Source code with tabs did not highlight correctly

[legendiguess]

Here some example Slice where t symbol in source code have one space behind:

That Slice give us that output:

Now i change space behind t from space to tab(which still one symbol, so range of highlight should not be changed):

And highlight in output is wrong now:

[brendanzab]

Yeah, I think annotate snippets should replace tab characters with a user configurable number of spaces, and take it into account when computing underlines. This is what I do in codespan at least!

[zbraniecki]

agree! I am swamped a bit these days but will try to debug it! PRs welcomed!

[zbraniecki]

agree! I am swamped a bit these days but will try to debug it! PRs welcomed!

[zbraniecki]

@legendiguess - can you retest against master? #27 got merged and I can't reproduce it anymore locally!

[legendiguess]

@zbraniecki
Just retested it - problem still here:

Here gist with minimal reproducible example https://gist.github.com/legendiguess/ccb197dac4bc77e3ae7571befc8ffbe2

[zbraniecki]

Ah, I see. Now I understand the issue.

@brendanzab 's solution is one option.

The other would be to only adjust the underline calculation to account for tabs in line, but I'm not sure if display of "\tt" is always 5 ascii characters.

[legendiguess]

The other would be to only adjust the underline calculation to account for tabs in line, but I'm not sure if display of "\tt" is always 5 ascii characters.

\t move next characters to the next tabulation column. so basically it's adds from 1 to 4 ascii characters, dependent on caret position off last tabulation column

[zbraniecki]

Yeah, so it may be tricky to predict. Wondering how rustc handles that in error reporting now.

[legendiguess]

Yeah, so it may be tricky to predict. Wondering how rustc handles that in error reporting now.

https://github.com/rust-lang/rust/blob/5e8897b7b51636f157630e6639b711d698e1d101/src/librustc_errors/styled_buffer.rs#L16

They don't handle \t in a fully "proper way"

[brendanzab]

I do this using a custom writer in codespan-reporting: https://github.com/brendanzab/codespan/blob/a77e646944765dfb338185b0ba9504500afb7304/codespan-reporting/src/term/config.rs#L56-L84

[brendanzab]

Oh, and importantly I also measure the length of strings taking the tab width into account: https://github.com/brendanzab/codespan/blob/a77e646944765dfb338185b0ba9504500afb7304/codespan-reporting/src/term/config.rs#L35-L45

[brendanzab]

Here's the relevant tests (excuse the not-so-nice test setup!): https://github.com/brendanzab/codespan/blob/a77e646944765dfb338185b0ba9504500afb7304/codespan-reporting/tests/term.rs#L415-L542

[brendanzab]

\t move next characters to the next tabulation column. so basically it's adds from 1 to 4 ascii characters, dependent on caret position off last tabulation column

Oh wait, I understand what you're saying now, @legendiguess - yes I don't handle this properly in codespan-reporting either 🤦‍♂