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