use __qualname__ to compute bound method repr (closes #21389)

Patch from Steven Barker.

Lib/test/test_descr.py

@@ -4423,6 +4423,61 @@ order (MRO) for bases """
         self.assertIn("__dict__", Base.__dict__)
         self.assertNotIn("__dict__", Sub.__dict__)
 
+    def test_bound_method_repr(self):
+        class Foo:
+            def method(self):
+                pass
+        self.assertRegex(repr(Foo().method),
+            r"<bound method .*Foo\.method of <.*Foo object at .*>>")
+
+
+        class Base:
+            def method(self):
+                pass
+        class Derived1(Base):
+            pass
+        class Derived2(Base):
+            def method(self):
+                pass
+        base = Base()
+        derived1 = Derived1()
+        derived2 = Derived2()
+        super_d2 = super(Derived2, derived2)
+        self.assertRegex(repr(base.method),
+            r"<bound method .*Base\.method of <.*Base object at .*>>")
+        self.assertRegex(repr(derived1.method),
+            r"<bound method .*Base\.method of <.*Derived1 object at .*>>")
+        self.assertRegex(repr(derived2.method),
+            r"<bound method .*Derived2\.method of <.*Derived2 object at .*>>")
+        self.assertRegex(repr(super_d2.method),
+            r"<bound method .*Base\.method of <.*Derived2 object at .*>>")
+
+        class Foo:
+            @classmethod
+            def method(cls):
+                pass
+        foo = Foo()
+        self.assertRegex(repr(foo.method), # access via instance
+            r"<bound method .*Foo\.method of <class '.*Foo'>>")
+        self.assertRegex(repr(Foo.method), # access via the class
+            r"<bound method .*Foo\.method of <class '.*Foo'>>")
+
+
+        class MyCallable:
+            def __call__(self, arg):
+                pass
+        func = MyCallable() # func has no __name__ or __qualname__ attributes
+        instance = object()
+        method = types.MethodType(func, instance)
+        self.assertRegex(repr(method),
+            r"<bound method \? of <object object at .*>>")
+        func.__name__ = "name"
+        self.assertRegex(repr(method),
+            r"<bound method name of <object object at .*>>")
+        func.__qualname__ = "qualname"
+        self.assertRegex(repr(method),
+            r"<bound method qualname of <object object at .*>>")
+
 
 class DictProxyTests(unittest.TestCase):
     def setUp(self):