Per Discord discussion, we're normalizing on a simple `!defined(_LIBCPP_HAS_NO_CONCEPTS)`
so that we can do a big search-and-replace for `!defined(_LIBCPP_HAS_NO_CONCEPTS)`
back into `_LIBCPP_STD_VER > 17` when we're ready to abandon support for concept-syntax-less
compilers.
Differential Revision: https://reviews.llvm.org/D118748
The tests for these are just copy-pasted from the tests for std::{strong,weak,partial}_order,
and then I added an extra clause in each (test_2()) to test the stuff that's not just the same
as std::*_order.
This also includes the fix for https://wg21.link/LWG3465 (which falls naturally out of the
"you must write it three times" style, but I've added test cases for it also).
There is an action item here to go back and give good diagnostics for SFINAE failures
in these CPOs. I've filed this as https://github.com/llvm/llvm-project/issues/53456 .
Differential Revision: https://reviews.llvm.org/D111514
The NFC part of D116809. We still want to enforce this in CI,
but the mechanism for that is still to-be-determined.
Differential Revision: https://reviews.llvm.org/D116809
This does not include `std::compare_*_fallback`; those are coming later.
There's still an open question of how to implement std::strong_order
for `long double`, which has 80 value bits and 48 padding bits on x86-64,
and which is presumably *not* IEEE 754-compliant on PPC64 and so on.
So that part is left unimplemented.
Differential Revision: https://reviews.llvm.org/D110738
Some of these were previously half-implemented in "ordering.h";
now they're all implemented, and tested.
Note that `constexpr` functions are implicitly `inline`, so the
standard wording omits `inline` on these; but Louis and I agree
that that's surprising and it's better to be explicit about it.
Differential Revision: https://reviews.llvm.org/D110515
There's really no reason to even have two different enums here,
but *definitely* we shouldn't have *three*, and they don't need
so many synonymous enumerator values.
Differential Revision: https://reviews.llvm.org/D110516
Implements parts of P1614, including synth-three-way and three way comparison for std::pair.
Reviewed By: #libc, Quuxplusone, Mordante
Differential Revision: https://reviews.llvm.org/D107721
Also, as a fly-by fix, use `inline` directly to define inline variables
(all compilers support it).
Differential Revision: https://reviews.llvm.org/D110208
Implementation of `three_way_comparable` and `three_way_comparable_with` concepts from <compare> header.
Please note that I have temporarily removed `<compare>` header from `<utility>` due to cyclic dependency that prevents using `<concepts>` header in `<compare>` one.
I tried to quickly resolve those issues including applying suggestions from @cjdb and dive deeper by myself but the problem seems more complicated that we thought initially.
I am in progress to prepare the patch with resolving this cyclic dependency between headers but for now I decided to put all that I have to the review to unblock people that depend on that functionality. At first glance the patch with resolving cyclic dependency is not so small (unless I find the way to make it smaller and cleaner) so I don't want to mix everything to one review.
Reviewed By: ldionne, cjdb, #libc, Quuxplusone
Differential Revision: https://reviews.llvm.org/D103478
Arthur O'Dwyer