Support Import-Name & Import-Namespace metadata

doc/pyproject_toml.rst

@@ -29,6 +29,7 @@ Version constraints:
 
 - For now, all packages should specify ``<5``, so they won't be impacted by
   changes in the next major version.
+- ``import-names`` and ``import-namespaces`` require ``flit_core >=4``.
 - ``license-files`` and license expressions in the ``license`` field require
   ``flit_core >=3.11``.
 - :ref:`pyproject_toml_project` requires ``flit_core >=3.2``.
@@ -113,6 +114,15 @@ classifiers
   A list of `Trove classifiers <https://pypi.python.org/pypi?%3Aaction=list_classifiers>`_.
   Add ``Private :: Do Not Upload`` into the list to prevent a private package
   from being uploaded to PyPI by accident.
+import-names
+  A list containing the importable module name in this package. You don't
+  normally need to supply this manually, but you can specify it with a
+  ``; private`` suffix to record that the module is not intended for public use.
+  This does not stop anyone importing it.
+import-namespaces
+  A list of import names in this package which are namespace packages. Like
+  ``import-names``, Flit will supply this metadata automatically if you use
+  namespace packages.
 dependencies & optional-dependencies
   See :ref:`pyproject_project_dependencies`.
 urls

flit_core/flit_core/common.py

@@ -350,8 +350,10 @@ class Metadata:
     provides_extra = ()
     license_files = ()
     dynamic = ()
+    import_name = ()
+    import_namespace = ()
 
-    metadata_version = "2.4"
+    metadata_version = "2.5"
 
     def __init__(self, data):
         data = data.copy()
@@ -441,6 +443,12 @@ def write_metadata_file(self, fp):
             normalised_extra = normalise_core_metadata_name(extra)
             fp.write(f'Provides-Extra: {normalised_extra}\n')
 
+        for name in self.import_name:
+            fp.write(f'Import-Name: {name}')
+
+        for name in self.import_namespace:
+            fp.write(f'Import-Namespace: {name}')
+
         if self.description is not None:
             fp.write(f'\n{self.description}\n')
 

flit_core/flit_core/config.py

@@ -33,26 +33,6 @@ class ConfigError(ValueError):
     'dev-requires'
 }
 
-metadata_allowed_fields = {
-    'module',
-    'author',
-    'author-email',
-    'maintainer',
-    'maintainer-email',
-    'home-page',
-    'license',
-    'keywords',
-    'requires-python',
-    'dist-name',
-    'description-file',
-    'requires-extra',
-} | metadata_list_fields
-
-metadata_required_fields = {
-    'module',
-    'author',
-}
-
 pep621_allowed_fields = {
     'name',
     'version',
@@ -72,8 +52,18 @@ class ConfigError(ValueError):
     'dependencies',
     'optional-dependencies',
     'dynamic',
+    'import-names',  # PEP 794
+    'import-namespaces'
+}
+
+allowed_dynamic_fields = {
+    'version',
+    'description',
+    'import-names',
+    'import-namespaces'
 }
 
+
 default_license_files_globs = ['COPYING*', 'LICEN[CS]E*', 'NOTICE*', 'AUTHORS*']
 license_files_allowed_chars = re.compile(r'^[\w\-\.\/\*\?\[\]]+$')
 
@@ -119,6 +109,34 @@ def prep_toml_config(d, path):
     if 'name' in module_tbl:
         loaded_cfg.module = module_tbl['name']
 
+    if 'import-names' in d['project']:
+        import_names_from_config = [
+            s.split(';')[0] for s in loaded_cfg.metadata['import_name']
+        ]
+        if import_names_from_config != [loaded_cfg.module]:
+            raise ConfigError(
+                f"Specified import-names {import_names_from_config} do not match "
+                f"the module present ({loaded_cfg.module})"
+            )
+    else:
+        loaded_cfg.metadata['import_name'] = [loaded_cfg.module]
+
+    namespace_parts = loaded_cfg.module.split('.')[:-1]
+    nspkgs_from_mod_name = [
+        '.'.join(namespace_parts[:i]) for i in range(1, len(namespace_parts) + 1)
+    ]
+    if 'import-namespaces' in d['project']:
+        nspkgs_from_config = [
+            s.split(';')[0] for s in loaded_cfg.metadata['import_namespace']
+        ]
+        if set(nspkgs_from_config) != set(nspkgs_from_mod_name):
+            raise ConfigError(
+                f"Specified import-namespaces {nspkgs_from_config} do not match "
+                f"the namespace packages present ({nspkgs_from_mod_name})"
+            )
+    else:
+        loaded_cfg.metadata['import_namespace'] = nspkgs_from_mod_name
+
     unknown_sections = set(dtool) - {'module', 'sdist', 'external-data'}
     unknown_sections = [s for s in unknown_sections if not s.lower().startswith('x-')]
     if unknown_sections:
@@ -331,6 +349,25 @@ def normalize_pkg_name(name: str) -> str:
     return name.replace('-','_')
 
 
+def normalize_import_name(name: str) -> str:
+    if ';' in name:
+        name, annotation = name.split(';', 1)
+        name = name.rstrip()
+        annotation = annotation.lstrip()
+        if annotation != 'private':
+            raise ConfigError(
+                f"{annotation!r} for import name {name!r} is not allowed "
+                "(the only valid annotation is 'private')"
+            )
+    else:
+        annotation = None
+
+    if not all(p.isidentifier() for p in name.split('.')):
+        raise ConfigError(f"{name!r} is not a valid import name")
+
+    return f"{name}; {annotation}" if annotation else name
+
+
 def read_pep621_metadata(proj, path) -> LoadedConfig:
     lc = LoadedConfig()
     md_dict = lc.metadata
@@ -577,13 +614,27 @@ def read_pep621_metadata(proj, path) -> LoadedConfig:
     if reqs_noextra:
         lc.reqs_by_extra['.none'] = reqs_noextra
 
+    if 'import-names' in proj:  # PEP 794
+        _check_list_of_str(proj, 'import-names')
+        md_dict['import_name'] = [
+            normalize_import_name(s) for s in proj['import-names']
+        ]
+
+    if 'import-namespaces' in proj:
+        _check_list_of_str(proj, 'import-namespaces')
+        md_dict['import_namespace'] = [
+            normalize_import_name(s) for s in proj['import-namespaces']
+        ]
+
     if 'dynamic' in proj:
         _check_list_of_str(proj, 'dynamic')
         dynamic = set(proj['dynamic'])
-        unrec_dynamic = dynamic - {'version', 'description'}
+        unrec_dynamic = dynamic - allowed_dynamic_fields
         if unrec_dynamic:
             raise ConfigError(
-                "flit only supports dynamic metadata for 'version' & 'description'"
+                "flit only supports dynamic metadata for:" + ', '.join(
+                    sorted(allowed_dynamic_fields)
+                )
             )
         if dynamic.intersection(proj):
             raise ConfigError(

flit_core/tests_core/test_config.py

@@ -16,6 +16,8 @@ def test_load_toml():
 def test_load_toml_ns():
     inf = config.read_flit_config(samples_dir / 'ns1-pkg' / 'pyproject.toml')
     assert inf.module == 'ns1.pkg'
+    assert inf.metadata['import_name'] == ['ns1.pkg']
+    assert inf.metadata['import_namespace'] == ['ns1']
 
 def test_load_normalization():
     inf = config.read_flit_config(samples_dir / 'normalization' / 'pyproject.toml')
@@ -388,6 +390,19 @@ def test_pep621_license_files(proj_license_files, files):
     assert info.metadata['license_files'] == files
 
 
+@pytest.mark.parametrize(('proj_extra', 'err_match'), [
+    ({"import-names": ["foo-bar"]}, "not a valid"),
+    ({"import-names": ["foobar; public"]}, "private"),
+    ({"import-names": ["module2"]}, "not match"),
+    ({"import-namespaces": ["namespace1"]}, "not match"),
+])
+def test_import_names_errors(proj_extra, err_match):
+    d = {'project': {'name': 'module1', 'version': '1.0', 'description': 'x'}}
+    d['project'].update(proj_extra)
+    with pytest.raises(config.ConfigError, match=err_match):
+        config.prep_toml_config(d, samples_dir)
+
+
 def test_old_style_metadata():
     with pytest.raises(config.ConfigError, match=re.escape("[tool.flit.metadata]")):
         config.read_flit_config(samples_dir / 'module1-old-metadata.toml')