[3.11] gh-105080: Fixed inconsistent signature on derived classes (GH… (#105274)
diff --git a/Lib/inspect.py b/Lib/inspect.py
index 14569a5..655b04b 100644
--- a/Lib/inspect.py
+++ b/Lib/inspect.py
@@ -2538,17 +2538,18 @@
factory_method = None
new = _signature_get_user_defined_method(obj, '__new__')
init = _signature_get_user_defined_method(obj, '__init__')
- # Now we check if the 'obj' class has an own '__new__' method
- if '__new__' in obj.__dict__:
- factory_method = new
- # or an own '__init__' method
- elif '__init__' in obj.__dict__:
- factory_method = init
- # If not, we take inherited '__new__' or '__init__', if present
- elif new is not None:
- factory_method = new
- elif init is not None:
- factory_method = init
+
+ # Go through the MRO and see if any class has user-defined
+ # pure Python __new__ or __init__ method
+ for base in obj.__mro__:
+ # Now we check if the 'obj' class has an own '__new__' method
+ if new is not None and '__new__' in base.__dict__:
+ factory_method = new
+ break
+ # or an own '__init__' method
+ elif init is not None and '__init__' in base.__dict__:
+ factory_method = init
+ break
if factory_method is not None:
sig = _get_signature_of(factory_method)
diff --git a/Lib/test/test_inspect.py b/Lib/test/test_inspect.py
index 2783f7f..fb4cba0 100644
--- a/Lib/test/test_inspect.py
+++ b/Lib/test/test_inspect.py
@@ -3688,6 +3688,24 @@
self.assertEqual(signature_func(foo), inspect.Signature())
self.assertEqual(inspect.get_annotations(foo), {})
+ def test_signature_on_derived_classes(self):
+ # gh-105080: Make sure that signatures are consistent on derived classes
+
+ class B:
+ def __new__(self, *args, **kwargs):
+ return super().__new__(self)
+ def __init__(self, value):
+ self.value = value
+
+ class D1(B):
+ def __init__(self, value):
+ super().__init__(value)
+
+ class D2(D1):
+ pass
+
+ self.assertEqual(inspect.signature(D2), inspect.signature(D1))
+
class TestParameterObject(unittest.TestCase):
def test_signature_parameter_kinds(self):
diff --git a/Misc/NEWS.d/next/Library/2023-06-02-02-38-26.gh-issue-105080.2imGMg.rst b/Misc/NEWS.d/next/Library/2023-06-02-02-38-26.gh-issue-105080.2imGMg.rst
new file mode 100644
index 0000000..efe8365
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2023-06-02-02-38-26.gh-issue-105080.2imGMg.rst
@@ -0,0 +1 @@
+Fixed inconsistent signature on derived classes for :func:`inspect.signature`
