Add rubocop to enforce deprecate! over discontinued

Library/Homebrew/rubocops/cask/discontinued.rb

@@ -0,0 +1,43 @@
+# typed: true
+# frozen_string_literal: true
+
+# TODO: Remove this when we remove `caveats { discontinued }` (likely for Homebrew 4.5.0)
+module RuboCop
+  module Cop
+    module Cask
+      # This cop corrects `caveats { discontinued }` to `deprecate!`.
+      class Discontinued < Base
+        include CaskHelp
+        extend AutoCorrector
+
+        MESSAGE = "Use `deprecate!` instead of `caveats { discontinued }`."
+
+        def on_cask_stanza_block(stanza_block)
+          stanza_block.stanzas.select(&:caveats?).each do |stanza|
+            find_discontinued_method_call(stanza.stanza_node) do |node|
+              if caveats_constains_only_discontinued?(node.parent)
+                add_offense(node.parent, message: MESSAGE) do |corrector|
+                  corrector.replace(node.parent.source_range,
+                                    "deprecate! date: \"#{Date.today}\", because: :discontinued")
+                end
+              else
+                add_offense(node, message: MESSAGE)
+              end
+            end
+          end
+        end
+
+        def_node_matcher :caveats_constains_only_discontinued?, <<~EOS
+          (block
+            (send nil? :caveats)
+            (args)
+            (send nil? :discontinued))
+        EOS
+
+        def_node_search :find_discontinued_method_call, <<~EOS
+          $(send nil? :discontinued)
+        EOS
+      end
+    end
+  end
+end

Library/Homebrew/rubocops/cask/discontinued.rbi

@@ -0,0 +1,25 @@
+# typed: strict
+
+module RuboCop
+  module Cop
+    module Cask
+      class Discontinued < Base
+        sig {
+          params(
+            base_node: RuboCop::AST::BlockNode,
+            block:     T.nilable(T.proc.params(node: RuboCop::AST::SendNode).void),
+          ).returns(T::Boolean)
+        }
+        def caveats_constains_only_discontinued?(base_node, &block); end
+
+        sig {
+          params(
+            base_node: RuboCop::AST::BlockNode,
+            block:     T.proc.params(node: RuboCop::AST::SendNode).void,
+          ).void
+        }
+        def find_discontinued_method_call(base_node, &block); end
+      end
+    end
+  end
+end

Library/Homebrew/rubocops/rubocop-cask.rb

@@ -13,6 +13,7 @@ require_relative "cask/mixin/cask_help"
 require_relative "cask/mixin/on_homepage_stanza"
 require_relative "cask/mixin/on_url_stanza"
 require_relative "cask/desc"
+require_relative "cask/discontinued"
 require_relative "cask/homepage_url_trailing_slash"
 require_relative "cask/no_overrides"
 require_relative "cask/on_system_conditionals"

Library/Homebrew/test/rubocops/cask/discontinued_spec.rb

@@ -0,0 +1,65 @@
+# frozen_string_literal: true
+
+require "rubocops/rubocop-cask"
+
+describe RuboCop::Cop::Cask::Discontinued, :config do
+  it "reports no offenses when there is no `caveats` stanza" do
+    expect_no_offenses <<~CASK
+      cask "foo" do
+        url "https://example.com/download/foo-v1.2.0.dmg",
+            verified: "example.com/download/"
+      end
+    CASK
+  end
+
+  it "reports no offenses when there is a `caveats` stanza without `discontinued`" do
+    expect_no_offenses <<~CASK
+      cask "foo" do
+        url "https://example.com/download/foo-v1.2.0.dmg",
+            verified: "example.com/download/"
+
+        caveats do
+          files_in_usr_local
+        end
+      end
+    CASK
+  end
+
+  it "reports an offense when there is a `caveats` stanza with `discontinued` and other caveats" do
+    expect_offense <<~CASK
+      cask "foo" do
+        url "https://example.com/download/foo-v1.2.0.dmg",
+            verified: "example.com/download/"
+
+        caveats do
+          discontinued
+          ^^^^^^^^^^^^ Use `deprecate!` instead of `caveats { discontinued }`.
+          files_in_usr_local
+        end
+      end
+    CASK
+  end
+
+  it "corrects `caveats { discontinued }` to `deprecate!`" do
+    expect_offense <<~CASK
+      cask "foo" do
+        url "https://example.com/download/foo-v1.2.0.dmg",
+            verified: "example.com/download/"
+
+        caveats do
+        ^^^^^^^^^^ Use `deprecate!` instead of `caveats { discontinued }`.
+          discontinued
+        end
+      end
+    CASK
+
+    expect_correction <<~CASK
+      cask "foo" do
+        url "https://example.com/download/foo-v1.2.0.dmg",
+            verified: "example.com/download/"
+
+        deprecate! date: "#{Date.today}", because: :discontinued
+      end
+    CASK
+  end
+end