Clean up compat.

Library/Homebrew/compat/hbc.rb

@@ -7,8 +7,7 @@ require "compat/hbc/dsl"
 
 module Hbc
   class << self
-    prepend(
-      Module.new do
+    module Compat
       def init
         Cache.delete_legacy_cache
 
@@ -17,7 +16,8 @@ module Hbc
 
         super
       end
-      end,
-    )
+    end
+
+    prepend Compat
   end
 end

Library/Homebrew/compat/hbc/cask_loader.rb

@@ -1,4 +1,9 @@
-module CaskLoaderCompatibilityLayer
+module Hbc
+  module CaskLoader
+    class FromContentLoader; end
+
+    class FromPathLoader < FromContentLoader
+      module Compat
         private
 
         def cask(header_token, **options, &block)
@@ -9,14 +14,9 @@ module CaskLoaderCompatibilityLayer
 
           super(header_token, **options, &block)
         end
-end
+      end
 
-module Hbc
-  module CaskLoader
-    class FromContentLoader; end
-
-    class FromPathLoader < FromContentLoader
-      prepend CaskLoaderCompatibilityLayer
+      prepend Compat
     end
   end
 end

Library/Homebrew/compat/hbc/cli/update.rb

@@ -4,20 +4,12 @@ module Hbc
   class CLI
     class Update < AbstractCommand
       def self.run(*_ignored)
-        odeprecated "`brew cask update`", "`brew update`", disable_on: Time.utc(2017, 7, 1)
-        result = SystemCommand.run(HOMEBREW_BREW_FILE, args:         ["update"],
-                                                       print_stderr: true,
-                                                       print_stdout: true)
-        exit result.exit_status
+        odisabled "`brew cask update`", "`brew update`"
       end
 
       def self.visible
         false
       end
-
-      def self.help
-        "a synonym for 'brew update'"
-      end
     end
   end
 end

Library/Homebrew/compat/os/mac.rb

@@ -1,10 +1,10 @@
 module OS
   module Mac
-    class << self
+    module_function
+
     def release
       odeprecated "MacOS.release", "MacOS.version"
       version
     end
   end
-  end
 end

Library/Homebrew/test/cask/cli_spec.rb

@@ -74,8 +74,8 @@ describe Hbc::CLI, :cask do
     end
   end
 
-  it "provides a help message for all commands" do
-    described_class.command_classes.each do |command_class|
+  it "provides a help message for all visible commands" do
+    described_class.command_classes.select(&:visible).each do |command_class|
       expect(command_class.help).to match(/\w+/), command_class.name
     end
   end