P0533R9: `constexpr` for `<cmath>` and `<cstdlib>`

[ldionne]

Link: https://wg21.link/P0533R9

Absolute values

• abs (int/long/long long/float/double/long double) — [libc++][math] Add constexpr for std::abs() #146633, [libc++][math] Add constexpr for std::abs() and relatives #202985
• labs, llabs
• fabs, fabsf, fabsl

Integer division

• div, ldiv, lldiv — [libc++][math] Implement C++23 (parts of) P0533: constexpr std::div() #104633

Manipulation functions

• frexp, frexpf, frexpl
• ilogb, ilogbf, ilogbl
• ldexp, ldexpf, ldexpl
• logb, logbf, logbl
• modf, modff, modfl
• scalbn, scalbnf, scalbnl
• scalbln, scalblnf, scalblnl

Rounding functions

• ceil, ceilf, ceill
• floor, floorf, floorl
• round, roundf, roundl
• lround, lroundf, lroundl
• llround, llroundf, llroundl
• trunc, truncf, truncl

Remainder / difference functions

• fmod, fmodf, fmodl
• remainder, remainderf, remainderl
• remquo, remquof, remquol
• fdim, fdimf, fdiml

Sign / nearest-value functions

• copysign, copysignf, copysignl
• nextafter, nextafterf, nextafterl
• nexttoward, nexttowardf, nexttowardl

Min / max / fma

• fmax, fmaxf, fmaxl
• fmin, fminf, fminl
• fma, fmaf, fmal

Classification / comparison functions

• fpclassify [libc++][math] Add constexpr to std::fpclassify #210993
• isfinite — 52bff45
• isinf — 52bff45
• isnan — 52bff45
• isnormal — 52bff45
• signbit — [libc++][math] Add constexpr for std::signbit() #105946
• isgreater — [libc++][math] Add constexpr to comparison functions #210075
• isgreaterequal — [libc++][math] Add constexpr to comparison functions #210075
• isless — [libc++][math] Add constexpr to comparison functions #210075
• islessequal — [libc++][math] Add constexpr to comparison functions #210075
• islessgreater — [libc++][math] Add constexpr to comparison functions #210075
• isunordered — [libc++][math] Add constexpr to comparison functions #210075

BEGIN-RST-NOTES
``isfinite``, ``isinf``, ``isnan`` and ``isnormal`` are implemented
END-RST-NOTES

[lknknm]

@ldionne should we link the tracking status of the implementations to the body of this issue as suggested in #139885 (comment)? Maybe it will make it easier for implementors to check the current status and link PRs to checkboxes (similar to what was done in the nodiscard initiative), or at least the GoogleDocs link provided by @0w0zzzzzz ?

[ldionne]

@lknknm See above! I think they should all be covered.

I didn't create sub-issues for now, but we could also do that if that makes it easier. The problem here is that I'm not certain what granularity you'd want for these issues.

[lknknm]

@ldionne Super nice! Thanks!

The granularity seems fine. I'm wondering if is there any way to track the specific clang Builtins towards this issue. I see they are usually listed down in clang/include/clang/Basic/Builtins.td but I'm not sure if we should propose a relation with the ones specific to this paper in the issue like you did.

It could be as simple as:

• frexp, frexpf, frexpl – constexpr builtin available/not available

When someone opens a PR:

• frexp, frexpf, frexpl – [PR link]

Wdyt? If you want you can allow me editing this issue to include them.