parse.y: remove "shadowing outer local variable" warning

You can now write the following without warning.

    user = User.all.find {|user| cond(user) }

Fixes [Feature #12490].
A patch from Soutaro Matsumoto <matsumoto@soutaro.com>.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@65369 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

NEWS

@@ -31,6 +31,11 @@ sufficient information, see the ChangeLog file or Redmine
 
 * Non-Symbol key in keyword arguments hash causes an exception.
 
+* "shadowing outer local variable" warning was removed.  [Feature #12490]
+  You can now write the following without warning.
+
+  user = User.all.find {|user| cond(user) }
+
 === Core classes updates (outstanding ones only)
 
 [Array]

parse.y

@@ -9220,7 +9220,6 @@ shadowing_lvar_0(struct parser_params *p, ID name)
 	    yyerror0("duplicated argument name");
 	}
 	else if (dvar_defined(p, name) || local_id(p, name)) {
-	    rb_warning1("shadowing outer local variable - %"PRIsWARN, rb_id2str(name));
 	    vtable_add(p->lvtbl->vars, name);
 	    if (p->lvtbl->used) {
 		vtable_add(p->lvtbl->used, (ID)p->ruby_sourceline | LVAR_USED);

test/lib/test/unit/assertions.rb

@@ -693,6 +693,16 @@ eom
         assert_warning(*args) {$VERBOSE = false; yield}
       end
 
+      def assert_no_warning(pat, msg = nil)
+        stderr = EnvUtil.verbose_warning {
+          EnvUtil.with_default_internal(pat.encoding) {
+            yield
+          }
+        }
+        msg = message(msg) {diff pat, stderr}
+        refute(pat === stderr, msg)
+      end
+
       def assert_no_memory_leak(args, prepare, code, message=nil, limit: 2.0, rss: false, **opt)
         # TODO: consider choosing some appropriate limit for MJIT and stop skipping this once it does not randomly fail
         skip 'assert_no_memory_leak may consider MJIT memory usage as leak' if defined?(RubyVM::MJIT) && RubyVM::MJIT.enabled?

test/ripper/test_parser_events.rb

@@ -1487,13 +1487,6 @@ class TestRipper::ParserEvents < Test::Unit::TestCase
     assert_equal("`$' without identifiers is not allowed as a global variable name", compile_error('$'))
   end
 
-  def test_warning_shadowing
-    fmt, *args = warning("x = 1; tap {|;x|}")
-    assert_match(/shadowing outer local variable/, fmt)
-    assert_equal("x", args[0])
-    assert_match(/x/, fmt % args)
-  end
-
   def test_warning_ignored_magic_comment
     fmt, *args = warning("1; #-*- frozen-string-literal: true -*-")
     assert_match(/ignored after any tokens/, fmt)

test/ruby/test_parse.rb

@@ -911,10 +911,8 @@ x = __ENCODING__
     assert_equal(expected, actual, bug5614)
   end
 
-  def test_shadowing_variable
-    assert_warning(/shadowing outer local variable/) {eval("a=1; tap {|a|}")}
-    a = "\u{3042}"
-    assert_warning(/#{a}/o) {eval("#{a}=1; tap {|#{a}|}")}
+  def test_no_shadowing_variable_warning
+    assert_no_warning(/shadowing outer local variable/) {eval("a=1; tap {|a|}")}
   end
 
   def test_unused_variable

test/ruby/test_rubyoptions.rb

@@ -782,20 +782,6 @@ class TestRubyOptions < Test::Unit::TestCase
     assert_in_out_err(["-w", "-"], "eval('a=1')", [], [], feature7730)
   end
 
-  def test_shadowing_variable
-    bug4130 = '[ruby-dev:42718]'
-    assert_in_out_err(["-we", "def foo\n""  a=1\n""  1.times do |a| end\n""  a\n""end"],
-                      "", [], ["-e:3: warning: shadowing outer local variable - a"], bug4130)
-    assert_in_out_err(["-we", "def foo\n""  a=1\n""  1.times do |a| end\n""end"],
-                      "", [],
-                      ["-e:3: warning: shadowing outer local variable - a",
-                       "-e:2: warning: assigned but unused variable - a",
-                      ], bug4130)
-    feature6693 = '[ruby-core:46160]'
-    assert_in_out_err(["-we", "def foo\n""  _a=1\n""  1.times do |_a| end\n""end"],
-                      "", [], [], feature6693)
-  end
-
   def test_script_from_stdin
     begin
       require 'pty'