I found this while writing up a separate bug (CPython doesn't use static analysis!).


In _ctypes/cfield.c, Z_set has a bug of some sort:

    if (PyLong_Check(value) || PyLong_Check(value)) {

See: https://hg.python.org/cpython/file/tip/Modules/_ctypes/cfield.c#l1378

...which has been there for at least 5 years: https://hg.python.org/cpython/rev/cab14be0ada1


I'm not sure what the original programmer meant - it's been around forever & I don't know what was there before it - but PyLong_Check(value) is evaluated twice. Which doesn't really make sense.

Compiling with /analyze found this quite easily:

c:\pythondev\repo\modules\_ctypes\cfield.c(1378): warning C6287: Redundant code:  the left and right sub-expressions are identical.



There's a similar issue in P_set, at line 1486.

Looks like a result of searching and replacing PyInt with PyLong - the diff can be found here, if anyone cares. https://hg.python.org/cpython-fullhistory/rev/f324631462a2.

Oddly, there was _another, older_ revision that fixed this correctly: https://hg.python.org/cpython-fullhistory/rev/003d35215ef2 - looks like there was a bad merge somewhere along the line.

Sorry, my mistake, I was looking at z_set instead of Z_set. The earlier fix had left Z_set out for some reason. Anyway, just some historical interest anyway.

New changeset 26859a7e385c by Martin Panter in branch '3.5':
Issue #25845: Drop redundant checks leftover from int to long conversion
https://hg.python.org/cpython/rev/26859a7e385c

New changeset 9be59ad8af80 by Martin Panter in branch 'default':
Issue #25845: Merge PyLong_Check() cleanup from 3.5
https://hg.python.org/cpython/rev/9be59ad8af80

History is good for understanding how things became the way they are. :) Thanks Alexander and Random!