This is a follow up patch from the following review comment: https://reviews.llvm.org/D55850?id=178767#inline-495051
Unpaired apostrophe, here and below.
The line break is no longer necessary.
Hmm. I think '' is acceptable for the unqualified case in this diagnostic because at least one of the operands has to be non-empty, but it might be better overall to say something like unqualified (not in quotes, of course).
I like the general effect of this, though; this is definitely a more readable diagnostic in the complex cases than it used to be.