1 #![feature(generators, generator_trait)]
3 use std::ops::{Generator, GeneratorState};
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")) }
16 let is_true = std::env::args().len() == 1;
17 let mut generator = || {
18 yield get_u32(is_true);
22 match Pin::new(&mut generator).resume(()) {
23 GeneratorState::Yielded(Ok(1)) => {}
24 _ => panic!("unexpected return from resume"),
26 match Pin::new(&mut generator).resume(()) {
27 GeneratorState::Complete("foo") => {}
28 _ => panic!("unexpected return from resume"),