From 83aef4d34022f293336f606dba8598cc7ac8f9f2 Mon Sep 17 00:00:00 2001
From: "Miss Islington (bot)"
 <31488909+miss-islington@users.noreply.github.com>
Date: Sat, 22 Jan 2022 09:28:48 -0800
Subject: [PATCH] bpo-43118: Fix bug in inspect.signature around
 'base.__text_signature__' (GH-30285) (#30765)

(cherry picked from commit 881a763cfe07ef4a5806ec78f13a9bc99e8909dc)

Co-authored-by: Weipeng Hong <hongweichen8888@sina.com>

Co-authored-by: Weipeng Hong <hongweichen8888@sina.com>
---
 Lib/inspect.py                                        |  4 ++--
 Lib/test/ann_module7.py                               | 11 +++++++++++
 Lib/test/test_inspect.py                              | 11 +++++++++++
 .../Library/2021-12-29-14-42-09.bpo-43118.BoVi_5.rst  |  3 +++
 4 files changed, 27 insertions(+), 2 deletions(-)
 create mode 100644 Lib/test/ann_module7.py
 create mode 100644 Misc/NEWS.d/next/Library/2021-12-29-14-42-09.bpo-43118.BoVi_5.rst

diff --git a/Lib/inspect.py b/Lib/inspect.py
index 6d43d8dad46b99..c5881cc808d21a 100644
--- a/Lib/inspect.py
+++ b/Lib/inspect.py
@@ -2511,9 +2511,9 @@ def _signature_from_callable(obj, *,
                     pass
                 else:
                     if text_sig:
-                        # If 'obj' class has a __text_signature__ attribute:
+                        # If 'base' class has a __text_signature__ attribute:
                         # return a signature based on it
-                        return _signature_fromstr(sigcls, obj, text_sig)
+                        return _signature_fromstr(sigcls, base, text_sig)
 
             # No '__text_signature__' was found for the 'obj' class.
             # Last option is to check if its '__init__' is
diff --git a/Lib/test/ann_module7.py b/Lib/test/ann_module7.py
new file mode 100644
index 00000000000000..8f890cd28025be
--- /dev/null
+++ b/Lib/test/ann_module7.py
@@ -0,0 +1,11 @@
+# Tests class have ``__text_signature__``
+
+from __future__ import annotations
+
+DEFAULT_BUFFER_SIZE = 8192
+
+class BufferedReader(object):
+    """BufferedReader(raw, buffer_size=DEFAULT_BUFFER_SIZE)\n--\n\n
+    Create a new buffered reader using the given readable raw IO object.
+    """
+    pass
diff --git a/Lib/test/test_inspect.py b/Lib/test/test_inspect.py
index 545dab5c6348f7..28e4f5b4a718a4 100644
--- a/Lib/test/test_inspect.py
+++ b/Lib/test/test_inspect.py
@@ -4218,6 +4218,17 @@ def func(*args, **kwargs):
         sig = inspect.signature(func)
         self.assertEqual(str(sig), '(self, a, b=1, /, *args, c, d=2, **kwargs)')
 
+    def test_base_class_have_text_signature(self):
+        # see issue 43118
+        from test.ann_module7 import BufferedReader
+        class MyBufferedReader(BufferedReader):
+            """buffer reader class."""
+
+        text_signature = BufferedReader.__text_signature__
+        self.assertEqual(text_signature, '(raw, buffer_size=DEFAULT_BUFFER_SIZE)')
+        sig = inspect.signature(MyBufferedReader)
+        self.assertEqual(str(sig), '(raw, buffer_size=8192)')
+
 
 class NTimesUnwrappable:
     def __init__(self, n):
diff --git a/Misc/NEWS.d/next/Library/2021-12-29-14-42-09.bpo-43118.BoVi_5.rst b/Misc/NEWS.d/next/Library/2021-12-29-14-42-09.bpo-43118.BoVi_5.rst
new file mode 100644
index 00000000000000..a37c22cd78c098
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2021-12-29-14-42-09.bpo-43118.BoVi_5.rst
@@ -0,0 +1,3 @@
+Fix a bug in :func:`inspect.signature` that was causing it to fail on some
+subclasses of classes with a ``__text_signature__`` referencing module
+globals. Patch by Weipeng Hong.