original.name="Unsafe_Invalid_4"
whiley.compile.strict=true
======
>>> main.whiley
type fun_t is function(int)->(int)

unsafe function f(int x) -> (int y):
    assert x >= 0
    return x

unsafe public export method test():
    fun_t x = &(int x -> f(x))

---
E613 main.whiley 8,25:28