error: expected i64, found str
  --> 1:24
   |
1  |   fn f() -> i64 { return "x" }
   |                          ^^^
   |

===
error: non-exhaustive match on enum `Shape`: missing variants: Triangle
  --> 2:25
   |
2  |   fn f(s: Shape) -> i64 { match s { Circle(r) => r, Rect(w) => w } }
   |                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   |
   = note: add an arm for: Triangle

===
error: pure function `f` calls io function `println`
  --> 1:18
   |
1  |   fn f() is pure { println("hi") }
   |                    ^^^^^^^^^^^^^
   |
   = note: pure functions cannot call functions with io effects
   = hint: remove the `is pure` annotation, or refactor to remove the io call

===
warning: unused variable `x`
  --> 2:3
   |
2  |     let x = 1
   |     ^^^^^^^^^
   |
