https://gcc.gnu.org/bugzilla/show_bug.cgi?id=127642
--- Comment #1 from d7d1cd <d7d1cd at mail dot ru> ---
However, the following example does not compile with 16.x compilers, even using
the C++23 standard:
$ cat header.h
#pragma once
#include <chrono>
inline void foo() {
std::ignore = std::format("{}", std::chrono::seconds{});
}
$ cat module.ixx
module;
#include "header.h"
export module M;
export using ::foo;
$ cat main.cc
#include "header.h"
import M;
$ g++ -std=c++23 -fmodules -fmax-errors=1 -c module.ixx main.cc
In file included from /usr/local/gcc-trunk/include/c++/16/chrono:3695,
from header.h:3,
from module.ixx:2,
of module M, imported at main.cc:2:
/usr/local/gcc-trunk/include/c++/16/bits/chrono_io.h:903:38: error:
conflicting type for imported declaration ‘constexpr const char* const
std::__format::__formatter_chrono<char>::_S_months [12]’
903 | static constexpr const _CharT* _S_months[]
| ^~~~~~~~~
In file included from /usr/local/gcc-trunk/include/c++/16/chrono:3695,
from header.h:3,
from main.cc:1:
/usr/local/gcc-trunk/include/c++/16/bits/chrono_io.h:903:38: note: existing
declaration ‘constexpr const char* const
std::__format::__formatter_chrono<char>::_S_months []’
903 | static constexpr const _CharT* _S_months[]
| ^~~~~~~~~
compilation terminated due to -fmax-errors=1.
https://godbolt.org/z/GTTEzKfnd
