Zig compiles C++ jthread with errors

[inschrift-spruch-raum]

Zig Version

0.13.0

Steps to Reproduce and Observed Behavior

I found an error when compiling a C++project using jthread
So I wrote a small demo

#include <iostream>
#include <thread>

int main() {
    std::jthread t([]{
        std::cout << "Thread executed\n";
    });
    return 0;
}

const std = @import("std");

pub fn build(b: *std.Build) void {
    const target = b.standardTargetOptions(.{});

    const optimize = b.standardOptimizeOption(.{});

    const exe = b.addExecutable(.{
        .name = "test",
        .target = target,
        .optimize = optimize,
    });

    exe.addCSourceFile(.{
        .file = b.path("src/main.cpp"),
        .flags = &.{"-std=c++20"},
    });

    exe.linkLibCpp();

    b.installArtifact(exe);
}

Found the following error message

zig build
install
└─ install sac
   └─ zig build-exe sac Debug native 1 errors
C:\Users\Raum\Documents\sac\src\main.cpp:5:10: error: no member named 'jthread' in namespace 'std'
    std::jthread t([]{
    ~~~~~^
error: the following command failed with 1 compilation errors:
C:\Users\Raum\AppData\Local\Microsoft\WinGet\Packages\zig.zig_Microsoft.Winget.Source_8wekyb3d8bbwe\zig-windows-x86_64-0.13.0\zig.exe build-exe -cflags -std=c++20 -- C:\Users\Raum\Documents\sac\src\main.cpp -ODebug -Mroot -lc++ --cache-dir C:\Users\Raum\Documents\sac\.zig-cache --global-cache-dir C:\Users\Raum\AppData\Local\zig --name sac --listen=-
Build Summary: 0/3 steps succeeded; 1 failed (disable with --summary none)
install transitive failure
└─ install sac transitive failure
   └─ zig build-exe sac Debug native 1 errors
error: the following build command failed with exit code 1:
C:\Users\Raum\Documents\sac\.zig-cache\o\61e53e351dc3c14719ba6a8761e0abb6\build.exe C:\Users\Raum\AppData\Local\Microsoft\WinGet\Packages\zig.zig_Microsoft.Winget.Source_8wekyb3d8bbwe\zig-windows-x86_64-0.13.0\zig.exe C:\Users\Raum\Documents\sac C:\Users\Raum\Documents\sac\.zig-cache C:\Users\Raum\AppData\Local\zig --seed 0xa1836ee2 -Z213377d274cdf92f

My environment is

zig env
{
 "zig_exe": "C:\\Users\\Raum\\AppData\\Local\\Microsoft\\WinGet\\Packages\\zig.zig_Microsoft.Winget.Source_8wekyb3d8bbwe\\zig-windows-x86_64-0.13.0\\zig.exe",
 "lib_dir": "C:\\Users\\Raum\\AppData\\Local\\Microsoft\\WinGet\\Packages\\zig.zig_Microsoft.Winget.Source_8wekyb3d8bbwe\\zig-windows-x86_64-0.13.0\\lib",
 "std_dir": "C:\\Users\\Raum\\AppData\\Local\\Microsoft\\WinGet\\Packages\\zig.zig_Microsoft.Winget.Source_8wekyb3d8bbwe\\zig-windows-x86_64-0.13.0\\lib\\std",
 "global_cache_dir": "C:\\Users\\Raum\\AppData\\Local\\zig",
 "version": "0.13.0",
 "target": "x86_64-windows.win10_fe...win10_fe-gnu",
 "env": {
  "ZIG_GLOBAL_CACHE_DIR": null,
  "ZIG_LOCAL_CACHE_DIR": null,
  "ZIG_LIB_DIR": null,
  "ZIG_LIBC": null,
  "ZIG_BUILD_RUNNER": null,
  "ZIG_VERBOSE_LINK": null,
  "ZIG_VERBOSE_CC": null,
  "ZIG_BTRFS_WORKAROUND": null,
  "ZIG_DEBUG_CMD": null,
  "CC": null,
  "NO_COLOR": null,
  "CLICOLOR_FORCE": null,
  "XDG_CACHE_HOME": null,
  "HOME": null
 }
}

Expected Behavior

Normal compilation

[alexrp]

It's not available because we're currently on LLVM 19 and libc++ only gained (non-experimental) std::jthread support in LLVM 20. This means it'll become available in Zig 0.15.0 when we upgrade to LLVM 20.

I'll close this issue because there isn't really anything in particular for us to do here; the support will come automatically with #22780.

[inschrift-spruch-raum]

be sorry
However, I still hope to be able to compile successfully in the current situation
Can you provide me with some ideas
Sorry to bother you.

[LearnWebGitHub]

be sorry However, I still hope to be able to compile successfully in the current situation Can you provide me with some ideas Sorry to bother you.

If you have the latest GCC (mine is 14) you can use libstdc++ instead of libc++. (Sometimes it can also solve ABI incompatibility issue if other libraries use libstc++. #18300)

Because the library is on your machine, it's not portable if you don't write a more complex build script, but it might solve the problem for now.
I'm still waiting for official support #3963

// remove this line: exe.linkLibCpp();

// libstdc++
const verion = "14.2.1";
const machine = "x86_64-pc-linux-gnu";
const lazy = std.Build.LazyPath;
exe.addIncludePath(lazy{ .cwd_relative = "/usr/include/c++/" ++ verion });
exe.addIncludePath(lazy{ .cwd_relative = "/usr/include/c++/" ++ verion ++ "/" ++ machine });
exe.addLibraryPath(lazy{ .cwd_relative = "/usr/lib/gcc/" ++ machine ++ "/" ++ verion });
exe.addObjectFile(lazy{ .cwd_relative = "/usr/lib/libstdc++.so" });
exe.addObjectFile(lazy{ .cwd_relative = "/usr/lib/libgcc_s.so" });
exe.linkLibC();

[inschrift-spruch-raum]

Thank you, I am also studying this plan
However, I compile in a Windows environment, and completing this task may be quite troublesome

[LearnWebGitHub]

Thank you, I am also studying this plan However, I compile in a Windows environment, and completing this task may be quite troublesome

Oops, I see. Hmmm...

Have you tried this?
Add -fexperimental-library when using -std=c++20

Or:
Not sure if it'd help but my solution without GCC (I'm on Debian, sorry for not having Windows environment now):
Download "jthread.hpp" and "stop_token.hpp" from Nico Josuttis' repo (He is one of the authors of std::jthread)
If you use -std=c++17 it should compile.
If you meet reference conflics when using -std=c++20 or -std=c++23 (I'm not sure about this but I guess if you meet this issue you might be able to use -fexperimental-library already), change their namespace from std to any name you want to avoid it.

const files = &[_][]const u8{
    "src/main.cpp",
};
const flags = &[_][]const u8{
    "-std=c++23",
    "-fexperimental-library",
    "-Wall",
    "-Wextra",
    "-Wpedantic",
};
exe.addCSourceFiles(.{
    .files = files,
    .flags = flags,
});
exe.addIncludePath(b.path("src"));

[inschrift-spruch-raum]

Solved it! It's really amazing...