🚀 go-pugleaf

John E. Potter wrote:
> 
> I have only found one compiler which accepts the following.  The others
> attempt to instantiate class N prior to completing class L.  As I read
> DWP-14.3 [temp.inst], class N<int> should not be instantiated in the
> following code.  It would be instantiated when some class L<int> function
> used an N<int>.
> 
> template <class T> class N;
> template <class T> class L { N<T>* ptr; };
> template <class T> class N { L<T> next; };
> int main () { L<int> l; }
> 
> Do I have one correct compiler that accepts it, several correct compilers
> which reject it, or (I hope not) all correct compilers because it is not
> specified?

You have one (at least semi-) correct compiler, and several broken ones.

> If the latter, is there any standard way to make this portable?  I can
> change ptr to a void* and reinterpret_castrate everything, but that is
> not very pleasing.

You could change the member to a void* and provide an (inline) access 
function that does the cast, in only one place.  Better to use 
non-broken compilers, of course.

Nathan Myers
ncm@cantrip.org  http://www.cantrip.org/
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