According to the commit history, the constructors removed by LWG4140 have never been added to libc++. Existence of non-public or deleted default constructor is observable, this patch tests that there's no such default constructor at all.
According to the commit history, the constructors removed by LWG4140 have never been added to libc++. Existence of non-public or deleted default constructor is observable, this patch tests that there's no such default constructor at all.