Only warn if repo of discontinued cask is archived.

Library/Homebrew/cask/audit.rb

@@ -492,7 +492,15 @@ module Cask
       metadata = SharedAudits.github_repo_data(user, repo)
       return if metadata.nil?
 
-      add_error "GitHub repo is archived" if metadata["archived"]
+      return unless metadata["archived"]
+
+      message = "GitHub repo is archived"
+
+      if cask.discontinued?
+        add_warning message
+      else
+        add_error message
+      end
     end
 
     def check_gitlab_repository_archived
@@ -504,7 +512,15 @@ module Cask
       metadata = SharedAudits.gitlab_repo_data(user, repo)
       return if metadata.nil?
 
-      add_error "GitLab repo is archived" if metadata["archived"]
+      return unless metadata["archived"]
+
+      message = "GitLab repo is archived"
+
+      if cask.discontinued?
+        add_warning message
+      else
+        add_error message
+      end
     end
 
     def check_github_repository

Library/Homebrew/cask/dsl.rb

@@ -80,6 +80,7 @@ module Cask
                             :url,
                             :version,
                             :appdir,
+                            :discontinued?,
                             *ORDINARY_ARTIFACT_CLASSES.map(&:dsl_key),
                             *ACTIVATABLE_ARTIFACT_CLASSES.map(&:dsl_key),
                             *ARTIFACT_BLOCK_CLASSES.flat_map { |klass| [klass.dsl_key, klass.uninstall_dsl_key] },
@@ -259,6 +260,10 @@ module Cask
       @caveats
     end
 
+    def discontinued?
+      @caveats&.discontinued?
+    end
+
     def auto_updates(auto_updates = nil)
       set_unique_stanza(:auto_updates, auto_updates.nil?) { auto_updates }
     end

Library/Homebrew/cask/dsl/caveats.rb

@@ -15,10 +15,15 @@ module Cask
     #
     # @api private
     class Caveats < Base
+      extend Predicable
+
+      attr_predicate :discontinued?
+
       def initialize(*args)
         super(*args)
         @built_in_caveats = {}
         @custom_caveats = []
+        @discontinued = false
       end
 
       def self.caveat(name, &block)
@@ -135,6 +140,7 @@ module Cask
       end
 
       caveat :discontinued do
+        @discontinued = true
         <<~EOS
           #{@cask} has been officially discontinued upstream.
           It may stop working correctly (or at all) in recent versions of macOS.