10 files changed, 110 insertions, 4 deletions
diff --git a/spec/ruby/optional/capi/ext/array_spec.c b/spec/ruby/optional/capi/ext/array_spec.c
index 2347798bb4..628c4df9d7 100644
--- a/spec/ruby/optional/capi/ext/array_spec.c
+++ b/spec/ruby/optional/capi/ext/array_spec.c
@@ -196,6 +196,7 @@ static VALUE copy_ary(RB_BLOCK_CALL_FUNC_ARGLIST(el, new_ary)) {
   return rb_ary_push(new_ary, el);
 }
 
+#ifndef RUBY_VERSION_IS_4_0
 static VALUE array_spec_rb_iterate(VALUE self, VALUE ary) {
   VALUE new_ary = rb_ary_new();
 
@@ -203,6 +204,7 @@ static VALUE array_spec_rb_iterate(VALUE self, VALUE ary) {
 
   return new_ary;
 }
+#endif
 
 static VALUE array_spec_rb_block_call(VALUE self, VALUE ary) {
   VALUE new_ary = rb_ary_new();
@@ -216,6 +218,7 @@ static VALUE sub_pair(RB_BLOCK_CALL_FUNC_ARGLIST(el, holder)) {
   return rb_ary_push(holder, rb_ary_entry(el, 1));
 }
 
+#ifndef RUBY_VERSION_IS_4_0
 static VALUE each_pair(VALUE obj) {
   return rb_funcall(obj, rb_intern("each_pair"), 0);
 }
@@ -227,6 +230,7 @@ static VALUE array_spec_rb_iterate_each_pair(VALUE self, VALUE obj) {
 
   return new_ary;
 }
+#endif
 
 static VALUE array_spec_rb_block_call_each_pair(VALUE self, VALUE obj) {
   VALUE new_ary = rb_ary_new();
@@ -241,10 +245,12 @@ static VALUE iter_yield(RB_BLOCK_CALL_FUNC_ARGLIST(el, ary)) {
   return Qnil;
 }
 
+#ifndef RUBY_VERSION_IS_4_0
 static VALUE array_spec_rb_iterate_then_yield(VALUE self, VALUE obj) {
   rb_iterate(rb_each, obj, iter_yield, obj);
   return Qnil;
 }
+#endif
 
 static VALUE array_spec_rb_block_call_then_yield(VALUE self, VALUE obj) {
   rb_block_call(obj, rb_intern("each"), 0, 0, iter_yield, obj);
@@ -308,9 +314,11 @@ void Init_array_spec(void) {
   rb_define_method(cls, "rb_ary_plus", array_spec_rb_ary_plus, 2);
   rb_define_method(cls, "rb_ary_unshift", array_spec_rb_ary_unshift, 2);
   rb_define_method(cls, "rb_assoc_new", array_spec_rb_assoc_new, 2);
+#ifndef RUBY_VERSION_IS_4_0
   rb_define_method(cls, "rb_iterate", array_spec_rb_iterate, 1);
   rb_define_method(cls, "rb_iterate_each_pair", array_spec_rb_iterate_each_pair, 1);
   rb_define_method(cls, "rb_iterate_then_yield", array_spec_rb_iterate_then_yield, 1);
+#endif
   rb_define_method(cls, "rb_block_call", array_spec_rb_block_call, 1);
   rb_define_method(cls, "rb_block_call_each_pair", array_spec_rb_block_call_each_pair, 1);
   rb_define_method(cls, "rb_block_call_then_yield", array_spec_rb_block_call_then_yield, 1);
diff --git a/spec/ruby/optional/capi/ext/digest_spec.c b/spec/ruby/optional/capi/ext/digest_spec.c
index 9993238cf2..65c8defa20 100644
--- a/spec/ruby/optional/capi/ext/digest_spec.c
+++ b/spec/ruby/optional/capi/ext/digest_spec.c
@@ -135,7 +135,9 @@ VALUE digest_spec_context_size(VALUE self, VALUE meta) {
     return SIZET2NUM(algo->ctx_size);
 }
 
+#ifndef PTR2NUM
 #define PTR2NUM(x) (rb_int2inum((intptr_t)(void *)(x)))
+#endif
 
 VALUE digest_spec_context(VALUE self, VALUE digest) {
     return PTR2NUM(context);
diff --git a/spec/ruby/optional/capi/ext/exception_spec.c b/spec/ruby/optional/capi/ext/exception_spec.c
index 0e8347ab0d..c3b94d7bcd 100644
--- a/spec/ruby/optional/capi/ext/exception_spec.c
+++ b/spec/ruby/optional/capi/ext/exception_spec.c
@@ -36,6 +36,13 @@ VALUE exception_spec_rb_set_errinfo(VALUE self, VALUE exc) {
   return Qnil;
 }
 
+NORETURN(VALUE exception_spec_rb_error_frozen_object(VALUE self, VALUE object));
+
+VALUE exception_spec_rb_error_frozen_object(VALUE self, VALUE object) {
+  rb_error_frozen_object(object);
+  UNREACHABLE_RETURN(Qnil);
+}
+
 VALUE exception_spec_rb_syserr_new(VALUE self, VALUE num, VALUE msg) {
   int n = NUM2INT(num);
   char *cstr = NULL;
@@ -66,6 +73,7 @@ void Init_exception_spec(void) {
   rb_define_method(cls, "rb_exc_new3", exception_spec_rb_exc_new3, 1);
   rb_define_method(cls, "rb_exc_raise", exception_spec_rb_exc_raise, 1);
   rb_define_method(cls, "rb_set_errinfo", exception_spec_rb_set_errinfo, 1);
+  rb_define_method(cls, "rb_error_frozen_object", exception_spec_rb_error_frozen_object, 1);
   rb_define_method(cls, "rb_syserr_new", exception_spec_rb_syserr_new, 2);
   rb_define_method(cls, "rb_syserr_new_str", exception_spec_rb_syserr_new_str, 2);
   rb_define_method(cls, "rb_make_exception", exception_spec_rb_make_exception, 1);
diff --git a/spec/ruby/optional/capi/ext/kernel_spec.c b/spec/ruby/optional/capi/ext/kernel_spec.c
index ff71a7e589..a8fed21b59 100644
--- a/spec/ruby/optional/capi/ext/kernel_spec.c
+++ b/spec/ruby/optional/capi/ext/kernel_spec.c
@@ -117,9 +117,11 @@ VALUE kernel_spec_rb_eval_string(VALUE self, VALUE str) {
   return rb_eval_string(RSTRING_PTR(str));
 }
 
+#ifndef RUBY_VERSION_IS_4_0
 VALUE kernel_spec_rb_eval_cmd_kw(VALUE self, VALUE cmd, VALUE args, VALUE kw_splat) {
   return rb_eval_cmd_kw(cmd, args, NUM2INT(kw_splat));
 }
+#endif
 
 VALUE kernel_spec_rb_raise(VALUE self, VALUE hash) {
   rb_hash_aset(hash, ID2SYM(rb_intern("stage")), ID2SYM(rb_intern("before")));
@@ -403,7 +405,9 @@ void Init_kernel_spec(void) {
   rb_define_method(cls, "rb_category_warn_deprecated_with_integer_extra_value", kernel_spec_rb_category_warn_deprecated_with_integer_extra_value, 1);
   rb_define_method(cls, "rb_ensure", kernel_spec_rb_ensure, 4);
   rb_define_method(cls, "rb_eval_string", kernel_spec_rb_eval_string, 1);
+#ifndef RUBY_VERSION_IS_4_0
   rb_define_method(cls, "rb_eval_cmd_kw", kernel_spec_rb_eval_cmd_kw, 3);
+#endif
   rb_define_method(cls, "rb_raise", kernel_spec_rb_raise, 1);
   rb_define_method(cls, "rb_throw", kernel_spec_rb_throw, 1);
   rb_define_method(cls, "rb_throw_obj", kernel_spec_rb_throw_obj, 2);
diff --git a/spec/ruby/optional/capi/ext/object_spec.c b/spec/ruby/optional/capi/ext/object_spec.c
index eab0eb7534..995bc38fcf 100644
--- a/spec/ruby/optional/capi/ext/object_spec.c
+++ b/spec/ruby/optional/capi/ext/object_spec.c
@@ -383,6 +383,16 @@ static VALUE object_spec_custom_alloc_func_p(VALUE self, VALUE klass) {
   return allocator ? Qtrue : Qfalse;
 }
 
+static VALUE object_spec_redefine_frozen(VALUE self) {
+    // The purpose of this spec is to verify that `frozen?`
+    // and `RB_OBJ_FROZEN` do not mutually recurse infinitely.
+    if (RB_OBJ_FROZEN(self)) {
+        return Qtrue;
+    }
+
+    return Qfalse;
+}
+
 void Init_object_spec(void) {
   VALUE cls = rb_define_class("CApiObjectSpecs", rb_cObject);
   rb_define_method(cls, "FL_ABLE", object_spec_FL_ABLE, 1);
@@ -455,6 +465,9 @@ void Init_object_spec(void) {
   rb_define_method(cls, "custom_alloc_func?", object_spec_custom_alloc_func_p, 1);
   rb_define_method(cls, "not_implemented_method", rb_f_notimplement, -1);
   rb_define_method(cls, "rb_ivar_foreach", object_spec_rb_ivar_foreach, 1);
+
+  cls = rb_define_class("CApiObjectRedefinitionSpecs", rb_cObject);
+  rb_define_method(cls, "frozen?", object_spec_redefine_frozen, 0);
 }
 
 #ifdef __cplusplus
diff --git a/spec/ruby/optional/capi/ext/rubyspec.h b/spec/ruby/optional/capi/ext/rubyspec.h
index 8aaec36f46..6c4bea5da0 100644
--- a/spec/ruby/optional/capi/ext/rubyspec.h
+++ b/spec/ruby/optional/capi/ext/rubyspec.h
@@ -35,8 +35,8 @@
    (RUBY_API_VERSION_MAJOR == (major) && RUBY_API_VERSION_MINOR < (minor)))
 #define RUBY_VERSION_SINCE(major,minor) (!RUBY_VERSION_BEFORE(major, minor))
 
-#if RUBY_VERSION_SINCE(3, 5)
-#define RUBY_VERSION_IS_3_5
+#if RUBY_VERSION_SINCE(4, 0)
+#define RUBY_VERSION_IS_4_0
 #endif
 
 #if RUBY_VERSION_SINCE(3, 4)
diff --git a/spec/ruby/optional/capi/ext/set_spec.c b/spec/ruby/optional/capi/ext/set_spec.c
new file mode 100644
index 0000000000..11a271b361
--- /dev/null
+++ b/spec/ruby/optional/capi/ext/set_spec.c
@@ -0,0 +1,65 @@
+#include "ruby.h"
+#include "rubyspec.h"
+
+#ifdef RUBY_VERSION_IS_4_0
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#define RBOOL(x) ((x) ? Qtrue : Qfalse)
+
+int yield_element_and_arg(VALUE element, VALUE arg) {
+  return RTEST(rb_yield_values(2, element, arg)) ? ST_CONTINUE : ST_STOP;
+}
+
+VALUE set_spec_rb_set_foreach(VALUE self, VALUE set, VALUE arg) {
+  rb_set_foreach(set, yield_element_and_arg, arg);
+  return Qnil;
+}
+
+VALUE set_spec_rb_set_new(VALUE self) {
+  return rb_set_new();
+}
+
+VALUE set_spec_rb_set_new_capa(VALUE self, VALUE capa) {
+  return rb_set_new_capa(NUM2INT(capa));
+}
+
+VALUE set_spec_rb_set_lookup(VALUE self, VALUE set, VALUE element) {
+  return RBOOL(rb_set_lookup(set, element));
+}
+
+VALUE set_spec_rb_set_add(VALUE self, VALUE set, VALUE element) {
+  return RBOOL(rb_set_add(set, element));
+}
+
+VALUE set_spec_rb_set_clear(VALUE self, VALUE set) {
+  return rb_set_clear(set);
+}
+
+VALUE set_spec_rb_set_delete(VALUE self, VALUE set, VALUE element) {
+  return RBOOL(rb_set_delete(set, element));
+}
+
+VALUE set_spec_rb_set_size(VALUE self, VALUE set) {
+  return SIZET2NUM(rb_set_size(set));
+}
+
+void Init_set_spec(void) {
+  VALUE cls = rb_define_class("CApiSetSpecs", rb_cObject);
+
+  rb_define_method(cls, "rb_set_foreach", set_spec_rb_set_foreach, 2);
+  rb_define_method(cls, "rb_set_new", set_spec_rb_set_new, 0);
+  rb_define_method(cls, "rb_set_new_capa", set_spec_rb_set_new_capa, 1);
+  rb_define_method(cls, "rb_set_lookup", set_spec_rb_set_lookup, 2);
+  rb_define_method(cls, "rb_set_add", set_spec_rb_set_add, 2);
+  rb_define_method(cls, "rb_set_clear", set_spec_rb_set_clear, 1);
+  rb_define_method(cls, "rb_set_delete", set_spec_rb_set_delete, 2);
+  rb_define_method(cls, "rb_set_size", set_spec_rb_set_size, 1);
+}
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
diff --git a/spec/ruby/optional/capi/ext/string_spec.c b/spec/ruby/optional/capi/ext/string_spec.c
index b49bb3f267..094013e049 100644
--- a/spec/ruby/optional/capi/ext/string_spec.c
+++ b/spec/ruby/optional/capi/ext/string_spec.c
@@ -440,6 +440,7 @@ static VALUE string_spec_rb_str_free(VALUE self, VALUE str) {
 static VALUE string_spec_rb_sprintf1(VALUE self, VALUE str, VALUE repl) {
   return rb_sprintf(RSTRING_PTR(str), RSTRING_PTR(repl));
 }
+
 static VALUE string_spec_rb_sprintf2(VALUE self, VALUE str, VALUE repl1, VALUE repl2) {
   return rb_sprintf(RSTRING_PTR(str), RSTRING_PTR(repl1), RSTRING_PTR(repl2));
 }
diff --git a/spec/ruby/optional/capi/ext/struct_spec.c b/spec/ruby/optional/capi/ext/struct_spec.c
index 413249e828..756cfca8dd 100644
--- a/spec/ruby/optional/capi/ext/struct_spec.c
+++ b/spec/ruby/optional/capi/ext/struct_spec.c
@@ -62,6 +62,10 @@ static VALUE struct_spec_rb_struct_size(VALUE self, VALUE st) {
   return rb_struct_size(st);
 }
 
+static VALUE struct_spec_rb_struct_initialize(VALUE self, VALUE st, VALUE values) {
+  return rb_struct_initialize(st, values);
+}
+
 #if defined(RUBY_VERSION_IS_3_3)
 /* Only allow setting three attributes, should be sufficient for testing. */
 static VALUE struct_spec_rb_data_define(VALUE self, VALUE superclass,
@@ -90,6 +94,7 @@ void Init_struct_spec(void) {
   rb_define_method(cls, "rb_struct_define_under", struct_spec_rb_struct_define_under, 5);
   rb_define_method(cls, "rb_struct_new", struct_spec_rb_struct_new, 4);
   rb_define_method(cls, "rb_struct_size", struct_spec_rb_struct_size, 1);
+  rb_define_method(cls, "rb_struct_initialize", struct_spec_rb_struct_initialize, 2);
 #if defined(RUBY_VERSION_IS_3_3)
   rb_define_method(cls, "rb_data_define", struct_spec_rb_data_define, 4);
 #endif
diff --git a/spec/ruby/optional/capi/ext/thread_spec.c b/spec/ruby/optional/capi/ext/thread_spec.c
index 6ee111b7b7..ac77e4e813 100644
--- a/spec/ruby/optional/capi/ext/thread_spec.c
+++ b/spec/ruby/optional/capi/ext/thread_spec.c
@@ -166,7 +166,7 @@ static VALUE thread_spec_ruby_native_thread_p_new_thread(VALUE self) {
 #endif
 }
 
-#ifdef RUBY_VERSION_IS_3_5
+#ifdef RUBY_VERSION_IS_4_0
 static VALUE thread_spec_ruby_thread_has_gvl_p(VALUE self) {
   return ruby_thread_has_gvl_p() ? Qtrue : Qfalse;
 }
@@ -185,7 +185,7 @@ void Init_thread_spec(void) {
   rb_define_method(cls,  "rb_thread_create", thread_spec_rb_thread_create, 2);
   rb_define_method(cls,  "ruby_native_thread_p", thread_spec_ruby_native_thread_p, 0);
   rb_define_method(cls,  "ruby_native_thread_p_new_thread", thread_spec_ruby_native_thread_p_new_thread, 0);
-#ifdef RUBY_VERSION_IS_3_5
+#ifdef RUBY_VERSION_IS_4_0
   rb_define_method(cls,  "ruby_thread_has_gvl_p", thread_spec_ruby_thread_has_gvl_p, 0);
 #endif
 }