Fix an UBSAN error in cp/parse.c (PR c++/86653).

2018-07-31  Martin Liska  <mliska@suse.cz>

        PR c++/86653
	* parser.c (cp_parser_condition): Initialize non_constant_p
        to false.

From-SVN: r263110

gcc/cp/ChangeLog

+2018-07-31  Martin Liska  <mliska@suse.cz>
+
+        PR c++/86653
+	* parser.c (cp_parser_condition): Initialize non_constant_p
+        to false.
+
 2018-07-28  David Malcolm  <dmalcolm@redhat.com>
 
 	* error.c (cp_printer): In the leading comment, move "%H" and "%I"

gcc/cp/parser.c

@@ -11721,7 +11721,7 @@ cp_parser_condition (cp_parser* parser)
       if (cp_parser_parse_definitely (parser))
 	{
 	  tree pushed_scope;
-	  bool non_constant_p;
+	  bool non_constant_p = false;
 	  int flags = LOOKUP_ONLYCONVERTING;
 
 	  if (!cp_parser_check_condition_declarator (parser, declarator, loc))