add deprecate module

Library/Homebrew/cmd/install.rb

@@ -315,6 +315,7 @@ module Homebrew
   end
 
   def install_formula(f)
+    opoo "#{f.name} has been deprecated" if f.is_deprecated?
     f.print_tap_action
     build_options = f.build
 

Library/Homebrew/cmd/reinstall.rb

@@ -61,6 +61,7 @@ module Homebrew
         onoe "#{f.full_name} is pinned. You must unpin it to reinstall."
         next
       end
+      opoo "#{f.name} has been deprecated" if f.is_deprecated?
       Migrator.migrate_if_needed(f)
       reinstall_formula(f)
       Cleanup.install_formula_clean!(f)

Library/Homebrew/cmd/upgrade.rb

@@ -150,6 +150,8 @@ module Homebrew
   def upgrade_formula(f)
     return if args.dry_run?
 
+    opoo "#{f.name} has been deprecated" if f.is_deprecated?
+
     if f.opt_prefix.directory?
       keg = Keg.new(f.opt_prefix.resolved_path)
       keg_had_linked_opt = true

Library/Homebrew/formula.rb

@@ -51,6 +51,7 @@ class Formula
   include FileUtils
   include Utils::Inreplace
   include Utils::Shell
+  include Utils::Deprecate
   extend Enumerable
   extend Forwardable
   extend Cachable
@@ -175,6 +176,16 @@ class Formula
   attr_accessor :follow_installed_alias
   alias follow_installed_alias? follow_installed_alias
 
+  # A Boolean indicating whether this formula is deprecated or not
+  # Defaults to false
+  attr_accessor :is_deprecated
+  alias is_deprecated? is_deprecated
+
+  # A Boolean indicating whether this formula is disabled
+  # Defaults to false
+  attr_accessor :is_disabled
+  alias is_disabled? is_disabled
+
   # @private
   def initialize(name, path, spec, alias_path: nil)
     @name = name
@@ -211,6 +222,8 @@ class Formula
     @follow_installed_alias = true
     @prefix_returns_versioned_prefix = false
     @oldname_lock = nil
+    @is_deprecated = false
+    @is_disabled = false
   end
 
   # @private

Library/Homebrew/utils.rb

@@ -13,6 +13,7 @@ require "utils/link"
 require "utils/popen"
 require "utils/svn"
 require "utils/tty"
+require "utils/deprecate"
 require "tap_constants"
 require "time"
 

Library/Homebrew/utils/deprecate.rb

@@ -0,0 +1,35 @@
+# frozen_string_literal: true
+
+module Utils
+  module Deprecate
+    # This module is common for both formulae and casks.
+    # To-do : Add support for casks + add disable method
+
+    def deprecate
+      self.is_deprecated = true
+
+      # deprecate all formulae dependent on this deprecated formula
+      all_formulae = ObjectSpace.each_object(Class).select { |klass| klass < Formula }
+      all_formulae.each do |f|
+        dependencies = f.recursive_dependencies.map(&:name)
+        f.is_deprecated = true if (dependencies.include? self.name)
+      end
+    end
+
+    # Deprecation can be revoked if the underlying problem is fixed
+    def revoke_deprecation
+      self.is_deprecated = false
+
+      # revoke deprecation from dependents as well
+      all_formulae = ObjectSpace.each_object(Class).select { |klass| klass < Formula }
+      all_formulae.each do |f|
+        dependencies = f.recursive_dependencies.map(&:name)
+        revoke = true
+        dependencies.each do |d|
+          revoke = !(d != self && d.is_deprecated?)
+        end
+        f.is_deprecated = false if revoke && (dependencies.include? self.name)
+      end
+    end
+  end
+end