Use "display-warning" instead of "warn"

ido-ubiquitous.el

@@ -77,7 +77,7 @@ be updated until you restart Emacs.")
 
 (require 'ido-completing-read+)
 
-(warn "The ido-ubiquitous package is now redundant. All functionality, including ido-ubiquitous-mode, has been merged into the ido-completing-read+ package. You should replace ido-ubiquitous with ido-completing-read+ in your Emacs config.")
+(display-warning 'ido-ubiquitous "The ido-ubiquitous package is now redundant. All functionality, including ido-ubiquitous-mode, has been merged into the ido-completing-read+ package. You should replace ido-ubiquitous with ido-completing-read+ in your Emacs config.")
 
 (define-obsolete-function-alias 'completing-read-ido-ubiquitous 'ido-completing-read+
   "ido-completing-read+ 4.0")