DISCLAIMER: First time contribution to cPython itself. I have read thru the contribution guide, but please LMK if I am missing anything.

This PR fixes an issue where calls inside of a lambda passed to a decorator can prematurely breakout of the current code block when using inspect.getsource (and lower level funcs).

Prior to this PR, the following code would produce an unexpected result (only getting the decorator line of the source code).

from inspect import getsource


def bar(*funcs):
    def decorator(func):
        return func

    return decorator


@bar(lambda x: bool(True), lambda x: False)
def foo():
    ...


print(getsource(foo))

Result:

@bar(lambda x: bool(True), lambda x: False)

This appears to happen because BlockFinder.tokeneater would naively close a decorator after encountering a closing patentheses: ). As stated in the bug report:

... it seems like this requires the following conditions to be true:

• lambdas are passed in decorator arguments
• there is more than one lambda
• at least one of the lambdas has a function call

The change that I made moves BlockFinder.decoratorhasargs to a computed property so that it should at least still be readable without being a breaking change. Please let me know if this (and the change that it introduces) is an acceptable solution.

Also, I opted to make a new inspect_fodder3.py because the alternative (while trying to keep like-code together) meant redoing all of the numbering of ...fodder2.py and a significant number of tests. This seemed a far nicer solution to not have to touch a significant majority of the inspect module tests. Happy to hear if this is acceptable.

https://bugs.python.org/issue46873