Fix memory leak at the same named alias [Bug #18516]

When aliasing a method to the same name method, set a separate bit
flag on that method definition, instead of the reference count
increment.  Although this kind of alias has no actual effect at
runtime, is used as the hack to suppress the method re-definition
warning.

1 files changed, 8 insertions, 1 deletions

diff --git a/vm_method.c b/vm_method.c
index 6867b5cf8c..b926654bdc 100644
--- a/vm_method.c
+++ b/vm_method.c
@@ -856,6 +856,7 @@ rb_method_entry_make(VALUE klass, ID mid, VALUE defined_class, rb_method_visibil
 	if (RTEST(ruby_verbose) &&
 	    type != VM_METHOD_TYPE_UNDEF &&
 	    (old_def->alias_count == 0) &&
+	    (!old_def->no_redef_warning) &&
 	    !make_refined &&
 	    old_def->type != VM_METHOD_TYPE_UNDEF &&
 	    old_def->type != VM_METHOD_TYPE_ZSUPER &&
@@ -1086,7 +1087,13 @@ method_entry_set(VALUE klass, ID mid, const rb_method_entry_t *me,
 		 rb_method_visibility_t visi, VALUE defined_class)
 {
     rb_method_entry_t *newme = rb_method_entry_make(klass, mid, defined_class, visi,
-						    me->def->type, method_definition_addref(me->def), 0, NULL);
+						    me->def->type, me->def, 0, NULL);
+    if (newme == me) {
+        me->def->no_redef_warning = TRUE;
+    }
+    else {
+        method_definition_addref(me->def);
+    }
     method_added(klass, mid);
     return newme;
 }