1013fe3c0cfd7582e94ef2d4bfd79da7ea1a1289 used to implement LWG2770, but
cb0d4df97490ec2d2b1cdf7574d26b1bc4063599 made LWG2770 unimplemented
again because of CWG2386.
This patch re-implements LWG2770, while keeping the libc++-specific
implementation strategy (which is controversial as noted in LWG4040).
Drive-by:
- Make the test coverage for the controversial part noted in LWG4040
libc++-only.
- Add the previously missed entry for LWG2770 to the documentation.
Add a few missing includes, remove two unnecessary ones and use
__cstddef/size_t.h instead of <cstddef> in a few places. This is a
collection of miscellaneous findings that collectively unblock other
modularization patches.
Many headers include `<cstddef>` just for size_t, and pulling in
additional content (e.g. the traits used for std::byte) is unnecessary.
To solve this problem, this patch splits up `<cstddef>` into
subcomponents so that headers can include only the parts that they
actually require.
This has the added benefit of making the modules build a lot stricter
with respect to IWYU, and also providing a canonical location where we
define `std::size_t` and friends (which were previously defined in
multiple headers like `<cstddef>` and `<ctime>`).
After this patch, there's still many places in the codebase where we
include `<cstddef>` when `<__cstddef/size_t.h>` would be sufficient.
This patch focuses on removing `<cstddef>` includes from __type_traits
to make these headers non-circular with `<cstddef>`. Additional
refactorings can be tackled separately.
As time went by, a few files have become mis-formatted w.r.t.
clang-format. This was made worse by the fact that formatting was not
being enforced in extensionless headers. This commit simply brings all
of libcxx/include in-line with clang-format again.
We might have to do this from time to time as we update our clang-format
version, but frankly this is really low effort now that we've formatted
everything once.
This patch runs clang-format on all of libcxx/include and libcxx/src, in
accordance with the RFC discussed at [1]. Follow-up patches will format
the benchmarks, the test suite and remaining parts of the code. I'm
splitting this one into its own patch so the diff is a bit easier to
review.
This patch was generated with:
find libcxx/include libcxx/src -type f \
| grep -v 'module.modulemap.in' \
| grep -v 'CMakeLists.txt' \
| grep -v 'README.txt' \
| grep -v 'libcxx.imp' \
| grep -v '__config_site.in' \
| xargs clang-format -i
A Git merge driver is available in libcxx/utils/clang-format-merge-driver.sh
to help resolve merge and rebase issues across these formatting changes.
[1]: https://discourse.llvm.org/t/rfc-clang-formatting-all-of-libc-once-and-for-all
Rename the `__tuple` directory in libc++ headers to `__tuple_dir`
to avoid file collision when installing. Historically, `__tuple` has
been a file and it has been replaced by a directory
in 2d52c6bfae801b016dd3627b8c0e7c4a99405549. Replacing a regular file
with a directory (or more importantly, the other way around when
downgrading) is not universally supported. Since this is an internal
header, its actual name should not matter, so just rename it to avoid
problems.
Differential Revision: https://reviews.llvm.org/D139270
