Error within if() if second parameter is empty
This will give an error:
set(A a)
# not set B
if(A AND B)
endif()
But this will be fine:
# not set B
if(B)
endif()
This will give an error:
set(A a)
# not set B
if(A AND B)
endif()
But this will be fine:
# not set B
if(B)
endif()