Pre-pitch: remove the implicit initialization of Optional variables

[davdroman (David Roman)]

@Jon_Shier

I haven't heard any actual harm or even damage that is unique to this feature vs. other implicit Swift behaviors

This thread exposes a few of the damages. Here's another one:

Optional properties get unwanted default values in memberwise initializers

extracting from another thread. i believe this behaviour is broken and needs fixing: struct S { var a: Int var b: Int? var c: Int? = nil } let x = S(a: 0, b: nil, c: nil) // ok let z = S(a: 0, b: nil) // ok let y = S(a: 0, c: nil) // *** HHHMMM??? let w = S(a: 0) // *** HHHMMM??? this is because the synthesized memberwise initializer is generated as: init(a: Int, b: Int? = nil, c: Int? = nil) i believe this is a mistake and it should be generated as: init(a: Int, b: Int?, c: Int…