std::byteswap was added to the <bit> header file in c++23 and has been implemented, but it was not exported in std.cc.in. Therefore, when using import std, std::byteswap cannot be used. Exporting it in std.cc.in can solve this problem. The new patch uses feature test macros, enabling the successful compilation of std.cc files under c++20.
Tested on x86_64-linux. Signed-off-by: hexne <print...@gmail.com> diff --git a/libstdc++-v3/src/c++23/std.cc.in b/libstdc++-v3/src/c++23/std.cc.in index 1c2346b9f63..48dce19d2de 100644 --- a/libstdc++-v3/src/c++23/std.cc.in +++ b/libstdc++-v3/src/c++23/std.cc.in @@ -671,6 +671,12 @@ export namespace std using std::popcount; using std::rotl; using std::rotr; + +#if __cpp_lib_byteswap + using std::byteswap; +#endif + + } // 22.9 <bitset>
