Some embedded platforms do not wish to support the C library functionality
for handling wchar_t because they have no use for it. It makes sense for
libc++ to work properly on those platforms, so this commit adds a carve-out
of functionality for wchar_t.
Unfortunately, unlike some other carve-outs (e.g. random device), this
patch touches several parts of the library. However, despite the wide
impact of this patch, I still think it is important to support this
configuration since it makes it much simpler to port libc++ to some
embedded platforms.
Differential Revision: https://reviews.llvm.org/D111265
Implement P1391 (https://wg21.link/p1391) which allows
`std::string_view` to be constructible from any contiguous range of
characters.
Note that a different paper (http://wg21.link/P1989) handles the generic
range constructor for `std::string_view`.
Reviewed By: ldionne, Quuxplusone, Mordante, #libc
Differential Revision: https://reviews.llvm.org/D110718
Adds MAKE_CSTRING and makes the operators of `MultiStringType` `constexpr`.
The code is copied from D96664 so it can be used in D80895.
Differential Revision: https://reviews.llvm.org/D102414
These function makes it easier to write generic unit tests for the
format header. It solves the issue where it's not possible to use
`templated_prefix"foo"`
where `templated_prefix` resolves to: nothing, `L`, `u8`, `u`,
or `U`. The templated_prefix would be more faster during execution.
Reviewed By: ldionne, #libc, curdeius
Differential Revision: https://reviews.llvm.org/D93414
Louis Dionne