C++0x Concepts - Dead?

[Christian Kamm]

> Christian Kamm wrote:
>> Is there a difference between
>> template Foo(T : U) {} and
>> template Foo(T) if(is(T : U)) {} ?
>> 

Walter Bright wrote:
> Yes. Constraints determine the list of candidate template declarations,
> but do not participate in the partial ordering of candidates to
> determine the 'best' match.

Thanks for the explanation!

I expect the reason is that for constrained templates it is impossible to 
determine whether all valid template arguments for one would lead to a valid 
instantiation of another?