Open Radar

 
Summary:
In Swift, the convention for naming method arguments is that the first argument name is part of the method name, e.g.

func doSomethingWithFoo(foo: Int) { }

Such that the method will be called like this:

self.doSomethingWithFoo(5)

For that reason, the compiler warns you not to name your first parameter using "with", so declaring your method like this raises a warning:

func doSomething(withFoo: Int) { }

Because then it won't be clear what you mean when you call

self.doSomething(5)

This is all fine so far. The problem is that if the first parameter is optional, then the calling convention is different. Suppose that I declare my method like this:

func doSomething(withFoo foo: Int = 5) { }

I can call it like this:

self.doSomething() // foo defaults to 5

Or like this:

self.doSomething(withFoo: 7) // foo is 7

The problem is that the compiler doesn't want me to name my first parameter with a "with" prefix, and so still complains, even though it makes the code clearer in this case.

Steps to Reproduce:
Run sample project. Observe spurious warning.

Expected Results:
Compiler should recognise that use of withX for first param is appropriate if parameter is optional

Actual Results:
Compiler complains that "with is implied for first parameter"

Version:
6.1