[Rubocop] Autocorrect Rakefile.

Rakefile

@@ -1,27 +1,32 @@
+# frozen_string_literal: true
+
 require 'rdoc/task'
 
-$:.unshift(File.expand_path('../ext', __FILE__))
+$LOAD_PATH.unshift(File.expand_path('ext', __dir__))
 
 task default: :test
-task compile: "extconf:compile"
+task compile: 'extconf:compile'
 
-desc "Run all tests"
+desc 'Run all tests'
 task test: :compile do
-  Dir[File.dirname(__FILE__) + '/test/**/*_test.rb'].each do |file|
+  Dir["#{File.dirname(__FILE__)}/test/**/*_test.rb"].each do |file|
     ruby file
   end
 end
 
 namespace :profile do
-  desc "Profile memory"
+  desc 'Profile memory'
   task memory: :compile do
-    sh 'valgrind --tool=memcheck --leak-check=yes --num-callers=10 --track-fds=yes ruby test/profile/memory.rb'
+    sh(
+      'valgrind --tool=memcheck --leak-check=yes --num-callers=10 ' \
+      '--track-fds=yes ruby test/profile/memory.rb'
+    )
   end
 end
 
 task :clean do
-  crap = "*.{bundle,so,o,obj,log}"
-  ["*.gem", "ext/**/#{crap}", "ext/**/Makefile"].each do |glob|
+  crap = '*.{bundle,so,o,obj,log}'
+  ['*.gem', "ext/**/#{crap}", 'ext/**/Makefile'].each do |glob|
     Dir.glob(glob).each do |file|
       rm(file)
     end
@@ -31,25 +36,25 @@ end
 namespace :extconf do
   task :makefile do
     Dir.chdir('ext') do
-      ruby "extconf.rb"
+      ruby 'extconf.rb'
     end
   end
 
   task make: :makefile do
     Dir.chdir('ext') do
-      sh(RUBY_PLATFORM =~ /win32/ ? 'nmake' : 'make') do |ok, res|
-        if !ok
-          require "fileutils"
+      sh(RUBY_PLATFORM.match?(/win32/) ? 'nmake' : 'make') do |ok, _res|
+        unless ok
+          require 'fileutils'
           FileUtils.rm_rf(Dir.glob('*.{so,o,dll,bundle}'))
         end
       end
     end
   end
 
-  desc "Compile the Ruby extension"
+  desc 'Compile the Ruby extension'
   task compile: :make do
-    if Dir.glob("ext/*.{o,so,dll}").length == 0
-      $stderr.puts("Failed to build ext.")
+    if Dir.glob('ext/*.{o,so,dll}').empty?
+      warn('Failed to build ext.')
       exit(1)
     end
   end
@@ -58,8 +63,8 @@ end
 namespace :docs do
   Rake::RDocTask.new('generate') do |rdoc|
     rdoc.title = 'Tedrahcu'
-    rdoc.main = "README.md"
+    rdoc.main = 'README.md'
     rdoc.rdoc_files.include('README.md', 'ext/tedrahcu.c')
-    rdoc.options << "--all" << "--charset" << "utf-8"
+    rdoc.options << '--all' << '--charset' << 'utf-8'
   end
-end
+end