gh-146401: add BuiltinImporter.discover() to find built-in modules

Lib/test/test_traceback.py

@@ -5004,6 +5004,26 @@ def func():
         actual = self.get_suggestion(func)
         self.assertIn("forget to import '_io'", actual)
 
+    def test_import_builtin_module_typo_suggestion(self):
+        def func():
+            import itertool # noqa: F401
+
+        actual = self.get_suggestion(func)
+        self.assertIn("Did you mean: 'itertools'?", actual)
+
+    def test_import_file_module_typo_suggestion(self):
+        def func():
+            import abs # noqa: F401
+
+        actual = self.get_suggestion(func)
+        self.assertIn("Did you mean: 'abc'?", actual)
+
+    def test_import_submodule_typo_suggestion(self):
+        def func():
+            import multiprocessing.dumy # noqa: F401
+
+        actual = self.get_suggestion(func)
+        self.assertIn("Did you mean: 'multiprocessing.dummy'?", actual)
 
 
 class PurePythonSuggestionFormattingTests(

Lib/traceback.py

@@ -1755,7 +1755,7 @@ def _compute_suggestion_error(exc_value, tb, wrong_name):
                 parent = importlib.util.find_spec(parent_name)
             else:
                 parent = None
-            d = []
+            d = list(sys.builtin_module_names)
             for finder in sys.meta_path:
                 if discover := getattr(finder, 'discover', None):
                     d += [spec.name for spec in discover(parent)]