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.
