Issue 24298: Fix signature() to properly unwrap wrappers around bound methods

1 files changed, 8 insertions, 0 deletions

diff --git a/Lib/inspect.py b/Lib/inspect.py
index a91f749..49e66ce 100644
--- a/Lib/inspect.py
+++ b/Lib/inspect.py
@@ -1911,6 +1911,14 @@ def _signature_internal(obj, follow_wrapper_chains=True, skip_bound_arg=True):
     # Was this function wrapped by a decorator?
     if follow_wrapper_chains:
         obj = unwrap(obj, stop=(lambda f: hasattr(f, "__signature__")))
+        if isinstance(obj, types.MethodType):
+            # If the unwrapped object is a *method*, we might want to
+            # skip its first parameter (self).
+            # See test_signature_wrapped_bound_method for details.
+            return _signature_internal(
+                obj,
+                follow_wrapper_chains=follow_wrapper_chains,
+                skip_bound_arg=skip_bound_arg)
 
     try:
         sig = obj.__signature__