diff options
Diffstat (limited to 'Include/internal/pycore_pymath.h')
| -rw-r--r-- | Include/internal/pycore_pymath.h | 11 |
1 files changed, 9 insertions, 2 deletions
diff --git a/Include/internal/pycore_pymath.h b/Include/internal/pycore_pymath.h index c299c64..e4d5778 100644 --- a/Include/internal/pycore_pymath.h +++ b/Include/internal/pycore_pymath.h @@ -19,8 +19,15 @@ extern "C" { * effect, we're trying to force a useful implementation of C89 errno * behavior. * Caution: - * This isn't reliable. See Py_OVERFLOWED comments. - * X and Y may be evaluated more than once. + * This isn't reliable. C99 no longer requires libm to set errno under + * any exceptional condition, but does require +- HUGE_VAL return + * values on overflow. A 754 box *probably* maps HUGE_VAL to a + * double infinity, and we're cool if that's so, unless the input + * was an infinity and an infinity is the expected result. A C89 + * system sets errno to ERANGE, so we check for that too. We're + * out of luck if a C99 754 box doesn't map HUGE_VAL to +Inf, or + * if the returned result is a NaN, or if a C89 box returns HUGE_VAL + * in non-overflow cases. */ static inline void _Py_ADJUST_ERANGE1(double x) { |