eza: fix icons option

Fixes the icons option for eza which was breaking completion in zsh.

modules/programs/eza.nix

@@ -49,10 +49,13 @@ with lib;
     };
 
     icons = mkOption {
-      type = types.bool;
-      default = false;
+      type = types.enum [ null true false "auto" "always" "never" ];
+      default = null;
       description = ''
         Display icons next to file names ({option}`--icons` argument).
+
+        Note, the support for Boolean values is deprecated.
+        Setting this option to `true` corresponds to `--icons=auto`.
       '';
     };
 
@@ -70,8 +73,15 @@ with lib;
   config = let
     cfg = config.programs.eza;
 
-    args = escapeShellArgs (optional cfg.icons "--icons"
-      ++ optional cfg.git "--git" ++ cfg.extraOptions);
+    iconsOption = let
+      v = if isBool cfg.icons then
+        (if cfg.icons then "auto" else null)
+      else
+        cfg.icons;
+    in optionals (v != null) [ "--icons" v ];
+
+    args = escapeShellArgs
+      (iconsOption ++ optional cfg.git "--git" ++ cfg.extraOptions);
 
     optionsAlias = optionalAttrs (args != "") { eza = "eza ${args}"; };
 
@@ -83,6 +93,12 @@ with lib;
       lla = "eza -la";
     };
   in mkIf cfg.enable {
+    warnings = optional (isBool cfg.icons) ''
+      Setting programs.eza.icons to a Boolean is deprecated.
+      Please update your configuration so that
+
+        programs.eza.icons = ${if cfg.icons then ''"auto"'' else "null"}'';
+
     home.packages = [ cfg.package ];
 
     programs.bash.shellAliases = optionsAlias