Re: [boost] [type traits] incomplete types

From: John Maddock (john_at_[hidden])
Date: 2007-09-12 12:45:24

Johan Råde wrote:
> When some type traits, for instance is_base_of,
> are called with incomplete types,
> then they may silently "return" incorrect results.
> It would be better if they failed to compile with incomplete types.
>
> Here is a suggestion how that might be implemented:
>
>    template<int> struct assert_complete0 {};
>
>    template<typename T> struct assert_complete :
>      public assert_complete0<sizeof(T)> {};
>
>    template<typename B, typename T> is_base_of :
>      public assert_complete<B>, public assert_complete<T> ...
>
> I have tested this with with VC 7.1, and it works.
> Will this work on other platforms?
> Are there any reasons not to add this check?

Nope, I've fixed this with a couple of static_asserts in the SVN trunk 
version.

John.