c++ intellisense not working after first build

After setting up and doing make Gaudi the contents of Gaudi/.vscode/c_cpp_properties.json are

{
    "configurations": [
        {
            "compileCommands": "/home/rmatev/vscode/stack/.output/Gaudi/compile_commands.json",
            "compilerPath": "",
            "includePath": [
                "../Gaudi/**"
            ],
            "name": "Linux",
            "intelliSenseMode": "linux-gcc-x64"
        }
    ],
    "version": 4
}

Note how compilerPath is empty. Doing another make fixes that (because now the toolchain is known).