`async fn` inside inherent impl produces generic parse error on 2015 edition #53714

comex · 2018-08-26T00:28:09Z

When compiling for the 2018 edition, rustc allows async fn both outside of an impl and within an inherent impl.

When compiling for the 2015 edition, async fn works outside of an impl, but putting one inside an inherent impl produces this error:

error: missing `fn`, `type`, or `const` for impl-item declaration
 --> src/lib.rs:4:9
  |
4 | impl A { async fn inside_impl() {} }
  |         ^ missing `fn`, `type`, or `const`

Either this should be allowed, or it should result in a better error message that recommends switching to the 2018 edition.

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

withoutboats · 2018-08-26T05:47:30Z

Since async blocks and some versions of the final await syntax cannot be permitted (for backward compatibility reasons), it seems preferable to disallow all async/await features on 2015 to simplifier the user story: async/await works on 2018.

@varkor

…n, r=varkor Deny `async fn` in 2015 edition This commit prevents code using `async fn` from being compiled in Rust 2015 edition. Compiling code of the form: ```rust async fn foo() {} ``` Will now result in the error: ``` error[E0670]: `async fn` is not permitted in the 2015 edition --> async.rs:1:1 | 1 | async fn foo() {} | ^^^^^ error: aborting due to error For more information about an error, try `rustc --explain E0670`. ``` This resolves rust-lang#58652 and also resolves rust-lang#53714. r? @varkor

@varkor

…n, r=varkor Deny `async fn` in 2015 edition This commit prevents code using `async fn` from being compiled in Rust 2015 edition. Compiling code of the form: ```rust async fn foo() {} ``` Will now result in the error: ``` error[E0670]: `async fn` is not permitted in the 2015 edition --> async.rs:1:1 | 1 | async fn foo() {} | ^^^^^ error: aborting due to error For more information about an error, try `rustc --explain E0670`. ``` This resolves rust-lang#58652 and also resolves rust-lang#53714. r? @varkor

@varkor

…n, r=varkor Deny `async fn` in 2015 edition This commit prevents code using `async fn` from being compiled in Rust 2015 edition. Compiling code of the form: ```rust async fn foo() {} ``` Will now result in the error: ``` error[E0670]: `async fn` is not permitted in the 2015 edition --> async.rs:1:1 | 1 | async fn foo() {} | ^^^^^ error: aborting due to error For more information about an error, try `rustc --explain E0670`. ``` This resolves rust-lang#58652 and also resolves rust-lang#53714. r? @varkor

@varkor

…n, r=varkor Deny `async fn` in 2015 edition This commit prevents code using `async fn` from being compiled in Rust 2015 edition. Compiling code of the form: ```rust async fn foo() {} ``` Will now result in the error: ``` error[E0670]: `async fn` is not permitted in the 2015 edition --> async.rs:1:1 | 1 | async fn foo() {} | ^^^^^ error: aborting due to error For more information about an error, try `rustc --explain E0670`. ``` This resolves rust-lang#58652 and also resolves rust-lang#53714. r? @varkor

@varkor

…n, r=varkor Deny `async fn` in 2015 edition This commit prevents code using `async fn` from being compiled in Rust 2015 edition. Compiling code of the form: ```rust async fn foo() {} ``` Will now result in the error: ``` error[E0670]: `async fn` is not permitted in the 2015 edition --> async.rs:1:1 | 1 | async fn foo() {} | ^^^^^ error: aborting due to error For more information about an error, try `rustc --explain E0670`. ``` This resolves rust-lang#58652 and also resolves rust-lang#53714. r? @varkor

jonas-schievink added the A-async-await Area: Async & Await label Jan 27, 2019

withoutboats added the A-diagnostics Area: Messages for errors, warnings, and lints label Feb 22, 2019

nikomatsakis mentioned this issue Feb 22, 2019

async fn should be disallowed entirely on 2015 edition #58652

Closed

doctorn mentioned this issue Feb 23, 2019

Deny async fn in 2015 edition #58678

Merged

bors closed this as completed in #58678 Feb 27, 2019

`async fn` inside inherent impl produces generic parse error on 2015 edition #53714

`async fn` inside inherent impl produces generic parse error on 2015 edition #53714

comex commented Aug 26, 2018

withoutboats commented Aug 26, 2018

async fn inside inherent impl produces generic parse error on 2015 edition #53714

async fn inside inherent impl produces generic parse error on 2015 edition #53714

Comments

comex commented Aug 26, 2018

withoutboats commented Aug 26, 2018

`async fn` inside inherent impl produces generic parse error on 2015 edition #53714

`async fn` inside inherent impl produces generic parse error on 2015 edition #53714