gh-121027: Make the functools.partial object a method descriptor (GH-121089)

Co-authored-by: d.grigonis <dgrigonis@users.noreply.github.com>

3 files changed, 20 insertions, 32 deletions

diff --git a/Lib/functools.py b/Lib/functools.py
index d04957c..a10493f 100644
--- a/Lib/functools.py
+++ b/Lib/functools.py
@@ -18,6 +18,7 @@ from abc import get_cache_token
 from collections import namedtuple
 # import types, weakref  # Deferred to single_dispatch()
 from reprlib import recursive_repr
+from types import MethodType
 from _thread import RLock
 
 # Avoid importing types, so we can speedup import time
@@ -314,12 +315,7 @@ class partial:
     def __get__(self, obj, objtype=None):
         if obj is None:
             return self
-        import warnings
-        warnings.warn('functools.partial will be a method descriptor in '
-                      'future Python versions; wrap it in staticmethod() '
-                      'if you want to preserve the old behavior',
-                      FutureWarning, 2)
-        return self
+        return MethodType(self, obj)
 
     def __reduce__(self):
         return type(self), (self.func,), (self.func, self.args,
@@ -402,7 +398,7 @@ class partialmethod(object):
     def __get__(self, obj, cls=None):
         get = getattr(self.func, "__get__", None)
         result = None
-        if get is not None and not isinstance(self.func, partial):
+        if get is not None:
             new_func = get(obj, cls)
             if new_func is not self.func:
                 # Assume __get__ returning something new indicates the
diff --git a/Lib/test/test_functools.py b/Lib/test/test_functools.py
index 1ce0f4d..492a16a 100644
--- a/Lib/test/test_functools.py
+++ b/Lib/test/test_functools.py
@@ -405,9 +405,7 @@ class TestPartial:
         self.assertEqual(A.meth(3, b=4), ((1, 3), {'a': 2, 'b': 4}))
         self.assertEqual(A.cmeth(3, b=4), ((1, A, 3), {'a': 2, 'b': 4}))
         self.assertEqual(A.smeth(3, b=4), ((1, 3), {'a': 2, 'b': 4}))
-        with self.assertWarns(FutureWarning) as w:
-            self.assertEqual(a.meth(3, b=4), ((1, 3), {'a': 2, 'b': 4}))
-        self.assertEqual(w.filename, __file__)
+        self.assertEqual(a.meth(3, b=4), ((1, a, 3), {'a': 2, 'b': 4}))
         self.assertEqual(a.cmeth(3, b=4), ((1, A, 3), {'a': 2, 'b': 4}))
         self.assertEqual(a.smeth(3, b=4), ((1, 3), {'a': 2, 'b': 4}))
 
diff --git a/Lib/test/test_inspect/test_inspect.py b/Lib/test/test_inspect/test_inspect.py
index 308c098..d39c3cc 100644
--- a/Lib/test/test_inspect/test_inspect.py
+++ b/Lib/test/test_inspect/test_inspect.py
@@ -3868,17 +3868,15 @@ class TestSignatureObject(unittest.TestCase):
 
         with self.subTest('partial'):
             class CM(type):
-                __call__ = functools.partial(lambda x, a: (x, a), 2)
+                __call__ = functools.partial(lambda x, a, b: (x, a, b), 2)
             class C(metaclass=CM):
-                def __init__(self, b):
+                def __init__(self, c):
                     pass
 
-            with self.assertWarns(FutureWarning):
-                self.assertEqual(C(1), (2, 1))
-            with self.assertWarns(FutureWarning):
-                self.assertEqual(self.signature(C),
-                                ((('a', ..., ..., "positional_or_keyword"),),
-                                ...))
+            self.assertEqual(C(1), (2, C, 1))
+            self.assertEqual(self.signature(C),
+                            ((('b', ..., ..., "positional_or_keyword"),),
+                            ...))
 
         with self.subTest('partialmethod'):
             class CM(type):
@@ -4024,14 +4022,12 @@ class TestSignatureObject(unittest.TestCase):
 
         with self.subTest('partial'):
             class C:
-                __init__ = functools.partial(lambda x, a: None, 2)
+                __init__ = functools.partial(lambda x, a, b: None, 2)
 
-            with self.assertWarns(FutureWarning):
-                C(1)  # does not raise
-            with self.assertWarns(FutureWarning):
-                self.assertEqual(self.signature(C),
-                                ((('a', ..., ..., "positional_or_keyword"),),
-                                ...))
+            C(1)  # does not raise
+            self.assertEqual(self.signature(C),
+                            ((('b', ..., ..., "positional_or_keyword"),),
+                            ...))
 
         with self.subTest('partialmethod'):
             class C:
@@ -4284,15 +4280,13 @@ class TestSignatureObject(unittest.TestCase):
 
         with self.subTest('partial'):
             class C:
-                __call__ = functools.partial(lambda x, a: (x, a), 2)
+                __call__ = functools.partial(lambda x, a, b: (x, a, b), 2)
 
             c = C()
-            with self.assertWarns(FutureWarning):
-                self.assertEqual(c(1), (2, 1))
-            with self.assertWarns(FutureWarning):
-                self.assertEqual(self.signature(c),
-                                ((('a', ..., ..., "positional_or_keyword"),),
-                                ...))
+            self.assertEqual(c(1), (2, c, 1))
+            self.assertEqual(self.signature(C()),
+                            ((('b', ..., ..., "positional_or_keyword"),),
+                            ...))
 
         with self.subTest('partialmethod'):
             class C: