Re: Re: #define __MUSL__ in features.h

[Rich Felker <dalias@libc.org>]

On Thu, Mar 15, 2018 at 12:55:29PM -0300, dgutson . wrote:
> > On Fri, Mar 29, 2013 at 09:44:05PM +0100, Daniel Cegiełka wrote:
> > > Is it possible to add to the features.h __MUSL__ definition?
> > >
> > > glibc can be identified by __GLIBC__, uclibc through __UCLIBC__ etc.
> >
> > Is this question in the FAQ yet? If not, it really should be. The
> > answer is no, it won't be added, because it's a bug to assume a
> > certain implementation has particular properties rather than testing.
> 
> That is a beautiful theory in an ideal world, but in the real world,
> 
> implementations have bugs, and sometimes we need to workaround these bugs.

If there's an actual bug you need to work around, detect it.
Hard-coding "musl is buggy" is not beneficial to us; rather it leads
to broken hacks lingering long after the bug is fixed.

> (e.g. the FD* issue reported by Martin Galvan).

That's not a bug. It's compiler warnings being wrongly produced for a
system header, probably because someone added -I/usr/include or
similar (normally GCC suppresses these).

The musl policy regarding not having a macro like __MUSL__ is doing
exactly what it's intended to do: encouraging developers and package
maintainers to come to us (or investigate on their own) and fix the
underlying portability problems (and sometimes musl bugs) rather than
writing hacks to a specific version of musl that will be wrong a few
versions later.

Rich