Add support for type annotations to attr: ast parsing (#3391)

changelog.d/3391.change.rst

@@ -0,0 +1 @@
+Updated ``attr:`` to also extract simple constants with type annotations -- by :user:`karlotness`

setuptools/config/expand.py

@@ -66,25 +66,21 @@ def __init__(self, name: str, spec: ModuleSpec):
         vars(self).update(locals())
         del self.self
 
+    def _find_assignments(self) -> Iterator[Tuple[ast.AST, ast.AST]]:
+        for statement in self.module.body:
+            if isinstance(statement, ast.Assign):
+                yield from ((target, statement.value) for target in statement.targets)
+            elif isinstance(statement, ast.AnnAssign) and statement.value:
+                yield (statement.target, statement.value)
+
     def __getattr__(self, attr):
         """Attempt to load an attribute "statically", via :func:`ast.literal_eval`."""
         try:
-            assignment_expressions = (
-                statement
-                for statement in self.module.body
-                if isinstance(statement, ast.Assign)
-            )
-            expressions_with_target = (
-                (statement, target)
-                for statement in assignment_expressions
-                for target in statement.targets
-            )
-            matching_values = (
-                statement.value
-                for statement, target in expressions_with_target
+            return next(
+                ast.literal_eval(value)
+                for target, value in self._find_assignments()
                 if isinstance(target, ast.Name) and target.id == attr
             )
-            return next(ast.literal_eval(value) for value in matching_values)
         except Exception as e:
             raise AttributeError(f"{self.name} has no attribute {attr}") from e
 

setuptools/tests/config/test_expand.py

@@ -85,6 +85,22 @@ def test_read_attr(self, tmp_path, monkeypatch):
         values = expand.read_attr('lib.mod.VALUES', {'lib': 'pkg/sub'}, tmp_path)
         assert values['c'] == (0, 1, 1)
 
+    @pytest.mark.parametrize(
+        "example",
+        [
+            "VERSION: str\nVERSION = '0.1.1'\nraise SystemExit(1)\n",
+            "VERSION: str = '0.1.1'\nraise SystemExit(1)\n",
+        ]
+    )
+    def test_read_annotated_attr(self, tmp_path, example):
+        files = {
+            "pkg/__init__.py": "",
+            "pkg/sub/__init__.py": example,
+        }
+        write_files(files, tmp_path)
+        # Make sure this attribute can be read statically
+        assert expand.read_attr('pkg.sub.VERSION', root_dir=tmp_path) == '0.1.1'
+
     def test_import_order(self, tmp_path):
         """
         Sometimes the import machinery will import the parent package of a nested