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#![feature(coroutines, coroutine_trait, stmt_expr_attributes)]
use std::ops::{Coroutine, CoroutineState};
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 `coroutine::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 coroutine = #[coroutine]
|| {
yield get_u32(is_true);
return "foo";
};
match Pin::new(&mut coroutine).resume(()) {
CoroutineState::Yielded(Ok(1)) => {}
_ => panic!("unexpected return from resume"),
}
match Pin::new(&mut coroutine).resume(()) {
CoroutineState::Complete("foo") => {}
_ => panic!("unexpected return from resume"),
}
}
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