This is the first step towards disentangling the debug mode and assertions
in libc++. This patch doesn't make any functional change: it simply moves
_LIBCPP_ASSERT-related stuff to its own file so as to make it clear that
libc++ assertions and the debug mode are different things. Future patches
will make it possible to enable assertions without enabling the debug
mode.
Differential Revision: https://reviews.llvm.org/D119769
This essentially reverts e02ed1c255 and puts in a new fix, which makes `path::iterator`
a true C++20 `bidirectional_iterator`, but downgrades it to an `input_iterator` in C++17.
Fixes#37852.
Differential Revision: https://reviews.llvm.org/D116489
The NFC part of D116809. We still want to enforce this in CI,
but the mechanism for that is still to-be-determined.
Differential Revision: https://reviews.llvm.org/D116809