3 files changed, 20 insertions, 0 deletions
diff --git a/spec/ruby/optional/capi/ext/exception_spec.c b/spec/ruby/optional/capi/ext/exception_spec.c
index 0e8347ab0d..e0d96b55e9 100644
--- a/spec/ruby/optional/capi/ext/exception_spec.c
+++ b/spec/ruby/optional/capi/ext/exception_spec.c
@@ -36,6 +36,11 @@ VALUE exception_spec_rb_set_errinfo(VALUE self, VALUE exc) {
   return Qnil;
 }
 
+VALUE exception_spec_rb_error_frozen_object(VALUE self, VALUE object) {
+    rb_error_frozen_object(object);
+    return Qnil;
+}
+
 VALUE exception_spec_rb_syserr_new(VALUE self, VALUE num, VALUE msg) {
   int n = NUM2INT(num);
   char *cstr = NULL;
@@ -66,6 +71,7 @@ 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/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/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));
 }