Introduce Bundler::Plugin::UnloadedSource

An inert placeholder source that stands in for a plugin source whose
handling plugin is not loaded, so that a lockfile referencing it can
still be parsed.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: hsbt

Manifest.txt

@@ -167,6 +167,7 @@ bundler/lib/bundler/plugin/installer/git.rb
 bundler/lib/bundler/plugin/installer/path.rb
 bundler/lib/bundler/plugin/installer/rubygems.rb
 bundler/lib/bundler/plugin/source_list.rb
+bundler/lib/bundler/plugin/unloaded_source.rb
 bundler/lib/bundler/process_lock.rb
 bundler/lib/bundler/remote_specification.rb
 bundler/lib/bundler/resolver.rb

bundler/lib/bundler/plugin.rb

@@ -4,11 +4,12 @@
 
 module Bundler
   module Plugin
-    autoload :DSL,        File.expand_path("plugin/dsl", __dir__)
-    autoload :Events,     File.expand_path("plugin/events", __dir__)
-    autoload :Index,      File.expand_path("plugin/index", __dir__)
-    autoload :Installer,  File.expand_path("plugin/installer", __dir__)
-    autoload :SourceList, File.expand_path("plugin/source_list", __dir__)
+    autoload :DSL,            File.expand_path("plugin/dsl", __dir__)
+    autoload :Events,         File.expand_path("plugin/events", __dir__)
+    autoload :Index,          File.expand_path("plugin/index", __dir__)
+    autoload :Installer,      File.expand_path("plugin/installer", __dir__)
+    autoload :SourceList,     File.expand_path("plugin/source_list", __dir__)
+    autoload :UnloadedSource, File.expand_path("plugin/unloaded_source", __dir__)
 
     class MalformattedPlugin < PluginError; end
     class UndefinedCommandError < PluginError; end

bundler/lib/bundler/plugin/unloaded_source.rb

@@ -0,0 +1,25 @@
+# frozen_string_literal: true
+
+module Bundler
+  module Plugin
+    # Stands in for a source handled by a plugin that is not loaded yet, so
+    # that the lockfile can still be parsed during the plugin install pass,
+    # and by external tools reading a lockfile without the plugin installed.
+    class UnloadedSource
+      include API::Source
+
+      # Unlike real plugin sources, where the handling class encodes the
+      # source type, all unloaded sources share this class, so the type must
+      # be compared explicitly.
+      def ==(other)
+        super && options["type"] == other.options["type"]
+      end
+
+      alias_method :eql?, :==
+
+      def hash
+        [super, options["type"]].hash
+      end
+    end
+  end
+end