Hi,
On Thu, Aug 14, 2025 at 03:01:07PM +0900, Gustavo A. R. Silva wrote:
> -Wflex-array-member-not-at-end was introduced in GCC-14, and we are
> getting ready to enable it, globally.
>
> Use the new TRAILING_OVERLAP() helper to fix the following warning:
>
> drivers/gpu/drm/nouveau/nvif/fifo.c:29:42: warning: structure containing a
> flexible array member is not at the end of another structure
> [-Wflex-array-member-not-at-end]
>
> This helper creates a union between a flexible-array member (FAM)
> and a set of members that would otherwise follow it. This overlays
> the trailing members onto the FAM while preserving the original
> memory layout.
>
> Signed-off-by: Gustavo A. R. Silva <gustavo...@kernel.org>
I took a look at the modified structure layout with the union from the
macro using pahole and found the layouts and sizes to be equivalent --
all the while fixing the warning you demonstrated.
Reviewed-by: Justin Stitt <justinst...@google.com>
> ---
> Changes in v3:
> - Use the new TRAILING_OVERLAP() helper.
There's really starting to be a lot of these helper macros!
>
> Changes in v2:
> - Adjust heap allocation.
>
> drivers/gpu/drm/nouveau/nvif/fifo.c | 5 ++---
> 1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/nouveau/nvif/fifo.c
> b/drivers/gpu/drm/nouveau/nvif/fifo.c
> index a463289962b2..b0ab80995d98 100644
> --- a/drivers/gpu/drm/nouveau/nvif/fifo.c
> +++ b/drivers/gpu/drm/nouveau/nvif/fifo.c
> @@ -25,13 +25,12 @@ static int
> nvif_fifo_runlists(struct nvif_device *device)
> {
> struct nvif_object *object = &device->object;
> - struct {
> - struct nv_device_info_v1 m;
> + TRAILING_OVERLAP(struct nv_device_info_v1, m, data,
> struct {
> struct nv_device_info_v1_data runlists;
> struct nv_device_info_v1_data runlist[64];
> } v;
> - } *a;
> + ) *a;
> int ret, i;
>
> if (device->runlist)
> --
> 2.43.0
>
>
Thanks
Justin
