Apply suggestions from code review

Co-authored-by: Nobuyoshi Nakada <nobu@ruby-lang.org>

Author: st0012

Rakefile

@@ -90,15 +90,14 @@ end
 task "#{path}.gem" => package_parser_files
 
 desc "Generate all files use racc and kpeg"
-task :generate do
-  unless ENV.key?('BUNDLE_GEMFILE')
+task :generate => parsed_files
+
+unless ENV.key?('BUNDLE_GEMFILE')
+  task :gem_install do
     Gem.install 'racc', '> 1.4.10'
     Gem.install 'kpeg', '>= 1.3.3'
   end
-
-  parsed_files.each do |file_name|
-    Rake::Task[file_name].invoke
-  end
+  file parsed_files => :gem_install
 end
 
 task :clean do

ext/rdoc/extconf.rb

@@ -2,7 +2,7 @@
 
 # Generate all parse files using racc and kpeg. This is not necessary for regular gem installation, but it is when
 # installing RDoc from the git source. Without this, the generated parse files would not exist and RDoc would not work
-system("rake generate") if Dir.exist?(File.join("..", "..", ".git"))
+system("rake generate") if File.exist?("../../.git")
 
 # RDoc doesn't actually have a native extension, but a Makefile needs to exist in order to successfully install the gem
 require "mkmf"