Fix DoubleNegation.

Library/.rubocop_todo.yml

@@ -151,13 +151,9 @@ Style/ConstantName:
 # Offense count: 10
 Style/DoubleNegation:
   Exclude:
-    - 'Homebrew/extend/ARGV.rb'
-    - 'Homebrew/formula_installer.rb'
     - 'Homebrew/os/mac/cctools_keg.rb'
     - 'Homebrew/os/mac/ruby_keg.rb'
     - 'Homebrew/os/mac/xcode.rb'
-    - 'Homebrew/requirement.rb'
-    - 'Homebrew/software_spec.rb'
 
 # Offense count: 1
 # Configuration parameters: EnforcedStyle, SupportedStyles.

Library/Homebrew/extend/ARGV.rb

@@ -216,7 +216,7 @@ module HomebrewArgvExtension
   end
 
   def build_all_from_source?
-    !!ENV["HOMEBREW_BUILD_FROM_SOURCE"]
+    !ENV["HOMEBREW_BUILD_FROM_SOURCE"].nil?
   end
 
   # Whether a given formula should be built from source during the current

Library/Homebrew/formula_installer.rb

@@ -24,7 +24,9 @@ class FormulaInstaller
     private(*names)
     names.each do |name|
       predicate = "#{name}?"
-      define_method(predicate) { !!send(name) }
+      define_method(predicate) do
+        send(name) ? true : false
+      end
       private(predicate)
     end
   end
@@ -71,7 +73,8 @@ class FormulaInstaller
   end
 
   def build_bottle?
-    !!@build_bottle && !formula.bottle_disabled?
+    return false unless @build_bottle
+    !formula.bottle_disabled?
   end
 
   def pour_bottle?(install_bottle_options = { warn: false })

Library/Homebrew/os/mac/xcode.rb

@@ -175,7 +175,7 @@ module OS
       # Returns true even if outdated tools are installed, e.g.
       # tools from Xcode 4.x on 10.9
       def installed?
-        !!detect_version
+        !detect_version.nil?
       end
 
       def update_instructions

Library/Homebrew/requirement.rb

@@ -56,7 +56,7 @@ class Requirement
   def satisfied?
     result = self.class.satisfy.yielder { |p| instance_eval(&p) }
     @satisfied_result = result
-    !!result
+    result ? true : false
   end
 
   # Overriding #fatal? is deprecated.

Library/Homebrew/software_spec.rb

@@ -65,11 +65,12 @@ class SoftwareSpec
   end
 
   def bottle_unneeded?
-    !!@bottle_disable_reason && @bottle_disable_reason.unneeded?
+    return false unless @bottle_disable_reason
+    @bottle_disable_reason.unneeded?
   end
 
   def bottle_disabled?
-    !!@bottle_disable_reason
+    @bottle_disable_reason ? true : false
   end
 
   attr_reader :bottle_disable_reason
@@ -318,7 +319,7 @@ class BottleSpecification
   end
 
   def tag?(tag)
-    !!checksum_for(tag)
+    checksum_for(tag) ? true : false
   end
 
   # Checksum methods in the DSL's bottle block optionally take