From e5e4db1748d09635c6b20c3b880e5b55d84f7dea Mon Sep 17 00:00:00 2001
From: Nobuyoshi Nakada <nobu@ruby-lang.org>
Date: Thu, 12 Dec 2024 19:47:34 +0900
Subject: [PATCH] [Feature #20884] Define toplevel "Ruby" module with constants

---
 test/ruby/test_rubyoptions.rb | 13 +------------
 variable.c                    |  3 ---
 version.c                     | 22 ++++++++++++++++++++++
 3 files changed, 23 insertions(+), 15 deletions(-)

diff --git a/test/ruby/test_rubyoptions.rb b/test/ruby/test_rubyoptions.rb
index ac4b5870eb..931d0cf7aa 100644
--- a/test/ruby/test_rubyoptions.rb
+++ b/test/ruby/test_rubyoptions.rb
@@ -1328,17 +1328,6 @@ class TestRubyOptions < Test::Unit::TestCase
   end
 
   def test_toplevel_ruby
-    reserved = ["", [], /::Ruby is reserved/]
-    env = {"RUBYOPT"=>""}
-    args = %w[-e Ruby=1]
-    assert_in_out_err([env, *args])
-    assert_in_out_err([env, "-w", *args], *reserved)
-    assert_in_out_err([env, "-W:deprecated", *args], *reserved)
-    assert_in_out_err([env, "-w", "-W:no-deprecated", *args])
-
-    args = ["-e", "class A; Ruby=1; end"]
-    assert_in_out_err([env, *args])
-    assert_in_out_err([env, "-w", *args])
-    assert_in_out_err([env, "-W:deprecated", *args])
+    assert_instance_of Module, ::Ruby
   end
 end
diff --git a/variable.c b/variable.c
index b73d38f469..66b960cabe 100644
--- a/variable.c
+++ b/variable.c
@@ -3626,9 +3626,6 @@ const_set(VALUE klass, ID id, VALUE val)
             }
         }
     }
-    if (klass == rb_cObject && id == idRuby) {
-        rb_warn_reserved_name_at(3.5, "::Ruby");
-    }
 }
 
 void
diff --git a/version.c b/version.c
index 02e1c0bcb0..7a28c4a38f 100644
--- a/version.c
+++ b/version.c
@@ -87,10 +87,29 @@ const char ruby_engine[] = "ruby";
 // Might change after initialization
 const char *rb_dynamic_description = ruby_description;
 
+static inline void
+define_ruby_const(const char *name, VALUE value, VALUE mRuby)
+{
+    rb_define_global_const(name, value);
+    if (strncmp(name, "RUBY_", rb_strlen_lit("RUBY_")) == 0) {
+        rb_define_const(mRuby, name + rb_strlen_lit("RUBY_"), value);
+    }
+}
+
+/* RDoc needs rb_define_global_const */
+#define rb_define_global_const(name, value) \
+    define_ruby_const(name, value, mRuby)
+
 /*! Defines platform-depended Ruby-level constants */
 void
 Init_version(void)
 {
+    /*
+     * The Ruby module that contains portable information among
+     * implementations.
+     */
+    VALUE mRuby = rb_define_module("Ruby");
+
     enum {ruby_patchlevel = RUBY_PATCHLEVEL};
     VALUE version = MKSTR(version);
     VALUE ruby_engine_name = MKSTR(engine);
@@ -201,6 +220,7 @@ define_ruby_description(const char *const jit_opt)
     append(ruby_description + ruby_description_opt_point);
 # undef append
 
+    VALUE mRuby = rb_path2class("Ruby");
     VALUE description = rb_obj_freeze(rb_usascii_str_new_static(desc, n));
     rb_dynamic_description = desc;
 
@@ -223,7 +243,9 @@ Init_ruby_description(ruby_cmdline_options_t *opt)
 void
 ruby_set_yjit_description(void)
 {
+    VALUE mRuby = rb_path2class("Ruby");
     rb_const_remove(rb_cObject, rb_intern("RUBY_DESCRIPTION"));
+    rb_const_remove(mRuby, rb_intern("DESCRIPTION"));
     define_ruby_description(YJIT_DESCRIPTION);
 }