bpo-38364: unwrap partialmethods just like we unwrap partials (#16600)

* bpo-38364: unwrap partialmethods just like we unwrap partials

The inspect.isgeneratorfunction, inspect.iscoroutinefunction and inspect.isasyncgenfunction already unwrap functools.partial objects, this patch adds support for partialmethod objects as well.

Also: Rename _partialmethod to __partialmethod__.
Since we're checking this attribute on arbitrary function-like objects,
we should use the namespace reserved for core Python.

---------

Co-authored-by: Petr Viktorin <encukou@gmail.com>

1 files changed, 12 insertions, 1 deletions

diff --git a/Lib/functools.py b/Lib/functools.py
index 55990e7..ee4197b 100644
--- a/Lib/functools.py
+++ b/Lib/functools.py
@@ -388,7 +388,7 @@ class partialmethod(object):
             keywords = {**self.keywords, **keywords}
             return self.func(cls_or_self, *self.args, *args, **keywords)
         _method.__isabstractmethod__ = self.__isabstractmethod__
-        _method._partialmethod = self
+        _method.__partialmethod__ = self
         return _method
 
     def __get__(self, obj, cls=None):
@@ -424,6 +424,17 @@ def _unwrap_partial(func):
         func = func.func
     return func
 
+def _unwrap_partialmethod(func):
+    prev = None
+    while func is not prev:
+        prev = func
+        while isinstance(getattr(func, "__partialmethod__", None), partialmethod):
+            func = func.__partialmethod__
+        while isinstance(func, partialmethod):
+            func = getattr(func, 'func')
+        func = _unwrap_partial(func)
+    return func
+
 ################################################################################
 ### LRU Cache function decorator
 ################################################################################