Merging r261669:
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    r261669 | aaronballman | 2016-02-23 10:55:15 -0800 (Tue, 23 Feb 2016) | 1 line
    
    Amends r252104 to evaluate the controlling expression in an unevaluated context. This eliminates false-positive diagnostics about null pointer dereferences (etc) in the controlling expression.
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    llvm-svn: 261684