dependency_collector: cleanup optional system deps

1 files changed, 14 insertions, 2 deletions

diff --git a/Library/Homebrew/extend/os/mac/dependency_collector.rb b/Library/Homebrew/extend/os/mac/dependency_collector.rb
index 8d660321e..f803c6f88 100644
--- a/Library/Homebrew/extend/os/mac/dependency_collector.rb
+++ b/Library/Homebrew/extend/os/mac/dependency_collector.rb
@@ -1,11 +1,23 @@
 class DependencyCollector
-  def ant_dep(tags)
+  def ant_dep_if_needed(tags)
     return if MacOS.version < :mavericks
     Dependency.new("ant", tags)
   end
 
-  def xz_dep(tags)
+  def xz_dep_if_needed(tags)
     return if MacOS.version >= :mavericks
     Dependency.new("xz", tags)
   end
+
+  def expat_dep_if_needed(tags)
+    # Tiger doesn't ship expat in /usr/lib
+    return if MacOS.version > :tiger
+    Dependency.new("expat", tags)
+  end
+
+  def ld64_dep_if_needed(*)
+    # Tiger's ld is too old to properly link some software
+    return if MacOS.version > :tiger
+    LD64Dependency.new
+  end
 end