[libc++] [C++20] [P0482] Add missing tests and synopses for char8_t.
Left to finish P0482:
* <cuchar> header.
* Parts of <memory_resource> concerning char8_t. Also, tests for hash<pmr::*string>.
Reviewed By: ldionne, #libc, Quuxplusone
Differential Revision: https://reviews.llvm.org/D99184
GitOrigin-RevId: 28f82bec7fa1bbe99ece9149adb3563041914d86
diff --git a/include/iosfwd b/include/iosfwd
index 0a0de99..f60437c 100644
--- a/include/iosfwd
+++ b/include/iosfwd
@@ -84,8 +84,11 @@
typedef basic_fstream<wchar_t> wfstream;
template <class state> class fpos;
-typedef fpos<char_traits<char>::state_type> streampos;
-typedef fpos<char_traits<wchar_t>::state_type> wstreampos;
+using streampos = fpos<char_traits<char>::state_type>;
+using wstreampos = fpos<char_traits<wchar_t>::state_type>;
+using u8streampos = fpos<char_traits<char8_t>::state_type>; // C++20
+using u16streampos = fpos<char_traits<char16_t>::state_type>;
+using u32streampos = fpos<char_traits<char32_t>::state_type>;
} // std