It doesn't serve much of a purpose since we can easily put its contents
inside __config. Removing it simplifies the modulemap once we are trying
to create a single top-level module.
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.
I don't know when, but at some point we lost test coverage to ensue that
all the headers are in the modulemap. This adds a test to make sure all
the headers (excluding a few which shouldn't be part of the modulemap)
are at least mentioned. This also fixes a few headers which bit-rotted
while we were missing the coverage.
[libcxx] <experimental/simd> Added internal storage type for class simd/simd_mask
[libcxx] <experimental/simd> Added all constructors of class simd/simd_mask and related tests
[libcxx] <experimental/simd> Added basic simd reference implementation, subscript operators of class simd/simd_mask and related tests
Reviewed By: #libc, philnik
Differential Revision: https://reviews.llvm.org/D144364
