zsh compilations: -w is not needed for _arguments
-w was unneeded and in fact incorrect:
The combination of -s with -w allows single-letter
options to be combined in a single word even if one or
more of the options take arguments. For example, if -a
takes an argument, with no -s `-ab' is considered as a
single (unhandled) option; with -s -ab is an option with
the argument `b'; with both -s and -w, -ab may be the
option -a and the option -b with arguments still to come.
That is, with -w, -xy <tab> arguments for -x would be completed.