Cannot match with a bare type variable

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The following code compiles and runs as expected:

    val x : List[T] forSome { type T } = List(42)
    val w = x match { case y : List[u] => ((z : u) => z)(y.head) }

but this slight variation does not:

    val x : T forSome { type T } = 42
    val w = x match { case y : u => ((z : u) => z)(y) }

It reports that it cannot find type u. You get the same error with this variation:

    val x : List[List[T]] forSome { type T } = List(List(42))
    val w = x match { case y : List[List[u]] => ((z : u) => z)(y.head.head) }

But in this case, I can imagine that the problem can be attributed to erasure.

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Imported From: https://issues.scala-lang.org/browse/SI-621?orig=1
Reporter: Geoffrey Alan Washburn (washburn)

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@ingoem said:
Test in pending/pos.

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@paulp said:
For the reference of whoever may pick up this bug: since at least 2.7.1, the final variation works as expected.

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Mohsen Lesani [X] (lesani) said:
The first code snippet fails with both 2.7.2 and trunk.
The second code snippet works with both 2.7.2 and trunk.

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Geoffrey Alan Washburn (washburn) said:
Replying to [comment:4 lesani]:

The first code snippet fails with both 2.7.2 and trunk.
The second code snippet works with both 2.7.2 and trunk.

Maybe you have a different definition of first and second, but that is not the behavior I am observing.

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@paulp said:
That's funny, because I think he does have a different definition of first and second, namely second and third. It's funny because when I logged the note above a few days ago I had to consider how to phrase it to avoid exactly that misunderstanding (thus "final variation".)

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@odersky said:
Milestone next_feature deleted

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@adriaanm said:
Unassigning and rescheduling to M6 as previous deadline was missed.