gh-127271: Remove the PyCell_Get usage for framelocalsproxy #130383
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| PyObject *value = framelocalsproxy_getval(frame->f_frame, co, i); | ||
| assert(value != NULL); |
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This doesn't look safe to me. I don't think we can rely on consistency between the earlier framelocalsproxy_getkeyindex call and the framelocalsproxy_getval here.
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Do you mean a very specific case where the content of the cell on that index is set to NULL by PyCell_Set from another thread? I think that's probably an outlier. If it's a normal fast variable, can it happen? Multi-threading can't affect the local fast variables on stack right?
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Yeah, I'm just thinking about the cell case.
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The normal Python operation won't set NULL to a cell right? So we should maybe raise some exception here if the value is NULL? That's the only case I can think of.
Co-authored-by: Sam Gross <[email protected]>
In #127272 a
PyCell_Getusage inframeobject.cwas missed from being replaced for free-threaded safety. I guess the reason was probably the function was labelled to return a borrowed reference and a deeper understanding of the piece of code is needed to make that change. (or maybe I'm just thinking too much and it just slipped away :))I made the change to use
PyCell_GetRefand changed the function to return a new reference (because otherwise it won't be safe in free-threaded build). However, there are a few places in the code where it does not care about the actual value stored, it only cares whether such value exists - so I added a util function to avoid havingPy_XDECREFs all around the code.