duplicates:

• SR-617 Self not always resolved dynamically with Generics

Issue Description:

There seems to be an issue in the way static methods are dynamically dispatched when a protocol extension is involved.

IF the inferred type of a variable is the protocol:

• AND the method is defined in the original protocol THEN the runtime type’s implementation is called, irrespective of whether there is a default implementation in the extension.

• AND the method is not defined in the original protocol, THEN the default implementation is called.

• ELSE IF the inferred type of the variable is the type THEN the type’s implementation is called.

When static variables are involved, the behaviour seems to be the opposite.
Consider the following code:

protocol Reusable: class {
    static var reuseID: String { get }
}

extension Reusable {
    static var reuseID: String { return String(Self) }
}

func register<T where T: Reusable>(cell: T.Type) {
    print(cell)
    print(cell.reuseID)
}

class Cell: Reusable {}
class SubCell: Cell {}

register(SubCell.self)

This prints:

SubCell
Cell

instead of the expected

SubCell
SubCell

What's more, commenting out the reuseID declaration on the Reusable protocol (leaving only the implementation in the extension) seems to fix the problem.