cli_parser: Add custom description support for global switches

Library/Homebrew/cli_parser.rb

@@ -42,8 +42,12 @@ def post_initialize
 
       def switch(*names, description: nil, env: nil, required_for: nil, depends_on: nil)
         global_switch = names.first.is_a?(Symbol)
-        names, env, description = common_switch(*names) if global_switch
-        description = option_to_description(*names) if description.nil?
+        names, env, default_description = common_switch(*names) if global_switch
+        if description.nil? && global_switch
+          description = default_description
+        elsif description.nil?
+          description = option_to_description(*names)
+        end
         process_option(*names, description)
         @parser.on(*names, *wrap_option_desc(description)) do
           enable_switch(*names)

Library/Homebrew/test/cli_parser_spec.rb

@@ -46,6 +46,11 @@
       parser.parse([])
       expect(Homebrew.args.pry?).to be true
     end
+
+    it ":verbose with custom description" do
+      _, _, _, desc = parser.processed_options.find { |short, _| short == "-v" }
+      expect(desc).to eq "Flag for verbosity"
+    end
   end
 
   describe "test long flag options" do