[boost] [type traits] incomplete types

From: Johan Råde (rade_at_[hidden])
Date: 2007-09-12 12:03:04

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?

Johan Råde
CTO, Qlucore AB