Badly misleading type error messages

[pschachte]

This code

resource res:int = 0

def foo(?val:int) use res { ?val = res }

foo(?x)
!println x

gives the compiler errors:

Error detected during type checking of module(s) tst
tst.wybe:6:2: Type error in call to proc println, argument 1
tst.wybe:6:2: Call from module top-level code to proc println with 1 argument(s), expected 2

which actually leads one away from the actual error (missing ! on call to foo).

I believe the cause is that foo(?x) is taken to bind x to a closure for !foo.