4.2.8 Global Configuration Check Options

4.2.8.1 :fail

If the :fail option is set to false, then the absence of the package or program requested will not result in the configure option failing. The :fail option defaults to true if the :set_define option is not defined, and defaults to false if the :set_define option is defined.

4.2.8.2 :on_fail

The :on_fail option can be set to a String or a Proc object. If the configuration operation fails (or would fail), the given message is printed or the Proc is called.

Examples:

configure do
  check_c_compiler "special-gcc", on_fail: "First install special gcc!"
end

configure do
  package_hint = lambda do
    puts "The following packages must be installed to build this project:"
    puts "- libsdl2-dev"
    puts "- libsdl2-image-dev"
    puts "- libsdl2-net-dev"
  end
  check_lib "SDL2", on_fail: package_hint
  check_lib "SDL2_image", on_fail: package_hint
  check_lib "SDL2_net", on_fail: package_hint
end

4.2.8.3 :set_define

If set, a build define of the specified String will be added to the CPPDEFINES construction variable array if the requested package is found.