ср, 22 сент. 2021 г. в 20:44, Jonathan Wakely <jwakely....@gmail.com>:
>
> On Wed, 22 Sept 2021 at 18:09, Antony Polukhin wrote:
> >
> > std::unique_ptr allows construction from std::unique_ptr of derived
> > type as per [unique.ptr.single.asgn] and [unique.ptr.single.ctor]. If
> > std::default_delete is used with std::unique_ptr, then after such
> > construction a delete is called on a pointer to base. According to
> > [expr.delete] calling a delete on a non similar object without a
> > virtual destructor is an undefined behavior.
> >
> > This patch turns that undefined behavior into static assertions inside
> > std::unique_ptr.
>
> The undefined behaviour only happens if the destructor is actually
> reached at runtime, but won't these static assertions make it
> ill-formed to instantiate these members, even if the UB never happens?
>
> For example, if you ensure that release() is called before
> destruction, the undefined delete never happens.

Ugh... I've missed that use case. Patch is just wrong, discard it

-- 
Best regards,
Antony Polukhin

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