Reject trailing return type for an operator auto().

	* decl.c (grokdeclarator): Reject trailing return types for
	all conversion operators, don't handle conversion operators
	in the previous checks that deal with auto.

From-SVN: r222248

gcc/cp/ChangeLog

+2015-04-20  Ville Voutilainen  <ville.voutilainen@gmail.com>
+
+	Reject trailing return type for an operator auto().
+	* decl.c (grokdeclarator): Reject trailing return types for
+	all conversion operators, don't handle conversion operators
+	in the previous checks that deal with auto.
+
 2015-04-20  Ilya Verbin  <ilya.verbin@intel.com>
 
 	* parser.c (cp_parser_omp_target_update): Add missed %> to error_at ().

gcc/cp/decl.c

@@ -9782,7 +9782,7 @@ grokdeclarator (const cp_declarator *declarator,
 			    virtualp = false;
 			  }
 		      }
-		    else if (!is_auto (type))
+		    else if (!is_auto (type) && sfk != sfk_conversion)
 		      {
 			error ("%qs function with trailing return type has"
 			       " %qT as its type rather than plain %<auto%>",
@@ -9790,7 +9790,8 @@ grokdeclarator (const cp_declarator *declarator,
 			return error_mark_node;
 		      }
 		  }
-		else if (declarator->u.function.late_return_type)
+		else if (declarator->u.function.late_return_type
+			 && sfk != sfk_conversion)
 		  {
 		    if (cxx_dialect < cxx11)
 		      /* Not using maybe_warn_cpp0x because this should
@@ -9899,6 +9900,8 @@ grokdeclarator (const cp_declarator *declarator,
 		    maybe_warn_cpp0x (CPP0X_EXPLICIT_CONVERSION);
 		    explicitp = 2;
 		  }
+		if (late_return_type_p)
+		  error ("a conversion function cannot have a trailing return type");
 	      }
 
 	    arg_types = grokparms (declarator->u.function.parameters,

gcc/testsuite/g++.dg/cpp0x/auto9.C

@@ -21,8 +21,8 @@ struct A
 
 struct A2
 {
-  operator auto () -> int;			// { dg-error "invalid use of" "" { target { ! c++14 } } }
-  operator auto *() -> int;			// { dg-error "auto" }
+  operator auto () -> int;			// { dg-error "invalid use of|trailing return type" }
+  operator auto*() -> int;			// { dg-error "invalid use of|trailing return type" }
 };
 
 template <typename> struct B