Format diff line to be easily clickable

[joshka]

Instead of {filename} at {line}, use {filename}:{line} as this is a
format that many editors allow to be clicked to navigate directly to the
line.

---

This is a small papercut issue. I like being able to Cmd+Click a filename and navigate directly to the problematic code when I'm running rustfmt check.

[ytmimi]

Thanks! I've tested this out in VSCode and it works! Just wondering, does it make sense to leave the trailing colon :?

[joshka]

Thanks! I've tested this out in VSCode and it works! Just wondering, does it make sense to leave the trailing colon :?

I can take it or leave it on that. The colon indicates that this message belongs to the following error, so I think it's worthwhile. That said, build errors from cargo build / rustc don't have the colon (but they do have some shiny colors to highlight the line with the clickable file link.

The other thing worth considering here is whether to drop the full path and just leave the project root path e.g. compare:

[cargo-make] INFO - Execute Command: "rustup" "run" "nightly" "cargo" "fmt" "--all" "--check"
Diff in /Users/joshka/local/ratatui/src/backend/crossterm.rs at line 17:
 };
...

vs:

   Compiling ratatui v0.25.0 (/Users/joshka/local/ratatui)
error[E0433]: failed to resolve: use of undeclared crate or module `scrate`
  --> src/backend/crossterm.rs:19:5

You might also consider changing the message to be more explicit about what the diff represents to make it clearer to newer contributors when the format check is called deep in some CI process.

e.g. something like:

error: Formatting check failed at src/backend/crossterm.rs:17. Diff:
...
run `<full command line without the --check>` to fix these changes

[ytmimi]

I can take it or leave it on that. The colon indicates that this message belongs to the following error, so I think it's worthwhile.

Okay, cool. I'm fine with leaving it 👍🏼

but they do have some shiny colors to highlight the line with the clickable file link

We produce colored output for our internal errors, when you have the right setting enabled. To test that out you can run

rustfmt --config=max_width=15,error_on_line_overflow=true <<< 'fn main() { println!("hello world!"); }'

The other thing worth considering here is whether to drop the full path

I've thought about that before. I think it's a chance I'd like to make a some point, but not in this PR.

You might also consider changing the message to be more explicit about what the diff represents to make it clearer to newer contributors when the format check is called deep in some CI process.

Thank you for the suggestion. I'll think on it. For now I'd like to keep the message as is.

[ytmimi]

After our discussion I'm feeling good about making this change.