On 09/07/2020 21.44, Tom Honermann wrote:
> On 7/9/20 3:16 PM, Jens Maurer wrote:
>> On 09/07/2020 18.28, Tom Honermann wrote:
>>> On 7/8/20 3:15 PM, Jens Maurer wrote:
>>>> Since all four well-known C++ implementations appear to
>>>> produce an error for the test cases at
>>>> https://compiler-explorer.com/z/4NDo-4
>>>> I'm fine with specifying these as ill-formed.
>>> I'm fine with that as well.
>>>
>>> Jens, would you consider such a change as evolutionary given that we don't know of any implementations (so far) that actually support these concatenations?
>> I'm not the one to make the call here.
> I know, I was just looking for an opinion from a CWG regular. Thank you.
>> Strictly speaking, it changes the standard for some feature from
>> "conditionally-supported" to "ill-formed", which does sound a bit
>> evolutionary, in particular since we depart a little further from
>> C here.
>>
>> However, personally, I'm ok with this going to Core right away.
>>
>> JF should make the call here.
>
> Agreed.
>
> We don't have a paper for this yet. If we have a volunteer to write a
> paper to make concatenations involving mixed L"", u8"", u"", and U""
> concatenations ill-formed, I'll be happy to discuss with JF with
> encouragement to take it straight to Core.

Here you are:

https://wiki.edg.com/pub/Wg21summer2020/SG16/concatenation.html

I think the overlap with P2029 is very manageable, so this can
go ahead regardless.

Jens