When a val overrides an abstract var

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The error message produced when you override an abstract var with a val is unclear,

For example:

abstract class A {
        var x : Int
}

class B extends A {
        val x = 2
}

produces the error:

error.scala:5: error: class B needs to be abstract, since variable x in class A of type Int is not defined
(Note that variables need to be initialized to be defined)
class B extends A {
^

It wuold be more obvious if this produced the same error as overriding a concrete var with a val, e.g.

abstract class A {
        var x = 1
}

class B extends A {
        override val x = 2
}

with the error message:

error.scala:6: error: error overriding variable x in class A of type Int;
 value x cannot override a mutable variable
        override val x = 2
                     ^

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Imported From: https://issues.scala-lang.org/browse/SI-36?orig=1
Reporter: Commit Message Bot (anonymous)

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@odersky said:
Milestone postponed deleted

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@paulp said:
(In r22481) When compilation fails because of an unimplemented abstract var,
give a more precise error message about what happened. Also avoid
issuing the same error twice because neither getter nor setter is
implemented. Closes #36, review by rytz.