False positive with new_ret_no_self if new is an async fn that returns a wrapper around Self. #4359

lukas-code · 2019-08-08T18:07:39Z

This code

#![feature(async_await)]

struct S;

impl S {
    async fn new() -> Result<Self, ()> {
        Ok(S)
    }
}

causes the following warning

warning: methods called `new` usually return `Self`
 --> src/lib.rs:7:5
  |
7 | /     async fn new() -> Result<Self, ()> {
8 | |         Ok(S)
9 | |     }
  | |_____^
  |
  = note: `#[warn(clippy::new_ret_no_self)]` on by default
  = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#new_ret_no_self

cargo clippy -V

clippy 0.0.212 (b041511 2019-08-07)

The text was updated successfully, but these errors were encountered:

new_ret_no_self: allow Self in inner type for impl Trait return types Check the inner types of associated types of a trait when checking for Self in the return type of a `new` method. This means that the following will no longer warn: ```rust trait Trait { type Inner; } struct S; impl S { fn new() -> impl Trait<Inner = Option<Self>> { struct TraitImpl; impl Trait for TraitImpl { type Inner = Option<S>; } TraitImpl } } ``` ```rust #![feature(async_await)] struct Connection; impl Connection { async fn new() -> Result<Self, ()> { Ok(S) } } ``` closes #4359

new_ret_no_self: allow Self in inner type for impl Trait return types Check the inner types of associated types of a trait when checking for Self in the return type of a `new` method. This means that the following will no longer warn: ```rust trait Trait { type Inner; } struct S; impl S { fn new() -> impl Trait<Inner = Option<Self>> { struct TraitImpl; impl Trait for TraitImpl { type Inner = Option<S>; } TraitImpl } } ``` ```rust #![feature(async_await)] struct Connection; impl Connection { async fn new() -> Result<Self, ()> { Ok(S) } } ``` closes #4359 changelog: fix `new_ret_no_self` lint for async `new` functions.

flip1995 added C-bug Category: Clippy is not doing the correct thing T-async-await Type: Issues related to async/await labels Aug 9, 2019

lukas-code mentioned this issue Aug 9, 2019

new_ret_no_self: allow Self in inner type for impl Trait return types #4365

Merged

bors closed this as completed in #4365 Aug 12, 2019

nbdd0121 mentioned this issue Jun 11, 2021

new_ret_no_self false positive when returning impl Trait<Self> #7344

Closed

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False positive with new_ret_no_self if new is an async fn that returns a wrapper around Self. #4359

False positive with new_ret_no_self if new is an async fn that returns a wrapper around Self. #4359

lukas-code commented Aug 8, 2019

False positive with new_ret_no_self if new is an async fn that returns a wrapper around Self. #4359

False positive with new_ret_no_self if new is an async fn that returns a wrapper around Self. #4359

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lukas-code commented Aug 8, 2019