[PATCH] SemaChecking: return type validation for member functions

[Richard Smith]

  From SemaDecl.cpp:

    // Check that the return type is not an abstract class type.
    // For record types, this is done by the AbstractClassUsageDiagnoser once
    // the class has been completely parsed.
    if (!DC->isRecord() &&
        SemaRef.RequireNonAbstractType(D.getIdentifierLoc(),
                                       R->getAs<FunctionType>()->getResultType(),
                                       diag::err_abstract_type_in_decl,
                                       SemaRef.AbstractReturnType))
      D.setInvalidType();

  So the bug is somewhere around the fact that `AbstractClassUsageDiagnoser` does not exist. =)

http://llvm-reviews.chandlerc.com/D2514