From b64d8e960122101a24a05d9f61bf2faf22e94308 Mon Sep 17 00:00:00 2001
From: Jeremy Evans <code@jeremyevans.net>
Date: Mon, 12 Aug 2019 15:14:47 -0700
Subject: [PATCH] Correctly show defined class for aliases of aliases

Previously, aliasing a method defined in an ancestor class would
show the ancestor class as the defined_class for the method, but
aliasing that alias method would result in the current class
showing as the defined_class for the method.

Fix this by copying the defined_class from the main alias
method to the chained alias method if we detect such an alias
chain.

Fixes [Bug #11888]
---
 test/ruby/test_alias.rb | 14 ++++++++++++++
 vm_method.c             |  8 +++++++-
 2 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/test/ruby/test_alias.rb b/test/ruby/test_alias.rb
index e81636fa43..ed78b150a9 100644
--- a/test/ruby/test_alias.rb
+++ b/test/ruby/test_alias.rb
@@ -35,6 +35,12 @@ def quux
     end
   end
 
+  class Alias4 < Alias0
+    alias foo1 foo
+    alias foo2 foo1
+    alias foo3 foo2
+  end
+
   def test_alias
     x = Alias2.new
     assert_equal "foo", x.bar
@@ -47,6 +53,14 @@ def test_alias
     assert_raise(NoMethodError) { x.quux }
   end
 
+  def test_alias_inspect
+    o = Alias4.new
+    assert_equal("TestAlias::Alias4(TestAlias::Alias0)#foo", o.method(:foo).inspect.split[1])
+    assert_equal("TestAlias::Alias4(TestAlias::Alias0)#foo1(foo)", o.method(:foo1).inspect.split[1])
+    assert_equal("TestAlias::Alias4(TestAlias::Alias0)#foo2(foo)", o.method(:foo2).inspect.split[1])
+    assert_equal("TestAlias::Alias4(TestAlias::Alias0)#foo3(foo)", o.method(:foo3).inspect.split[1])
+  end
+
   class C
     def m
       $SAFE
diff --git a/vm_method.c b/vm_method.c
index da891229f8..4c83e647cc 100644
--- a/vm_method.c
+++ b/vm_method.c
@@ -1603,7 +1603,13 @@ rb_alias(VALUE klass, ID alias_name, ID original_name)
 
 	alias_me = method_entry_set(target_klass, alias_name, orig_me, visi, orig_me->owner);
 	RB_OBJ_WRITE(alias_me, &alias_me->owner, target_klass);
-	RB_OBJ_WRITE(alias_me, &alias_me->defined_class, defined_class);
+        if (orig_me->owner == defined_class &&
+            orig_me->owner != orig_me->defined_class &&
+            alias_me->owner == alias_me->defined_class) {
+            defined_class = orig_me->defined_class;
+        }
+
+        RB_OBJ_WRITE(alias_me, &alias_me->defined_class, defined_class);
     }
 }
 
-- 
2.22.0