[all-commits] [llvm/llvm-project] 762001: [libc++] Do not guard inclusion of wchar.h with _L...

[Steven Cooreman via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 762001118c068317ec67274221497be2e6499c6a
      https://github.com/llvm/llvm-project/commit/762001118c068317ec67274221497be2e6499c6a
  Author: Steven Cooreman <steven.cooreman at gmail.com>
  Date:   2025-02-18 (Tue, 18 Feb 2025)

  Changed paths:
    M libcxx/include/__mbstate_t.h

  Log Message:
  -----------
  [libc++] Do not guard inclusion of wchar.h with _LIBCPP_HAS_WIDE_CHARACTERS (#126924)

`mbstate_t` needs to be visible to libcpp, even when it is not providing
wide
character functionality (i.e. `_LIBCPP_HAS_WIDE_CHARACTERS` is turned
off)
and thus not using any of the C library's wide character functions.

There are C libraries (such as newlib-nano/nanolib/picolibc) which do
provide their definition of `mbstate_t` in `<wchar.h>` even though they
do not
come with wide character functions.

Since there is a way to conditionally include the C library's
`<wchar.h>`
only if it exists, we should rely on the fact that if it exists, it will
provide `mbstate_t`. Removing this guard will allow using libc++ on top
of
newlib-nano/picolibc while not breaking the cases where it is used on
top
of a C library which doesn't provide `<wchar.h>` (since it would then
still
go look for `<uchar.h>` or error out).



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