[PATCH] Fix for libc++ bug #20096 http://llvm.org/bugs/show_bug.cgi?id=20096

[Marshall Clow]

Eric - I believe that invoking the destructor in this case is not well formed, because the destructor has been explicitly deleted. 

See section 8.4.2/2:
A program that refers to a deleted function implicitly or explicitly, other than to declare it, is ill-formed. [ Note: This includes calling the function implicitly or explicitly and forming a pointer or pointer-to-member to the function. It applies even for references in expressions that are not potentially-evaluated. If a function
is overloaded, it is referenced only if the function is selected by overload resolution. — end note ]

http://reviews.llvm.org/D4306