cbp Testcase

bar.cpp

int main()
{
	#ifdef FOO
	std::cout << "foo" << std::endl;
	#endif 

	#ifdef BAR
	std::cout << "bar" << std::endl;
	#endif 
}

CMakeLists.txt

cmake_minimum_required(VERSION 3.0)

add_executable(foo foo.cpp)
target_compile_definitions(foo PRIVATE FOO)

add_executable(bar bar.cpp)
target_compile_definitions(bar PRIVATE BAR)

foo.cpp

int main()
{
	#ifdef FOO
	std::cout << "foo" << std::endl;
	#endif 

	#ifdef BAR
	std::cout << "bar" << std::endl;
	#endif 
}