Bug report

Bug description:

If a protocol is named Protocol or Generic then it will ignore any defined members.

when you get lazy with naming in your unit tests this makes for quite a head scratcher...

Minimal Reproduction

import typing


class Protocol(typing.Protocol):
    a: int


members = typing.get_protocol_members(Protocol)

assert members == {"a"}, f"Expected members to be {{'a'}}, got {members}"

Output:

Traceback (most recent call last):
  File ".../test_protocol.py", line 10, in <module>
    assert members == {"a"}, f"Expected members to be {{'a'}}, got {members}"
           ^^^^^^^^^^^^^^^^
AssertionError: Expected members to be {'a'}, got frozenset()

Expected Output:

Nothing, script should succeed without error.

Investigation

The problem appears to stem from the _get_protocol_attrs function used by _ProtocolMeta which is defined as follows:

The if statement on line 1887 is too loose in what it matches.

Possibile Fix

The check for base needs to be more specific, either using the instance itself:

if base in {Protocol, Generic}:
    continue

or checking the module too, in order to ensure its the correct class being excluded:

if base.__name__ in {'Protocol', 'Generic'} and base.__module__ == 'typing':
    continue

CPython versions tested on:

3.14

Operating systems tested on:

macOS

Linked PRs

• gh-145688: Fix _get_protocol_attrs matching user classes named "Protocol" or "Generic" #145724