CUDA-Q and CMake
**********************

CUDA-Q provides a full compiler toolchain for building 
out quantum-classical applications. Since most C++ projects 
provide some sort of integration with CMake, it becomes imperative 
for our toolchain to integrate well with the CMake build system. 

CUDA-Q provides CMake configuration files that allow downstream 
application developers to create hybrid quantum-classical source code 
and build it with the typical CMake workflow, which will natively 
leverage :code:`nvq++` for compilation of CUDA-Q source files. 

To see how this works, let's create a trivial example. Suppose we have 
a folder named :code:`myCudaQApp` and within that folder we have 
a simple CUDA-Q source file, like `ghz.cpp`. With a local 
CUDA-Q installation present on the system, we can create the 
following top-level :code:`CMakeLists.txt` file to build this file with 
:code:`nvq++`:

.. code:: bash 

    cmake_minimum_required(VERSION 3.24 FATAL_ERROR)
    project(myCudaQApp LANGUAGES CXX)
    find_package(CUDAQ REQUIRED)
    add_executable(ghz_exe ghz.cpp)

To configure and build this file, all we need to do is execute the following from the top level of the :code:`myCudaQApp` folder:

.. code:: bash 

    mkdir build && cd build 
    cmake .. -G Ninja -DCUDAQ_DIR="$CUDA_QUANTUM_PATH/lib/cmake/cudaq"
    ninja
    ./ghz_exe 

Notice that by running the :code:`ninja` command with :code:`--verbose`, you'll see that 
:code:`nvq++` was used to compile and link the executable.