Re: [viro-vfs:work.fd 11/19] fs/select.c:860:3: error: cannot jump from this goto statement to its label

[Nathan Chancellor <nathan@kernel.org>]

On Fri, Jun 07, 2024 at 04:24:28PM +0100, Al Viro wrote:
> > >> fs/select.c:860:3: error: cannot jump from this goto statement to its label
> >      860 |                 goto out;
> >          |                 ^
> >    fs/select.c:862:12: note: jump bypasses initialization of variable with __attribute__((cleanup))
> >      862 |         CLASS(fd, f)(fd);
> >          |                   ^
> >    13 warnings and 1 error generated.
> 
> Sigh...  That's why declarations in the middle of block really stink.
> Sadly, the use of CLASS() very much invites that kind of crap.
> For this series I decided to suppress the gag reflex and see how
> it goes, but... ouch.
> 
> Worse, neither current gcc, nor clang 14 catch that kind of crap ;-/

Hmmm, I am able to reproduce this with clang 14.0.6 from kernel.org [1]
with x86_64 allnoconfig:

$ make -skj"$(nproc)" ARCH=x86_64 LLVM=1 allnoconfig fs/select.o
fs/select.c:860:3: error: cannot jump from this goto statement to its label
                goto out;
                ^
fs/select.c:862:12: note: jump bypasses initialization of variable with __attribute__((cleanup))
        CLASS(fd, f)(fd);
                  ^
1 error generated.

$ clang --version | head -1
ClangBuiltLinux clang version 14.0.6 (https://github.com/llvm/llvm-project f28c006a5895fc0e329fe15fead81e37457cb1d1)

It is a bug that GCC does not warn about this as far as I understand it:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91951

[1]: https://mirrors.edge.kernel.org/pub/tools/llvm/

Cheers,
Nathan