Am Donnerstag, den 12.08.2021, 16:58 +0000 schrieb Joseph Myers:
> On Mon, 24 May 2021, Uecker, Martin wrote:
>
> > - else if (VOID_TYPE_P (TREE_TYPE (type1))
> > - && !TYPE_ATOMIC (TREE_TYPE (type1)))
> > - {
> > - if ((TREE_CODE (TREE_TYPE (type2)) == ARRAY_TYPE)
> > - && (TYPE_QUALS (strip_array_types (TREE_TYPE (type2)))
> > - & ~TYPE_QUALS (TREE_TYPE (type1))))
> > - warning_at (colon_loc, OPT_Wdiscarded_array_qualifiers,
> > - "pointer to array loses qualifier "
> > - "in conditional expression");
> > -
> > - if (TREE_CODE (TREE_TYPE (type2)) == FUNCTION_TYPE)
> > + else if ((VOID_TYPE_P (TREE_TYPE (type1))
> > + && !TYPE_ATOMIC (TREE_TYPE (type1)))
> > + || (VOID_TYPE_P (TREE_TYPE (type2))
> > + && !TYPE_ATOMIC (TREE_TYPE (type2))))
>
> Here you're unifying the two cases where one argument is (not a null
> pointer constant and) a pointer to qualified or unqualified void (and the
> other argument is not a pointer to qualified or unqualified void). The
> !TYPE_ATOMIC checks are because of the general rule that _Atomic is a type
> qualifier only syntactically, so _Atomic void doesn't count as qualified
> void for this purpose.
>
> > + {
> > + tree t1 = TREE_TYPE (type1);
> > + tree t2 = TREE_TYPE (type2);
> > + if (!VOID_TYPE_P (t1))
> > + {
> > + /* roles are swapped */
> > + t1 = t2;
> > + t2 = TREE_TYPE (type1);
> > + }
>
> But here you don't have a TYPE_ATOMIC check before swapping. So if t1 is
> _Atomic void and t2 is void, the types don't get swapped.
>
> > + /* for array, use qualifiers of element type */
> > + if (flag_isoc2x)
> > + t2 = t2_stripped;
> > + result_type = build_pointer_type (qualify_type (t1, t2));
>
> And then it looks to me like this will end up with _Atomic void * as the
> result type, when a conditional expression between _Atomic void * and
> void * should actually have type void *.
>
> If that's indeed the case, I think the swapping needs to occur whenever t1
> is not *non-atomic* void, so that the condition for swapping matches the
> condition checked in the outer if. (And of course there should be a
> testcase for that.)
>
> I didn't see any other issues in this version of the patch.
Committed with this change and the additional test.
Martin
>
