Should std::unique_ptr be permitted

Question

This is a very simple question. Consider the following code:

#include 
#include 

typedef std::unique_ptr UniqueVo         


        

Answer 1

GCC actually has code to prevent it, but it didn't work until recently.

GCC's unique_ptr has a static assertion in default_deleter::operator() that should reject incomplete types:

    static_assert(sizeof(_Tp)>0,
                  "can't delete pointer to incomplete type");

However, as an extension GCC supports sizeof(void), so the assertion doesn't fail, and because it appears in a system header doesn't even give a warning (unless you use -Wsystem-headers).

I discovered this problem myself recently so to fix it I added this 10 days ago:

    static_assert(!is_void<_Tp>::value,
                  "can't delete pointer to incomplete type");

So using the latest code on trunk your example fails to compile, as required by the standard.