Bug report

help() output oflambda with manually set__annotations__ is slightly scrambled.

f = lambda a, b, c: 0              # lambdas cannot have annotationsf.__annotations__['return'] = int  # but you can set them manuallyhelp(f)                            # superfluous ")" and missed last char# <lambda> lambda a, b, c) -> inimport inspectprint(inspect.signature(f))        # correctly displays# (a, b, c) -> int

Note

This is a minor glitch for an atypical (perhaps even unsupported) use of annotations.

Hypothesis

Perhapshelp() uses (the same logic as)inspect.signature() and (to reflectlambda syntax) wants to drop the brackets "(...)", but then has aone-off error for its text slice (picking") -> in" instead of" -> int")

Environment

• CPython versions tested on: 3.6.8 - 3.11.4, 3.12.0b4
• Operating system and architecture: Windows 11

Linked PRs

• gh-107155: Fixhelp(lambda_func) whenlambda_func has `__annotati… #107401
• [3.12] gh-107155: Fix help() for lambda function with return annotati… #115612
• [3.11] gh-107155: Fix help() for lambda function with return annotati… #115613