1 files changed, 9 insertions, 0 deletions
diff --git a/Library/Homebrew/build_options.rb b/Library/Homebrew/build_options.rb
index e9a06f4e0..1c44af147 100644
--- a/Library/Homebrew/build_options.rb
+++ b/Library/Homebrew/build_options.rb
@@ -101,6 +101,15 @@ class BuildOptions
     @options - @args
   end
 
+  # @private
+  def invalid_options
+    @args - @options
+  end
+
+  def invalid_option_names
+    invalid_options.map(&:flag).sort
+  end
+
   private
 
   def option_defined?(name)