forwardable.rb: adjust backtrace by tail call

* lib/forwardable.rb (def_instance_delegator): adjust backtrace of
  method body by tail call optimization.  adjusting the delegated
  target is still done by deleting backtrace.
* lib/forwardable.rb (def_single_delegator): ditto.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@53383 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 2 insertions, 0 deletions

diff --git a/test/test_forwardable.rb b/test/test_forwardable.rb
index a474e4ad76..550280de19 100644
--- a/test/test_forwardable.rb
+++ b/test/test_forwardable.rb
@@ -187,6 +187,7 @@ class TestForwardable < Test::Unit::TestCase
     extend Forwardable
 
     def_delegator :bar, :baz
+    def_delegator :caller, :itself, :c
 
     class Exception
     end
@@ -197,6 +198,7 @@ class TestForwardable < Test::Unit::TestCase
       Foo.new.baz
     }
     assert_not_match(/\/forwardable\.rb/, e.backtrace[0])
+    assert_equal(caller(0, 1)[0], Foo.new.c[0])
   end
 
   class Foo2 < BasicObject