Crash on invalid type parameter bound expression in conditional block

[StanFromIreland]

Crash report

What happened?

Found by the cpython3 fuzzer, see https://oss-fuzz.com/testcase-detail/5164455094976512.

>>> try:a
... finally:
...  class h[l:{7for*()in 0}]:2
python: Python/compile.c:1163: _PyCompile_LeaveConditionalBlock: Assertion `c->u->u_in_conditional_block > 0' failed.
            Aborted (core dumped)

I think I know how to fix it, I will open a PR.

CPython versions tested on:

CPython main branch

Operating systems tested on:

Linux

Output from running 'python -VV' on the command line:

No response

Linked PRs

• gh-145187: Fix crash on invalid type parameter bound expression in conditional block #145188
• [3.14] gh-145187: Fix crash on invalid type parameter bound expression in conditional block (GH-145188) #145196

[gpshead]

i could reproduce it on debug builds of 3.14 but not 3.13 so I triggered the 3.14 backport. thanks for the fix!