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 graphics/povray37 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 short>'
820 | static_assert(is_same<_CharT, typename traits_type::char_type>::value,
| ^
./base/configbase.h:159:19: note: in instantiation of template class 'std::basic_string<unsigned short>' requested here
159 | inline UCS2String ASCIItoUCS2String(const char *s)
| ^
/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 `POVMSUCS2` as `char16_t` instead of
`unsigned short`, `UCS2` as `char16_t` instead of `unsigned short`, and
`UCS4` as `char32_t` instead of `unsigned int` in the passed-in
`CPPFLAGS` variable.
Also, patch up `vfe.cpp` and `vfeconf.h` to use `char16_t` and
`u16string` instead of the non-standard types.
[1] https://libcxx.llvm.org/ReleaseNotes/19.html#deprecations-and-removals
PR: 282645
Approved by: bsd@philippost.de (maintainer)
MFH: 2024Q4
6133473e42