Re: [PATCH 0/2] kbuild: Switch from '-fms-extensions' to '-fms-anonymous-structs' when available

Nicolas Schier
2026-03-12T12:10:36Z

On Mon, 23 Feb 2026 12:10:27 -0700, Nathan Chancellor wrote:
> The kernel enabled '-fms-extensions' in commit c4781dc3d1cf ("Kbuild:
> enable -fms-extensions") in 6.19 to gain access to a Microsoft
> (originally Plan 9) extension around including a tagged structure/union
> anonymously in an other structure/union. Since then, Clang 23.0.0
> (current main) has added a flag to enable only that extension, rather
> than all Microsoft extensions, '-fms-anonymous-structs' [1]. Using this
> narrower compiler option would have avoided the build error fixed by
> commit a6773e6932cb ("jfs: Rename _inline to avoid conflict with clang's
> '-fms-extensions'"). While these errors are not expected to be common,
> using the narrower option when available has no drawbacks because the
> kernel only cares about this extension in '-fms-extensions', no others.
> While this could result in build errors for folks using
> '-fms-anonymous-structs' if a developer uses another extension in
> '-fms-extensions' (either intentionally or unintentionally), flagging
> these uses for further scrutiny seems worthwhile.
>
> [...]

Applied to kbuild/kbuild-next.git (kbuild-next), thanks!

[1/2] kbuild: Consolidate C dialect options
https://git.kernel.org/kbuild/c/ec4c2827
[2/2] kbuild: Use '-fms-anonymous-structs' if it is available
https://git.kernel.org/kbuild/c/0d3fccf6

Please look out for regression or issue reports or other follow up
comments, as they may result in the patch/series getting dropped,
reverted or modified (e.g. trailers).

Acks from arch maintainers are still welcome!

Best regards,
--
Nicolas