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17df50a5 XL |
1 | #![feature(generators, generator_trait)] |
2 | ||
3 | use std::ops::{Generator, GeneratorState}; | |
4 | use std::pin::Pin; | |
5 | ||
6 | // The following implementation of a function called from a `yield` statement | |
7 | // (apparently requiring the Result and the `String` type or constructor) | |
8 | // creates conditions where the `generator::StateTransform` MIR transform will | |
9 | // drop all `Counter` `Coverage` statements from a MIR. `simplify.rs` has logic | |
10 | // to handle this condition, and still report dead block coverage. | |
11 | fn get_u32(val: bool) -> Result<u32, String> { | |
12 | if val { Ok(1) } else { Err(String::from("some error")) } | |
13 | } | |
14 | ||
15 | fn main() { | |
16 | let is_true = std::env::args().len() == 1; | |
17 | let mut generator = || { | |
18 | yield get_u32(is_true); | |
19 | return "foo"; | |
20 | }; | |
21 | ||
22 | match Pin::new(&mut generator).resume(()) { | |
23 | GeneratorState::Yielded(Ok(1)) => {} | |
24 | _ => panic!("unexpected return from resume"), | |
25 | } | |
26 | match Pin::new(&mut generator).resume(()) { | |
27 | GeneratorState::Complete("foo") => {} | |
28 | _ => panic!("unexpected return from resume"), | |
29 | } | |
30 | } |