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Diffstat (limited to 'vendor/async-trait/src/lib.rs')
| -rw-r--r-- | vendor/async-trait/src/lib.rs | 257 |
1 files changed, 0 insertions, 257 deletions
diff --git a/vendor/async-trait/src/lib.rs b/vendor/async-trait/src/lib.rs deleted file mode 100644 index bc9bd923..00000000 --- a/vendor/async-trait/src/lib.rs +++ /dev/null @@ -1,257 +0,0 @@ -//! [![github]](https://github.com/dtolnay/async-trait) [![crates-io]](https://crates.io/crates/async-trait) [![docs-rs]](https://docs.rs/async-trait) -//! -//! [github]: https://img.shields.io/badge/github-8da0cb?style=for-the-badge&labelColor=555555&logo=github -//! [crates-io]: https://img.shields.io/badge/crates.io-fc8d62?style=for-the-badge&labelColor=555555&logo=rust -//! [docs-rs]: https://img.shields.io/badge/docs.rs-66c2a5?style=for-the-badge&labelColor=555555&logo=docs.rs -//! -//! <br> -//! -//! <h4>Type erasure for async trait methods</h4> -//! -//! The stabilization of async functions in traits in Rust 1.75 did not include -//! support for using traits containing async functions as `dyn Trait`. Trying -//! to use dyn with an async trait produces the following error: -//! -//! ```compile_fail -//! pub trait Trait { -//! async fn f(&self); -//! } -//! -//! pub fn make() -> Box<dyn Trait> { -//! unimplemented!() -//! } -//! ``` -//! -//! ```text -//! error[E0038]: the trait `Trait` is not dyn compatible -//! --> src/main.rs:5:22 -//! | -//! 5 | pub fn make() -> Box<dyn Trait> { -//! | ^^^^^^^^^ `Trait` is not dyn compatible -//! | -//! note: for a trait to be dyn compatible it needs to allow building a vtable -//! for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility> -//! --> src/main.rs:2:14 -//! | -//! 1 | pub trait Trait { -//! | ----- this trait is not dyn compatible... -//! 2 | async fn f(&self); -//! | ^ ...because method `f` is `async` -//! = help: consider moving `f` to another trait -//! ``` -//! -//! This crate provides an attribute macro to make async fn in traits work with -//! dyn traits. -//! -//! Please refer to [*why async fn in traits are hard*][hard] for a deeper -//! analysis of how this implementation differs from what the compiler and -//! language deliver natively. -//! -//! [hard]: https://smallcultfollowing.com/babysteps/blog/2019/10/26/async-fn-in-traits-are-hard/ -//! -//! <br> -//! -//! # Example -//! -//! This example implements the core of a highly effective advertising platform -//! using async fn in a trait. -//! -//! The only thing to notice here is that we write an `#[async_trait]` macro on -//! top of traits and trait impls that contain async fn, and then they work. We -//! get to have `Vec<Box<dyn Advertisement + Sync>>` or `&[&dyn Advertisement]`, -//! for example. -//! -//! ``` -//! use async_trait::async_trait; -//! -//! #[async_trait] -//! trait Advertisement { -//! async fn run(&self); -//! } -//! -//! struct Modal; -//! -//! #[async_trait] -//! impl Advertisement for Modal { -//! async fn run(&self) { -//! self.render_fullscreen().await; -//! for _ in 0..4u16 { -//! remind_user_to_join_mailing_list().await; -//! } -//! self.hide_for_now().await; -//! } -//! } -//! -//! struct AutoplayingVideo { -//! media_url: String, -//! } -//! -//! #[async_trait] -//! impl Advertisement for AutoplayingVideo { -//! async fn run(&self) { -//! let stream = connect(&self.media_url).await; -//! stream.play().await; -//! -//! // Video probably persuaded user to join our mailing list! -//! Modal.run().await; -//! } -//! } -//! # -//! # impl Modal { -//! # async fn render_fullscreen(&self) {} -//! # async fn hide_for_now(&self) {} -//! # } -//! # -//! # async fn remind_user_to_join_mailing_list() {} -//! # -//! # struct Stream; -//! # async fn connect(_media_url: &str) -> Stream { Stream } -//! # impl Stream { -//! # async fn play(&self) {} -//! # } -//! ``` -//! -//! <br><br> -//! -//! # Supported features -//! -//! It is the intention that all features of Rust traits should work nicely with -//! #\[async_trait\], but the edge cases are numerous. Please file an issue if -//! you see unexpected borrow checker errors, type errors, or warnings. There is -//! no use of `unsafe` in the expanded code, so rest assured that if your code -//! compiles it can't be that badly broken. -//! -//! > ☑ Self by value, by reference, by mut reference, or no self;<br> -//! > ☑ Any number of arguments, any return value;<br> -//! > ☑ Generic type parameters and lifetime parameters;<br> -//! > ☑ Associated types;<br> -//! > ☑ Having async and non-async functions in the same trait;<br> -//! > ☑ Default implementations provided by the trait;<br> -//! > ☑ Elided lifetimes.<br> -//! -//! <br> -//! -//! # Explanation -//! -//! Async fns get transformed into methods that return `Pin<Box<dyn Future + -//! Send + 'async_trait>>` and delegate to an async block. -//! -//! For example the `impl Advertisement for AutoplayingVideo` above would be -//! expanded as: -//! -//! ``` -//! # const IGNORE: &str = stringify! { -//! impl Advertisement for AutoplayingVideo { -//! fn run<'async_trait>( -//! &'async_trait self, -//! ) -> Pin<Box<dyn core::future::Future<Output = ()> + Send + 'async_trait>> -//! where -//! Self: Sync + 'async_trait, -//! { -//! Box::pin(async move { -//! /* the original method body */ -//! }) -//! } -//! } -//! # }; -//! ``` -//! -//! <br><br> -//! -//! # Non-threadsafe futures -//! -//! Not all async traits need futures that are `dyn Future + Send`. To avoid -//! having Send and Sync bounds placed on the async trait methods, invoke the -//! async trait macro as `#[async_trait(?Send)]` on both the trait and the impl -//! blocks. -//! -//! <br> -//! -//! # Elided lifetimes -//! -//! Be aware that async fn syntax does not allow lifetime elision outside of `&` -//! and `&mut` references. (This is true even when not using #\[async_trait\].) -//! Lifetimes must be named or marked by the placeholder `'_`. -//! -//! Fortunately the compiler is able to diagnose missing lifetimes with a good -//! error message. -//! -//! ```compile_fail -//! # use async_trait::async_trait; -//! # -//! type Elided<'a> = &'a usize; -//! -//! #[async_trait] -//! trait Test { -//! async fn test(not_okay: Elided, okay: &usize) {} -//! } -//! ``` -//! -//! ```text -//! error[E0726]: implicit elided lifetime not allowed here -//! --> src/main.rs:9:29 -//! | -//! 9 | async fn test(not_okay: Elided, okay: &usize) {} -//! | ^^^^^^- help: indicate the anonymous lifetime: `<'_>` -//! ``` -//! -//! The fix is to name the lifetime or use `'_`. -//! -//! ``` -//! # use async_trait::async_trait; -//! # -//! # type Elided<'a> = &'a usize; -//! # -//! #[async_trait] -//! trait Test { -//! // either -//! async fn test<'e>(elided: Elided<'e>) {} -//! # } -//! # #[async_trait] -//! # trait Test2 { -//! // or -//! async fn test(elided: Elided<'_>) {} -//! } -//! ``` - -#![doc(html_root_url = "https://docs.rs/async-trait/0.1.88")] -#![allow( - clippy::default_trait_access, - clippy::doc_markdown, - clippy::elidable_lifetime_names, - clippy::explicit_auto_deref, - clippy::if_not_else, - clippy::items_after_statements, - clippy::match_like_matches_macro, - clippy::module_name_repetitions, - clippy::needless_lifetimes, - clippy::shadow_unrelated, - clippy::similar_names, - clippy::too_many_lines, - clippy::trivially_copy_pass_by_ref -)] - -extern crate proc_macro; - -mod args; -mod bound; -mod expand; -mod lifetime; -mod parse; -mod receiver; -mod verbatim; - -use crate::args::Args; -use crate::expand::expand; -use crate::parse::Item; -use proc_macro::TokenStream; -use quote::quote; -use syn::parse_macro_input; - -#[proc_macro_attribute] -pub fn async_trait(args: TokenStream, input: TokenStream) -> TokenStream { - let args = parse_macro_input!(args as Args); - let mut item = parse_macro_input!(input as Item); - expand(&mut item, args.local); - TokenStream::from(quote!(#item)) -} |