Add an option to render more context around lines.

[RDambrosio016]

When you have a diagnostic and a couple of single labels explaining context, it is sort of confusing to see where the error actually is in the code at a glance. It would be great if there was a "put these many source lines around each label. And ideally a "include this span in the diagnostic too, but without a label.

[Johann150]

#257 adressed the configurability of how many lines of context should be shown around labels.

[Johann150]

For your other point, why don't you just put a (secondary) label on the context that you want to explain?

[RDambrosio016]

That is what i did, but i ended up scrapping it because:
The diagnostic references two nodes in a statement, i just want 3 - 5 lines around each label's location to tell the user "this is where the wrong stuff is" without having them have to go to the line. But this gets very cluttered in real world code. For example a try statement in js code (which is what i am doing) is usually decently large. And i reference something in the try {} block and the finally {} block, both of which may be large.

Overall, having another colored line adds clutter to the diagnostic, Your eyes should drift straight to the two places which are labelled, and you should instantly know where that code is. Having more things for the user to consider is ugly.

[RDambrosio016]

I think i will use the pre-release version for now with the context lines option for now. Then i will just update once it is released 👍

Edit: realized this is for multiline labels only for now, which isnt exactly what i need. hope an option for single labels could be added in the future.

[Johann150]

Ah yes, its more of context inside labels. Mistake on my part 😓

[ratmice]

@RDambrosio016 Any chance you could post an example (of the output generated) for such a case where either what you're trying to achieve or how it looks using secondary labels?

[RDambrosio016]

Sure, this is what it normally looks like . You cant really tell where exactly in the code it is unless you go back and look at the line numbers. This is how it is with a secondary label, i personally dont like it, and if the catch for example had a ton of stuff in it it would end up looking horrid.

Ideally i would just be able to say "3 lines of context around each label".

[Johann150]

If you took the approach with a secondary label, you could adjust how many lines of context within the secondary label are shown (as I mentioned above). This would resolve the case of "if the catch had a ton of stuff in it". Your personal preference aside, I think this is a good alternative. Here is an example of how it would look using the current version:

from this source code

while(true){
    try{
        foo();
        foo();
        foo();
        foo();
        foo();
        foo();
        foo();
        foo();
        foo();
        foo();
        foo();
        if(condition()){
            continue;
        }
    }catch{
        bar();
        bar();
        bar();
        bar();
        bar();
        bar();
    }finally{
        break;
    }
}

This example shows me some other problems though:

1. Something got lost on the way of resolving File column/line should consistently point to the first primary label instead of the first label #259 with locus at first primary label #260 and the locus is at the earliest label again (notice the error is supposedly on line 2 instead of line 25).
2. What you mentioned already: The context should also work for secondary labels and single line labels. But I think it would be enough to enable this feature only if the label is inside another multiline label.
3. Another thing that might make sense is to add something like tertiary labels which would look better than my "This is the finally block." label. They should not be rendered but just force the specific line to be shown.

[RDambrosio016]

Another thing that might make sense is to add something like tertiary labels which would look better than my "This is the finally block." label. They should not be rendered but just force the specific line to be shown.

I disagree with doing it like this, it should be something separate, maybe Context, a diagnostic would have a Vec<Context>. A context basically just holds a range and lines in those ranges will be rendered but without a label or coloring.

[Johann150]

I found that there already is #29, which is I think more close to what you were trying to get at. In that light I think suggestion № 3 is not necessary.

№ 1 has already been solved in #282.

[elkowar]

I'd really love a solution that allows me to both specify a range of lines to display without requiring a label around it (i.e. the proposed "context" field on a diagnostic), as well as allowing me to specify a default amount of lines of context for any label.
That latter option should imo just be part of the config struct, such that one can set
config.context_before = 2 and config.context_after = 2 so specify "show at least 2 lines before and two lines after my label as context.

I'd assume that implementing that latter half at least should be pretty trivial - I might try myself at a PR for that!