duplicates:

• SR-7425 ambiguity error when class constraining protocol extension fulfills protocol requirement

Issue Description:

Possibly related to SR-7940

Consider the following:

protocol Foo: class {
    var foo: Int { get }
}

extension Foo where Self: Bar {
    func run() {
        _ = foo
    }
}

class Bar {
    var foo: Int = 0
}

This produces:
error: ambiguous use of 'foo'
_ = foo
^

Given the type constraint on the protocol, don't the 2 candidates have be the same? What's a situation where they'd differ? I tried adjusting the call site to

_ = (self as Foo).foo
_ = (self as Bar).foo

to compare results, but every time, it appears to call the same method. This is true whether foo is defined in a protocol extension or not, whether I'm calling run on a subclass of Bar or not.