Unify 'which' and which_s' utility methods

'which' only returns a Pathname or nil, and doesn't care about anything
sent to stderr, so just silence it by default and combine the two
methods.

Closes Homebrew/homebrew#12115.

Signed-off-by: Jack Nagel <jacknagel@gmail.com>

Library/Homebrew/cmd/doctor.rb

@@ -633,7 +633,7 @@ def check_for_multiple_volumes
 end
 
 def check_for_git
-  unless which_s "git" then <<-EOS.undent
+  unless which "git" then <<-EOS.undent
     Git could not be found in your PATH.
     Homebrew uses Git for several internal functions, and some formulae use Git
     checkouts instead of stable tarballs. You may want to install Git:
@@ -643,7 +643,7 @@ def check_for_git
 end
 
 def check_git_newline_settings
-  return unless which_s "git"
+  return unless which "git"
 
   autocrlf = `git config --get core.autocrlf`.chomp
   safecrlf = `git config --get core.safecrlf`.chomp
@@ -774,7 +774,7 @@ def check_missing_deps
 end
 
 def check_git_status
-  return unless which_s "git"
+  return unless which "git"
   HOMEBREW_REPOSITORY.cd do
     unless `git status -s -- Library/Homebrew/ 2>/dev/null`.chomp.empty? then <<-EOS.undent
       You have uncommitted modifications to Homebrew's core.
@@ -803,7 +803,7 @@ end
 
 def check_git_version
   # see https://github.com/blog/642-smart-http-support
-  return unless which_s "git"
+  return unless which "git"
   `git --version`.chomp =~ /git version (\d)\.(\d)\.(\d)/
 
   if $2.to_i < 6 or $2.to_i == 6 and $3.to_i < 6 then <<-EOS.undent
@@ -815,7 +815,7 @@ def check_git_version
 end
 
 def check_for_enthought_python
-  if which_s "enpkg" then <<-EOS.undent
+  if which "enpkg" then <<-EOS.undent
     Enthought Python was found in your PATH.
     This can cause build problems, as this software installs its own
     copies of iconv and libxml2 into directories that are picked up by
@@ -825,7 +825,7 @@ def check_for_enthought_python
 end
 
 def check_for_bad_python_symlink
-  return unless which_s "python"
+  return unless which "python"
   # Indeed Python --version outputs to stderr (WTF?)
   `python --version 2>&1` =~ /Python (\d+)\./
   unless $1 == "2" then <<-EOS.undent

Library/Homebrew/cmd/update.rb

@@ -4,7 +4,7 @@ require 'cmd/untap'
 module Homebrew extend self
 
   def update
-    abort "Please `brew install git' first." unless which_s "git"
+    abort "Please `brew install git' first." unless which "git"
 
     # ensure GIT_CONFIG is unset as we need to operate on .git/config
     ENV.delete('GIT_CONFIG')

Library/Homebrew/cmd/versions.rb

@@ -2,7 +2,7 @@ require 'formula'
 
 module Homebrew extend self
   def versions
-    raise "Please `brew install git` first" unless which_s "git"
+    raise "Please `brew install git` first" unless which "git"
     raise "Please `brew update' first" unless (HOMEBREW_REPOSITORY/".git").directory?
 
     raise FormulaUnspecifiedError if ARGV.named.empty?

Library/Homebrew/download_strategy.rb

@@ -80,7 +80,7 @@ class CurlDownloadStrategy < AbstractDownloadStrategy
       safe_system '/usr/bin/tar', 'xf', @tarball_path
       chdir
     when :xz
-      raise "You must install XZutils: brew install xz" unless which_s "xz"
+      raise "You must install XZutils: brew install xz" unless which "xz"
       safe_system "xz -dc \"#{@tarball_path}\" | /usr/bin/tar xf -"
       chdir
     when :pkg
@@ -322,7 +322,7 @@ class GitDownloadStrategy < AbstractDownloadStrategy
   end
 
   def fetch
-    raise "You must install Git: brew install git" unless which_s "git"
+    raise "You must install Git: brew install git" unless which "git"
 
     ohai "Cloning #{@url}"
 
@@ -455,7 +455,7 @@ class MercurialDownloadStrategy < AbstractDownloadStrategy
   def cached_location; @clone; end
 
   def fetch
-    raise "You must install Mercurial: brew install mercurial" unless which_s "hg"
+    raise "You must install Mercurial: brew install mercurial" unless which "hg"
 
     ohai "Cloning #{@url}"
 
@@ -496,7 +496,7 @@ class BazaarDownloadStrategy < AbstractDownloadStrategy
   def cached_location; @clone; end
 
   def fetch
-    raise "You must install bazaar first" unless which_s "bzr"
+    raise "You must install bazaar first" unless which "bzr"
 
     ohai "Cloning #{@url}"
     unless @clone.exist?
@@ -539,7 +539,7 @@ class FossilDownloadStrategy < AbstractDownloadStrategy
   def cached_location; @clone; end
 
   def fetch
-    raise "You must install fossil first" unless which_s "fossil"
+    raise "You must install fossil first" unless which "fossil"
 
     ohai "Cloning #{@url}"
     unless @clone.exist?

Library/Homebrew/utils.rb

@@ -147,9 +147,8 @@ def puts_columns items, star_items=[]
   end
 end
 
-def which cmd, silent=false
-  cmd += " 2>/dev/null" if silent
-  path = `/usr/bin/which #{cmd}`.chomp
+def which cmd
+  path = `/usr/bin/which #{cmd} 2>/dev/null`.chomp
   if path.empty?
     nil
   else
@@ -157,19 +156,15 @@ def which cmd, silent=false
   end
 end
 
-def which_s cmd
-  which cmd, true
-end
-
 def which_editor
   editor = ENV['HOMEBREW_EDITOR'] || ENV['EDITOR']
   # If an editor wasn't set, try to pick a sane default
   return editor unless editor.nil?
 
   # Find Textmate
-  return 'mate' if which_s "mate"
+  return 'mate' if which "mate"
   # Find # BBEdit / TextWrangler
-  return 'edit' if which_s "edit"
+  return 'edit' if which "edit"
   # Default to vim
   return '/usr/bin/vim'
 end
@@ -405,7 +400,7 @@ module MacOS extend self
       # Xcode 4.3 xc* tools hang indefinately if xcode-select path is set thus
       raise if `xcode-select -print-path 2>/dev/null`.chomp == "/"
 
-      raise unless which_s "xcodebuild"
+      raise unless which "xcodebuild"
       `xcodebuild -version 2>/dev/null` =~ /Xcode (\d(\.\d)*)/
       raise if $1.nil? or not $?.success?
       $1

bin/brew

@@ -72,7 +72,7 @@ begin
 
   # Add example external commands to PATH before checking.
   ENV['PATH'] += ":#{HOMEBREW_REPOSITORY}/Library/Contributions/cmds"
-  if which_s "brew-#{cmd}"
+  if which "brew-#{cmd}"
     %w[CACHE CELLAR LIBRARY_PATH PREFIX REPOSITORY].each do |e|
       ENV["HOMEBREW_#{e}"] = Object.const_get "HOMEBREW_#{e}"
     end