merge revision(s) 53383,55366: [Backport #12478]

	* 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.

	* lib/forwardable.rb (Forwardable._delegator_method): extract
	  method generator and deal with non-module objects.
	  [ruby-dev:49656] [Bug #12478]


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_2@58085 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 34 insertions, 36 deletions

diff --git a/lib/forwardable.rb b/lib/forwardable.rb
index 602cd8b815..e78b9ed1e0 100644
--- a/lib/forwardable.rb
+++ b/lib/forwardable.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 #   forwardable.rb -
 #       $Release Version: 1.1$
@@ -177,33 +178,44 @@ module Forwardable
   #   q.push 23  #=> NoMethodError
   #
   def def_instance_delegator(accessor, method, ali = method)
-    accessor = accessor.to_s
-    if method_defined?(accessor) || private_method_defined?(accessor)
-      accessor = "#{accessor}()"
-    end
+    gen = Forwardable._delegator_method(self, accessor, method, ali)
 
-    line_no = __LINE__; str = %{
-      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
-      end
-    }
     # If it's not a class or module, it's an instance
-    begin
-      module_eval(str, __FILE__, line_no)
-    rescue
-      instance_eval(str, __FILE__, line_no)
-    end
-
+    (Module === self ? self : singleton_class).module_eval(&gen)
   end
 
   alias delegate instance_delegate
   alias def_delegators def_instance_delegators
   alias def_delegator def_instance_delegator
+
+  def self._delegator_method(obj, accessor, method, ali)
+    accessor = accessor.to_s unless Symbol === accessor
+
+    if Module === obj ?
+         obj.method_defined?(accessor) || obj.private_method_defined?(accessor) :
+         obj.respond_to?(accessor, true)
+      accessor = "#{accessor}()"
+    end
+
+    line_no = __LINE__+1; str = "#{<<-"begin;"}\n#{<<-"end;"}"
+    begin;
+      proc do
+        def #{ali}(*args, &block)
+          begin
+            #{accessor}
+          ensure
+            $@.delete_if {|s| ::Forwardable::FILE_REGEXP =~ s} if $@ and !::Forwardable::debug
+          end.__send__ :#{method}, *args, &block
+        end
+      end
+    end;
+
+    RubyVM::InstructionSequence
+      .compile(str, __FILE__, __FILE__, line_no,
+               trace_instruction: false,
+               tailcall_optimization: true)
+      .eval
+  end
 end
 
 # SingleForwardable can be used to setup delegation at the object level as well.
@@ -274,23 +286,9 @@ module SingleForwardable
   # the method of the same name in _accessor_).  If _new_name_ is
   # provided, it is used as the name for the delegate method.
   def def_single_delegator(accessor, method, ali = method)
-    accessor = accessor.to_s
-    if method_defined?(accessor) || private_method_defined?(accessor)
-      accessor = "#{accessor}()"
-    end
-
-    line_no = __LINE__; str = %{
-      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
-      end
-    }
+    gen = Forwardable._delegator_method(self, accessor, method, ali)
 
-    instance_eval(str, __FILE__, line_no)
+    instance_eval(&gen)
   end
 
   alias delegate single_delegate