> rustup show
Default host: x86_64-pc-windows-msvc
...
active toolchain
----------------
nightly-x86_64-pc-windows-msvc (default)
rustc 1.29.0-nightly (6a1c0637c 2018-07-23)
Feedback
-
Having rustfix merged into cargo was a great idea. As someone who does a lot of Python at home and work, and often educates people on how/why to migrate to Python 3, having an automated, officially supported tool at everyone’s finger tips is going to pay dividends here. 
-
I found it a little confusing that after adding #![feature(rust_2018_preview)] to main.rs and no other changes, I was doomed to hit this error:
error: the working directory of this project is detected as dirty, and `cargo fix` can potentially perform destructive changes; if you'd like to suppress this error pass
`--allow-dirty`, or commit the changes to these files:
* src/main.rs
Is there any way to special case the #![feature(rust_2018_preview)] diff since literally everyone will hit it? Or when this is stable, will that flag not be needed so that this transition would be smoother for everyone?
-
Git-ignored files shouldn’t be worried about as dirty, but I already saw an issue for that somewhere.
-
cargo fix should automatically fix extern crate's. I was getting warnings, but they all seemed like they should be fixed mechanically.
cargo-features = ["edition"]
...
[package]
edition = '2018'
Running
> cargo +nightly fix --prepare-for 2018 --all-targets --all-features --allow-dirty
Checking rust-belt v1.2.0 (file:///C:/Users/User/PycharmProjects/rust-belt)
warning: unused extern crate
--> src\main.rs:6:1
|
6 | extern crate ai_behavior;
| ^^^^^^^^^^^^^^^^^^^^^^^^^ help: remove it
|
note: lint level defined here
--> src\main.rs:4:9
|
4 | #![warn(rust_2018_idioms)]
| ^^^^^^^^^^^^^^^^
= note: #[warn(unused_extern_crates)] implied by #[warn(rust_2018_idioms)]
warning: `extern crate` is not idiomatic in the new edition
--> src\main.rs:7:1
|
7 | extern crate music;
| ^^^^^^^^^^^^^^^^^^^ help: convert it to a `use`
warning: unused extern crate
--> src\main.rs:8:1
|
8 | extern crate opengl_graphics;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: remove it
warning: unused extern crate
--> src\main.rs:9:1
|
9 | extern crate piston_window;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: remove it
warning: `extern crate` is not idiomatic in the new edition
--> src\main.rs:10:1
|
10 | extern crate rand;
| ^^^^^^^^^^^^^^^^^^ help: convert it to a `use`
warning: unused extern crate
--> src\main.rs:11:1
|
11 | extern crate sprite;
| ^^^^^^^^^^^^^^^^^^^^ help: remove it
...
Finished dev [unoptimized + debuginfo] target(s) in 2.65s
- Some of the
extern crate lints were invalid. For example it told me:
warning: `extern crate` is not idiomatic in the new edition
--> src\main.rs:7:1
|
7 | extern crate music;
| ^^^^^^^^^^^^^^^^^^^ help: convert it to a `use`
But when I changed it to a use, I got another warning:
warning: unused import: `music`
--> src\main.rs:6:5
|
6 | use music;
| ^^^^^
|
= note: #[warn(unused_imports)] on by default
Other times the lint told me to remove the extern crate correctly.
Overall, the experience was positive, but I wonder if it would be possible to provide an option to condense the 3 steps (#![feature(rust_2018_preview)], #![warn(rust_2018_idioms)], and Cargo.toml) changes into a single step.
Something like: cargo fix --migrate-to 2018 that would condense all of these steps into a single go.
In the end, I had rust-belt fully migrated to Rust 2018 in about 30 minutes using cargo fix on Windows (probably less tested, which is why I chose to do it on Windows). Diff can be viewed on GitHub.
