dependency_collector: distinguish macOS deps by OS

Library/Homebrew/dependency.rb

@@ -261,4 +261,9 @@ class UsesFromMacOSDependency < Dependency
   def dup_with_formula_name(formula)
     self.class.new(formula.full_name.to_s, tags, env_proc, option_names, bounds: bounds)
   end
+
+  sig { returns(String) }
+  def inspect
+    "#<#{self.class.name}: #{name.inspect} #{tags.inspect} #{bounds.inspect}>"
+  end
 end

Library/Homebrew/dependency_collector.rb

@@ -65,6 +65,8 @@ class DependencyCollector
   def cache_key(spec)
     if spec.is_a?(Resource) && spec.download_strategy <= CurlDownloadStrategy
       File.extname(spec.url)
+    elsif spec.is_a?(UsesFromMacOSDependency)
+      "#{spec.name}-#{spec.bounds}"
     else
       spec
     end