Onboard Rubocop Naming/MemoizedInstanceVariableName rule to RubyGems.

lib/rubygems/command_manager.rb

@@ -84,7 +84,7 @@ class Gem::CommandManager
   # Return the authoritative instance of the command manager.
 
   def self.instance
-    @command_manager ||= new
+    @instance ||= new
   end
 
   ##
@@ -99,7 +99,7 @@ class Gem::CommandManager
   # Reset the authoritative instance of the command manager.
 
   def self.reset
-    @command_manager = nil
+    @instance = nil
   end
 
   ##

lib/rubygems/installer.rb

@@ -387,7 +387,7 @@ class Gem::Installer
   # we'll be installing into.
 
   def installed_specs
-    @specs ||= begin
+    @installed_specs ||= begin
       specs = []
 
       Gem::Util.glob_files_in_dir("*.gemspec", File.join(gem_home, "specifications")).each do |path|

lib/rubygems/request_set.rb

@@ -108,7 +108,7 @@ class Gem::RequestSet
     @requests            = []
     @sets                = []
     @soft_missing        = false
-    @sorted              = nil
+    @sorted_requests     = nil
     @specs               = nil
     @vendor_set          = nil
     @source_set          = nil
@@ -426,7 +426,7 @@ class Gem::RequestSet
   end
 
   def sorted_requests
-    @sorted ||= strongly_connected_components.flatten
+    @sorted_requests ||= strongly_connected_components.flatten
   end
 
   def specs

lib/rubygems/specification.rb

@@ -2236,7 +2236,7 @@ class Gem::Specification < Gem::BasicSpecification
   # The platform this gem runs on.  See Gem::Platform for details.
 
   def platform
-    @new_platform ||= Gem::Platform::RUBY
+    @new_platform ||= Gem::Platform::RUBY # rubocop:disable Naming/MemoizedInstanceVariableName
   end
 
   def pretty_print(q) # :nodoc:
@@ -2711,6 +2711,8 @@ class Gem::Specification < Gem::BasicSpecification
     end
 
     @installed_by_version ||= nil
+
+    nil
   end
 
   def flatten_require_paths # :nodoc:

lib/rubygems/stub_specification.rb

@@ -182,7 +182,7 @@ class Gem::StubSpecification < Gem::BasicSpecification
   ##
   # The full Gem::Specification for this gem, loaded from evalling its gemspec
 
-  def to_spec
+  def spec
     @spec ||= if @data
       loaded = Gem.loaded_specs[name]
       loaded if loaded && loaded.version == version
@@ -190,6 +190,7 @@ class Gem::StubSpecification < Gem::BasicSpecification
 
     @spec ||= Gem::Specification.load(loaded_from)
   end
+  alias_method :to_spec, :spec
 
   ##
   # Is this StubSpecification valid? i.e. have we found a stub line, OR does