ASDF 3 has made some changes which may cause problems with older ASD files. 
Some warnings are disabled by default for compatibility with older projects. 
The Lispbuilder ASD files need to be checked with these warnings enabled to 
ensure future interoperability.

{{{
(asdf:enable-deferred-warnings-check)
(setf asdf:*compile-file-failure-behaviour* 'error)
(setf asdf:*compile-file-warnings-behaviour* 'error) ; for the pedantic
(asdf:operate 'asdf:load-op :lispbuilder-sdl) ; etc
}}}