pkg_resources: Runtime fixes to make typing annotations work (pypa#4262)

Author: abravalheri

newsfragments/4262.feature.rst

@@ -0,0 +1,3 @@
+Improved `AttributeError` error message if ``pkg_resources.EntryPoint.require`` is called without extras or distribution
+Gracefully "do nothing" when trying to activate a ``pkg_resources.Distribution`` with a `None` location, rather than raising a `TypeError`
+-- by :user:`Avasam`

pkg_resources/__init__.py

@@ -920,10 +920,10 @@ def find_plugins(self, plugin_env, full_env=None, installer=None, fallback=True)
                     # success, no need to try any more versions of this project
                     break
 
-        distributions = list(distributions)
-        distributions.sort()
+        sorted_distributions = list(distributions)
+        sorted_distributions.sort()
 
-        return distributions, error_info
+        return sorted_distributions, error_info
 
     def require(self, *requirements):
         """Ensure that distributions matching `requirements` are activated
@@ -1635,7 +1635,7 @@ def _validate_resource_path(path):
         )
 
     def _get(self, path) -> bytes:
-        if hasattr(self.loader, 'get_data'):
+        if hasattr(self.loader, 'get_data') and self.loader:
             return self.loader.get_data(path)
         raise NotImplementedError(
             "Can't perform this operation for loaders without 'get_data()'"
@@ -2490,8 +2490,9 @@ def resolve(self):
             raise ImportError(str(exc)) from exc
 
     def require(self, env=None, installer=None):
-        if self.extras and not self.dist:
-            raise UnknownExtra("Can't require() without a distribution", self)
+        if not self.dist:
+            error_cls = UnknownExtra if self.extras else AttributeError
+            raise error_cls("Can't require() without a distribution", self)
 
         # Get the requirements for this entry point with all its extras and
         # then resolve them. We have to pass `extras` along when resolving so
@@ -2557,11 +2558,11 @@ def parse_group(cls, group, lines, dist=None):
     def parse_map(cls, data, dist=None):
         """Parse a map of entry point groups"""
         if isinstance(data, dict):
-            data = data.items()
+            _data = data.items()
         else:
-            data = split_sections(data)
+            _data = split_sections(data)
         maps = {}
-        for group, lines in data:
+        for group, lines in _data:
             if group is None:
                 if not lines:
                     continue
@@ -2823,7 +2824,7 @@ def activate(self, path=None, replace=False):
         if path is None:
             path = sys.path
         self.insert_on(path, replace=replace)
-        if path is sys.path:
+        if path is sys.path and self.location is not None:
             fixup_namespace_packages(self.location)
             for pkg in self._get_metadata('namespace_packages.txt'):
                 if pkg in sys.modules:
@@ -2891,15 +2892,13 @@ def load_entry_point(self, group, name):
 
     def get_entry_map(self, group=None):
         """Return the entry point map for `group`, or the full entry map"""
-        try:
-            ep_map = self._ep_map
-        except AttributeError:
-            ep_map = self._ep_map = EntryPoint.parse_map(
+        if not hasattr(self, "_ep_map"):
+            self._ep_map = EntryPoint.parse_map(
                 self._get_metadata('entry_points.txt'), self
             )
         if group is not None:
-            return ep_map.get(group, {})
-        return ep_map
+            return self._ep_map.get(group, {})
+        return self._ep_map
 
     def get_entry_info(self, group, name):
         """Return the EntryPoint object for `group`+`name`, or ``None``"""