Based on Joseph’s review comment on May 30, 2025:
https://gcc.gnu.org/pipermail/gcc-patches/2025-May/685211.html
I will push this patch to GCC15.
Qing
> On Jul 24, 2025, at 09:36, Qing Zhao <qing.z...@oracle.com> wrote:
>
> Ping.
>
> The patch has been committed to trunk 2 months ago.
>
> Okay for committing to GCC15 now?
>
> thanks.
>
> Qing
>
>> On Jul 17, 2025, at 17:26, Qing Zhao <qing.z...@oracle.com> wrote:
>>
>> There is only one last_field for a structure type, but there might
>> be multiple last_fields for a union type, therefore we should ORed
>> the result of TYPE_INCLUDES_FLEXARRAY for multiple last_fields of
>> a union type.
>>
>> PR c/120354
>>
>> gcc/c/ChangeLog:
>>
>> * c-decl.cc (finish_struct): Or the results for TYPE_INCLUDES_FLEXARRAY.
>>
>> gcc/testsuite/ChangeLog:
>>
>> * gcc.dg/pr120354.c: New test.
>>
>> (cherry picked from commit 70418e6c0120cfce33ab69628602dfdadbed683a)
>>
>> Bootstrapped and regression tested on both X86 and aarch64.
>> Okay for backporting to GCC15?
>>
>> thanks.
>>
>> Qing
>> ---
>> gcc/c/c-decl.cc | 9 ++++++---
>> gcc/testsuite/gcc.dg/pr120354.c | 33 +++++++++++++++++++++++++++++++++
>> 2 files changed, 39 insertions(+), 3 deletions(-)
>> create mode 100644 gcc/testsuite/gcc.dg/pr120354.c
>>
>> diff --git a/gcc/c/c-decl.cc b/gcc/c/c-decl.cc
>> index 42e17dcdbf8..5032ba13779 100644
>> --- a/gcc/c/c-decl.cc
>> +++ b/gcc/c/c-decl.cc
>> @@ -9665,15 +9665,18 @@ finish_struct (location_t loc, tree t, tree
>> fieldlist, tree attributes,
>> DECL_NOT_FLEXARRAY (x) = !is_flexible_array_member_p (is_last_field, x);
>>
>> /* Set TYPE_INCLUDES_FLEXARRAY for the context of x, t.
>> - when x is an array and is the last field. */
>> + when x is an array and is the last field.
>> + There is only one last_field for a structure type, but there might
>> + be multiple last_fields for a union type, therefore we should ORed
>> + the result for multiple last_fields. */
>> if (TREE_CODE (TREE_TYPE (x)) == ARRAY_TYPE)
>> TYPE_INCLUDES_FLEXARRAY (t)
>> - = is_last_field && c_flexible_array_member_type_p (TREE_TYPE (x));
>> + |= is_last_field && c_flexible_array_member_type_p (TREE_TYPE (x));
>> /* Recursively set TYPE_INCLUDES_FLEXARRAY for the context of x, t
>> when x is an union or record and is the last field. */
>> else if (RECORD_OR_UNION_TYPE_P (TREE_TYPE (x)))
>> TYPE_INCLUDES_FLEXARRAY (t)
>> - = is_last_field && TYPE_INCLUDES_FLEXARRAY (TREE_TYPE (x));
>> + |= is_last_field && TYPE_INCLUDES_FLEXARRAY (TREE_TYPE (x));
>>
>> if (warn_flex_array_member_not_at_end
>> && !is_last_field
>> diff --git a/gcc/testsuite/gcc.dg/pr120354.c
>> b/gcc/testsuite/gcc.dg/pr120354.c
>> new file mode 100644
>> index 00000000000..6749737a173
>> --- /dev/null
>> +++ b/gcc/testsuite/gcc.dg/pr120354.c
>> @@ -0,0 +1,33 @@
>> +/* PR120354: Test for -Wflex-array-member-not-at-end on union with
>> + flexible array members. */
>> +/* { dg-do compile } */
>> +/* { dg-options "-Wflex-array-member-not-at-end" } */
>> +
>> +struct P {};
>> +union L {};
>> +
>> +union X {
>> + int x[];
>> + struct P y;
>> +};
>> +
>> +struct T {
>> + union X x; /* { dg-warning "structure containing a flexible array
>> member is not at the end of another structure" } */
>> + int plug;
>> +};
>> +
>> +struct Q {
>> + int len;
>> + int data[];
>> +};
>> +
>> +union Y {
>> + struct Q q;
>> + union L y;
>> +};
>> +
>> +struct S {
>> + union Y y; /* { dg-warning "structure containing a flexible array
>> member is not at the end of another structure" } */
>> + int plug;
>> +};
>> +
>> --
>> 2.31.1
>>
>
