How to create a nix shell for C++ programming

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1

I seem to have installed everything for C++, but lsp still doesn’t see the header files for some reason.

2

Define “installed”. If you put it in your config, remove it.
If you made a shell.nix or some mkShell environment, share that code.

3

My flake.nix:

{
  description = "C++ dev";

  inputs = {
    nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";
  };

  outputs = { self, nixpkgs }:
    let
      system = "x86_64-linux";
      pkgs = nixpkgs.legacyPackages.${system};
    in
    {
      devShells.${system}.default = pkgs.mkShell.override {
      } {
        packages = with pkgs; [
          cmake
          ninja
          pkg-config
          clang
          lld
          lldb
          clang-tools
        ];

        shellHook = ''
          echo "C++ dev environment"
          clang++ --version
        '';
      };
    };
}
4
5 
{
  description = "C++ dev";

  inputs = {
    nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";
  };

  outputs = { self, nixpkgs }:
    let
      system = "x86_64-linux";
      pkgs = nixpkgs.legacyPackages.${system};
    in
    {
      devShells.${system}.default = pkgs.mkShell.override {
        stdenv = pkgs.clang19Stdenv;
      } {
        packages = with pkgs; [
          cmake
        ];
        shellHook = ''
          echo "C++ dev environment"
        '';
      };
    };
}

Still not working

6

What exactly does “not working” mean?

7

The program is now being compiled, but the code editors (I tried in helix and zed-editor) show the error 'iostream' file not found (clang pp_file_not_found)

8

Do you have a compile_commands.json?

9

No, but how do I create it? (sorry, I’m just a newbie and I haven’t figured it out yet)

10

Hi there,
I use Zed Editor with C++ too and ran into the same issue with header files. I found a workaround in some discussions and while it’s definitely not ideal - it’s a nice temporary fix, at least for me, who still learning NixOS :sweat_smile:.

In your CMakeLists.txt, add this:

set(CMAKE_EXPORT_COMPILE_COMMANDS ON CACHE INTERNAL "")
if(CMAKE_EXPORT_COMPILE_COMMANDS)
    set(CMAKE_CXX_STANDARD_INCLUDE_DIRECTORIES
      ${CMAKE_CXX_IMPLICIT_INCLUDE_DIRECTORIES})
endif()

Then, run:

cmake -S . -B build/
cmake -DCMAKE_EXPORT_COMPILE_COMMANDS=1
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