bpo-46571: improve `typing.no_type_check` to skip foreign objects (GH-31042)

There are several changes:
1. We now don't explicitly check for any base / sub types, because new name check covers it
2. I've also checked that `no_type_check` do not modify foreign functions. It was the same as with `type`s
3. I've also covered `except TypeError` in `no_type_check` with a simple test case, it was not covered at all
4. I also felt like adding `lambda` test is a good idea: because `lambda` is a bit of both in class bodies: a function and an assignment

<!-- issue-number: [bpo-46571](https://bugs.python.org/issue46571) -->
https://bugs.python.org/issue46571
<!-- /issue-number -->

1 files changed, 15 insertions, 5 deletions

diff --git a/Lib/typing.py b/Lib/typing.py
index 8f923fa..ad1435e 100644
--- a/Lib/typing.py
+++ b/Lib/typing.py
@@ -2131,13 +2131,23 @@ def no_type_check(arg):
     This mutates the function(s) or class(es) in place.
     """
     if isinstance(arg, type):
-        arg_attrs = arg.__dict__.copy()
-        for attr, val in arg.__dict__.items():
-            if val in arg.__bases__ + (arg,):
-                arg_attrs.pop(attr)
-        for obj in arg_attrs.values():
+        for key in dir(arg):
+            obj = getattr(arg, key)
+            if (
+                not hasattr(obj, '__qualname__')
+                or obj.__qualname__ != f'{arg.__qualname__}.{obj.__name__}'
+                or getattr(obj, '__module__', None) != arg.__module__
+            ):
+                # We only modify objects that are defined in this type directly.
+                # If classes / methods are nested in multiple layers,
+                # we will modify them when processing their direct holders.
+                continue
+            # Instance, class, and static methods:
             if isinstance(obj, types.FunctionType):
                 obj.__no_type_check__ = True
+            if isinstance(obj, types.MethodType):
+                obj.__func__.__no_type_check__ = True
+            # Nested types:
             if isinstance(obj, type):
                 no_type_check(obj)
     try: