The gnatclean command has the form:
$ gnatclean switches `names`
where names is a list of source file names. Suffixes .ads and
adb may be omitted. If a project file is specified using switch
-P, then names may be completely omitted.
In normal mode, gnatclean delete the files produced by the compiler and, if switch -c is not specified, by the binder and the linker. In informative-only mode, specified by switch -n, the list of files that would have been deleted in normal mode is listed, but no file is actually deleted.