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Auto merge of #116447 - oli-obk:gen_fn, r=compiler-errors

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Implement `gen` blocks in the 2024 edition

Coroutines tracking issue https://github.com/rust-lang/rust/issues/43122
`gen` block tracking issue https://github.com/rust-lang/rust/issues/117078

This PR implements `gen` blocks that implement `Iterator`. Most of the logic with `async` blocks is shared, and thus I renamed various types that were referring to `async` specifically.

An example usage of `gen` blocks is

```rust
fn foo() -> impl Iterator<Item = i32> {
    gen {
        yield 42;
        for i in 5..18 {
            if i.is_even() { continue }
            yield i * 2;
        }
    }
}
```

The limitations (to be resolved) of the implementation are listed in the tracking issue
This commit is contained in:
bors 2023-10-29 00:03:52 +00:00
commit 2cad938a81
75 changed files with 1096 additions and 148 deletions
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12
compiler/rustc_hir/src/hir.rs
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@ -1522,6 +1522,9 @@ pub enum CoroutineKind {
/// An explicit `async` block or the body of an async function.
Async(CoroutineSource),
/// An explicit `gen` block or the body of a `gen` function.
Gen(CoroutineSource),
/// A coroutine literal created via a `yield` inside a closure.
Coroutine,
}
@ -1538,6 +1541,14 @@ impl fmt::Display for CoroutineKind {
k.fmt(f)
}
CoroutineKind::Coroutine => f.write_str("coroutine"),
CoroutineKind::Gen(k) => {
if f.alternate() {
f.write_str("`gen` ")?;
} else {
f.write_str("gen ")?
}
k.fmt(f)
}
}
}
}
@ -2251,6 +2262,7 @@ impl From<CoroutineKind> for YieldSource {
// Guess based on the kind of the current coroutine.
CoroutineKind::Coroutine => Self::Yield,
CoroutineKind::Async(_) => Self::Await { expr: None },
CoroutineKind::Gen(_) => Self::Yield,
}
}
}