \
+    RUBY3_WARNING_PUSH()               \
+    RUBY3_WARNING_IGNORED(-Wlong-long) \
+    long long                          \
+    RUBY3_WARNING_POP()
+
+#elif defined(HAVE_LONG_LONG)
+# define HAVE_TRUE_LONG_LONG 1
+# define LONG_LONG long long
+
+#elif SIZEOF___INT64 > 0
+# define HAVE_LONG_LONG 1
+# define LONG_LONG __int64
+# undef SIZEOF_LONG_LONG
+# define SIZEOF_LONG_LONG SIZEOF___INT64
+
+#else
+# error Hello!  Ruby developers believe this message must not happen.
+# error If you encounter this message, can you file a bug report?
+# error Remember to attach a detailed description of your environment.
+# error Thank you!
+#endif
diff --git a/include/ruby/backward/2/r_cast.h b/include/ruby/backward/2/r_cast.h
new file mode 100644
index 0000000000..ed529c8968
--- /dev/null
+++ b/include/ruby/backward/2/r_cast.h
@@ -0,0 +1,27 @@
+/**                                                     \noop-*-C++-*-vi:ft=cpp
+ * @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  `RUBY3`   or   `ruby3`   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 old #R_CAST
+ *
+ * Nobody is actively using this macro.
+ */
+#ifndef RUBY_BACKWARD2_R_CAST_H
+#define RUBY_BACKWARD2_R_CAST_H
+#define R_CAST(st)   (struct st*)
+#define RMOVED(obj)  (R_CAST(RMoved)(obj))
+#endif /* RUBY_BACKWARD2_R_CAST_H */
diff --git a/include/ruby/backward/2/rmodule.h b/include/ruby/backward/2/rmodule.h
new file mode 100644
index 0000000000..bb0fc047a6
--- /dev/null
+++ b/include/ruby/backward/2/rmodule.h
@@ -0,0 +1,30 @@
+/**                                                     \noop-*-C++-*-vi:ft=cpp
+ * @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  `RUBY3`   or   `ruby3`   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      Orphan macros.
+ *
+ * These macros  seems broken since at  least 2011. Nobody (except  ruby itself
+ * who is implementing the internals) could have used those macros for a while.
+ * Kept public as-is here to keep some theoretical backwards compatibility.
+ */
+#ifndef RMODULE_IV_TBL
+#define RMODULE_IV_TBL(m) RCLASS_IV_TBL(m)
+#define RMODULE_CONST_TBL(m) RCLASS_CONST_TBL(m)
+#define RMODULE_M_TBL(m) RCLASS_M_TBL(m)
+#define RMODULE_SUPER(m) RCLASS_SUPER(m)
+#endif
diff --git a/include/ruby/backward/2/stdalign.h b/include/ruby/backward/2/stdalign.h
new file mode 100644
index 0000000000..2d970edc9d
--- /dev/null
+++ b/include/ruby/backward/2/stdalign.h
@@ -0,0 +1,26 @@
+/**                                                     \noop-*-C++-*-vi:ft=cpp
+ * @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  `RUBY3`   or   `ruby3`   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 #RUBY_ALIGNAS / #RUBY_ALIGNOF
+ */
+#include "ruby/3/stdalign.h"
+
+#undef RUBY_ALIGNAS
+#undef RUBY_ALIGNOF
+#define RUBY_ALIGNAS RUBY3_ALIGNAS
+#define RUBY_ALIGNOF RUBY3_ALIGNOF
diff --git a/include/ruby/backward/2/stdarg.h b/include/ruby/backward/2/stdarg.h
new file mode 100644
index 0000000000..7b37bd4571
--- /dev/null
+++ b/include/ruby/backward/2/stdarg.h
@@ -0,0 +1,43 @@
+/**                                                     \noop-*-C++-*-vi:ft=cpp
+ * @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  `RUBY3`   or   `ruby3`   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 old #_
+ *
+ * Nobody should  ever use these  macros any  longer.  No konwn  compilers lack
+ * prototypes today.  It's 21st century.  Just forget them.
+ */
+
+#undef _
+#ifdef HAVE_PROTOTYPES
+# define _(args) args
+#else
+# define _(args) ()
+#endif
+
+#undef __
+#ifdef HAVE_STDARG_PROTOTYPES
+# define __(args) args
+#else
+# define __(args) ()
+#endif
+
+#ifdef __cplusplus
+#define ANYARGS ...
+#else
+#define ANYARGS
+#endif
diff --git a/include/ruby/backward/cxxanyargs.hpp b/include/ruby/backward/cxxanyargs.hpp
index 7eaaa632a4..8fda5fe906 100644
--- a/include/ruby/backward/cxxanyargs.hpp
+++ b/include/ruby/backward/cxxanyargs.hpp
@@ -1,7 +1,5 @@
-#ifndef RUBY_BACKWARD_CXXANYARGS_HPP // -*- C++ -*-
-#define RUBY_BACKWARD_CXXANYARGS_HPP
+///                                                     \noop-*-C++-*-vi:ft=cpp
 /// @file
-/// @brief      Provides old prototypes for C++ programs.
 /// @author     \@shyouhei
 /// @copyright  This  file  is  a  part   of  the  programming  language  Ruby.
 ///             Permission  is hereby  granted, to  either redistribute  and/or
@@ -10,6 +8,23 @@
 /// @note       DO NOT  MODERNIZE THIS FILE!   As the  file name implies  it is
 ///             meant to  be a backwards  compatibility shim.  Please  stick to
 ///             C++ 98 and never use newer features, like `constexpr`.
+/// @brief      Provides old prototypes for C++ programs.
+#ifndef RUBY_BACKWARD_CXXANYARGS_HPP
+#define RUBY_BACKWARD_CXXANYARGS_HPP
+#include "ruby/3/config.h"
+#include "ruby/3/intern/class.h"
+#include "ruby/3/intern/cont.h"
+#include "ruby/3/intern/hash.h"
+#include "ruby/3/intern/proc.h"
+#include "ruby/3/intern/thread.h"
+#include "ruby/3/intern/variable.h"
+#include "ruby/3/intern/vm.h"
+#include "ruby/3/iterator.h"
+#include "ruby/3/method.h"
+#include "ruby/3/value.h"
+#include "ruby/3/variable.h"
+#include "ruby/backward/2/stdarg.h"
+#include "ruby/st.h"
 
 extern "C++" {
 
diff --git a/include/ruby/backward/rubysig.h b/include/ruby/backward/rubysig.h
index 58b13cab1c..7a1ca35f20 100644
--- a/include/ruby/backward/rubysig.h
+++ b/include/ruby/backward/rubysig.h
@@ -20,28 +20,10 @@
 #define RUBYSIG_H
 #include "ruby/ruby.h"
 
-#if defined(__cplusplus)
-extern "C" {
-#if 0
-} /* satisfy cc-mode */
-#endif
-#endif
-
-RUBY_SYMBOL_EXPORT_BEGIN
-
 #define RUBY_CRITICAL(statements) do {statements;} while (0)
 #define DEFER_INTS (0)
 #define ENABLE_INTS (1)
 #define ALLOW_INTS do {CHECK_INTS;} while (0)
 #define CHECK_INTS rb_thread_check_ints()
 
-RUBY_SYMBOL_EXPORT_END
-
-#if defined(__cplusplus)
-#if 0
-{ /* satisfy cc-mode */
-#endif
-}  /* extern "C" { */
-#endif
-
 #endif