Another GLIBC build error with GCC6

[Jeff Law]

On 08/18/2015 11:18 AM, Marek Polacek wrote:
> On Tue, Aug 18, 2015 at 10:13:00AM -0700, Steve Ellcey wrote:
>> On Tue, 2015-08-18 at 10:04 -0700, Paul Eggert wrote:
>>> Steve Ellcey wrote:
>>>> I put the old and new
>>>> code segments in a small test program and compiled it on MIPS (32 and 64
>>>> bit modes) and verified that the generated code was identical for both
>>>> versions in that setting.
>>>
>>> That's good enough for me.  I installed the patch.
>>>
>>> Wasn't there a similar problem with DT_EXTRATAGIDX?  See, for example:
>>>
>>> https://sourceware.org/ml/libc-alpha/2015-07/msg00742.html
>>
>> For some reason, I am no longer seeing this problem.  I don't see any
>> changes in GLIBC or GCC that look like they would have made this problem
>> go away so I am not sure what is going on.
>
> If this is about shift overflow warnings:
> I've changed the -Wshift-overflow warning to not warn when left-shifting 1
> into the sign bit.  It caused way too much noise.  If you still want to see
> even those, use -Wshift-overflow=2.
> <https://gcc.gnu.org/ml/gcc-patches/2015-08/msg00617.html>
And note that left shifting 1 into the sign bit may be downgraded from 
undefined to implementation defined behaviour for C (it's already 
changed for C++14).

Jeff