ENH: support shared libraries on Windows when explicitly enabled

Fixes #525.

Author: dnicolodi

docs/reference/pyproject-settings.rst

@@ -34,6 +34,17 @@ use them and examples.
    ``meson-python`` itself. It can be overrridden by the :envvar:`MESON`
    environment variable.
 
+.. option:: tool.meson-python.shared-libs-win32
+
+   A boolean indicating whether shared libraries should be supported on
+   Windows. ``meson-python`` installs shared libraries in a dedicated location
+   and uses RPATH or equivalent mechanisms to have Python modules and native
+   executables load them form there. Windows does not have an equivalent
+   mechanism to set the DLL load path. Supporting shared libraries on Windows
+   requires collaboration from the package. To make sure that package authors
+   are aware of this requirement, ``meson-python`` raises an error if a
+   package contains DLLs and this option is not set.
+
 .. option:: tool.meson-python.args.dist
 
    Extra arguments to be passed to the ``meson dist`` command.

mesonpy/__init__.py

@@ -311,10 +311,12 @@ def __init__(
         metadata: Metadata,
         manifest: Dict[str, List[Tuple[pathlib.Path, str]]],
         limited_api: bool,
+        shared_libs_win32: bool,
     ) -> None:
         self._metadata = metadata
         self._manifest = manifest
         self._limited_api = limited_api
+        self._shared_libs_win32 = shared_libs_win32
 
     @property
     def _has_internal_libs(self) -> bool:
@@ -430,6 +432,9 @@ def _install_path(self, wheel_file: mesonpy._wheelfile.WheelFile, origin: Path,
 
         if self._has_internal_libs:
             if _is_native(origin):
+                if sys.platform == 'win32' and not self._shared_libs_win32:
+                    raise NotImplementedError(f'Bundling libraries in wheel is not supported on {sys.platform}')
+
                 # When an executable, libray, or Python extension module is
                 # dynamically linked to a library built as part of the project,
                 # Meson adds a library load path to it pointing to the build
@@ -566,6 +571,7 @@ def _string_or_path(value: Any, name: str) -> str:
     scheme = _table({
         'meson': _string_or_path,
         'limited-api': _bool,
+        'shared-libs-win32': _bool,
         'args': _table({
             name: _strings for name in _MESON_ARGS_KEYS
         }),
@@ -757,6 +763,10 @@ def __init__(
             if not value:
                 self._limited_api = False
 
+        # Shared library support on Windows requires collaboration
+        # from the package, make sure the developpers aknowledge this.
+        self._shared_libs_win32 = pyproject_config.get('shared-libs-win32', False)
+
     def _run(self, cmd: Sequence[str]) -> None:
         """Invoke a subprocess."""
         # Flush the line to ensure that the log line with the executed
@@ -920,13 +930,13 @@ def sdist(self, directory: Path) -> pathlib.Path:
     def wheel(self, directory: Path) -> pathlib.Path:
         """Generates a wheel in the specified directory."""
         self.build()
-        builder = _WheelBuilder(self._metadata, self._manifest, self._limited_api)
+        builder = _WheelBuilder(self._metadata, self._manifest, self._limited_api, self._shared_libs_win32)
         return builder.build(directory)
 
     def editable(self, directory: Path) -> pathlib.Path:
         """Generates an editable wheel in the specified directory."""
         self.build()
-        builder = _EditableWheelBuilder(self._metadata, self._manifest, self._limited_api)
+        builder = _EditableWheelBuilder(self._metadata, self._manifest, self._limited_api, self._shared_libs_win32)
         return builder.build(directory, self._source_dir, self._build_dir, self._build_command, self._editable_verbose)
 
 

mesonpy/_rpath.py

@@ -19,7 +19,7 @@
 if sys.platform == 'win32' or sys.platform == 'cygwin':
 
     def fix_rpath(filepath: Path, libs_relative_path: str) -> None:
-        raise NotImplementedError(f'Bundling libraries in wheel is not supported on {sys.platform}')
+        pass
 
 elif sys.platform == 'darwin':
 

tests/test_tags.py

@@ -77,7 +77,7 @@ def test_python_host_platform(monkeypatch):
 def wheel_builder_test_factory(content, pure=True, limited_api=False):
     manifest = defaultdict(list)
     manifest.update({key: [(pathlib.Path(x), os.path.join('build', x)) for x in value] for key, value in content.items()})
-    return mesonpy._WheelBuilder(None, manifest, limited_api)
+    return mesonpy._WheelBuilder(None, manifest, limited_api, False)
 
 
 def test_tag_empty_wheel():

tests/test_wheel.py

@@ -231,7 +231,8 @@ def test_entrypoints(wheel_full_metadata):
 
 def test_top_level_modules(package_module_types):
     with mesonpy._project() as project:
-        builder = mesonpy._EditableWheelBuilder(project._metadata, project._manifest, project._limited_api)
+        builder = mesonpy._EditableWheelBuilder(
+            project._metadata, project._manifest, project._limited_api, project._shared_libs_win32)
         assert set(builder._top_level_modules) == {
             'file',
             'package',