Re: [review][fixed_string] End of review period approaching and a plea

From: Alexander Grund (alexander.grund_at_[hidden])
Date: 2019-12-05 07:59:08

On 04.12.19 19:30, Andrey Semashev via Boost wrote:
> On 2019-12-04 18:24, Alexander Grund via Boost wrote:
>>
>>> I would hope to see close to the same semantics as std::array<T,0>,
>>> which I believe allows data() to return nullptr.
>>
>> I don't think so:
>>
>> "There is a special case for a zero-length array (|N == 0|). In that 
>> case, array.begin() == array.end(), which is some unique value. The 
>> effect of calling front() or back() on a zero-sized array is 
>> undefined." from https://en.cppreference.com/w/cpp/container/array
>>
>> IMO this excludes nullptr as that won't be unique
>
> I don't think iterators from different instances of a container are 
> comparable. IOW, "unique" means distinct from any possible values of 
> valid iterators obtained from this particular container instance.
>
> That might not apply to pointers, though. I don't remember whether 
> there are any guarantees wrt. data() of a zero-sized array, for example.
You are right:
"If size() is 0, data() may or may not return a null pointer." 
https://en.cppreference.com/w/cpp/container/array/data