`inspect.getsource` regressions for functions decorated with multi-line `@(...)` decorators.

[yilei]

Bug report

Bug description:

Here is the code snippet:

import inspect
import sys


def decorator_builder(**kwargs):
    class DecoratorChain:
        def __init__(self, **kw):
            self.kwargs = kw

        def with_option(self, value):
            self.kwargs["option"] = value
            return self

        def __call__(self, fn):
            return fn

    return DecoratorChain(**kwargs)


@(
    decorator_builder(
        version=1,
        name="example",
    ).with_option("test")
)
def function():
    return "hello"


print("Source is:")
print(inspect.getsource(function))

On Python 3.12, the output is expected:

Source is:
@(
    decorator_builder(
        version=1,
        name="example",
    ).with_option("test")
)
def function():
    return "hello"

On Python 3.13.7, the output is missing the first line @(:

Source is:
    decorator_builder(
        version=1,
        name="example",
    ).with_option("test")
)
def function():
    return "hello"

On Python 3.13.9 and current main branch, the output just contains the lines inside @(...):

Source is:
    decorator_builder(
        version=1,
        name="example",
    ).with_option("test")

I bisected the changes:

1. inspect.getsource does not work for a class-defined code object #116987 resulted in the missing @( first line.
2. gh-137477: Fix inspect.getblock() for generator expressions #137488 (and the [3.13] gh-137477: Fix inspect.getblock() for generator expressions (GH-137488) #137995 backport) resulted in containing only the lines inside @(...)

CPython versions tested on:

3.13, 3.14, CPython main branch

Operating systems tested on:

Linux

[picnixz]

It could be a duplicate of #139838.

[picnixz]

cc @serhiy-storchaka

[serhiy-storchaka]

Yes, this is a duplicate of #139838. Although this is more realistic use case which can occur in real code.

[picnixz]

I'm closing this one but forwards the repro