Improve comment for co_nlocalsplus #126993
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ZeroIntensity
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Nov 19, 2024
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Summary:
In CPython's code.h it says of `PyCodeObject::co_nlocalsplus`:
```
int co_nlocalsplus; /* number of local + cell + free variables */
```
This turns out to be very misleading - it IS the number of those variables but that number is not equal to the sum of the count of each type. The reason for this is some variables can be both a local and a cell.
For more context see: https://github.com/python/cpython/blob/d6b3e78504b3168c432b20002dbcf8ec9a435e61/Objects/codeobject.c#L334
PR up to fix the comment: python/cpython#126993
Reviewed By: martindemello
Differential Revision: D66140761
fbshipit-source-id: 635e6d01616ac27c56af8159590283ab5ffbf0e1
DinoV
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Nov 21, 2024
ebonnal
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Jan 12, 2025
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I just spent several hours fixing a bug in the Cinder JIT as a result of a misunderstanding of the value of
co_nlocalsplus. The existing comment impliedco_nlocalsplusis just the literal sum ofco_nlocals+co_ncellvars+co_nfreevars. However, this is not the case. It may be smaller than this as locals can also be cells.