Allow using system absl

meson.build

@@ -1,34 +1,51 @@
 project('ashuffle', ['c', 'cpp'], default_options: ['cpp_std=c++17', 'warning_level=2'])
 
 cmake = import('cmake')
+cpp = meson.get_compiler('cpp')
 
-absl = cmake.subproject('absl', cmake_options: [
-  '-DCMAKE_CXX_STANDARD=17',
-])
-
-# Note: Unfortunately, meson does not pull in the "dependent" libraries
-# correctly so we have to list them here. If you take a dependency on some
-# addtional absl features, you will probably need to add more `dependency`
-# lines here. This could also be broken on upgrades.
-absl_all = [
+# absl dependencies need to be explicited...
+# It might be possible to use cmake dependencies (e.g. "absl:string"
+# defined in abslTargets.cmake in the future but that does not seem
+# worth the time trying to figure that out.
+absl_libs = [
     # Via Base:
-    absl.dependency('raw_logging_internal'),
+    'raw_logging_internal',
 
     # Via Strings:
-    absl.dependency('int128'),
-    absl.dependency('str_format_internal'),
-    absl.dependency('strings_internal'),
-    absl.dependency('strings'),
+    'int128',
+    'str_format_internal',
+    'strings_internal',
+    'strings'
 ]
 
+absl_deps = []
+if not get_option('unsupported_use_system_absl')
+    absl = cmake.subproject('absl', cmake_options: [
+        '-DCMAKE_CXX_STANDARD=17',
+    ])
+
+    absl_deps = []
+    foreach lib : absl_libs
+        absl_deps += absl.dependency(lib)
+    endforeach
+else
+    # note that the system's absl needs to be compiled for C++17 standard
+    # or final link will fail.
+    foreach lib : absl_libs
+        dep = cpp.find_library('absl_' + lib)
+        if dep.found()
+            absl_deps += dep
+        endif
+    endforeach
+endif
 libmpdclient = dependency('libmpdclient')
 
 sources = files(
     'src/ashuffle.cc',
     'src/load.cc',
-	'src/args.cc',
-	'src/getpass.cc',
-	'src/rule.cc',
+    'src/args.cc',
+    'src/getpass.cc',
+    'src/rule.cc',
     'src/shuffle.cc',
 )
 
@@ -38,55 +55,54 @@ src_inc = include_directories('src')
 root_inc = include_directories('.')
 
 ashuffle = executable(
-	'ashuffle',
-	executable_sources,
-	dependencies: absl_all + [libmpdclient],
-	install: true
+    'ashuffle',
+    executable_sources,
+    dependencies: absl_deps + [libmpdclient],
+    install: true
 )
 
 clang_tidy = run_target('ashuffle-clang-tidy',
     command : files('scripts/run-clang-tidy') + executable_sources
 )
 
-# We only generate tests if we are *not running in tidy mode
 if get_option('tests').enabled()
 
-googletest = cmake.subproject('googletest', cmake_options: [
-  '-DBUILD_GMOCK=ON',
-  '-DCMAKE_CXX_STANDARD=17',
-])
-
-gtest_deps = [
-  dependency('threads'),
-  googletest.dependency('gtest'),
-  googletest.dependency('gmock'),
-  googletest.dependency('gmock_main'),
-]
-
-mpdfake_inc = include_directories('t')
-mpdfake_dep = declare_dependency(include_directories : mpdfake_inc)
-
-test_options = [
-    'werror=true',
-]
-
-tests = {
-    'rule': ['t/rule_test.cc'],
-    'shuffle': ['t/shuffle_test.cc'],
-    'load': ['t/load_test.cc'],
-    'args': ['t/args_test.cc'],
-    'ashuffle': ['t/ashuffle_test.cc'],
-}
-
-foreach test_name, test_sources : tests
-    test_exe = executable(
-        test_name + '_test',
-        sources + test_sources,
-        include_directories : src_inc,
-        dependencies : absl_all + gtest_deps + [mpdfake_dep],
-        override_options : test_options,
-    )
-    test(test_name, test_exe)
-endforeach
+    googletest = cmake.subproject('googletest', cmake_options: [
+        '-DBUILD_GMOCK=ON',
+        '-DCMAKE_CXX_STANDARD=17',
+    ])
+
+    gtest_deps = [
+        dependency('threads'),
+        googletest.dependency('gtest'),
+        googletest.dependency('gmock'),
+        googletest.dependency('gmock_main'),
+    ]
+
+    mpdfake_inc = include_directories('t')
+    mpdfake_dep = declare_dependency(include_directories : mpdfake_inc)
+
+    test_options = [
+        'werror=true',
+    ]
+
+    tests = {
+        'rule': ['t/rule_test.cc'],
+        'shuffle': ['t/shuffle_test.cc'],
+        'load': ['t/load_test.cc'],
+        'args': ['t/args_test.cc'],
+        'ashuffle': ['t/ashuffle_test.cc'],
+    }
+
+    foreach test_name, test_sources : tests
+        test_exe = executable(
+            test_name + '_test',
+            sources + test_sources,
+            include_directories : src_inc,
+            dependencies : absl_deps, gtest_deps + [mpdfake_dep],
+            override_options : test_options,
+        )
+        test(test_name, test_exe)
+    endforeach
 
 endif # tests feature

meson_options.txt

@@ -1,2 +1,2 @@
-option('tidy_mode', type : 'feature', value : 'disabled')
 option('tests', type : 'feature', value : 'disabled')
+option('unsupported_use_system_absl', type : 'boolean', value : 'false')