Re: [musl] Re: OS detection wrong on Alpine Linux 3.10

[Szabolcs Nagy]

* Bruno Haible <bruno@clisp.org> [2020-09-20 13:19:13 +0200]:
> Dmitry V. Levin wrote:
> > Is this __DEFINED_va_list macro the official way of detecting musl?
> 
> No, but in a world where the musl people don't want to provide an official
> way [1][2] and the Alpine Linux people break their previously working way of
> detecting musl [3], we (GNU) need to use our own heuristics to fulfil the
> practical need of programs (especially test suites) to distinguish musl
> systems from glibc systems.

we have not seen a "practical need of programs
to distinguish musl systems from glibc systems".

instead we have seen a practical need to detect
specific c runtime behaviours and extensions.

even in the glibc world using __GLIBC__ to detect
features is not reliable since there are heavily
patched glibcs out there. (though the way glibc
handles api and abi stability means it mostly
works, but this is unreasonable to expect across
different implementations)