[Python-checkins] bpo-38026: fix inspect.getattr_static (GH-15676)

[Miss Islington (bot)]

https://github.com/python/cpython/commit/bdcbb83c6640c2b30d0e1a2a497e9ba34cc53b26
commit: bdcbb83c6640c2b30d0e1a2a497e9ba34cc53b26
branch: 3.8
author: Miss Islington (bot) <31488909+miss-islington at users.noreply.github.com>
committer: GitHub <noreply at github.com>
date: 2019-09-04T21:25:59-07:00
summary:

bpo-38026: fix inspect.getattr_static (GH-15676)


It should avoid dynamic lookup including `isinstance`.

This is a regression caused by GH-5351.
(cherry picked from commit 8f9cc8771ffb8d0e21be287eaed42ae06087acca)

Co-authored-by: Inada Naoki <songofacandy at gmail.com>

files:
A Misc/NEWS.d/next/Library/2019-09-04-20-34-14.bpo-38026.0LLRX-.rst
M Lib/inspect.py

diff --git a/Lib/inspect.py b/Lib/inspect.py
index 99a580bd2f23..a616f2d49b7d 100644
--- a/Lib/inspect.py
+++ b/Lib/inspect.py
@@ -1558,7 +1558,7 @@ def _shadowed_dict(klass):
         except KeyError:
             pass
         else:
-            if not (isinstance(class_dict, types.GetSetDescriptorType) and
+            if not (type(class_dict) is types.GetSetDescriptorType and
                     class_dict.__name__ == "__dict__" and
                     class_dict.__objclass__ is entry):
                 return class_dict
@@ -1580,7 +1580,7 @@ def getattr_static(obj, attr, default=_sentinel):
         klass = type(obj)
         dict_attr = _shadowed_dict(klass)
         if (dict_attr is _sentinel or
-            isinstance(dict_attr, types.MemberDescriptorType)):
+            type(dict_attr) is types.MemberDescriptorType):
             instance_result = _check_instance(obj, attr)
     else:
         klass = obj
diff --git a/Misc/NEWS.d/next/Library/2019-09-04-20-34-14.bpo-38026.0LLRX-.rst b/Misc/NEWS.d/next/Library/2019-09-04-20-34-14.bpo-38026.0LLRX-.rst
new file mode 100644
index 000000000000..166cd867514c
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2019-09-04-20-34-14.bpo-38026.0LLRX-.rst
@@ -0,0 +1,2 @@
+Fixed :func:`inspect.getattr_static` used ``isinstance`` while it should
+avoid dynamic lookup.