ENH: Add support for targeting Android

Author: mhsmith

mesonpy/__init__.py

@@ -744,6 +744,38 @@ def __init__(
                     self._meson_cross_file.write_text(cross_file_data, encoding='utf-8')
                     self._meson_args['setup'].extend(('--cross-file', os.fspath(self._meson_cross_file)))
 
+        # Android may be native-compiled (e.g. with Termux), or cross-compiled (e.g.
+        # with cibuildwheel), in which case we should generate a cross file.
+        # sys.cross_compiling isn't an official Python API, but it originated from
+        # crossenv and has been followed by other cross-compiling tools.
+        elif (
+            sysconfig.get_platform().startswith('android-')
+            and getattr(sys, 'cross_compiling', False)
+        ):
+            cpu = platform.machine()
+            cpu_family = (
+                'arm' if cpu.startswith('arm') else 'x86' if cpu.endswith('86') else cpu
+            )
+
+            cross_file_data = textwrap.dedent(f'''
+                # Binaries are controlled by environment variables, so they don't need
+                # to be repeated here.
+                [host_machine]
+                system = 'android'
+                subsystem = 'android'
+                kernel = 'linux'
+                cpu_family = {cpu_family!r}
+                cpu = {cpu!r}
+                endian = {sys.byteorder!r}
+
+                [properties]
+                # cibuildwheel's cross virtual environment will make Meson believe it's
+                # running on Android when it's actually running on Linux or macOS.
+                needs_exe_wrapper = true
+            ''')
+            self._meson_cross_file.write_text(cross_file_data, encoding='utf-8')
+            self._meson_args['setup'].extend(('--cross-file', os.fspath(self._meson_cross_file)))
+
         # Support iOS targets. iOS does not have native build tools and always
         # requires cross compilation: synthesize the appropriate cross file.
         elif sysconfig.get_platform().startswith('ios-'):

tests/test_project.py

@@ -378,6 +378,48 @@ def test_archflags_envvar_parsing_invalid(package_purelib_and_platlib, monkeypat
         os.environ.pop('_PYTHON_HOST_PLATFORM', None)
 
 
+@pytest.mark.parametrize(
+    ('cpu', 'cpu_family'),
+    [
+        ('aarch64', 'aarch64'),
+        ('armv7l', 'arm'),
+        ('armv8l', 'arm'),
+        ('i686', 'x86'),
+        ('x86_64', 'x86_64'),
+    ],
+)
+@pytest.mark.parametrize('cross', [True, False])
+def test_android_project(package_simple, monkeypatch, tmp_path, cpu, cpu_family, cross):
+    # Mock being on Android
+    monkeypatch.setattr(sys, 'platform', 'android')
+    monkeypatch.setattr(sys, 'byteorder', 'little')
+    monkeypatch.setattr(platform, 'machine', Mock(return_value=cpu))
+    monkeypatch.setattr(sysconfig, 'get_platform', Mock(return_value='android-24'))
+    if cross:
+        monkeypatch.setattr(sys, 'cross_compiling', True, raising=False)
+        monkeypatch.setenv('STRIP', '/path/to/strip')
+
+    # Create a project.
+    project = mesonpy.Project(source_dir=package_simple, build_dir=tmp_path)
+
+    # When cross-compiling, a cross file should be generated and used.
+    setup_args = project._meson_args['setup']
+    cross_path = tmp_path / 'meson-python-cross-file.ini'
+    if cross:
+        assert setup_args[-2:] == ['--cross-file', str(cross_path)]
+        cross_config = cross_path.read_text().splitlines()
+        assert "system = 'android'" in cross_config
+        assert "subsystem = 'android'" in cross_config
+        assert "kernel = 'linux'" in cross_config
+        assert f"cpu_family = '{cpu_family}'" in cross_config
+        assert f"cpu = '{cpu}'" in cross_config
+        assert "endian = 'little'" in cross_config
+        assert 'needs_exe_wrapper = true' in cross_config
+    else:
+        assert '--cross-file' not in setup_args
+        assert not cross_path.exists()
+
+
 @pytest.mark.skipif(sys.version_info < (3, 13), reason='requires Python 3.13 or higher')
 @pytest.mark.parametrize('multiarch', [
     'arm64-iphoneos',