[Patch, libstdc++/68877] Reimplement __is_[nothrow_]swappable

[Jonathan Wakely]

On 22/12/15 22:58 +0100, Daniel Krügler wrote:
>2015-12-22 22:42 GMT+01:00 Jonathan Wakely <jwakely@redhat.com>:
>> On 21/12/15 12:45 +0100, Daniel Krügler wrote:
>>>
>>> 2015-12-14 21:48 GMT+01:00 Daniel Krügler <daniel.kruegler@gmail.com>:
>>>>
>>>> This is a reimplementation of __is_swappable and
>>>> __is_nothrow_swappable according to
>>>>
>>>> http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2015/n4511.html
>>>>
>>>> and also adds a missing usage of __is_nothrow_swappable in the swap
>>>> overload for arrays. Strictly speaking the latter change differs from
>>>> the Standard specification which requires the expression
>>>> noexcept(swap(*a, *b)) to be used. On the other hand the Standard is
>>>> broken in this regard, as pointed out by
>>>>
>>>> http://cplusplus.github.io/LWG/lwg-active.html#2554
>>
>>
>> The patch doesn't apply cleanly because it repeats some of the new
>> files either twice or three times (and also has some trailing
>> whitespace that shouldn't be there). After fixing the patch to only
>> create new files once it applies, but then I get some FAILs:
>>
>> FAIL: 20_util/is_nothrow_swappable/value.cc (test for excess errors)
>> FAIL: 20_util/is_swappable/value.cc (test for excess errors)
>>
>> I don't have time to analyse these today, so I'll wait until you're
>> able to do so. There's no great rush to fix this, as long as it's in
>> stage 3.
>
>Thanks for looking at this. When will stage 3 end?

Probably in two or three months time.