------- Comment #1 from redi at gcc dot gnu dot org 2010-03-03 10:30 ------- -Wignored-qualifiers is for warning about qualifiers on return types, which are ignored. I don't think it has anything to do with discarded qualifiers on function arguments.
-pedantic-errors will give an error on your code -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43245
