gh-145031: suggest the module in "python -m module"

Lib/runpy.py

@@ -100,6 +100,22 @@ def _run_module_code(code, init_globals=None,
     # may be cleared when the temporary module goes away
     return mod_globals.copy()
 
+
+def _get_possible_name_list(wrong_name):
+    try:
+        if parent_name := wrong_name.rpartition('.')[0]:
+            parent = importlib.util.find_spec(parent_name)
+        else:
+            parent = None
+        d = []
+        for finder in sys.meta_path:
+            if discover := getattr(finder, 'discover', None):
+                d += [spec.name for spec in discover(parent)]
+        return d
+    except Exception:
+        return None
+
+
 # Helper to get the full name, spec and code for a module
 def _get_module_details(mod_name, error=ImportError):
     if mod_name.startswith("."):
@@ -138,7 +154,12 @@ def _get_module_details(mod_name, error=ImportError):
                     f"'{mod_name}' as the module name.")
         raise error(msg.format(mod_name, type(ex).__name__, ex)) from ex
     if spec is None:
-        raise error("No module named %s" % mod_name)
+        message = "No module named %r" % mod_name
+        if (d := _get_possible_name_list(mod_name)):
+            from traceback import _calculate_closed_name
+            if (suggestion := _calculate_closed_name(mod_name, d)):
+                message += ". Did you mean: %r?" % suggestion
+        raise error(message)
     if spec.submodule_search_locations is not None:
         if mod_name == "__main__" or mod_name.endswith(".__main__"):
             raise error("Cannot use package as __main__ module")

Lib/test/test_cmd_line_script.py

@@ -771,7 +771,7 @@ def test_consistent_sys_path_for_module_execution(self):
                 "-Im", "script_pkg", cwd=work_dir
             )
             traceback_lines = stderr.decode().splitlines()
-            self.assertIn("No module named script_pkg", traceback_lines[-1])
+            self.assertIn("No module named 'script_pkg'", traceback_lines[-1])
 
     def test_nonexisting_script(self):
         # bpo-34783: "./python script.py" must not crash
@@ -829,6 +829,11 @@ def test_zipfile_run_filter_syntax_warnings_by_module(self):
             )
             self.assertEqual(err.count(b': SyntaxWarning: '), 12)
 
+    def test_typo_in_module_name_suggests_similar_module(self):
+        # python -m randon  -> expect suggestion for 'random'
+        rc, out, err = assert_python_failure("-m", "randon")
+        self.assertIn(b"No module named 'randon'", err)
+        self.assertIn(b"Did you mean: 'random'?", err)
 
 def tearDownModule():
     support.reap_children()

Lib/test/test_pdb.py

@@ -4210,7 +4210,7 @@ def test_module_without_a_main(self):
         stdout, stderr = self._run_pdb(
             ['-m', module_name], "", expected_returncode=1
         )
-        self.assertIn("ImportError: No module named t_main.__main__;", stdout)
+        self.assertIn("ImportError: No module named 't_main.__main__'", stdout)
 
     def test_package_without_a_main(self):
         pkg_name = 't_pkg'
@@ -4231,7 +4231,7 @@ def test_package_without_a_main(self):
     def test_nonexistent_module(self):
         assert not os.path.exists(os_helper.TESTFN)
         stdout, stderr = self._run_pdb(["-m", os_helper.TESTFN], "", expected_returncode=1)
-        self.assertIn(f"ImportError: No module named {os_helper.TESTFN}", stdout)
+        self.assertIn(f"ImportError: No module named {os_helper.TESTFN!r}", stdout)
 
     def test_dir_as_script(self):
         with os_helper.temp_dir() as temp_dir:

Lib/traceback.py

@@ -1778,6 +1778,20 @@ def _compute_suggestion_error(exc_value, tb, wrong_name):
 
     if not_normalized and wrong_name in d:
         return wrong_name
+
+    suggestion = _calculate_closed_name(wrong_name, d)
+
+    # If no direct attribute match found, check for nested attributes
+    if not suggestion and isinstance(exc_value, AttributeError):
+        with suppress(Exception):
+            nested_suggestion = _check_for_nested_attribute(exc_value.obj, wrong_name, d)
+            if nested_suggestion:
+                return nested_suggestion
+
+    return suggestion
+
+
+def _calculate_closed_name(wrong_name, d):
     try:
         import _suggestions
     except ImportError:
@@ -1810,14 +1824,6 @@ def _compute_suggestion_error(exc_value, tb, wrong_name):
         if not suggestion or current_distance < best_distance:
             suggestion = possible_name
             best_distance = current_distance
-
-    # If no direct attribute match found, check for nested attributes
-    if not suggestion and isinstance(exc_value, AttributeError):
-        with suppress(Exception):
-            nested_suggestion = _check_for_nested_attribute(exc_value.obj, wrong_name, d)
-            if nested_suggestion:
-                return nested_suggestion
-
     return suggestion
 
 

Misc/NEWS.d/next/Library/2026-02-22-12-39-31.gh-issue-145031.-4yezd.rst

@@ -0,0 +1 @@
+Suggest a possible module name in ``python -m module`` if the module name is wrong.