Diagnostics improvements for 3.9

[Hans Wennborg via cfe-commits]

I've merged the lot in r278020.

Thanks,
Hans

On Fri, Aug 5, 2016 at 7:43 PM, Hans Wennborg <hans at chromium.org> wrote:
> These all sgtm for 3.9. Go ahead and merge with
> utils/release/merge.sh, or I'll do it when I get in on Monday.
>
> Cheers,
> Hans
>
> On Fri, Aug 5, 2016 at 6:52 PM, Richard Trieu <rtrieu at google.com> wrote:
>> Typos and unused test variables fixed in r277900
>>
>> On Fri, Aug 5, 2016 at 6:46 PM, Richard Smith <richard at metafoo.co.uk> wrote:
>>>
>>> On Fri, Aug 5, 2016 at 6:33 PM, Richard Smith <richard at metafoo.co.uk>
>>> wrote:
>>>>
>>>> These all look OK for the branch. Hans, the second one fixes a crasher,
>>>> so I'd like to take at least that one. The others fix warning false
>>>> positives (which are not regressions) and look fairly safe.
>>>
>>>
>>> Correction: looks like the final one is in fact a fix for a diagnostic
>>> regression.
>>>
>>>>
>>>> On Fri, Aug 5, 2016 at 4:39 PM, Richard Trieu <rtrieu at google.com> wrote:
>>>>>
>>>>> Hans, Richard,
>>>>>
>>>>> These are some last minute diagnostic improvements for 3.9.
>>>>>
>>>>> http://llvm.org/viewvc/llvm-project?rev=277796&view=rev
>>>>> r277796
>>>>> Don't warn when negative values, like -1, are used to initialize
>>>>> unsigned bit fields.
>>>>>
>>>>> http://llvm.org/viewvc/llvm-project?rev=277797&view=rev
>>>>> r277797
>>>>> Fix crash with type alias in Template Type Diffing
>>>>
>>>>
>>>> (You have a typo Internalal in this.)
>>>>
>>>>>
>>>>> http://llvm.org/viewvc/llvm-project?rev=277866&view=rev
>>>>> r277866
>>>>> Fix false positive in -Wunsequenced and templates
>>>>>
>>>>> http://llvm.org/viewvc/llvm-project?rev=277889&view=rev
>>>>> r277889
>>>>> Fixes for two false positives in -Wreturn-stack-address dealing with
>>>>> parameter variables and reference to pointer types.
>>>>
>>>>
>>>> (Test has some x3 variables that are unused.)
>>>
>>>
>>