parse.y: fix cmdarg in command_args

* parse.y (call_args): fix invalid CMDARG state after command_args
  followed by tLBRACE_ARG.  [ruby-core:86551] [Bug #14690]

From: Ilya Bylich <ibylich@gmail.com>

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@63168 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

2 files changed, 17 insertions, 0 deletions

diff --git a/parse.y b/parse.y
index 21cb2884f7..655cd85031 100644
--- a/parse.y
+++ b/parse.y
@@ -2170,7 +2170,20 @@ command_args	:   {
 		    }
 		  call_args
 		    {
+			/* call_args can be followed by tLBRACE_ARG (that does CMDARG_PUSH(0) in the lexer)
+			 * but the push must be done after CMDARG_POP() in the parser.
+			 * So this code does CMDARG_POP() to pop 0 pushed by tLBRACE_ARG,
+			 * CMDARG_POP() to pop 1 pushed by command_args,
+			 * and CMDARG_PUSH(0) to restore back the flag set by tLBRACE_ARG.
+			 */
+			int lookahead = 0;
+			switch (yychar) {
+			  case tLBRACE_ARG:
+			    lookahead = 1;
+			}
+			if (lookahead) CMDARG_POP();
 			CMDARG_POP();
+			if (lookahead) CMDARG_PUSH(0);
 			$$ = $2;
 		    }
 		;
diff --git a/test/ruby/test_parse.rb b/test/ruby/test_parse.rb
index b05dbe2a0f..6160aa1452 100644
--- a/test/ruby/test_parse.rb
+++ b/test/ruby/test_parse.rb
@@ -1196,6 +1196,10 @@ x = __ENCODING__
     end
   end
 
+  def test_cdmarg_after_command_args_and_tlbrace_arg
+    assert_valid_syntax('let () { m(a) do; end }')
+  end
+
 =begin
   def test_past_scope_variable
     assert_warning(/past scope/) {catch {|tag| eval("BEGIN{throw tag}; tap {a = 1}; a")}}