This test covers the special case of renaming a type switch var.

-- p.go --
package p

func _(x interface{}) {
	switch y := x.(type) { //@rename("y", z, yToZ)
	case string:
		print(y) //@rename("y", z, yToZ)
	default:
		print(y) //@rename("y", z, yToZ)
	}
}

-- @yToZ/p.go --
package p

func _(x interface{}) {
	switch z := x.(type) { //@rename("y", z, yToZ)
	case string:
		print(z) //@rename("y", z, yToZ)
	default:
		print(z) //@rename("y", z, yToZ)
	}
}