Prevent deps of build-time deps from leaking into the build environment

When decided what dependencies should be part of the build environment
(and have appropriate entries added to variables like PKG_CONFIG_PATH),
we select the entire dependency tree except for

 (1) inactive optional and recommended deps (2) indirect build-time deps
 (i.e., build-time deps of other deps)

There is a third category that sould be excluded: dependencies of direct
build-time deps. These are irrelevant to the build, and including them
can cause unexpected linkages.

1 files changed, 13 insertions, 0 deletions

diff --git a/Library/Homebrew/test/test_dependency_expansion.rb b/Library/Homebrew/test/test_dependency_expansion.rb
index 90d4dcc36..cf22b6170 100644
--- a/Library/Homebrew/test/test_dependency_expansion.rb
+++ b/Library/Homebrew/test/test_dependency_expansion.rb
@@ -95,4 +95,17 @@ class DependencyExpansionTests < Test::Unit::TestCase
 
     assert_equal [@bar, @baz], deps
   end
+
+  def test_keep_dep_but_prune_recursive_deps
+    f = stub(:deps => [
+      build_dep(:foo, [:build], [@bar]),
+      build_dep(:baz, [:build]),
+    ])
+
+    deps = Dependency.expand(f) do |dependent, dep|
+      Dependency.keep_but_prune_recursive_deps if dep.build?
+    end
+
+    assert_equal [@foo, @baz], deps
+  end
 end