trait Quux extends Any trait QuuxRef extends AnyRef final class Bippy(val x: Any) extends AnyVal with Quux object Foo { def foo1[A <: Product](a: A) = { type X = a.type } def foo2[A <: Product with Quux](a: A) = { type X = a.type } def foo3(a: Product) = { type X = a.type } def foo4(a: Product with Quux) = { type X = a.type } def foo5(x: Quux with Product) = (x eq "abc") && ("abc" eq x) def foo6(x: Quux with Product { def f: Int }) = (x eq "abc") && ("abc" eq x) def foo7(x: Quux with Product { def eq(other: String): Boolean }) = (x eq "abc") && ("abc" eq x) def ok1[A <: QuuxRef](a: A) = { type X = a.type } def ok2[A <: Product with QuuxRef](a: A) = { type X = a.type } def ok3(a: QuuxRef) = { type X = a.type } def ok4(a: Product with QuuxRef) = { type X = a.type } def ok5(x: QuuxRef with Product) = (x eq "abc") && ("abc" eq x) def ok6(x: QuuxRef with Product { def f: Int }) = (x eq "abc") && ("abc" eq x) def ok7(x: QuuxRef { def eq(other: String): Boolean }) = (x eq "abc") && ("abc" eq x) def bad1(x: Bippy, y: Bippy) = x eq y } object Bar { def f(x: Quux { def g(x: Int): Int }): Int = x g 5 f(new Quux { def g(x: String) = x }) f(new Quux { def g(x: Int) = x }) }