zsh/Completion/Core/_parameters

#autoload

# This should be used to complete parameter names if you need some of the
# extra options of compadd. It completes only non-local parameters.

# If you specify a -g option with a pattern, the pattern will be used to
# restrict the type of parameters matched.

local expl pattern fakes faked tmp

pattern=(-g \*)
zparseopts -D -K -E g:=pattern

fakes=()
faked=()
if zstyle -a ":completion:${curcontext}:" fake-parameters tmp; then
  for i in "$tmp[@]"; do
    if [[ "$i" = *:* ]]; then
      faked=( "$faked[@]" "$i" )
    else
      fakes=( "$fakes[@]" "$i" )
    fi
  done
fi

_wanted parameters expl parameter \
    compadd "$@" -Q - \
        "${(@k)parameters[(R)${pattern[2]}~*local*]}" \
        "$fakes[@]" \
        "${(@)${(@M)faked:#${~pattern[2]}}%%:*}"