Use `PATH` where possible.

Library/Homebrew/brew.rb

@@ -12,9 +12,9 @@ require "pathname"
 HOMEBREW_LIBRARY_PATH = Pathname.new(__FILE__).realpath.parent
 $:.unshift(HOMEBREW_LIBRARY_PATH.to_s)
 require "global"
+require "tap"
 
 if ARGV == %w[--version] || ARGV == %w[-v]
-  require "tap"
   puts "Homebrew #{HOMEBREW_VERSION}"
   puts "Homebrew/homebrew-core #{CoreTap.instance.version_string}"
   exit 0
@@ -47,13 +47,15 @@ begin
     end
   end
 
+  path = PATH.new(ENV["PATH"])
+
   # Add contributed commands to PATH before checking.
-  Dir["#{HOMEBREW_LIBRARY}/Taps/*/*/cmd"].each do |tap_cmd_dir|
-    ENV["PATH"] += "#{File::PATH_SEPARATOR}#{tap_cmd_dir}"
-  end
+  path.append(Pathname.glob(Tap::TAP_DIRECTORY/"*/*/cmd"))
 
   # Add SCM wrappers.
-  ENV["PATH"] += "#{File::PATH_SEPARATOR}#{HOMEBREW_SHIMS_PATH}/scm"
+  path.append(HOMEBREW_SHIMS_PATH/"scm")
+
+  ENV["PATH"] = path
 
   if cmd
     internal_cmd = require? HOMEBREW_LIBRARY_PATH.join("cmd", cmd)

Library/Homebrew/cmd/sh.rb

@@ -23,7 +23,7 @@ module Homebrew
     ENV.setup_build_environment
     if superenv?
       # superenv stopped adding brew's bin but generally users will want it
-      ENV["PATH"] = ENV["PATH"].split(File::PATH_SEPARATOR).insert(1, "#{HOMEBREW_PREFIX}/bin").join(File::PATH_SEPARATOR)
+      ENV["PATH"] = PATH.new(PATH.new(ENV["PATH"]).to_a.insert(1, HOMEBREW_PREFIX/"bin"))
     end
     ENV["PS1"] = 'brew \[\033[1;32m\]\w\[\033[0m\]$ '
     ENV["VERBOSE"] = "1"

Library/Homebrew/diagnostic.rb

@@ -100,7 +100,7 @@ module Homebrew
 
       # See https://github.com/Homebrew/legacy-homebrew/pull/9986
       def check_path_for_trailing_slashes
-        all_paths = ENV["PATH"].split(File::PATH_SEPARATOR)
+        all_paths = PATH.new(ENV["PATH"]).to_a
         bad_paths = all_paths.select { |p| p[-1..-1] == "/" }
         return if bad_paths.empty?
 

Library/Homebrew/extend/ENV/shared.rb

 require "formula"
 require "compilers"
 require "development_tools"
+require "PATH"
 
 # Homebrew extends Ruby's `ENV` to make our code more readable.
 # Implemented in {SharedEnvExtension} and either {Superenv} or
@@ -80,7 +81,7 @@ module SharedEnvExtension
   end
 
   def append_path(key, path)
-    append key, path, File::PATH_SEPARATOR if File.directory? path
+    self[key] = PATH.new(self[key]).append(path)
   end
 
   # Prepends a directory to `PATH`.
@@ -92,7 +93,7 @@ module SharedEnvExtension
   # (e.g. <pre>ENV.prepend_path "PATH", which("emacs").dirname</pre>)
   def prepend_path(key, path)
     return if %w[/usr/bin /bin /usr/sbin /sbin].include? path.to_s
-    prepend key, path, File::PATH_SEPARATOR if File.directory? path
+    self[key] = PATH.new(self[key]).prepend(path)
   end
 
   def prepend_create_path(key, path)
@@ -196,7 +197,7 @@ module SharedEnvExtension
 
   # @private
   def userpaths!
-    paths = self["PATH"].split(File::PATH_SEPARATOR)
+    paths = PATH.new(self["PATH"]).to_a
     # put Superenv.bin and opt path at the first
     new_paths = paths.select { |p| p.start_with?("#{HOMEBREW_REPOSITORY}/Library/ENV", "#{HOMEBREW_PREFIX}/opt") }
     # XXX hot fix to prefer brewed stuff (e.g. python) over /usr/bin.
@@ -211,7 +212,7 @@ module SharedEnvExtension
         nil
       end
     end - %w[/usr/X11/bin /opt/X11/bin]
-    self["PATH"] = new_paths.uniq.join(File::PATH_SEPARATOR)
+    self["PATH"] = PATH.new(new_paths.uniq)
   end
 
   def fortran
@@ -244,7 +245,7 @@ module SharedEnvExtension
     else
       if (gfortran = which("gfortran", (HOMEBREW_PREFIX/"bin").to_s))
         ohai "Using Homebrew-provided fortran compiler."
-      elsif (gfortran = which("gfortran", ORIGINAL_PATHS.join(File::PATH_SEPARATOR)))
+      elsif (gfortran = which("gfortran", PATH.new(ORIGINAL_PATHS)))
         ohai "Using a fortran compiler found at #{gfortran}."
       end
       if gfortran

Library/Homebrew/extend/ENV/super.rb

@@ -104,7 +104,7 @@ module Superenv
     path = PATH.new(Superenv.bin)
 
     # Formula dependencies can override standard tools.
-    path.append(deps.map { |d| d.opt_bin.to_s })
+    path.append(deps.map(&:opt_bin))
     path.append(homebrew_extra_paths)
     path.append("/usr/bin", "/bin", "/usr/sbin", "/sbin")
 

Library/Homebrew/global.rb

@@ -56,7 +56,7 @@ HOMEBREW_PULL_OR_COMMIT_URL_REGEX = %r[https://github\.com/([\w-]+)/([\w-]+)?/(?
 require "compat" unless ARGV.include?("--no-compat") || ENV["HOMEBREW_NO_COMPAT"]
 
 ENV["HOMEBREW_PATH"] ||= ENV["PATH"]
-ORIGINAL_PATHS = ENV["HOMEBREW_PATH"].split(File::PATH_SEPARATOR).map do |p|
+ORIGINAL_PATHS = PATH.new(ENV["HOMEBREW_PATH"]).to_a.map do |p|
   begin
     Pathname.new(p).expand_path
   rescue

Library/Homebrew/requirement.rb

@@ -96,7 +96,7 @@ class Requirement
     # PATH.
     parent = satisfied_result_parent
     return unless parent
-    return if ENV["PATH"].split(File::PATH_SEPARATOR).include?(parent.to_s)
+    return if PATH.new(ENV["PATH"]).to_a.include?(parent.to_s)
     ENV.append_path("PATH", parent)
   end
 
@@ -151,11 +151,11 @@ class Requirement
   end
 
   def which(cmd)
-    super(cmd, ORIGINAL_PATHS.join(File::PATH_SEPARATOR))
+    super(cmd, PATH.new(ORIGINAL_PATHS))
   end
 
   def which_all(cmd)
-    super(cmd, ORIGINAL_PATHS.join(File::PATH_SEPARATOR))
+    super(cmd, PATH.new(ORIGINAL_PATHS))
   end
 
   class << self

Library/Homebrew/utils.rb

@@ -293,7 +293,7 @@ def quiet_system(cmd, *args)
 end
 
 def which(cmd, path = ENV["PATH"])
-  path.split(File::PATH_SEPARATOR).each do |p|
+  PATH.new(path).to_a.each do |p|
     begin
       pcmd = File.expand_path(cmd, p)
     rescue ArgumentError
@@ -307,7 +307,7 @@ def which(cmd, path = ENV["PATH"])
 end
 
 def which_all(cmd, path = ENV["PATH"])
-  path.to_s.split(File::PATH_SEPARATOR).map do |p|
+  PATH.new(path).to_a.map do |p|
     begin
       pcmd = File.expand_path(cmd, p)
     rescue ArgumentError
@@ -416,7 +416,7 @@ def nostdout
 end
 
 def paths(env_path = ENV["PATH"])
-  @paths ||= env_path.split(File::PATH_SEPARATOR).collect do |p|
+  @paths ||= PATH.new(env_path).to_a.collect do |p|
     begin
       File.expand_path(p).chomp("/")
     rescue ArgumentError