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List comprehensions cause subinterpreter crashes #135450
Description
Crash report
What happened?
If you use any list comprehension inside a subinterpreter (either through _interpreters or through interpreters), an assertion fails in _PyCode_CheckNoExternalState:
import _interpreters
interp = _interpreters.create()
_interpreters.run_string(interp, "[None for _ in []]")python: Objects/codeobject.c:1982: _PyCode_CheckNoExternalState: Assertion `counts->locals.hidden.total == 0' failed.
This was originally causing failures in #134606. I think that assertion can be removed, because _PyCode_CheckNoExternalState seems to have no need for the number of hidden locals being zero.
CPython versions tested on:
CPython main branch
Operating systems tested on:
Linux
Output from running 'python -VV' on the command line:
No response
Activity
ericsnowcurrently commentedon Jun 13, 2025
I added that assertion with the gut instinct that we'd have to remove it. It just wasn't clear to me at the time where to expect hidden variables relative to "external" state in a code object. Comprehensions make sense. Thanks for identifying this.
ZeroIntensity commentedon Jun 13, 2025
Ok, yeah, that makes sense. I kept staring at that assertion trying to figure out why the function wanted that as a precondition. Thanks for the insight!
gh-135450: Remove assertion in `_PyCode_CheckNoExternalState` (gh-135466
pythongh-135450: Remove assertion in `_PyCode_CheckNoExternalState` (p…
[3.14] gh-135450: Remove assertion in `_PyCode_CheckNoExternalState` (g…
ericsnowcurrently commentedon Jun 19, 2025
Thanks for the fix, @ZeroIntensity.
pythongh-135450: Remove assertion in `_PyCode_CheckNoExternalState` (p…
pythongh-135450: Remove assertion in `_PyCode_CheckNoExternalState` (p…
pythongh-135450: Remove assertion in `_PyCode_CheckNoExternalState` (p…
pythongh-135450: Remove assertion in `_PyCode_CheckNoExternalState` (p…