http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49631
--- Comment #1 from Joseph S. Myers <jsm28 at gcc dot gnu.org> 2011-07-05 17:05:41 UTC --- Also note that at least -shared and -pie are driver options that are currently marked as Common rather than Driver so as to have help text in common.opt; as part of fixing this issue, such options can change to have the correct Driver marking (and not Common).
