We start with a simple hello world example (hello-world.cpp):

#include <cstdlib>
#include <iostream>
#include <string>

const std::string cmake_system_name = SYSTEM_NAME;

int main() {
  std::cout << "Hello from " << cmake_system_name << std::endl;

  return EXIT_SUCCESS;
}

We will also use the unchanged CMakeLists.txt from the previous recipe:

# set minimum cmake version
cmake_minimum_required(VERSION 3.5 FATAL_ERROR)

# project name and language
project(recipe-01 LANGUAGES CXX)

set(CMAKE_CXX_STANDARD 11)
set(CMAKE_CXX_EXTENSIONS OFF)
set(CMAKE_CXX_STANDARD_REQUIRED ON)

include(GNUInstallDirs)
set(CMAKE_ARCHIVE_OUTPUT_DIRECTORY
  ${CMAKE_BINARY_DIR}/${CMAKE_INSTALL_LIBDIR})
set(CMAKE_LIBRARY_OUTPUT_DIRECTORY
  ${CMAKE_BINARY_DIR}/${CMAKE_INSTALL_LIBDIR})
set(CMAKE_RUNTIME_OUTPUT_DIRECTORY
  ${CMAKE_BINARY_DIR}/${CMAKE_INSTALL_BINDIR})

# define executable and its source file
add_executable(hello-world hello-world.cpp)

# we will print the system name in the code
target_compile_definitions(hello-world
  PUBLIC
    "SYSTEM_NAME=\"${CMAKE_SYSTEM_NAME}\""
  )

install(
  TARGETS
    hello-world
  DESTINATION
    ${CMAKE_INSTALL_BINDIR}
  )

To cross-compile the source code, we will need to install a cross-compiler for C++ and optionally for C and Fortran. One option is to use packaged MinGW compilers. As an alternative to packaged cross-compilers, we can also build a suite of cross-compilers from sources using MXE (the M cross environment): http://mxe.cc.