Normalise extra names when reading config

flit_core/flit_core/common.py

@@ -370,10 +370,6 @@ def __init__(self, data):
     def _normalise_field_name(self, n):
         return n.lower().replace('-', '_')
 
-    def _normalise_core_metadata_name(self, name):
-        # Normalized Names (PEP 503)
-        return re.sub(r"[-_.]+", "-", name).lower()
-
     def _extract_extras(self, req):
         match = re.search(r'\[([^]]*)\]', req)
         if match:
@@ -385,7 +381,7 @@ def _extract_extras(self, req):
     def _normalise_requires_dist(self, req):
         extras = self._extract_extras(req)
         if extras:
-            normalised_extras = [self._normalise_core_metadata_name(extra) for extra in extras]
+            normalised_extras = [normalise_core_metadata_name(extra) for extra in extras]
             normalised_extras_str = ', '.join(normalised_extras)
             normalised_req = re.sub(r'\[([^]]*)\]', f"[{normalised_extras_str}]", req)
             return normalised_req
@@ -437,7 +433,7 @@ def write_metadata_file(self, fp):
             fp.write(u'Project-URL: {}\n'.format(url))
 
         for extra in self.provides_extra:
-            normalised_extra = self._normalise_core_metadata_name(extra)
+            normalised_extra = normalise_core_metadata_name(extra)
             fp.write(u'Provides-Extra: {}\n'.format(normalised_extra))
 
         if self.description is not None:
@@ -459,6 +455,10 @@ def make_metadata(module, ini_info):
     return Metadata(md_dict)
 
 
+def normalise_core_metadata_name(name):
+    """Normalise a project or extra name (as in PEP 503, also PEP 685)"""
+    return re.sub(r"[-_.]+", "-", name).lower()
+
 
 def normalize_dist_name(name: str, version: str) -> str:
     """Normalizes a name and a PEP 440 version

flit_core/flit_core/config.py

@@ -17,6 +17,7 @@
     except ImportError:
         import tomli as tomllib
 
+from .common import normalise_core_metadata_name
 from .versionno import normalise_version
 
 log = logging.getLogger(__name__)
@@ -381,7 +382,31 @@ def _prep_metadata(md_sect, path):
 
     # Move dev-requires into requires-extra
     reqs_noextra = md_dict.pop('requires_dist', [])
-    res.reqs_by_extra = md_dict.pop('requires_extra', {})
+
+    reqs_extra = md_dict.pop('requires_extra', {})
+    extra_names_by_normed = {}
+    for e, reqs in reqs_extra.items():
+        if not all(isinstance(a, str) for a in reqs):
+            raise ConfigError(
+                f'Expected a string list for requires-extra group {e}'
+            )
+        if not name_is_valid(e):
+            raise ConfigError(
+                f'requires-extra group name {e!r} is not valid'
+            )
+        enorm = normalise_core_metadata_name(e)
+        extra_names_by_normed.setdefault(enorm, set()).add(e)
+        res.reqs_by_extra[enorm] = reqs
+
+    clashing_extra_names = [
+        g for g in extra_names_by_normed.values() if len(g) > 1
+    ]
+    if clashing_extra_names:
+        fmted = ['/'.join(sorted(g)) for g in clashing_extra_names]
+        raise ConfigError(
+            f"requires-extra group names clash: {'; '.join(fmted)}"
+        )
+
     dev_requires = md_dict.pop('dev_requires', None)
     if dev_requires is not None:
         if 'dev' in res.reqs_by_extra:
@@ -434,6 +459,8 @@ def read_pep621_metadata(proj, path) -> LoadedConfig:
     if 'name' not in proj:
         raise ConfigError('name must be specified in [project] table')
     _check_type(proj, 'name', str)
+    if not name_is_valid(proj['name']):
+        raise ConfigError(f"name {proj['name']} is not valid")
     md_dict['name'] = proj['name']
     lc.module = md_dict['name'].replace('-', '_')
 
@@ -592,13 +619,29 @@ def read_pep621_metadata(proj, path) -> LoadedConfig:
             raise ConfigError(
                 'Expected a dict of lists in optional-dependencies field'
             )
+        extra_names_by_normed = {}
         for e, reqs in optdeps.items():
             if not all(isinstance(a, str) for a in reqs):
                 raise ConfigError(
                     'Expected a string list for optional-dependencies ({})'.format(e)
                 )
+            if not name_is_valid(e):
+                raise ConfigError(
+                    f'optional-dependencies group name {e!r} is not valid'
+                )
+            enorm = normalise_core_metadata_name(e)
+            extra_names_by_normed.setdefault(enorm, set()).add(e)
+            lc.reqs_by_extra[enorm] = reqs
+
+        clashing_extra_names = [
+            g for g in extra_names_by_normed.values() if len(g) > 1
+        ]
+        if clashing_extra_names:
+            fmted = ['/'.join(sorted(g)) for g in clashing_extra_names]
+            raise ConfigError(
+                f"optional-dependencies group names clash: {'; '.join(fmted)}"
+            )
 
-        lc.reqs_by_extra = optdeps.copy()
         md_dict['provides_extra'] = sorted(lc.reqs_by_extra.keys())
 
     md_dict['requires_dist'] = \
@@ -633,6 +676,13 @@ def read_pep621_metadata(proj, path) -> LoadedConfig:
 
     return lc
 
+
+def name_is_valid(name) -> bool:
+    return bool(re.match(
+        r"^([A-Z0-9]|[A-Z0-9][A-Z0-9._-]*[A-Z0-9])$", name, re.IGNORECASE
+    ))
+
+
 def pep621_people(people, group_name='author') -> dict:
     """Convert authors/maintainers from PEP 621 to core metadata fields"""
     names, emails = [], []

flit_core/tests_core/samples/extras-newstyle.toml

@@ -0,0 +1,13 @@
+[build-system]
+requires = ["flit_core >=2,<4"]
+build-backend = "flit_core.buildapi"
+
+[project]
+name = "module1"
+version = "0.1"
+description = "Example for testing"
+dependencies = ["toml"]
+
+[project.optional-dependencies]
+test = ["pytest"]
+cus__Tom = ["requests"]  # To test normalisation

flit_core/tests_core/samples/extras.toml

@@ -12,4 +12,4 @@ requires = ["toml"]
 
 [tool.flit.metadata.requires-extra]
 test = ["pytest"]
-custom = ["requests"]
+cus__Tom = ["requests"]  # To test normalisation

flit_core/tests_core/test_config.py

@@ -81,9 +81,20 @@ def test_extras():
     assert requires_dist == {
         'toml',
         'pytest ; extra == "test"',
-        'requests ; extra == "custom"',
+        'requests ; extra == "cus-tom"',
     }
-    assert set(info.metadata['provides_extra']) == {'test', 'custom'}
+    assert set(info.metadata['provides_extra']) == {'test', 'cus-tom'}
+
+def test_extras_newstyle():
+    # As above, but with new-style [project] table
+    info = config.read_flit_config(samples_dir / 'extras-newstyle.toml')
+    requires_dist = set(info.metadata['requires_dist'])
+    assert requires_dist == {
+        'toml',
+        'pytest ; extra == "test"',
+        'requests ; extra == "cus-tom"',
+    }
+    assert set(info.metadata['provides_extra']) == {'test', 'cus-tom'}
 
 def test_extras_dev_conflict():
     with pytest.raises(config.ConfigError, match=r'dev-requires'):
@@ -141,6 +152,10 @@ def test_bad_include_paths(path, err_match):
     ({'dynamic': ['version']}, r'dynamic.*\[project\]'),
     ({'authors': ['thomas']}, r'author.*\bdict'),
     ({'maintainers': [{'title': 'Dr'}]}, r'maintainer.*title'),
+    ({'name': 'mödule1'}, r'not valid'),
+    ({'name': 'module1_'}, r'not valid'),
+    ({'optional-dependencies': {'x_': []}}, r'not valid'),
+    ({'optional-dependencies': {'x_a': [], 'X--a': []}}, r'clash'),
 ])
 def test_bad_pep621_info(proj_bad, err_match):
     proj = {'name': 'module1', 'version': '1.0', 'description': 'x'}