Generate options immediately following depends_on

Given

  depends_on 'gnutls' => :recommended
  depends_on 'libgcrypt' unless build.without? 'gnutls'

the dependency on libgcrypt should be enabled by default. However, the
corresponding option has not yet been generated, so the condition is
true and the dependency is disabled.

Instead, add a hook method that fires after each depends_on and adds the
appropriate option.

Library/Homebrew/formula.rb

@@ -420,8 +420,6 @@ class Formula
 
     raise NameError if !klass.ancestors.include? Formula
 
-    klass.finalize_dsl
-
     return klass.new(name) if install_type == :from_name
     return klass.new(name, path.to_s)
   rescue NoMethodError
@@ -743,6 +741,7 @@ private
 
     def depends_on dep
       dependencies.add(dep)
+      post_depends_on
     end
 
     def option name, description=nil
@@ -805,20 +804,15 @@ private
       @test = block
     end
 
-    # This method is called once by `factory` before creating any instances.
-    # It allows the DSL to finalize itself, reducing complexity in the constructor.
-    def finalize_dsl
-      # Synthesize options for optional dependencies
-      dependencies.deps.select(&:optional?).each do |dep|
-        unless build.has_option? "with-#{dep.name}"
-          option "with-#{dep.name}", "Build with #{dep.name} support"
-        end
-      end
+    private
 
-      # Synthesize options for recommended dependencies
-      dependencies.deps.select(&:recommended?).each do |dep|
-        unless build.has_option? "without-#{dep.name}"
-          option "without-#{dep.name}", "Build without #{dep.name} support"
+    def post_depends_on
+      # Generate with- and without- options for optional and recommended deps
+      dependencies.deps.each do |dep|
+        if dep.optional? && !build.has_option?("with-#{dep.name}")
+          build.add("with-#{dep.name}", "Build with #{dep.name} support")
+        elsif dep.recommended? && !build.has_option?("without-#{dep.name}")
+          build.add("without-#{dep.name}", "Build without #{dep.name} support")
         end
       end
     end