search by desc with formula-cask option

Library/Homebrew/cmd/search.rb

@@ -78,7 +78,7 @@ module Homebrew
     string_or_regex = query_regexp(query)
 
     if args.desc?
-      search_descriptions(string_or_regex)
+      search_descriptions(string_or_regex, args)
     elsif args.pull_request?
       only = if args.open? && !args.closed?
         "open"

Library/Homebrew/extend/os/mac/search.rb

@@ -7,11 +7,13 @@ require "cask/cask_loader"
 module Homebrew
   module Search
     module Extension
-      def search_descriptions(string_or_regex)
+      def search_descriptions(string_or_regex, args)
         super
 
         puts
 
+        return if args.formula?
+
         ohai "Casks"
         Cask::Cask.to_a.extend(Searchable)
                   .search(string_or_regex, &:name)

Library/Homebrew/search.rb

@@ -19,7 +19,9 @@ module Homebrew
       raise "#{query} is not a valid regex."
     end
 
-    def search_descriptions(string_or_regex)
+    def search_descriptions(string_or_regex, args)
+      return if args.cask?
+
       ohai "Formulae"
       CacheStoreDatabase.use(:descriptions) do |db|
         cache_store = DescriptionCacheStore.new(db)