src/test/ui/question-mark-type-infer.rs

   1 #![feature(question_mark, question_mark_carrier)]
   2
   3 // Test that type inference fails where there are multiple possible return types
   4 // for the `?` operator.
   5
   6 fn f(x: &i32) -> Result<i32, ()> {
   7     Ok(*x)
   8 }
   9
  10 fn g() -> Result<Vec<i32>, ()> {
  11     let l = [1, 2, 3, 4];
  12     l.iter().map(f).collect()? //~ ERROR type annotations needed
  13 }
  14
  15 fn main() {
  16     g();
  17 }