Added comment about narrow contract for Span(T* begin, T* end) ctor

[ViralTaco]

Hi,
Following issue: #22289
It's completely overkill, even though it's just a comment. But it's what it'll take for me to sleep tonight.
I've only added a comment to clarrify that this constructor comes with a narrow contract.

[laanwj]

~0 ACK 39cb974
This comment is correct, however I don't know what else one would expect when passing an invalid range into this function.

[ViralTaco]

I don't know what else one would expect when passing an invalid range into this function.

Defined behavior?

[maflcko]

The docs say that this is UB, so why would anyone assume the opposite?

https://en.cppreference.com/w/cpp/container/span/span

The behavior is undefined if [first, first + count) is not a valid range, if It does not actually model contiguous_iterator, or if extent != std::dynamic_extent && count != extent.

[ViralTaco]

The docs say that this is UB, so why would anyone assume the opposite?

https://en.cppreference.com/w/cpp/container/span/span

The behavior is undefined if [first, first + count) is not a valid range, if It does not actually model contiguous_iterator, or if extent != std::dynamic_extent && count != extent.

Following issue: #22289

[fanquake]

Going to close this for now, given #22289 is also closed.