[swift-evolution] Proposal: Deprecate optionals in string interpolation

[Krystof Vasa]

The string interpolation is one of the strong sides of Swift, but also one of its weaknesses. 

It has happened to me more than once that I've used the interpolation with an optional by mistake and the result is then far from the expected result. 

This happened mostly before Swift 2.0's guard expression, but has happened since as well.

The user will seldomly want to really get the output "Optional(something)", but is almost always expecting just "something". I believe this should be addressed by a warning to force the user to check the expression to prevent unwanted results. If you indeed want the output of an optional, it's almost always better to use the ?? operator and supply a null value placeholder, e.g. "\(myOptional ?? "<<none>>")", or use myOptional.debugDescription - which is a valid expression that will always return a non-optional value to force the current behavior.

Krystof