title: ARC file compilation issue
body: <p>ProjectA is ARC, SubProject is manually reference counted i.e not ARC.</p>
  
  <p>ProjectA has SubProject embedded within it and builds it as a target dependency. So I thought that would mean it didn't matter if the SubProject was ARC or not, as ProjectA is linking to the compiled unit. </p>
  
  <p>However, in ProjectA I import a header from SubProject and that header contains enums that are not ARC compliant. i.e (ARC forbids Object-C objects in struct).</p>
  
  <p>Am I missing something simple to resolve this? </p>
  
  <p>Thanks</p>