rust/rustc_ast_pretty at f967532a47eb728ada44473a5c4c2eca1a45fe30 - rust

mirror of https://github.com/rust-lang/rust.git synced 2024-11-22 06:44:35 +00:00

History

bors f967532a47 Auto merge of #118420 - compiler-errors:async-gen, r=eholk Introduce support for `async gen` blocks I'm delighted to demonstrate that `async gen` block are not very difficult to support. They're simply coroutines that yield `Poll<Option<T>>` and return `()`. This PR is WIP and in draft mode for now -- I'm mostly putting it up to show folks that it's possible. This PR needs a lang-team experiment associated with it or possible an RFC, since I don't think it falls under the jurisdiction of the `gen` RFC that was recently authored by oli (https://github.com/rust-lang/rfcs/pull/3513, https://github.com/rust-lang/rust/issues/117078). ### Technical note on the pre-generator-transform yield type: The reason that the underlying coroutines yield `Poll<Option<T>>` and not `Poll<T>` (which would make more sense, IMO, for the pre-transformed coroutine), is because the `TransformVisitor` that is used to turn coroutines into built-in state machine functions would have to destructure and reconstruct the latter into the former, which requires at least inserting a new basic block (for a `switchInt` terminator, to match on the `Poll` discriminant). This does mean that the desugaring (at the `rustc_ast_lowering` level) of `async gen` blocks is a bit more involved. However, since we already need to intercept both `.await` and `yield` operators, I don't consider it much of a technical burden. r? `@ghost`	2023-12-08 19:13:57 +00:00
..
src	Auto merge of #118420 - compiler-errors:async-gen, r=eholk	2023-12-08 19:13:57 +00:00
Cargo.toml	Remove `IterDelimited`.	2023-11-22 08:13:21 +11:00

bors f967532a47 Auto merge of #118420 - compiler-errors:async-gen, r=eholk

Introduce support for `async gen` blocks

I'm delighted to demonstrate that `async gen` block are not very difficult to support. They're simply coroutines that yield `Poll<Option<T>>` and return `()`.

**This PR is WIP and in draft mode for now** -- I'm mostly putting it up to show folks that it's possible. This PR needs a lang-team experiment associated with it or possible an RFC, since I don't think it falls under the jurisdiction of the `gen` RFC that was recently authored by oli (https://github.com/rust-lang/rfcs/pull/3513, https://github.com/rust-lang/rust/issues/117078).

### Technical note on the pre-generator-transform yield type:

The reason that the underlying coroutines yield `Poll<Option<T>>` and not `Poll<T>` (which would make more sense, IMO, for the pre-transformed coroutine), is because the `TransformVisitor` that is used to turn coroutines into built-in state machine functions would have to destructure and reconstruct the latter into the former, which requires at least inserting a new basic block (for a `switchInt` terminator, to match on the `Poll` discriminant).

This does mean that the desugaring (at the `rustc_ast_lowering` level) of `async gen` blocks is a bit more involved. However, since we already need to intercept both `.await` and `yield` operators, I don't consider it much of a technical burden.

r? `@ghost`

2023-12-08 19:13:57 +00:00

src Auto merge of #118420 - compiler-errors:async-gen, r=eholk 2023-12-08 19:13:57 +00:00

Cargo.toml Remove IterDelimited. 2023-11-22 08:13:21 +11:00