After dyn_cast'ing, it generally makes sense to check the *output* of
the dyn_cast against NULL rather than the *input*. Fixes PR6025.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@93435 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed