All supported compilers that support C++20 now support concepts. So, remove
`_LIB_LIBCPP_HAS_NO_CONCEPTS` in favor of `_LIBCPP_STD_VER > 17`. Similarly in
the tests, remove `// UNSUPPORTED: libcpp-no-concepts`.
Differential Revision: https://reviews.llvm.org/D121528
The logic here is that we are disabling *only* things in `std::ranges::`.
Everything in `std::` is permitted, including `default_sentinel`, `contiguous_iterator`,
`common_iterator`, `projected`, `swappable`, and so on. Then, we include
anything from `std::ranges::` that is required in order to make those things
work: `ranges::swap`, `ranges::swap_ranges`, `input_range`, `ranges::begin`,
`ranges::iter_move`, and so on. But then that's all. Everything else (including
notably all of the "views" and the `std::views` namespace itself) is still
locked up behind `_LIBCPP_HAS_NO_INCOMPLETE_RANGES`.
Differential Revision: https://reviews.llvm.org/D118736
- add some test cases for `cbegin`/`cend`;
- make class definitions generally follow the order in which they are
used;
- add a missing include.
Reviewed By: philnik
Differential Revision: https://reviews.llvm.org/D119214
var-const points out that `ranges::begin` is (non-normatively
but explicitly) always supposed to return a `std::input_or_output_iterator`,
and `Incomplete*` is not a `std::input_or_output_iterator` because it
has no `operator++`. Therefore, we should never return `Incomplete*`
from `ranges::begin(x)`, even when `x` is `Incomplete(&)[]`. Instead,
just SFINAE away.
Differential Revision: https://reviews.llvm.org/D118963
For example, `std::ranges::range<Holder<Incomplete>*>` should be
well-formed false, not a hard error at compile time.
Differential Revision: https://reviews.llvm.org/D116239
The big change here is that they now work as intended for rvalues,
e.g. `ranges::cbegin(std::string_view("hello"))`.
Also, add tests verifying their return types.
Differential Revision: https://reviews.llvm.org/D116199
Joe Loser