On Tue, 2017-12-19 at 14:55 -0500, Jason Merrill wrote:
> On 12/17/2017 11:29 AM, David Malcolm wrote:
> > On Mon, 2017-12-11 at 18:45 -0500, Jason Merrill wrote:
> > > On 11/10/2017 04:45 PM, David Malcolm wrote:
> > > > + STRIP_ANY_LOCATION_WRAPPER (format_tree);
> > > > +
> > > > if (VAR_P (format_tree))
> > > > {
> > > > /* Pull out a constant value if the front end
> > > > didn't. */
> > >
> > > It seems like we want fold_for_warn here instead of the special
> > > variable
> > > handling. That probably makes sense for the other places you
> > > change in
> > > this patch, too.
> >
> > Here's an updated version of the patch which uses fold_for_warn,
> > rather than STRIP_ANY_LOCATION_WRAPPER.
> >
> > In one place it was necessary to add a STRIP_NOPS, since the
> > fold_for_warn can add a cast around a:
> > ADDR_EXPR <POINTER_TYPE(ARRAY_TYPE(char))> (
> > STRING_CST)
> > turning it into a:
> > NOP_EXPR<POINTER_TYPE(char))> (
> > ADDR_EXPR <POINTER_TYPE(ARRAY_TYPE(char))> (
> > STRING_CST))
>
> Hmm, that seems like a bug. fold_for_warn shouldn't change the type
> of
> the result.
In a similar vein, is the result of decl_constant_value (decl) required
to be the same type as that of the decl?
What's happening for this testcase (g++.dg/warn/Wformat-1.C) is that we
have a VAR_DECL with a DECL_INITIAL, but the types of the two don't
quite match up.
decl_constant_value returns an unshare_expr clone of the DECL_INITIAL,
and this is what's returned from fold_for_warn.
Am I right in thinking
(a) that the bug here is that a DECL_INITIAL ought to have the same
type as its decl, and so there's a missing cast where that gets
set up, or
(b) should decl_constant_value handle such cases, and introduce a cast
if it uncovers them?
Thanks
Dave
> > + format_tree = fold_for_warn (format_tree);
> > +
> > if (VAR_P (format_tree))
> > {
> > /* Pull out a constant value if the front end didn't. */
>
> I was suggesting dropping the if (VAR_P... block, since pulling out
> the
> constant value should now be covered by fold_for_warn.
>
> > - format_tree = TREE_OPERAND (format_tree, 0);
> > + {
> > + format_tree = fold_for_warn (TREE_OPERAND (format_tree, 0));
> > + }
>
> Why the added braces?
(I messed up; will be fixed in the next version)
