On Thu, 11 Dec 2025, Qing Zhao wrote:
> diff --git a/gcc/c/c-decl.cc b/gcc/c/c-decl.cc
> index 0a368e410e5..35a70414cff 100644
> --- a/gcc/c/c-decl.cc
> +++ b/gcc/c/c-decl.cc
> @@ -9083,6 +9083,11 @@ grokfield (location_t loc,
> width ? &width : NULL, decl_attrs, expr, NULL,
> DEPRECATED_NORMAL);
>
> + /* When this field has name, its type is a top level type, we should
> + call verify_counted_by_for_top_anonymous_type. */
> + if (DECL_NAME (value) != NULL_TREE)
> + verify_counted_by_for_top_anonymous_type (TREE_TYPE (value));
So this is using the type of the field, as opposed to the type from the
declaration specifiers.
> +/* Caller should make sure the TYPE is a top-level type (i.e. not being
> + nested in other structure/uniona). For such type, verify its counted_by
> + if it (or its pointee type) is an anonymous structure/union. */
> +
> +void
> +verify_counted_by_for_top_anonymous_type (tree type)
> +{
> + tree checked_type = NULL_TREE;
> + if (POINTER_TYPE_P (type) && RECORD_OR_UNION_TYPE_P (TREE_TYPE (type)))
> + checked_type = TREE_TYPE (type);
> + else if (RECORD_OR_UNION_TYPE_P (type))
> + checked_type = type;
And this is expecting the type passed to be either a structure or union
type, or a pointer thereto.
I'd expect this to miss cases where the named field is e.g. a pointer to
pointer to structure or union without a tag. Or pointer to function
returning pointer to array of pointers to structure or union without a
tag, etc.
On the other hand, it might duplicate checks in cases where the check has
already occurred - for example, because the anonymous structure or union
comes from typeof rather than a direct definition in the declaration
specifiers.
I think you could make grokfield use declspecs->type rather than TREE_TYPE
(value) to avoid the issue with pointers to pointers and similar, at which
point verify_counted_by_for_top_anonymous_type should no longer need to
special-case pointers itself. And if the check in grokfield is
conditional on declspecs->typespec_kind == ctsk_tagdef, that should avoid
duplicate checks. (Of course testcases need to be added for uses such as
pointers to pointers and pointers to functions and arrays of pointers to
structures.)
--
Joseph S. Myers
[email protected]
