How to fail CMake gracefully when an include file

Question

In CMakeLists.txt, I would like to check that bzlib.h exists:

include(CheckIncludeFiles)
check_include_file(bzlib.h HAVE_BZLIB_H)
if(NOT HAVE_BZLIB_H)
    # How can I exit cmake with an error message if bzlib.h does not exists?
endif()

Answer 1

It's quite easy: message( FATAL_ERROR "Your message" )