Allow multiple unsatisfied fatal requirements

Closes Homebrew/homebrew#13335.

Library/Homebrew/build.rb

@@ -56,7 +56,7 @@ at_exit do
 end
 
 def install f
-  f.external_deps.each { |dep| dep.modify_build_environment }
+  f.requirements.each { |dep| dep.modify_build_environment }
 
   f.recursive_deps.uniq.each do |dep|
     dep = Formula.factory dep

Library/Homebrew/dependencies.rb

@@ -19,11 +19,11 @@ class DependencyCollector
     :chicken, :jruby, :lua, :node, :perl, :python, :rbx, :ruby
   ].freeze
 
-  attr_reader :deps, :external_deps
+  attr_reader :deps, :requirements
 
   def initialize
     @deps = Dependencies.new
-    @external_deps = Set.new
+    @requirements = Set.new
   end
 
   def add spec
@@ -35,7 +35,7 @@ class DependencyCollector
     # dependency needed for the current platform.
     return if dep.nil?
     # Add dep to the correct bucket
-    (dep.is_a?(Requirement) ? @external_deps : @deps) << dep
+    (dep.is_a?(Requirement) ? @requirements : @deps) << dep
   end
 
 private

Library/Homebrew/exceptions.rb

@@ -65,12 +65,15 @@ class FormulaInstallationAlreadyAttemptedError < Homebrew::InstallationError
   end
 end
 
-class UnsatisfiedRequirement < Homebrew::InstallationError
-  attr :dep
+class UnsatisfiedRequirements < Homebrew::InstallationError
+  attr :reqs
 
-  def initialize formula, dep
-    @dep = dep
-    super formula, "An unsatisfied requirement failed this build."
+  def initialize formula, reqs
+    @reqs = reqs
+    message = (reqs.length == 1) \
+                ? "An unsatisfied requirement failed this build." \
+                : "Unsatisifed requirements failed this build."
+    super formula, message
   end
 end
 

Library/Homebrew/formula.rb

@@ -423,7 +423,7 @@ class Formula
   end
 
   def deps;         self.class.dependencies.deps;         end
-  def external_deps; self.class.dependencies.external_deps; end
+  def requirements; self.class.dependencies.requirements; end
 
   # deps are in an installable order
   # which means if a depends on b then b will be ordered before a in this list

Library/Homebrew/formula_installer.rb

@@ -43,7 +43,8 @@ class FormulaInstaller
 
     f.recursive_deps.each do |dep|
       if dep.installed? and not dep.keg_only? and not dep.linked_keg.directory?
-        raise CannotInstallFormulaError, "You must `brew link #{dep}' before #{f} can be installed"
+        raise CannotInstallFormulaError,
+              "You must `brew link #{dep}' before #{f} can be installed"
       end
     end unless ignore_deps
 
@@ -66,15 +67,25 @@ class FormulaInstaller
       EOS
     end
 
-    f.external_deps.each do |dep|
-      unless dep.satisfied?
-        puts dep.message
-        if dep.fatal? and not ignore_deps
-          raise UnsatisfiedRequirement.new(f, dep)
+    # Build up a list of unsatisifed fatal requirements
+    first_message = true
+    unsatisfied_fatals = []
+    f.requirements.each do |req|
+      unless req.satisfied?
+        # Newline between multiple messages
+        puts unless first_message
+        puts req.message
+        first_message = false
+        if req.fatal? and not ignore_deps
+          unsatisfied_fatals << req
         end
       end
     end
 
+    unless unsatisfied_fatals.empty?
+      raise UnsatisfiedRequirements.new(f, unsatisfied_fatals)
+    end
+
     unless ignore_deps
       needed_deps = f.recursive_deps.reject{ |d| d.installed? }
       unless needed_deps.empty?

Library/Homebrew/test/test_external_deps.rb

@@ -12,9 +12,9 @@ class ExternalDepsTests < Test::Unit::TestCase
     end
 
     # Should have found a dep
-    assert d.external_deps.size == 1
+    assert d.requirements.size == 1
 
-    d.external_deps do |dep|
+    d.requirements do |req|
       assert !d.satisfied?
     end
   end
@@ -26,9 +26,9 @@ class ExternalDepsTests < Test::Unit::TestCase
     end
 
     # Should have found a dep
-    assert d.external_deps.size == 1
+    assert d.requirements.size == 1
 
-    d.external_deps do |dep|
+    d.requirements do |req|
       assert d.satisfied?
     end
   end