Optimize map { ... }.compact calls (#15513)

* Optimize map { ... }.compact

using Enumerable#filter_map, supported since Ruby 2.7

* Add poyfill for Enumerable#filter_map

lib/enumerable.rb

@@ -0,0 +1,26 @@
+# frozen_string_literal: true
+
+module Enumerable
+  # TODO: Remove this once stop to support Ruby 2.6
+  if RUBY_VERSION < '2.7.0'
+    def filter_map
+      if block_given?
+        result = []
+        each do |element|
+          res = yield element
+          result << res if res
+        end
+        result
+      else
+        Enumerator.new do |yielder|
+          result = []
+          each do |element|
+            res = yielder.yield element
+            result << res if res
+          end
+          result
+        end
+      end
+    end
+  end
+end

lib/paperclip/attachment_extensions.rb

@@ -27,7 +27,7 @@ module Paperclip
       return true  if original_filename == other_filename
       return false if original_filename.nil?
 
-      formats = styles.values.map(&:format).compact
+      formats = styles.values.filter_map(&:format)
 
       return false if formats.empty?