Allow requirements to specify env options

Library/Homebrew/build.rb

@@ -57,9 +57,8 @@ end
 def post_superenv_hacks f
   # Only allow Homebrew-approved directories into the PATH, unless
   # a formula opts-in to allowing the user's path.
-  if f.env.userpaths?
+  if f.env.userpaths? or f.recursive_requirements.any? { |rq| rq.env.userpaths? }
-    paths = ORIGINAL_PATHS.map{|pn| pn.realpath.to_s rescue nil } - %w{/usr/X11/bin /opt/X11/bin}
+    ENV.userpaths!
-    ENV['PATH'] = "#{ENV['PATH']}:#{paths.join(':')}"
   end
 end
 

Library/Homebrew/dependencies.rb

@@ -1,3 +1,5 @@
+require 'build_environment'
+
 ## This file defines dependencies and requirements.
 ##
 ## A dependency is a formula that another formula needs to install.
@@ -169,6 +171,10 @@ class Requirement
   # See X11Dependency
   def modify_build_environment; nil end
 
+  def env
+    @env ||= self.class.env
+  end
+
   def eql?(other)
     other.is_a? self.class and hash == other.hash
   end
@@ -181,6 +187,12 @@ class Requirement
     def fatal(val=nil)
       val.nil? ? @fatal : @fatal = val
     end
+
+    def env(*settings)
+      @env ||= BuildEnvironment.new
+      settings.each { |s| @env << s }
+      @env
+    end
   end
 end
 

Library/Homebrew/extend/ENV.rb

@@ -431,6 +431,11 @@ class << ENV
     append 'CPPFLAGS', "-DNCURSES_OPAQUE=0"
   end
 
+  def userpaths!
+    paths = ORIGINAL_PATHS.map { |p| p.realpath.to_s rescue nil } - %w{/usr/X11/bin /opt/X11/bin}
+    self['PATH'] = paths.unshift(*self['PATH'].split(":")).uniq.join(":")
+  end
+
   def fortran
     fc_flag_vars = %w{FCFLAGS FFLAGS}
 

Library/Homebrew/requirements.rb

@@ -102,6 +102,8 @@ class MPIDependency < Requirement
 
   fatal true
 
+  env :userpaths
+
   def initialize *lang_list
     @lang_list = lang_list
     @non_functional = []