On Wed, 22 Sept 2021 at 18:56, Antony Polukhin <antosh...@gmail.com> wrote: > > 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
It's a horrible (and probably unrealistic) use case, but we're required to accept it. I should a test case to the testsuite, just to make sure we continue to accept it without errors.
