Re: [boost] a question about scoped_ptr and checked_delete

Bronek Kozicki wrote:

As I understand, checked_delete is being used by scoped_ptr to prevent deletion of incomplete type. However, this very simple program is accepted by MSVC6, MSVC71 and MinGW (GCC) 3.4.4, even though implicit destructor of A is deleting incomplete class A::impl.

Apparently, ~A is being implicitly generated at the end of the translation unit, where A::impl is complete. If you add ~impl that prints something, you'll see that it is actually being called. If you remove the definition of A::impl, the program will no longer compile. At least under MSVC 7.1.