zsh-completion: _loginctl - general bug fixes

1) the iterator `fun' has an local scope. after running the completer,
it will no longer be defined.

2) use _describe instead of calling compadd. Using compadd without
calling _description or something similar before, restricts the
user's ability to customize what is presented to them.
zstyle ':completion:*' format 'Completing %d'
  - now displays an header showing what is being completed.
zstyle ':completion::complete:loginctl-*::users' users user1 user2
  - allows the user to manually specify which users is offered
zstyle :completion::complete:loginctl-kill-user:\* \
ignored-patterns '(100<0-4>|user1)'
  - selectively ignore some users when completing loginctl kill-user
    <tab>
Sessions, UIDs now have descriptions when selecting them.

3) removed the call to _loginctl_all_seats in _loginctl_attach(), since
_loginctl_seats calls it a second time, right before adding matches.
There isn't a noticeable difference doing this.

shell-completion/zsh/_loginctl

@@ -1,15 +1,43 @@
 #compdef loginctl
 
-_loginctl_all_sessions(){_sys_all_sessions=($(loginctl --no-legend list-sessions | { while read a b; do echo " $a"; done; }) )}
-_loginctl_all_users()   {_sys_all_users=(   $(loginctl --no-legend list-users    | { while read a b; do echo " $a"; done; }) )}
-_loginctl_all_seats()   {_sys_all_seats=(   $(loginctl --no-legend list-seats    | { while read a b; do echo " $a"; done; }) )}
+_loginctl_all_sessions() {
+  local session description
+  loginctl --no-legend list-sessions | while read -r session description; do
+    _sys_all_sessions+=( "$session" )
+    _sys_all_sessions_descr+=( "${session}:$description" )
+  done
+}
 
+_loginctl_all_users() {
+  local uid description
+  loginctl --no-legend list-users | while read -r uid description; do
+    _sys_all_users+=( "$uid" )
+    _sys_all_users_descr+=( "${uid}:$description" )
+  done
+}
+
+_loginctl_all_seats() {
+  local seat description
+  loginctl --no-legend list-seats | while read -r seat description; do
+    _sys_all_seats+=( "$seat" )
+    _sys_all_seats_descr+=( "${seat}:$description" )
+  done
+}
+
+local fun
 # Completion functions for SESSIONS
 for fun in session-status show-session activate lock-session unlock-session terminate-session kill-session ; do
   (( $+functions[_loginctl_$fun] )) || _loginctl_$fun()
   {
+    local -a _sys_all_sessions{,_descr}
+
     _loginctl_all_sessions
-    compadd "$@" -a - _sys_all_sessions
+    for _ignore in $words[2,-1]; do
+      _sys_all_sessions[(i)$_ignore]=()
+      _sys_all_sessions_descr[(i)$_ignore:*]=()
+    done
+
+    _describe -t systemd-sessions session _sys_all_sessions_descr _sys_all_sessions "$@"
   }
 done
 
@@ -17,16 +45,34 @@ done
 for fun in user-status show-user enable-linger disable-linger terminate-user kill-user ; do
   (( $+functions[_loginctl_$fun] )) || _loginctl_$fun()
   {
-    _loginctl_all_users
-    compadd "$@" -a - _sys_all_users
+    local -a _sys_all_users{,_descr}
+    zstyle -a ":completion:${curcontext}:users" users _sys_all_users
+
+    if ! (( $#_sys_all_users )); then
+      _loginctl_all_users
+    fi
+
+    for _ignore in $words[2,-1]; do
+      _sys_all_users[(i)$_ignore]=()
+      _sys_all_users_descr[(i)$_ignore:*]=()
+    done
+    # using the common tag `users' here, not rolling our own `systemd-users' tag
+    _describe -t users user ${_sys_all_users_descr:+_sys_all_users_descr} _sys_all_users "$@"
   }
 done
 
 # Completion functions for SEATS
 (( $+functions[_loginctl_seats] )) || _loginctl_seats()
 {
+  local -a _sys_all_seats{,_descr}
+
   _loginctl_all_seats
-  compadd "$@" -a - _sys_all_seats
+  for _ignore in $words[2,-1]; do
+    _sys_all_seats[(i)$_ignore]=()
+    _sys_all_seats_descr[(i)$_ignore:*]=()
+  done
+
+  _describe -t systemd-seats seat _sys_all_seats_descr _sys_all_seats "$@"
 }
 for fun in seat-status show-seat terminate-seat ; do
   (( $+functions[_loginctl_$fun] )) || _loginctl_$fun()
@@ -36,8 +82,6 @@ done
 # Completion functions for ATTACH
 (( $+functions[_loginctl_attach] )) || _loginctl_attach()
 {
-  _loginctl_all_seats
-
   _arguments -w -C -S -s \
     ':seat:_loginctl_seats' \
     '*:device:_files'
@@ -78,7 +122,7 @@ done
   if (( CURRENT == 1 )); then
     _describe -t commands 'loginctl command' _loginctl_cmds || compadd "$@"
   else
-    local curcontext="$curcontext"
+    local curcontext="$curcontext" _ignore
 
     cmd="${${_loginctl_cmds[(r)$words[1]:*]%%:*}}"