cpp/experimental/weak ptr/weak ptr

Constructs a new that potentially shares an object with.

@1@ Default constructor. Constructs empty. @2@ Constructs new which shares an object managed by. If manages no object,  manages no object too. The templated overloads don't participate in overload resolution unless either is implicitly convertible to, or  is the type "array of  " for some type  and some number , and  is the type "array of unknown bound of (possibly cv-qualified) ". @3@ Move constructors. Moves a instance from  into. After this, is empty and. The templated overload doesn't participate in overload resolution unless either is implicitly convertible to, or  is the type "array of  " for some type  and some number , and  is the type "array of unknown bound of (possibly cv-qualified) ".