From 6279e45cdefa3e61ca1c9c8085b15727cb2f4a60 Mon Sep 17 00:00:00 2001
From: Nobuyoshi Nakada <nobu@ruby-lang.org>
Date: Fri, 25 Oct 2019 00:06:43 +0900
Subject: [PATCH] Arguments forwarding is not allowed in lambda [Feature
 #16253]

---
 parse.y                  | 24 +++++++++++++-----------
 test/ruby/test_syntax.rb |  2 ++
 2 files changed, 15 insertions(+), 11 deletions(-)

diff --git a/parse.y b/parse.y
index 657e521982..c3e385e0af 100644
--- a/parse.y
+++ b/parse.y
@@ -4781,6 +4781,19 @@ f_arglist	: '(' f_args rparen
 			SET_LEX_STATE(EXPR_BEG);
 			p->command_start = TRUE;
 		    }
+		| '(' args_forward rparen
+		    {
+			arg_var(p, idFWD_REST);
+			arg_var(p, idFWD_KWREST);
+			arg_var(p, idFWD_BLOCK);
+		    /*%%%*/
+			$$ = new_args_tail(p, Qnone, idFWD_KWREST, idFWD_BLOCK, &@2);
+			$$ = new_args(p, Qnone, Qnone, idFWD_REST, Qnone, $$, &@2);
+		    /*% %*/
+		    /*% ripper: paren!(params_new(Qnone, Qnone, $2, Qnone, Qnone, Qnone, Qnone)) %*/
+			SET_LEX_STATE(EXPR_BEG);
+			p->command_start = TRUE;
+		    }
 		|   {
 			$<num>$ = p->in_kwarg;
 			p->in_kwarg = 1;
@@ -4883,17 +4896,6 @@ f_args		: f_arg ',' f_optarg ',' f_rest_arg opt_args_tail
 		    {
 			$$ = new_args(p, Qnone, Qnone, Qnone, Qnone, $1, &@$);
 		    }
-		| args_forward
-		    {
-			arg_var(p, idFWD_REST);
-			arg_var(p, idFWD_KWREST);
-			arg_var(p, idFWD_BLOCK);
-		    /*%%%*/
-			$$ = new_args_tail(p, Qnone, idFWD_KWREST, idFWD_BLOCK, &@1);
-			$$ = new_args(p, Qnone, Qnone, idFWD_REST, Qnone, $$, &@$);
-		    /*% %*/
-		    /*% ripper: params_new(Qnone, Qnone, $1, Qnone, Qnone, Qnone, Qnone) %*/
-		    }
 		| /* none */
 		    {
 			$$ = new_args_tail(p, Qnone, Qnone, Qnone, &@0);
diff --git a/test/ruby/test_syntax.rb b/test/ruby/test_syntax.rb
index 5b933d9682..5bbcbef3a4 100644
--- a/test/ruby/test_syntax.rb
+++ b/test/ruby/test_syntax.rb
@@ -1476,6 +1476,8 @@ eom
     assert_valid_syntax('def foo(...) end')
     assert_syntax_error('iter do |...| end', /unexpected/)
     assert_syntax_error('iter {|...|}', /unexpected/)
+    assert_syntax_error('->... {}', /unexpected/)
+    assert_syntax_error('->(...) {}', /unexpected/)
     assert_syntax_error('def foo(x, y, z) bar(...); end', /unexpected/)
     assert_syntax_error('def foo(x, y, z) super(...); end', /unexpected/)
     assert_syntax_error('def foo(...) yield(...); end', /unexpected/)