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

3 files changed, 38 insertions, 18 deletions

diff --git a/ChangeLog b/ChangeLog
index b535efeb4f..d3118cf40d 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+Wed Dec 30 11:28:57 2015  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* 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.
+
 Wed Dec 30 11:18:42 2015  Elliot Winkler  <elliot.winkler@gmail.com>
 
 	* lib/forwardable.rb (def_instance_delegator) fix delegating to
diff --git a/lib/forwardable.rb b/lib/forwardable.rb
index f27437af82..390e1460cf 100644
--- a/lib/forwardable.rb
+++ b/lib/forwardable.rb
@@ -182,23 +182,28 @@ module Forwardable
       accessor = "#{accessor}()"
     end
 
-    line_no = __LINE__; str = %{
+    line_no = __LINE__; str = %{proc do
       def #{ali}(*args, &block)
         begin
-          #{accessor}.__send__(:#{method}, *args, &block)
-        rescue ::Exception
-          $@.delete_if{|s| ::Forwardable::FILE_REGEXP =~ s} unless ::Forwardable::debug
-          ::Kernel::raise
-        end
+          #{accessor}
+        ensure
+          $@.delete_if {|s| ::Forwardable::FILE_REGEXP =~ s} if $@ and !::Forwardable::debug
+        end.__send__(:#{method}, *args, &block)
       end
-    }
+    end}
+
+    gen = RubyVM::InstructionSequence
+          .compile(str, __FILE__, __FILE__, line_no,
+                   trace_instruction: false,
+                   tailcall_optimization: true)
+          .eval
+
     # If it's not a class or module, it's an instance
     begin
-      module_eval(str, __FILE__, line_no)
+      module_eval(&gen)
     rescue
-      instance_eval(str, __FILE__, line_no)
+      instance_eval(&gen)
     end
-
   end
 
   alias delegate instance_delegate
@@ -278,18 +283,23 @@ module SingleForwardable
       accessor = "#{accessor}()"
     end
 
-    line_no = __LINE__; str = %{
+    line_no = __LINE__; str = %{proc do
       def #{ali}(*args, &block)
         begin
-          #{accessor}.__send__(:#{method}, *args, &block)
-        rescue ::Exception
-          $@.delete_if{|s| ::Forwardable::FILE_REGEXP =~ s} unless ::Forwardable::debug
-          ::Kernel::raise
-        end
+          #{accessor}
+        ensure
+          $@.delete_if {|s| ::Forwardable::FILE_REGEXP =~ s} if $@ and !::Forwardable::debug
+        end.__send__(:#{method}, *args, &block)
       end
-    }
+    end}
+
+    gen = RubyVM::InstructionSequence
+          .compile(str, __FILE__, __FILE__, line_no,
+                   trace_instruction: false,
+                   tailcall_optimization: true)
+          .eval
 
-    instance_eval(str, __FILE__, line_no)
+    instance_eval(&gen)
   end
 
   alias delegate single_delegate
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