Dynamic templated virtuals - I still often want them

[Steven Schveighoffer]

On 7/29/20 9:37 AM, Arafel wrote:

> You could of course special-case the syntax to disable these cases, but 
> for the users it would be an unexpected outlier in how the templates work.

I think it's a 2-stage process. 1) instantiate the template with the 
type ONLY. If it can't be instantiated, then it's not valid. 2) check 
for normal overriding rules. If it cannot override the base function, 
then it's an error.

One difference might have to be attribute inference, as you may not want 
the template to infer more restrictive attributes than you need, and 
there is no way to say e.g. @gc.

-Steve