original.name="VarDecl_Invalid_4"
js.execute.ignore=true
======
>>> main.whiley
type nat is (int x) where x >= 0

function f(int x) -> (nat r):
    nat y = (nat) x
    return y

public export method test():
   assume f(0) == 0
   assume f(1) == 1
   assume f(-1) == -1
---
E702 main.whiley 4,12:18
E718 main.whiley 4,12:18