Re: [Boost-Users] type_traits::is_POD<> problem

From: John Maddock (john_maddock_at_[hidden])
Date: 2002-06-06 06:12:37

> I'm using MSVC6.0 with service-pack 6.0 installed. But I'm getting
> some
> weird problems.
>
> Consider the following simple program:
>
> ----------------------------------------------------
> struct q
> {
>      int x;
> };
>
> int main()
> {
>         int t;
>         t = boost::is_POD< int >::value;             // Ok, t = true;
>         t = boost::is_POD< void >::value;          // Ok?, t = true
> (is
> 'void' considered a POD?);
>         t = boost::is_POD< q >::value;              // Error, t =
> false
> }
> ----------------------------------------------------
>
> Unless my definition of a POD type is incorrect, I think that q is
> considered POD, right?
>
> Am I doing something wrong here, or is the combination boost and msvc
> fatal
> once again?

No, there is no way within the current language that is_POD can deduce that
q is a POD.  Hopefully the next version of the standard will address this,
but until then about the only option is to provide a specialisation of
is_POD for known non-trivial POD types.

John Maddock
http://ourworld.compuserve.com/homepages/john_maddock/index.htm