duplicates:

• SR-852 [QoI] Poor diagnostic with missing "self." in convenience initializer

Issue Description:

The compiler gives a confusing diagnostic when implementing a delegating initializer and calling init instead of self.init. For example:

struct Check {
    init() {}

    init(name: String) {
        init()
    }
}

This gives the error: "initializers may only be declared within a type".

In this case, I think the error should be something like "delegating initializers must use self.init to call other initializers" with a fix-it to add the "self." prefix.