Fix parser to recognize operator?:

This change lets grok_op_properties print its useful "ISO C++ prohibits
overloading operator ?:" message instead of the cryptic error message about
a missing type-specifier before '?' token.

2019-11-06  Matthias Kretz  <m.kretz@gsi.de>

	* parser.c (cp_parser_operator): Parse operator?: as an
	attempt to overload the conditional operator.

From-SVN: r277887

gcc/cp/ChangeLog

+2019-11-06  Matthias Kretz  <m.kretz@gsi.de>
+
+	* parser.c (cp_parser_operator): Parse operator?: as an
+	attempt to overload the conditional operator.
+
 2019-11-05  Jason Merrill  <jason@redhat.com>
 
 	Implement C++20 operator<=>.

gcc/cp/parser.c

@@ -15542,6 +15542,15 @@ cp_parser_operator (cp_parser* parser, location_t start_loc)
       op = COMPONENT_REF;
       break;
 
+    case CPP_QUERY:
+      op = COND_EXPR;
+      /* Consume the `?'.  */
+      cp_lexer_consume_token (parser->lexer);
+      /* Look for the matching `:'.  */
+      cp_parser_require (parser, CPP_COLON, RT_COLON);
+      consumed = true;
+      break;
+
     case CPP_OPEN_PAREN:
       {
         /* Consume the `('.  */

gcc/testsuite/g++.dg/parse/operator9.C

+// { dg-do compile }
+
+struct A {};
+struct B {};
+int operator?:(bool, A, B);  // { dg-error "prohibits overloading" }

gcc/testsuite/g++.old-deja/g++.jason/operator.C

@@ -5,7 +5,7 @@
 typedef __SIZE_TYPE__ size_t;
 
 struct A {
-  int operator?:(int a, int b);	   // { dg-error "expected type-specifier" } 
+  int operator?:(int a, int b);	   // { dg-error "prohibits overloading" } 
   static int operator()(int a);	   // { dg-error "14:.static int A::operator\\(\\)\\(int\\). must be a nonstatic member function" }
   static int operator+(A,A);	   // { dg-error "14:.static int A::operator\\+\\(A, A\\). must be either a non-static member function or a non-member function" } 
   int operator+(int a, int b = 1); // { dg-error "7:.int A::operator\\+\\(int, int\\). must have either zero or one argument" }