DO-NOT-MERGE: Problem with homebrew's libsamplerate in combination with Xcode 12+

[mgeier]

WARNING: This is not supposed to be merged!

This is just to illustrate a potential problem, as shown in CI.

The libsamplerate package of course doesn't have to be installed with brew, but it might be, probably as a dependency of another used package.

Anyway, when installing libsamplerate with brew, everything works fine, see 9f3a3d2.

But wait for it ...

[mgeier]

... because if we change from the default Xcode 11.7 to Xcode 12 (see 93828f3), the macOS tests fail with this error (https://github.com/Prior99/libsamplerate-sys/pull/8/checks?check_run_id=1252962481):

  /Users/runner/work/libsamplerate-sys/libsamplerate-sys/libsamplerate/tests/clone_test.c:68:26: error: implicit declaration of function 'src_clone' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
          if ((src_state_cloned = src_clone (src_state, &error)) == NULL)
                                  ^

This is likely related to this change in libsndfile: libsndfile/libsamplerate@945b993
See also libsndfile/libsamplerate#70 (comment).

I'm not sure what's causing this, but there seems to be some confusion between the libsamplerate installed by brew and the one taken from the submodule of libsamplerate-sys.

Strangely, this error only appears with Xcode 12 and 12.2, but not with version 11.7 and below.

Whatever it is, I think the build system of libsamplerate-sys should try to not be confused by other versions of libsamplerate that happen to be installed at the moment.

[mgeier]

BTW, Xcode 12 will become the default in a few days (see actions/runner-images#1712), probably making the problem more apparent.

[mgeier]

This might actually be a bug in libsamplerates tests, but anyway, with #9 we can work around this (and speed up the build time in the process).