Feature request: Inline virtual text for suggestions

[cpmsmith]

Neovim 0.10 has been out for a while now, with support for virt_text_pos = "inline", i.e. virtual text which is visible in the middle of text, leaving the text in the buffer at its position visible instead of replacing it, in the style of LSP inlay hints.

It would be nice if copilot.lua used inline virtual text to display suggestions, as currently suggestions in the middle of a line obscure what remains on the line. This very often causes confusion around things like auto-pairs, e.g. in this example:

If I dismiss the suggestion, I can see that the opening bracket has been auto-paired, but I have no way to tell while the Copilot suggestion is active.

And if I accept the suggestion, it appears as though the closing bracket was added by Copilot, even though it didn't appear in the suggestion.

This is all much more noticeable if there is more than one remaining character on the line, e.g. when replacing the first argument of multiple in a function call, the suggestion may cover up the existing values for the following arguments.

Notes

• In this example, when I did accept the suggestion, it actually moves my cursor after the closing bracket. Does that mean that the closing bracket is actually part of the suggestion and is being hidden, or automatically made to not conflict somehow?
• Can inline virtual text have multiple lines?

[kedom1337]

Not having this is currently my top issue with using copilot. Having this would make the whole experience so much better

[AntoineGS]

I cannot seem to find a way to trigger a mid-line suggestion, whether I put virt_text_pos = "inline" or not the behavior seems the same.
I have created a branch with the change if you would like see for yourself: virt_text_inline.

[cpmsmith]

@AntoineGS I messed around with it briefly, and I think setting virt_text_win_col overrides virt_text_pos = "inline". I got it to show up, though it'll need some behaviour changes around highlighting, and distinguishing exactly which suggestions should appear this way

[AntoineGS]

Good find, it does work without virt_text_win_col, I will play around with it and see how we can integrate the feature.

[AntoineGS]

I think I got it working properly, would you mind pulling the new code from the virt_text_inline branch?
I have had to manipulate the suggestions from Copilot as it assumes replacing the whole line, it seems to behave fine in my (currently) limited testing.
Let me know what you think, I think it's a real improvement when auto-completing with partial line suggestions!

Edit: yeah I am really digging the behavior, thanks for the suggestion :P :P