Fix a false negative for ``unused-import`` (#7621)

When linting multiple modules & one module uses an import in a type annotation & the same import is unused in a subsequent module.

Closes #4150

Co-authored-by: Pierre Sassoulas <pierre.sassoulas@gmail.com>

1 files changed, 33 insertions, 0 deletions

diff --git a/tests/test_self.py b/tests/test_self.py
index 65b76f661..ae3b41d98 100644
--- a/tests/test_self.py
+++ b/tests/test_self.py
@@ -297,6 +297,39 @@ class TestRunTC:
             actual_output = actual_output[actual_output.find("\n") :]
         assert self._clean_paths(expected_output.strip()) == actual_output.strip()
 
+    def test_type_annotation_names(self) -> None:
+        """Test resetting the `_type_annotation_names` list to `[]` when leaving a module.
+
+        An import inside `module_a`, which is used as a type annotation in `module_a`, should not prevent
+        emitting the `unused-import` message when the same import occurs in `module_b` & is unused.
+        See: https://github.com/PyCQA/pylint/issues/4150
+        """
+        module1 = join(
+            HERE, "regrtest_data", "imported_module_in_typehint", "module_a.py"
+        )
+
+        module2 = join(
+            HERE, "regrtest_data", "imported_module_in_typehint", "module_b.py"
+        )
+        expected_output = textwrap.dedent(
+            f"""
+        ************* Module module_b
+        {module2}:1:0: W0611: Unused import uuid (unused-import)
+        """
+        )
+        args = [
+            module1,
+            module2,
+            "--disable=all",
+            "--enable=unused-import",
+            "-rn",
+            "-sn",
+        ]
+        out = StringIO()
+        self._run_pylint(args, out=out)
+        actual_output = self._clean_paths(out.getvalue().strip())
+        assert self._clean_paths(expected_output.strip()) in actual_output.strip()
+
     def test_import_itself_not_accounted_for_relative_imports(self) -> None:
         expected = "Your code has been rated at 10.00/10"
         package = join(HERE, "regrtest_data", "dummy")