[rubygems/rubygems] Move build artifact detection logic for root gemspec to bundler from Gem::Specification.

Gem::Specification#missing_extension? is heavily called from RubyGems.
  We should reduce extra method call from this place.

https://github.com/rubygems/rubygems/commit/e24e59d44d

lib/bundler/rubygems_ext.rb

@@ -74,6 +74,23 @@ module Gem
       end
     end
 
+    alias_method :rg_missing_extensions?, :missing_extensions?
+    def missing_extensions?
+      # When we use this methods with local gemspec, we don't handle
+      # build status of extension correctly. So We need to find extension
+      # files in require_paths.
+      # TODO: Gem::Specification couldn't access extension name from extconf.rb
+      #       so we find them with heuristic way. We should improve it.
+      if source.respond_to?(:root)
+        return false if (full_require_paths - [extension_dir]).any? do |path|
+          File.exist?(File.join(path, "#{name}.#{RbConfig::CONFIG['DLEXT']}")) ||
+          !Dir.glob(File.join(path, name, "*.#{RbConfig::CONFIG['DLEXT']}")).empty?
+        end
+      end
+
+      rg_missing_extensions?
+    end
+
     remove_method :gem_dir if instance_methods(false).include?(:gem_dir)
     def gem_dir
       full_gem_path

lib/rubygems/specification.rb

@@ -2184,16 +2184,6 @@ class Gem::Specification < Gem::BasicSpecification
     return false if default_gem?
     return false if File.exist? gem_build_complete_path
 
-    # When we use this methods with local gemspec, we don't handle
-    # build status of extension correctly. So We need to find extension
-    # files in require_paths.
-    # TODO: Gem::Specification couldn't access extension name from extconf.rb
-    #       so we find them with heuristic way. We should improve it.
-    return false if (full_require_paths - [extension_dir]).any? do |path|
-      File.exist?(File.join(path, "#{name}.#{RbConfig::CONFIG['DLEXT']}")) ||
-      !Dir.glob(File.join(path, name, "*.#{RbConfig::CONFIG['DLEXT']}")).empty?
-    end
-
     true
   end