Fix/namespace entrypoint resolution

src/pkgconf/_path_entrypoints.py

@@ -53,9 +53,9 @@ def module_path(name: str) -> str:
     module = import_module_no_exec(name)
     # Check if submodule_search_locations is set on the spec.
     if module.__spec__.submodule_search_locations:
-        # If it contains a single path, use it.
-        if len(module.__spec__.submodule_search_locations) == 1:
-            return module.__spec__.submodule_search_locations[0]
+        # Namespace packages may span multiple locations. Return the first one,
+        # which matches the import system search order.
+        return next(iter(module.__spec__.submodule_search_locations))
     # Traversables often implement __fspath__, attempt to use it.
     traversable = importlib.resources.files(module)
     if isinstance(traversable, os.PathLike):

tests/packages/namespace-pkgconfig-primary/namespace/pkgconf/namespace-pkgconfig-primary.pc

@@ -0,0 +1 @@
+prefix=${pcfiledir}

tests/packages/namespace-pkgconfig-primary/pyproject.toml

@@ -0,0 +1,13 @@
+[build-system]
+build-backend = 'hatchling.build'
+requires = ['hatchling']
+
+[project]
+name = 'namespace-pkgconfig-primary'
+version = '1.0.0'
+
+[project.entry-points.pkg_config]
+namespace-pkgconfig-primary = 'namespace.pkgconf'
+
+[tool.hatch.build.targets.wheel]
+packages = ['namespace']

tests/packages/namespace-pkgconfig-secondary/namespace/pkgconf/namespace-pkgconfig-secondary.pc

@@ -0,0 +1 @@
+prefix=${pcfiledir}

tests/packages/namespace-pkgconfig-secondary/pyproject.toml

@@ -0,0 +1,10 @@
+[build-system]
+build-backend = 'hatchling.build'
+requires = ['hatchling']
+
+[project]
+name = 'namespace-pkgconfig-secondary'
+version = '1.0.0'
+
+[tool.hatch.build.targets.wheel]
+packages = ['namespace']

tests/test_python_module.py

@@ -39,6 +39,37 @@ def test_pkg_config_path_namespace(env, packages):
     assert path == [pathlib.Path(env.scheme['purelib'], 'namespace')]
 
 
+def test_pkg_config_path_namespace_multiple_locations(env, packages, tmp_path):
+    dst = tmp_path / 'namespace-pkgconfig-primary'
+    shutil.copytree(packages / 'namespace-pkgconfig-primary', dst)
+
+    env.install(['-e', dst])
+    env.install_from_path(packages / 'namespace-pkgconfig-secondary', from_sdist=False)
+
+    script = """
+import os
+import warnings
+import pkgconf
+import pkgconf._path_entrypoints
+
+warnings.simplefilter('error', pkgconf._path_entrypoints.PathWarning)
+paths = [
+    path for path in pkgconf.get_pkg_config_path()
+    if path.endswith(os.path.join('namespace', 'pkgconf'))
+]
+assert len(paths) == 1, paths
+"""
+    process = subprocess.run(
+        [os.fspath(env.interpreter), '-c', script],
+        env=env.env,
+        capture_output=True,
+        text=True,
+        check=False,
+    )
+
+    assert process.returncode == 0, process.stderr
+
+
 def test_pkg_config_path_error_on_import(env, packages):
     path = list(env.introspectable.call('pkgconf.get_pkg_config_path'))
     assert len(path) == 0