[swift-evolution] 'T != Type' in where clause

[Joe Groff]

> On Feb 27, 2017, at 4:34 PM, Rex Fenley via swift-evolution <swift-evolution at swift.org> wrote:
> 
> I often find myself running into situations where I'll receive "Ambiguous use of..." for overloaded functions or operators. In every case these situations would be easily solved if I could specify "Generic != CertainType" in the where clause of one of the overloads so I can disambiguate the cases. Could this be added to language?

Do you have a concrete example where you need this? It'd be good to know whether the types are ambiguous due to type checker bugs, or whether there's a principle by which they could be naturally ordered. Instead of overloading, can you do the type test via `if !(x is CertainType)` within a single implementation?

-Joe