On 18. Aug 2025, at 13:56, Bo Persson via Std-Proposals <std-proposals_at_[hidden]> wrote:
>
> On 2025-08-18 at 13:18, Andrey Semashev via Std-Proposals wrote:
>> On 18 Aug 2025 13:33, Ben Crowhurst via Std-Proposals wrote:
>>>
>>> There is a history of STL implementations introducing string
>>> optimisations, for example, copy-on-write in GCC (<=4), adoption of
>>> small string optimisation (SSO) - with varying details across GCC,
>>> Clang, and MSVC.
>>>
>>> Focusing on SSO, using std::string, along with std::string_view and move
>>> semantics, introduces a frustrating folly.
>> Why? What is the problem with SSO?
>
> If you get a string_view to a string, and then move the string, the string_view may, or may not, move along - all because of SSO.

If you have a string_view or a span to a moved from object there is no reason to believe that the view/span is still valid. It is at least implementation defined behavior if not undefined behavior. If the view still works after a move you just got lucky. It is quite similar for iterators to be invalid for some containers after certain operations on the container.

This is certainly not a reason to disallow SSO. If you need a string+string_view with a specific behavior you should implement your own. (Hopefully compatible/convertible to a std::string.)
>
> I too prefer the performance of small strings over fixing this.
>
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