Compiler warning for _Py_InIntegralTypeRange

[brettcannon]

Bug report

Python/pytime.c:297:10: warning: implicit conversion from 'long' to 'double' changes value from 9223372036854775807 to 9223372036854775808 [-Wimplicit-int-float-conversion]
    if (!_Py_InIntegralTypeRange(time_t, intpart)) {
         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
./Include/internal/pycore_pymath.h:72:45: note: expanded from macro '_Py_InIntegralTypeRange'
    (_Py_IntegralTypeMin(type) <= v && v <= _Py_IntegralTypeMax(type))
                                         ~~ ^~~~~~~~~~~~~~~~~~~~~~~~~
./Include/internal/pycore_pymath.h:61:88: note: expanded from macro '_Py_IntegralTypeMax'
    (_Py_IS_TYPE_SIGNED(type) ? (((((type)1 << (sizeof(type)*CHAR_BIT - 2)) - 1) << 1) + 1) : ~(type)0)
                                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~
Python/pytime.c:352:14: warning: implicit conversion from 'long' to 'double' changes value from 9223372036854775807 to 9223372036854775808 [-Wimplicit-int-float-conversion]
        if (!_Py_InIntegralTypeRange(time_t, intpart)) {
             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
./Include/internal/pycore_pymath.h:72:45: note: expanded from macro '_Py_InIntegralTypeRange'
    (_Py_IntegralTypeMin(type) <= v && v <= _Py_IntegralTypeMax(type))
                                         ~~ ^~~~~~~~~~~~~~~~~~~~~~~~~
./Include/internal/pycore_pymath.h:61:88: note: expanded from macro '_Py_IntegralTypeMax'
    (_Py_IS_TYPE_SIGNED(type) ? (((((type)1 << (sizeof(type)*CHAR_BIT - 2)) - 1) << 1) + 1) : ~(type)0)
                                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~
Python/pytime.c:518:10: warning: implicit conversion from 'long' to 'double' changes value from 9223372036854775807 to 9223372036854775808 [-Wimplicit-int-float-conversion]
    if (!_Py_InIntegralTypeRange(_PyTime_t, d)) {
         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
./Include/internal/pycore_pymath.h:72:45: note: expanded from macro '_Py_InIntegralTypeRange'
    (_Py_IntegralTypeMin(type) <= v && v <= _Py_IntegralTypeMax(type))
                                         ~~ ^~~~~~~~~~~~~~~~~~~~~~~~~
./Include/internal/pycore_pymath.h:61:88: note: expanded from macro '_Py_IntegralTypeMax'
    (_Py_IS_TYPE_SIGNED(type) ? (((((type)1 << (sizeof(type)*CHAR_BIT - 2)) - 1) << 1) + 1) : ~(type)0)
                                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~
3 warnings generated.

Your environment

• CPython main (3.11.0rc2 time frame)
• clang 10

Linked PRs

• gh-97786: Fix compiler warnings in pytime.c #101826
• [3.11] gh-97786: Fix compiler warnings in pytime.c (GH-101826) #102062
• [3.10] gh-97786: Fix compiler warnings in pytime.c (GH-101826) #102150

[brettcannon]

Reported for WebAssembly builds at #97786 .

[vstinner]

See also #83458.

This bug was one of my motivations to add math.nextafter() and math.ulp(), to help me understanding this issue :-D

[vstinner]

See also #78604.

[vstinner]

My abandonned attempt to fix this warning using nextafter(): PR #17933. I abandonned my PR because I didn't have time to work on it.

[gpshead]

cc: @mdickinson as a numeric details expert

[mdickinson]

I had half a solution to this at one point (the nextafter-based solution looks attractive in principle, but doesn't end up doing the right thing, unfortunately); I can try to pick this up if that's helpful. I'm out of cycles for this weekend, though, so it won't be before next weekend.

[gpshead]

this warning has been around a while, no rush. I just figured you're the best to understand it.

clang on any platform will reproduce it.

[arhadthedev]

The issue seems to be fixed. Should it be closed then?