As noted in the libc++ 19 release notes [1], std::char_traits<> is now
only provided for char, char8_t, char16_t, char32_t and wchar_t, and any
instantiation for other types will fail.
This causes archivers/pbzip2 to fail to compile with clang 19 and libc++
19, resulting in errors similar to:
/usr/include/c++/v1/string:820:42: error: implicit instantiation of undefined template 'std::char_traits<unsigned char>'
820 | static_assert(is_same<_CharT, typename traits_type::char_type>::value,
| ^
./BZ2StreamScanner.h:128:25: note: in instantiation of template class 'std::basic_string<unsigned char>' requested here
128 | basic_string<CharType> _bz2Header;
| ^
/usr/include/c++/v1/__fwd/string.h:23:29: note: template is declared here
23 | struct _LIBCPP_TEMPLATE_VIS char_traits;
| ^
This can be fixed by defining `_bz2Header` and `_bz2HeaderZero` as
`std::vector<CharType>` instead of `std::basic_string<CharType>`. It
requieres a few other changes, such as replacing `operator=` with
`assign`, and `compare` with `equal`.
[1] https://libcxx.llvm.org/ReleaseNotes/19.html#deprecations-and-removals
PR: 282528
Approved by: farrokhi (maintainer)
MFH: 2024Q4
(cherry picked from commit 29c80f114e)
