livecheck: allow parent formula reference in resources

Library/Homebrew/livecheck.rb

@@ -60,14 +60,14 @@ class Livecheck
   sig {
     params(
       # Name of formula to inherit livecheck info from.
-      formula_name: String,
+      formula_name: T.any(String, Symbol),
-    ).returns(T.nilable(String))
+    ).returns(T.nilable(T.any(String, Symbol)))
   }
   def formula(formula_name = T.unsafe(nil))
     case formula_name
     when nil
       @referenced_formula_name
-    when String
+    when String, :parent
       @referenced_formula_name = formula_name
     end
   end

Library/Homebrew/livecheck/livecheck.rb

@@ -850,6 +850,7 @@ module Homebrew
       resource_version_info = {}
 
       livecheck = resource.livecheck
+      livecheck_reference = livecheck.formula
       livecheck_url = livecheck.url
       livecheck_regex = livecheck.regex
       livecheck_strategy = livecheck.strategy
@@ -858,6 +859,7 @@ module Homebrew
       livecheck_url_string = livecheck_url_to_string(livecheck_url, resource) if livecheck_url
 
       urls = [livecheck_url_string] if livecheck_url_string
+      urls = ["None"] if livecheck_reference == :parent
       urls ||= checkable_urls(resource)
 
       checked_urls = []
@@ -893,6 +895,7 @@ module Homebrew
           end
           puts "Strategy:         #{strategy.blank? ? "None" : strategy_name}"
           puts "Regex:            #{livecheck_regex.inspect}" if livecheck_regex.present?
+          puts "Formula Ref:      #{resource.owner.name} (parent)" if livecheck_reference == :parent
         end
 
         if livecheck_strategy.present?
@@ -904,19 +907,26 @@ module Homebrew
             next
           end
         end
-        puts if debug && strategy.blank?
+        puts if debug && strategy.blank? && livecheck_reference != :parent
-        next if strategy.blank?
+        next if strategy.blank? && livecheck_reference != :parent
 
-        strategy_args = {
+        if livecheck_reference == :parent
-          url:,
+          match_version_map = { formula_latest => Version.new(formula_latest) }
-          regex:         livecheck_regex,
+          cached = true
-          homebrew_curl: false,
+        else
-        }.compact
+          strategy_args = {
+            url:,
+            regex:         livecheck_regex,
+            homebrew_curl: false,
+          }.compact
+
+          strategy_data = strategy.find_versions(**strategy_args, &livecheck_strategy_block)
+          match_version_map = strategy_data[:matches]
+          regex = strategy_data[:regex]
+          messages = strategy_data[:messages]
+          cached = strategy_data[:cached]
+        end
 
-        strategy_data = strategy.find_versions(**strategy_args, &livecheck_strategy_block)
-        match_version_map = strategy_data[:matches]
-        regex = strategy_data[:regex]
-        messages = strategy_data[:messages]
         checked_urls << url
 
         if messages.is_a?(Array) && match_version_map.blank?
@@ -927,14 +937,14 @@ module Homebrew
         end
 
         if debug
-          if strategy_data[:url].present? && strategy_data[:url] != url
+          if strategy_data&.dig(:url).present? && strategy_data[:url] != url
             puts "URL (strategy):   #{strategy_data[:url]}"
           end
-          puts "URL (final):      #{strategy_data[:final_url]}" if strategy_data[:final_url].present?
+          puts "URL (final):      #{strategy_data[:final_url]}" if strategy_data&.dig(:final_url).present?
-          if strategy_data[:regex].present? && strategy_data[:regex] != livecheck_regex
+          if strategy_data&.dig(:regex).present? && strategy_data[:regex] != livecheck_regex
             puts "Regex (strategy): #{strategy_data[:regex].inspect}"
           end
-          puts "Cached?:          Yes" if strategy_data[:cached] == true
+          puts "Cached?:          Yes" if cached == true
         end
 
         match_version_map.delete_if do |_match, version|
@@ -987,16 +997,16 @@ module Homebrew
         end
         resource_version_info[:meta][:url][:original] = original_url
         resource_version_info[:meta][:url][:processed] = url if url != original_url
-        if strategy_data[:url].present? && strategy_data[:url] != url
+        if strategy_data&.dig(:url).present? && strategy_data[:url] != url
           resource_version_info[:meta][:url][:strategy] = strategy_data[:url]
         end
-        resource_version_info[:meta][:url][:final] = strategy_data[:final_url] if strategy_data[:final_url]
+        resource_version_info[:meta][:url][:final] = strategy_data[:final_url] if strategy_data&.dig(:final_url)
         resource_version_info[:meta][:strategy] = strategy.present? ? strategy_name : nil
         if strategies.present?
           resource_version_info[:meta][:strategies] = strategies.map { |s| livecheck_strategy_names[s] }
         end
         resource_version_info[:meta][:regex] = regex.inspect if regex.present?
-        resource_version_info[:meta][:cached] = true if strategy_data[:cached] == true
+        resource_version_info[:meta][:cached] = true if cached == true
       rescue => e
         Homebrew.failed = true
         if json