mirror of
https://github.com/rust-lang/rust.git
synced 2024-11-23 07:14:28 +00:00
33 lines
1.5 KiB
Plaintext
33 lines
1.5 KiB
Plaintext
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| 1|fn get_u32(val: bool) -> Result<u32, String> {
|
|
12| 1| if val { Ok(1) } else { Err(String::from("some error")) }
|
|
^0
|
|
13| 1|}
|
|
14| |
|
|
15| 1|fn main() {
|
|
16| 1| let is_true = std::env::args().len() == 1;
|
|
17| 1| let mut generator = || {
|
|
18| 1| yield get_u32(is_true);
|
|
19| 1| return "foo";
|
|
20| 1| };
|
|
21| |
|
|
22| 1| match Pin::new(&mut generator).resume(()) {
|
|
23| 1| GeneratorState::Yielded(Ok(1)) => {}
|
|
24| 0| _ => panic!("unexpected return from resume"),
|
|
25| | }
|
|
26| 1| match Pin::new(&mut generator).resume(()) {
|
|
27| 1| GeneratorState::Complete("foo") => {}
|
|
28| 0| _ => panic!("unexpected return from resume"),
|
|
29| | }
|
|
30| 1|}
|
|
|