implicit instantiation of undefined templates with wasi-sdk-21

[sparker-arm]

I've been building wasi-sdk from source, for a few years, and running benchmarks on a variety of runtimes on x64 and aarch64 platforms. I'm currently building wasi-sdk on ubuntu 22.04 with the system GCC 11.4.

Today, I've tried to update my benchmarking suite to use wasi-sdk-21 and I'm not having much joy, I get errors like this when compiling my C++ benchmarks:

error: implicit instantiation of undefined template 'std::basic_ofstream<char>'
  495 |   std::ofstream output_file;
      |                 ^
wasi-sdk/share/wasi-sysroot/include/c++/v1/__fwd/fstream.h:26:28: note: template is declared here
   26 | class _LIBCPP_TEMPLATE_VIS basic_ofstream;

The two benchmarks that I've looked into are targeting -std=c++11.

Do you know what's changed between 20 and 21 that could cause this..? I'm assuming that I've missed something but I'm also somewhat suspicious of libc++ here as there's an open ticket which look like it could be related.

Any help would be greatly appreciated.

[sparker-arm]

I can reproduce this with an official build.

With the example taken from here:

$ cat open-file.cc 
#include <iostream>
#include <fstream>
using namespace std;

int main () {
  ofstream myfile;
  myfile.open ("example.txt");
  myfile << "Writing this to a file.\n";
  myfile.close();
  return 0;
}

$ /opt/wasi-sdk/bin/clang++ open-file.cc -S
open-file.cc:6:12: error: implicit instantiation of undefined template 'std::basic_ofstream<char>'
    6 |   ofstream myfile;
      |            ^
/opt/wasi-sdk/bin/../share/wasi-sysroot/include/c++/v1/__fwd/fstream.h:26:28: note: template is declared here
   26 | class _LIBCPP_TEMPLATE_VIS basic_ofstream;
      |                            ^
1 error generated.

[pmp-p]

maybe related #373

[sparker-arm]

Thanks @pmp-p, it looks like the same bug and the reproducer passes on main.