explicit declaration of return type with compound type parameter fails #7647
Description
From StackOverflow: http://stackoverflow.com/questions/17559687/compile-time-constraints-on-the-order-of-function-composition-in-scala
Compilation fails for a method that explicitly declares a return a type with a compound type parameter, but succeeds and infers the same type when the return type is not explicitly declared:
scala> trait Foo[A] { def bar[B](b: B): Foo[A with B] }
defined trait Foo
scala> def baz[A](foo: Foo[A]) = foo bar 1
baz: [A](foo: Foo[A])Foo[A with Int]
scala> def baz[A](foo: Foo[A]): Foo[A with Int] = foo bar 1
<console>:8: error: type mismatch;
found : Int(1)
required: Nothing
def baz[A](foo: Foo[A]): Foo[A with Int] = foo bar 1
^