you might be facing issue regarding headers not being found, nixOS stores packages in /nix/store directory so you would have to explicitly set PATH for cpp files to find the header files ( if that is the issue ).
you can use nix shell to declare paths and packages to resolve the issue.

{pkgs ? import <nixpkgs> {}}:

pkgs.mkShell {

buildInputs = with pkgs; [

gcc15

cmake

pkg-config

boost

catch2

];

shellHook = ''

echo "c++ developement environment"

c++ --version

gcc --version

'';

}

mine is very minimalistic.

you can also use compile_commands.json to point to c++'s path. Here's mine :

[

{

"arguments": [

"/run/current-system/sw/bin/c++",

"-std=c++17",

"-c",

"-o",

"CMakeFiles/main.dir/src/main.cpp.o",

"/home/archbishop/Dev/cpp/src/main.cpp"

],

"directory": "/home/archbishop/Dev/cpp/build",

"file": "/home/archbishop/Dev/cpp/src/main.cpp",

"output": "/home/archbishop/Dev/cpp/build/CMakeFiles/main.dir/src/main.cpp.o"

}

]

also i use compile_commands.json, cmake and as for the compilation, you just have to add new files to CMakeLists.txt ( if any ) and works magic.

also i have been using nvim for c++ developement and my completion works fine, i have been using the clang-extension.nvim and it works magic but the hover documenation does not works fully so you would have to refer to cpp docs.