return type and templates

[bearophile]

Jonathan M Davis:

> It's not going to work for the compiler to figure out what
> types might work with a given template constraint and then
> have it pick one when you don't tell the template what
> type to be instantiated with.

It could work if the type system become more powerful, but what 
are the costs in compiler complexity, compilation times, and 
possible bugs in user code?

Bye,
bearophile