Re: [GIT PULL] MM updates for 6.14-rc1

[Uros Bizjak <ubizjak@gmail.com>]

On Sat, Jan 25, 2025 at 11:09 PM Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
> On Fri, 24 Jan 2025 at 16:22, Andrew Morton <akpm@linux-foundation.org> wrote:
> >
> > Linus, please merge the MM updates for the 6.14 development cycle,
>
> This does not build at all for me.
>
> I get
>
>     ./arch/x86/include/asm/current.h:49:9: error: call to undeclared
> function '__typeof_unqual__'; ISO C99 and later do not support
> implicit function declarations [-Wimplicit-function-declaration]
>
> when running the Rust 'bindgen', and what seems to be going on is that
> my version of *gcc* does support __typeof_unqual__, so I end up with
>
>     CONFIG_CC_HAS_TYPEOF_UNQUAL=y
>
> in my kernel config, but I think that 'bindgen' that generates the
> Rust bindings is based on LLVM, and clearly does not understand

__typeof_unqual__ is available in Clang 19.1.0 in all C modes as an
extension [1] and as reported in [2], bindgen 0,70.1 seems to parse
__typeof_unqual__ okay.

[1] https://releases.llvm.org/19.1.0/tools/clang/docs/ReleaseNotes.html
[2] https://lore.kernel.org/lkml/9fa81826-8fa6-47e4-a0a2-4916e5d042a7@stanley.mountain/

Maybe configure could detect bindgen version and disable
CC_HAS_TYPEOF_UNQUAL [3] if it is too old?

[3] https://lore.kernel.org/lkml/20241208204708.3742696-3-ubizjak@gmail.com/

Uros.