macOS support (#72)

* Fix build assumptions for librt and opus

meson.build:
Only require librt when building zalsa. The library is also not
available on macOS, which makes it even more so important to not search
for it and require it by default.
Require the existence of `opus/opus_custom.h` to be able to build with
opus support. The existence of the header file depends on whether opus
has been built using the `--enable-custom-modes` configure option.

* Force the creation of symlinks

scripts/meson_create_symlink:
Force the creation of symlinks so that existing files are overwritten.

* Add build workflow for latest macOS

.github/workflows/build.yml:
Extend build workflow by job for building on latest macOS.

.github/workflows/build.yml

@@ -54,3 +54,13 @@ jobs:
         run: meson build && ninja -C build
       - name: Install jack-example-tools
         run: ninja -C build install
+  build_macos_latest:
+    runs-on: macos-latest
+    steps:
+      - uses: actions/checkout@v2
+      - name: Install dependencies
+        run: brew install jack meson opus pkg-config readline
+      - name: Build jack-example-tools
+        run: meson build && ninja -C build
+      - name: Install jack-example-tools
+        run: ninja -C build install

meson.build

@@ -8,14 +8,17 @@ project(
 
 os = build_machine.system()
 cc = meson.get_compiler('c')
-lib_m = cc.find_library('m')
-lib_rt = cc.find_library('rt')
 
 alsa_required = false
 if get_option('alsa_in_out').enabled() or get_option('zalsa').enabled()
   alsa_required = true
 endif
 
+lib_rt_required = false
+if get_option('zalsa').enabled()
+  lib_rt_required = true
+endif
+
 libsamplerate_required = false
 if get_option('alsa_in_out').enabled() or get_option('jack_netsource').enabled()
   libsamplerate_required = true
@@ -75,10 +78,13 @@ lib_jacknet = cc.find_library('jacknet', required: get_option('jack_net'))
 
 dep_alsa = dependency('alsa', version: '>=1.0.18', required: alsa_required)
 dep_opus = dependency('opus', version: '>=0.9.0', required: get_option('opus_support'))
+header_opus_custom = cc.check_header('opus/opus_custom.h')
 dep_readline = dependency('readline', required: get_option('readline_support'))
 dep_samplerate = dependency('samplerate', required: libsamplerate_required)
 dep_sndfile = dependency('sndfile', required: get_option('jack_rec'))
 dep_threads = dependency('threads')
+lib_m = cc.find_library('m')
+lib_rt = cc.find_library('rt', required: lib_rt_required)
 lib_zita_alsa_pcmi = cc.find_library('zita-alsa-pcmi', required: get_option('zalsa'))
 lib_zita_resampler = cc.find_library('zita-resampler', required: get_option('zalsa'))
 has_ppoll = cc.has_function('ppoll', prefix: '#define _GNU_SOURCE\n#include <sys/poll.h>')
@@ -101,7 +107,7 @@ if get_option('jack_netsource').enabled() or (get_option('jack_netsource').auto(
 endif
 
 opus_support = false
-if get_option('opus_support').enabled() or (get_option('opus_support').auto() and dep_opus.found())
+if get_option('opus_support').enabled() or (get_option('opus_support').auto() and dep_opus.found() and header_opus_custom)
   opus_support = true
 endif
 
@@ -117,7 +123,7 @@ endif
 
 build_zalsa = false
 if get_option('zalsa').enabled() or (
-  get_option('zalsa').auto() and dep_alsa.found() and lib_zita_alsa_pcmi.found() and lib_zita_resampler.found()
+  get_option('zalsa').auto() and dep_alsa.found() and lib_rt.found() and lib_zita_alsa_pcmi.found() and lib_zita_resampler.found()
 )
   build_zalsa = true
 endif

scripts/meson_create_symlink

@@ -8,4 +8,4 @@
 
 set -eu
 
-ln -sv "$2" "$MESON_INSTALL_DESTDIR_PREFIX/$1/$3"
+ln -fsv "$2" "$MESON_INSTALL_DESTDIR_PREFIX/$1/$3"