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Date: Wed, 23 Mar 2016 11:05:53 -0400
From: Rich Felker <>
Subject: Re: Why there's no __MUSL__ macro question

On Wed, Mar 23, 2016 at 03:17:58PM +0100, Shiz wrote:
> > On 23 Mar 2016, at 14:28, Kurt H Maier <> wrote:
> > 
> > On Wed, Mar 23, 2016 at 01:08:16PM +0000, Sirgio Marques wrote:
> >> 
> >> How are we expected to solve this kind of problem if not by using the
> >> __MUSL__ macro?
> > 
> > The recommended solution is to fix the code to be portable, instead of
> > installing yet another special-case workaround.
> > 
> > In this case, wrapping the "#include <execinfo.h>" line in an
> > #ifdef __GLIBC__ would be more appropriate than special-casing for musl,
> > since musl is not the only environment that lacks execinfo.h.  I suspect
> > this code would also fail to build on cygwin, for instance.
> > 
> > If there existed a __MUSL__ macro, the maintainers of software like this
> > would just use it instead of writing portable code.  By refusing to
> > implement a __MUSL__ macro, musl is helping to urge projects in the
> > right direction.
> Alternatively, a better approach would be the detection of <execinfo.h>’s
> existence by something like ./configure and defining a HAVE_EXECINFO_H macro
> as a result that the file can use. That way you’re not cluttering the source
> files with platform-specific information.

Indeed, hard-coding __GLIBC__ is not really a lot better. One of the
biggest problems with a hypothetical __MUSL__ is hard-coding
assumptions that "musl lacks X" (which can become false in the
future). A better approach is testing the the interface you want to
use. This can be done purely with makefile logic if you don't like


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