zsh: completion: add _force_rehash completer

zsh/completion.zsh

@@ -35,6 +35,23 @@ complete-word-or-complete-list-of-files() {
 zle -N complete-word-or-complete-list-of-files
 bindkey '^I' complete-word-or-complete-list-of-files
 
+# Force a reload of the completion system if nothing matched; this fixes
+# installing a program and then trying to tab-completing its name.
+_force_rehash() {
+	if (( CURRENT == 1 )); then
+		rehash
+	fi
+	# we didn't really complete anything.
+	return 1
+}
+
+# list of completers to use
+zstyle ':completion:::::' completer \
+	_force_rehash _expand _complete _prefix _ignored _approximate
+#TODO: keep _prefix or not?
+
+# ===== completion appearance
+# use ls colors for completion
 # Fallback to built in ls colors
 #zstyle ':completion:*' list-colors ''
 zstyle ':completion:*' list-colors "${(@s.:.)LS_COLORS}"
@@ -48,9 +65,6 @@ zstyle ':completion:*' select-prompt '%SScrolling active: current selection at %
 # Add simple colors to kill
 zstyle ':completion:*:*:kill:*:processes' list-colors '=(#b) #([0-9]#) ([0-9a-z-]#)*=01;34=0=01'
 
-# list of completers to use
-zstyle ':completion:*::::' completer _expand _complete _ignored _approximate
-
 zstyle ':completion:*' menu select=1 _complete _ignored _approximate
 
 # insert all expansions for expand completer