Description
Here's my code in main.rs :
async fn main() {}
Here's the output:
error[E0670]: `async fn` is not permitted in Rust 2015
--> main.rs:1:1
|
1 | async fn main() {}
| ^^^^^ to use `async fn`, switch to Rust 2018 or later
|
= help: set `edition = "2021"` in `Cargo.toml`
= note: for more on editions, read https://doc.rust-lang.org/edition-guide
error[E0752]: `main` function is not allowed to be `async`
--> main.rs:1:1
|
1 | async fn main() {}
| ^^^^^^^^^^^^^^^ `main` function is not allowed to be `async`
error: aborting due to 2 previous errors
Some errors have detailed explanations: E0670, E0752.
For more information about an error, try `rustc --explain E0670`.
Here is my Cargo.toml file:
[package]
name = "visualizer"
version = "0.1.0"
edition = '2021'
Here is what it auto-generates in Cargo.lock file:
# This file is automatically @generated by Cargo.
# It is not intended for manual editing.
version = 3
[[package]]
name = "visualizer"
version = "0.1.0"
ATTEMPTED SOLUTION:
I removed the async keyword in async fn main() {} so it became fn main() {} in main.rs. Then I did the following in the terminal:
$ cargo fix --edition
Checking visualizer v0.1.0 ( // I manually removed the path for privacy reasons )
warning: `src/main.rs` is already on the latest edition (2021), unable to migrate further
If you are trying to migrate from the previous edition (2018), the
process requires following these steps:
1. Start with `edition = "2018"` in `Cargo.toml`
2. Run `cargo fix --edition`
3. Modify `Cargo.toml` to set `edition = "2021"`
4. Run `cargo build` or `cargo test` to verify the fixes worked
More details may be found at
https://doc.rust-lang.org/edition-guide/editions/transitioning-an-existing-project-to-a-new-edition.html
Finished dev [unoptimized + debuginfo] target(s) in 0.29s
So I changed edition = "2021" into edition = "2015" in Cargo.toml. Then I did the following in the terminal:
$ cargo fix --edition
Checking visualizer v0.1.0 ( // I manually removed the path for privacy reasons )
Migrating src/main.rs from 2015 edition to 2018
Finished dev [unoptimized + debuginfo] target(s) in 0.95s
Then I edited back from edition = "2015" to edition = "2021" and did the following in the terminal:
$ cargo build
Compiling visualizer v0.1.0 ( // I manually removed the path for privacy reasons )
Finished dev [unoptimized + debuginfo] target(s) in 0.37s
$ cargo test
Compiling visualizer v0.1.0 ( // I manually removed the path for privacy reasons )
Finished test [unoptimized + debuginfo] target(s) in 0.26s
Running unittests ( // I manually removed the path for privacy reasons )
running 0 tests
test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.00s
Then I changed back from fn main() {} to async fn main() {} in main.rs, and here's the output I get:
error[E0670]: `async fn` is not permitted in Rust 2015
--> main.rs:1:1
|
1 | async fn main() {}
| ^^^^^ to use `async fn`, switch to Rust 2018 or later
|
= help: set `edition = "2021"` in `Cargo.toml`
= note: for more on editions, read https://doc.rust-lang.org/edition-guide
error[E0752]: `main` function is not allowed to be `async`
--> main.rs:1:1
|
1 | async fn main() {}
| ^^^^^^^^^^^^^^^ `main` function is not allowed to be `async`
error: aborting due to 2 previous errors
Some errors have detailed explanations: E0670, E0752.
For more information about an error, try `rustc --explain E0670`.
[Done] exited with code=1 in 0.1 seconds
Thus, my attempted solution has failed.
Rust Version
rust-analyzer 2022-05-09
Editor:
VSCode
Operating System:
Archlinux
rust-analyzer version: rust-analyzer version: 5d5bbec 2022-05-09 stable
rustc version: rustc 1.59.0 (9d1b210 2022-02-23)
relevant settings: (eg. client settings, or environment variables like CARGO, RUSTUP_HOME or CARGO_HOME)