bug#36882: Qemu 4.2.0 build for x86_64-linux fails

[Mathieu Othacehe]

Hey!

> I’d rather go for #2.  To do that, we could modify the ‘set-paths’ phase
> to manually remove glibc from C_INCLUDE_PATH (fragile), or we could
> modify GCC (perhaps removing the ‘remove_duplicates’ call for SYSTEM).
>
> Either way, this wouldn’t work well with ‘guix environment’, where glibc
> ends up in /gnu/store/…-profile, so it does not appear as duplicate to
> GCC.

[...]

> Looking at ‘cppdefault.c’ in GCC, I don’t see where glibc-2.31/include
> comes from; it seems that ‘INCLUDE_DEFAULTS’ is undefined on glibc
> systems.

It's indeed undefined and glibc comes from NATIVE_SYSTEM_HEADER_DIR at
the end of the file you mentioned. It is a consequence of passing
--with-native-system-header-dir=glibc in (gnu packages gcc).

About the environment issue, we have the same problem on master. You can
run the following command:


>
> Thoughts?
>
> Incidentally, do we have problems building anything other than QEMU?
>
> Thanks,
> Ludo’.