[PATCH] Improve genmatch errors

[Richard Biener]

For a misplaced :s like

(simplify
 (plus (minus@1:s @1 @2) (minus @2 @0))
 (plus @1 @0))

we were giving

test.pd:2:16 error: not implemented: predicate on leaf operand
 (plus (minus@1:s @1 @2) (minus @2 @0))
               ^

which is at least confusing.  The following patch improves this to

test.pd:2:16 error: expected expression operand
 (plus (minus@1:s @1 @2) (minus @2 @0))
               ^

also handling any other garbage after operands and rejecting

test.pd:2:21 error: expected expression operand
 (plus (minus:s@1 @1@2) (minus @2 @0))
                    ^
which was previously accepted.

Bootstrap on x86_64-unknown-linux-gnu in progress, no changes in
generated files.

Richard.

2015-09-17  Richard Biener  <rguent...@suse.de>

        * genmatch.c (parser::parse_expr): Improve error message
        for mis-placed flags.

Index: gcc/genmatch.c
===================================================================
--- gcc/genmatch.c      (revision 227779)
+++ gcc/genmatch.c      (working copy)
@@ -3857,6 +3858,9 @@ parser::parse_expr ()
          e->expr_type = expr_type;
          return op;
        }
+      else if (!(token->flags & PREV_WHITE))
+       fatal_at (token, "expected expression operand");
+
       e->append_op (parse_op ());
     }
   while (1);