On Fri, Mar 04, 2016 at 07:19:56PM +0100, Jakub Jelinek wrote:
> > --- gcc/c-family/c-common.c
> > +++ gcc/c-family/c-common.c
> > @@ -11443,6 +11443,10 @@ resolve_overloaded_builtin (location_t loc, tree
> > function,
> > && orig_code != BUILT_IN_ATOMIC_STORE_N)
> > result = sync_resolve_return (first_param, result, orig_format);
> >
> > + if (fetch_op)
> > + /* Prevent -Wunused-value warning. */
> > + TREE_USED (result) = true;
> > +
>
> Can't sync_resolve_return return error_mark_node?
> If it could, perhaps it would be saver to move this a few lines above the
> sync_resolve_return call, where we've already checked that result is not
> error_mark_node.
That seemed right but now I remember why I put setting TREE_USED here. Setting
TREE_USED on the result of build_function_call_vec (a CALL_EXPR) wouldn't
suppress the warning, it needs to be set on the result of sync_resolve_return
(a CONVERT_EXPR). Setting TREE_USED on error_mark_node doesn't ICE so I didn't
check for that as I think it should be harmless.
So I'm keeping the patch as-is, please let me know you still want to see some
adjustments.
Marek
