1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
|
import annotation.tailrec
trait Universe {
type T <: AnyRef
}
final class Bug {
var i = 1
def stop() = { i -= 1; i < 0 }
// the alias bypasses the fast path in erasures InfoTransformer
// predicated on `TypeMap.noChangeToSymbols`
type Alias = Any
@tailrec
// So we get two symbols for `universe`, the original on the ValDef
// and a clone in the MethodType of `f`.
def f(universe: Universe, l: Alias): universe.T = {
if (stop()) null.asInstanceOf[universe.T] else f(universe, null)
}
@tailrec
def g(universe: Universe)(l: Alias): universe.T = {
if (stop()) null.asInstanceOf[universe.T] else g(universe)(l)
}
@tailrec
def h(universe: Universe)(l: List[universe.T]): List[universe.T] = {
if (stop()) Nil else h(universe)(l)
}
}
object Test extends App {
assert(new Bug().f(null, null) == null)
assert(new Bug().g(null)(null) == null)
assert(new Bug().h(null)(null) == Nil)
}
|
