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#![feature(generators, generator_trait)]
use std::ops::{Generator, GeneratorState};
use std::pin::Pin;
// The following implementation of a function called from a `yield` statement
// (apparently requiring the Result and the `String` type or constructor)
// creates conditions where the `generator::StateTransform` MIR transform will
// drop all `Counter` `Coverage` statements from a MIR. `simplify.rs` has logic
// to handle this condition, and still report dead block coverage.
fn get_u32(val: bool) -> Result<u32, String> {
if val { Ok(1) } else { Err(String::from("some error")) }
}
fn main() {
let is_true = std::env::args().len() == 1;
let mut generator = || {
yield get_u32(is_true);
return "foo";
};
match Pin::new(&mut generator).resume(()) {
GeneratorState::Yielded(Ok(1)) => {}
_ => panic!("unexpected return from resume"),
}
match Pin::new(&mut generator).resume(()) {
GeneratorState::Complete("foo") => {}
_ => panic!("unexpected return from resume"),
}
}
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