[3.7] bpo-36492: Fix passing special keyword arguments to some functions. (GH-12637) (GH-12645)

The following arguments can be passed as keyword arguments for passing
to other function if the corresponding required argument is passed as
positional:

- "func" in functools.partialmethod(), weakref.finalize(),
  profile.Profile.runcall(), cProfile.Profile.runcall(),
  bdb.Bdb.runcall(), trace.Trace.runfunc() and
  curses.wrapper().
- "function" in unittest.addModuleCleanup() and
  unittest.TestCase.addCleanup().
- "fn" in the submit() method of concurrent.futures.ThreadPoolExecutor
  and concurrent.futures.ProcessPoolExecutor.
- "callback" in contextlib.ExitStack.callback(),
  contextlib.AsyncExitStack.callback() and
  contextlib.AsyncExitStack.push_async_callback().
- "c" and "typeid" in multiprocessing.managers.Server.create().
- "obj" in weakref.finalize().

(cherry picked from commit 42a139ed88c487f325a241c6ee8b308b3c045975)

1 files changed, 14 insertions, 1 deletions

diff --git a/Lib/functools.py b/Lib/functools.py
index b734899b56..1daa1d1775 100644
--- a/Lib/functools.py
+++ b/Lib/functools.py
@@ -323,7 +323,20 @@ class partialmethod(object):
     callables as instance methods.
     """
 
-    def __init__(self, func, *args, **keywords):
+    def __init__(*args, **keywords):
+        if len(args) >= 2:
+            self, func, *args = args
+        elif not args:
+            raise TypeError("descriptor '__init__' of partialmethod "
+                            "needs an argument")
+        elif 'func' in keywords:
+            func = keywords.pop('func')
+            self, *args = args
+        else:
+            raise TypeError("type 'partialmethod' takes at least one argument, "
+                            "got %d" % (len(args)-1))
+        args = tuple(args)
+
         if not callable(func) and not hasattr(func, "__get__"):
             raise TypeError("{!r} is not callable or a descriptor"
                                  .format(func))