rust-lang/rustfmt

rustfmt changes code between stable and beta

Manishearth opened this issue · 3 comments

Manishearth commented

With the following code:

fn main() {
    let arr = [
        ("en-001", "", "Hello from 🗺️"),  // WORLD
        ("en-002", "", "Hello from 🌍"), // AFRICA
    ];
}

playground

rustfmt considers it correctly formatted under Rust 1.79, but will remove the space before // WORLD under Rust 1.80-beta3 (and nightly)

This is caused by unicode-width 0.1.13, which changed the predicted widths of a lot of Unicode characters, including emoji. The new version is more accurate, but these changes have not been made in a way that guarantees any kind of stability. The issue I have filed asks for such an API.

In the meantime, should rust/rustfmt pin to 0.1.2?

Jules-Bertholet commented

From the README:

The following list enumerates areas where Rustfmt does not work or where the stability guarantees do not apply (we don't make a distinction between the two because in the future Rustfmt might work on code where it currently does not):

  • […]
  • Code containing non-ascii unicode characters
Manishearth commented

Ah, cool.

calebcartwright commented

agreed not guaranteed to have stable formatting in this particular case but good find and thank you for sharing it

probably worth a mention in the relnotes and blog post for the release though. if that ship hasn't already sailed i can look into it later tonight