Fix gutter misalignments

[dtolnay]

Fixes #130.

This code attempts to print a value of type codespan::LineNumber with padding and alignment:

codespan/codespan-reporting/src/term/views/source_snippet/gutter.rs

Lines 34 to 39 in 6cec7d5

	write!(
	writer,
	"{line: >width$}",
	line = line_number,
	width = self.gutter_padding,
	)?;

But the Display impl for LineNumber just ignores the requested padding and alignment:

codespan/codespan/src/index.rs

Lines 74 to 78 in 6cec7d5

	impl fmt::Display for LineNumber {
	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
	write!(f, "{}", self.0)
	}
	}

Repro:

use codespan::Files;
use codespan_reporting::diagnostic::{Diagnostic, Label};
use codespan_reporting::term::emit;
use codespan_reporting::term::termcolor::{ColorChoice, StandardStream};

fn main() {
    let mut files = Files::new();
    let content = "\n\n\n\n\n\naaaaaaaaaa\n\nbbbbbbbbbb\ncccccccccc\n";
    let file = files.add("path/to", content);
    let diagnostic = Diagnostic::new_error("it failed", Label::new(file, 8..34, "error"));
    let writer = StandardStream::stderr(ColorChoice::Auto);
    let config = codespan_reporting::term::Config::default();
    emit(&mut writer.lock(), &config, &files, &diagnostic).unwrap();
}

Before:

error: it failed

    ┌── path/to:7:3 ───
    │
 7 │   aaaaaaaaaa
    │ ╭───^
 8 │ │ 
 9 │ │ bbbbbbbbbb
 10 │ │ cccccccccc
    │ ╰─────^ error
    │

After:

error: it failed

    ┌── path/to:7:3 ───
    │
  7 │   aaaaaaaaaa
    │ ╭───^
  8 │ │ 
  9 │ │ bbbbbbbbbb
 10 │ │ cccccccccc
    │ ╰─────^ error
    │

[dtolnay]

Would it be possible to get a patch release once this is merged?

[ebkalderon]

@dtolnay Excellent sleuthing! I would love to see at least a patch release for this as well.

[brendanzab]

Ahhhhh thanks for this! ❤️

[brendanzab]

We should probably add a test for this... 🤔