Trigger inherited and const_set callbacks after const has been defined

[Misc #21143]
[Bug #21193]

The previous change caused a backward compatibility issue with code
that called `Object.const_source_location` from the `inherited` callback.

To fix this, the order is now:

- Define the constant
- Invoke `inherited`
- Invoke `const_set`

Author: byroot

class.c

@@ -1004,8 +1004,9 @@ rb_define_class(const char *name, VALUE super)
     }
     klass = rb_define_class_id(id, super);
     rb_vm_register_global_object(klass);
+    rb_const_set_raw(rb_cObject, id, klass);
     rb_class_inherited(super, klass);
-    rb_const_set(rb_cObject, id, klass);
+    rb_const_added(klass, id);
 
     return klass;
 }
@@ -1043,8 +1044,10 @@ rb_define_class_id_under_no_pin(VALUE outer, ID id, VALUE super)
     }
     klass = rb_define_class_id(id, super);
     rb_set_class_path_string(klass, outer, rb_id2str(id));
+
+    rb_const_set_raw(outer, id, klass);
     rb_class_inherited(super, klass);
-    rb_const_set(outer, id, klass);
+    rb_const_added(outer, id);
 
     return klass;
 }

internal/variable.h

@@ -16,6 +16,8 @@
 #include "shape.h"              /* for rb_shape_t */
 
 /* variable.c */
+void rb_const_added(VALUE klass, ID const_name);
+void rb_const_set_raw(VALUE klass, ID id, VALUE val);
 void rb_gc_mark_global_tbl(void);
 void rb_gc_update_global_tbl(void);
 size_t rb_generic_ivar_memsize(VALUE);

spec/ruby/core/class/fixtures/callback_order.rb

@@ -3,15 +3,25 @@ module Callbacks
     class Base
       def self.inherited(subclass)
         subclass.const_set(:INHERITED_NAME, subclass.name)
-        ORDER << [:inherited, subclass, eval("defined?(#{subclass.name})")]
+        ORDER << [
+          :inherited,
+          subclass,
+          eval("defined?(#{subclass.name})"),
+          Object.const_source_location(subclass.name) ? :location : :unknown_location,
+        ]
         super
       end
     end
 
     ORDER = []
 
     def self.const_added(const_name)
-      ORDER << [:const_added, const_name, eval("defined?(#{const_name})")]
+      ORDER << [
+        :const_added,
+        const_name,
+        eval("defined?(#{const_name})"),
+        const_source_location(const_name) ? :location : :unknown_location,
+      ]
       super
     end
 

spec/ruby/core/class/inherited_spec.rb

@@ -106,8 +106,8 @@ class << top; protected :inherited; end
   ruby_version_is "3.5" do # https://bugs.ruby-lang.org/issues/21143
     it "is invoked before `const_added`" do
       CoreClassSpecs::Callbacks::ORDER.should == [
-        [:inherited, CoreClassSpecs::Callbacks::Child, nil],
-        [:const_added, :Child, "constant"],
+        [:inherited, CoreClassSpecs::Callbacks::Child, "constant", :location],
+        [:const_added, :Child, "constant", :location],
       ]
     end
   end

spec/ruby/optional/capi/class_spec.rb

@@ -389,8 +389,8 @@
         ScratchPad.record([])
         @s.rb_define_class_id_under(CApiClassSpecs::Callbacks, :Subclass, CApiClassSpecs::Callbacks)
         ScratchPad.recorded.should == [
-          [:inherited, "CApiClassSpecs::Callbacks::Subclass"],
-          [:const_added, :Subclass],
+          [:inherited, "CApiClassSpecs::Callbacks::Subclass", :location],
+          [:const_added, :Subclass, :location],
         ]
       end
     end

spec/ruby/optional/capi/fixtures/class.rb

@@ -104,11 +104,11 @@ module M
 
   class Callbacks
     def self.inherited(child)
-      ScratchPad << [:inherited, child.name]
+      ScratchPad << [:inherited, child.name, Object.const_source_location(child.name) ? :location : :unknown_location]
     end
 
     def self.const_added(const_name)
-      ScratchPad << [:const_added, const_name]
+      ScratchPad << [:const_added, const_name, const_source_location(const_name) ? :location : :unknown_location]
     end
   end
 end

variable.c

@@ -2624,7 +2624,6 @@ rb_autoload(VALUE module, ID name, const char *feature)
 }
 
 static void const_set(VALUE klass, ID id, VALUE val);
-static void const_added(VALUE klass, ID const_name);
 
 struct autoload_arguments {
     VALUE module;
@@ -2733,7 +2732,7 @@ rb_autoload_str(VALUE module, ID name, VALUE feature)
     VALUE result = rb_mutex_synchronize(autoload_mutex, autoload_synchronized, (VALUE)&arguments);
 
     if (result == Qtrue) {
-        const_added(module, name);
+        rb_const_added(module, name);
     }
 }
 
@@ -3604,8 +3603,8 @@ set_namespace_path(VALUE named_namespace, VALUE namespace_path)
     RB_VM_LOCK_LEAVE();
 }
 
-static void
-const_added(VALUE klass, ID const_name)
+void
+rb_const_added(VALUE klass, ID const_name)
 {
     if (GET_VM()->running) {
         VALUE name = ID2SYM(const_name);
@@ -3680,11 +3679,17 @@ const_set(VALUE klass, ID id, VALUE val)
     }
 }
 
+void
+rb_const_set_raw(VALUE klass, ID id, VALUE val)
+{
+    const_set(klass, id, val);
+}
+
 void
 rb_const_set(VALUE klass, ID id, VALUE val)
 {
     const_set(klass, id, val);
-    const_added(klass, id);
+    rb_const_added(klass, id);
 }
 
 static struct autoload_data *

vm_insnhelper.c

@@ -5752,8 +5752,9 @@ vm_declare_class(ID id, rb_num_t flags, VALUE cbase, VALUE super)
     VALUE c = rb_define_class_id(id, s);
     rb_define_alloc_func(c, rb_get_alloc_func(c));
     rb_set_class_path_string(c, cbase, rb_id2str(id));
+    rb_const_set_raw(cbase, id, c);
     rb_class_inherited(s, c);
-    rb_const_set(cbase, id, c);
+    rb_const_added(cbase, id);
     return c;
 }