inspect.getsource does not work for a class-defined code object

[blhsing]

Bug report

Bug description:

In the following MRE, code.co_firstlineno correctly returns 4, the first line number of the class definition, but getsource(code) returns the content of the entire file:

import sys
from inspect import getsource

class A:
    code = sys._getframe(0).f_code
    print(code.co_firstlineno)
    print(getsource(code))

This is because inspect.findsource uses a regex pattern that does not match class:

cpython/Lib/inspect.py

Line 1155 in a8e93d3

pat = re.compile(r'^(\s*def\s)|(\s*async\s+def\s)|(.*(?<!\w)lambda(:|\s))|^(\s*@)')

CPython versions tested on:

3.12

Operating systems tested on:

Linux, Windows

Linked PRs

• gh-116987: Remove re pattern check in inspect.findsource as it's not needed anymore #117025