[oe] [meta-oe][PATCH] xterm: Fix latent issue found with musl

[Adrian Bunk]

On Fri, Dec 13, 2019 at 01:55:33PM -0800, Khem Raj wrote:
> On Thu, Dec 12, 2019 at 8:37 PM Adrian Bunk <bunk at stusta.de> wrote:
> > On Thu, Dec 12, 2019 at 12:22:52PM -0800, Khem Raj wrote:
>...
> > > +_POSIX_SOURCE is app-defined not system
> >
> > This is true for musl, not for glibc.
> >
> > The handling of _POSIX_SOURCE and _POSIX_VERSION differs between musl
> > and glibc due to glibc supporting older POSIX versions, and glibc also
> > supporting developers of portable code to select some specific older
> > POSIX version.
> >
> No thats not right.
> _POSIX_SOURCE (like all FTMs) is
> defined by the application to request a feature/standards profile
> it's not libc telling you "this is posix" or anything like that.

It is also defined when _POSIX_C_SOURCE is defined, or _GNU_SOURCE,
or when the default non-strict gcc mode is used.

The latter means that it is in practice nearly always defined when the 
libc supports applications written against older versions of POSIX.

> _POSIX_VERSION tells you that
>...

_POSIX_VERSION being defined tells you that you have unistd.h included.

With glibc the value of _POSIX_VERSION depends on what feature/standards 
profile the application has requested.

cu
Adrian