initialization checker should list uninitialized fields in warning

[olhotak]

Compiler version

main

Minimized code

def leak(a: Any) = ???

class Sup {
    val a = ???
    leak(this)
}

class Sub extends Sup {
    val b = ???
}

Output

-- Warning: Sup.scala:5:9 ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
5 |    leak(this)
  |         ^^^^
  |         Cannot prove the argument is fully initialized. Only fully initialized values are safe to leak. Calling trace:
  |         -> class Sub extends Sup {	[ Sup.scala:8 ]
  |            ^
  |         -> class Sup {	[ Sup.scala:3 ]
  |            ^
  |         -> leak(this)	[ Sup.scala:5 ]
  |                 ^^^^

Expectation

The warning would be more helpful if it could list the fields (in this case b) that are not initialized and the subclasses (in this case Sub) that they're in.