https://gcc.gnu.org/bugzilla/show_bug.cgi?id=605
--- Comment #7 from Andrew Pinski <pinskia at gcc dot gnu.org> --- Looks like we only document -YP, is supported and not -Y P; likewise for -Y M, @item -YP,@var{dirs} @opindex YP Search the directories @var{dirs}, and no others, for libraries specified with @option{-l}. @item -Ym,@var{dir} @opindex Ym Look in the directory @var{dir} to find the M4 preprocessor. The assembler uses this option. @c This is supposed to go with a -Yd for predefined M4 macro files, but @c the generic assembler that comes with Solaris takes just -Ym. @end table I don't know how important it is to support this though.