PATCH: cleanup chsh completion for different platforms

[Oliver Kiddle <okiddle@xxxxxxxxxxx>]

chsh is worse than most things when it comes to platform differences
with there even being a variety of different implementations on Linux.
This is an attempt to make it a bit more useful.

Oliver

diff --git a/Completion/Unix/Command/_chsh b/Completion/Unix/Command/_chsh
index 006aa82a1..97552e3ac 100644
--- a/Completion/Unix/Command/_chsh
+++ b/Completion/Unix/Command/_chsh
@@ -1,67 +1,40 @@
 #compdef chsh chpass
-
-local variant help=h
-local -a args shells
-
 case $OSTYPE in
-  darwin*|*bsd*)
-    args=( '(-a)-s[specify new login shell]:shell:($shells)' )
-  ;|
-  (free|net|open)bsd*)
-    args+=( '(-s 1)-a[specify user database entry]:passwd entry' )
-  ;|
-  darwin*)
-    args+=(
-      '-l[specify location of user]:location'
-      '-u[specify authentication name]:auth user'
-    )
+(darwin*|*bsd*)
+  _arguments : \
+      '-s[Specify user login shell]:shell:(${(Z+Cn+)"$(</etc/shells)"})' \
+      "-l[Specify location of user]:node:" \
+      "-u[Specify authentication name]:auth user:" \
+      "1:user name:_users"
   ;;
-  (free|net)bsd*)
-    args+=(
-      '(-y)-l[update only the local password file]'
-      '(-l)-y[force YP database entry to be changed]'
-    )
-  ;|
-  freebsd*)
-    args+=(
-      '-p[specify encrypted password field]:password hash'
-      '-e[change account expire time]:expiry time'
-      '-d[specify NIS domain]:domain'
-      '-h[specify NIS server to query]:NIS server:_hosts'
-      '-o[force use of RPC-based updates]'
-    )
-  ;;
-  (linux-gnu)
-    _pick_variant -r variant util-linux=util-linux suse=pwdutils debian -v
-    args=( -S : '(-)'{-s+,--shell=}'[specify new login shell]:shell:($shells)' )
-    case $variant in
-      suse|util-linux)
-	shells=( $(_call_program shells $words[1] -l) )
-        args+=(
-	  '(-)'{-l,--list-shells}'[print shells in /etc/shells]'
-	  '(-)'{-v,--version}'[display version information]'
-        )
-	help=u
-      ;|
-      util-linux|debian)
-	args+=( '(-)-'{$help,-help}'[display help information]' )
-      ;|
-      suse)
-        args+=(
-	  '(-)'{-u,--usage}'[display short usage message]'
-	  '(-)--help[display help information]'
-	  '(-D --binddn)'{-D+,--binddn=}'[specify LDAP disingushed name to bind]:binddn'
-	  '(-P --path)'{-P+,--path=}'[specify path to search for passwd and shadow files]:path:_directories'
-	  '(-q --quiet)'{-q,--quiet}"[don't be verbose]"
-	  '--service=[use specified name service]:service:(files nis nisplus ldap)'
-	)
-      ;;
-      debian)
-	args+=( '(-R --root)'{-R+,--root=}'[specify directory to chroot into]:directory:_directories' )
-      ;;
-    esac
+(linux-gnu)
+  if { =chsh -v } >&/dev/null
+  then
+      local -a opts shells
+      shells=( $(=chsh -l) )
+      _arguments : \
+	  "(-)-s[Specify your login shell]:shell:($shells)" \
+	  "(-)--shell[Specify your login shell]:shell:($shells)" \
+	  "(-)-l[Print shells in /etc/shells]" \
+	  "(-)--list-shells[Print shells in /etc/shells]" \
+	  "(-)-u[Print a usage message and exit]" \
+	  "(-)--help[Print a usage message and exit]" \
+	  "(-)-v[Print version information and exit]" \
+	  "(-)--version[Print version information and exit]" \
+	  "1:user name:_users"
+      return
+  fi
+  # else fall through
+  ;&
+(*)
+  local s=''
+  # Use $s to cause all options to be treated as mutually exclusive
+  [[ $words[CURRENT-1] = -* ]] && s="(-)$words[CURRENT-1]"
+  # This fiddling with $s is a hack to cause "_arguments  : --" to use
+  # the /etc/shells listing for -s or --shell even when the description
+  # of that option has been pulled from the GNU --help output.
+  [[ $words[CURRENT-1] = (-s|--shell) ]] &&
+    s="$s"'[ ]:shell:(${(Z+Cn+)"$(</etc/shells)"})'
+  _arguments : $s "1:user name:_users" --
   ;;
 esac
-
-(( $#shells )) || shells=( ${(Z+Cn+)"$(</etc/shells)"} )
-_arguments $args '1:user name:_users'