On 09/29/2014 11:46 AM, Andrew Sutton wrote:
The main reason for the restriction is that concept definitions are normalized into a single constraint-expression. And it's not obvious how things like using declarations and static-assertions should be interpreted within the constraint language.
A using-declaration just affects name lookup. They and typedefs/aliases can help to make the return statement easier to write.
That said, having a static_assert inside a concept kind of defeats the purpose since it triggers a diagnostic when its condition isn't satisfied. That's not very SFINAE friendly :)
True. It might still be useful if for some reason testing a concept for a certain class of types indicates an error somewhere else. And people are likely to try it, as indicated by the bug report. :)
Maybe the restriction can relaxed when we consider the TS for adoption in 17.
I suppose, but I'd prefer not to wait that long. I guess we can talk about it on the call today.
Jason
