Mark Dickinson added the comment:
Thanks for this. I took a look at the 5 reports for Objects/longobject.c, and I
don't think there's any action to be taken on any of them. (Two false
positives; two "dead assignments" that are used when asserts are enabled, and
one division-by-zero that depends on a function being called in a way that
never happens in practice.)
* Objects/longobject.c:2823 Assigned value is garbage or undefined
This is a false positive. Here we have:
a_bits <= a_size * PyLongShift
shift_digits = (a_bits - DBL_MANT_DIG - 2) / PyLong_SHIFT;
and then we call v_rshift(x_digits, ..., a_size - shift_digits, ...), which
fills the first a_size - shift_digits entries of x_digits. Since DBL_MANT_DIG
>= PyLong_SHIFT, we have shift_digits < a_size, so x_digits[0] is always
initialised by v_rshift.
* Objects/longobject.c:2723 Dead assignment
The value of the assignment is used in a following assert statement; I don't
think this should be changed.
* Objects/longobject.c:2463 Dead assignment
Again, the value of the assignment is used in an assert.
* Objects/longobject.c:1828 Division by zero
This function will never get called with bits=0. There are asserts to check
this.
* Objects/longobject.c:2830 Assigned value is garbage or undefined
This is another false positive, similar to the first one. Analysing the
arithmetic shows that x_digits[0] is always defined.
----------
nosy: +mark.dickinson
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Python tracker <rep...@bugs.python.org>
<http://bugs.python.org/issue30287>
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