Make scope show_start / show_end highlight based

[jackcogdill]

Problem

The scope start/end can only be configured as underline or off.

Expected behavior

It would be more flexible for theming to support a highlight group (which could include underline by default). Underline is not suitable for my personal taste, but I would still like to have distinct highlighting for the scope start.

This used to be possible in version 2:

[lukas-reineke]

The scope underline highlights are automatically generated. It's not super trivial to add support for a separate option for this.

I'm not against merging a PR that adds this, but I don't think I will work on it.
If you want a workaround, you can overwrite the generated highlight groups yourself, it would be @ibl.scope.underline.N, where N is the scope index. If you only use one scope highlight group, it's always 1.

[jackcogdill]

I was able to use the workaround, thanks.

require('ibl').setup(opts)
vim.cmd.highlight('clear @ibl.scope.underline.1')
vim.cmd.highlight('link @ibl.scope.underline.1 MyHighlightGroup')

For additional context, the underlines in my terminal / neovim setup follow the current text color. For individual terms this looks fine, but underlining an entire line looks bad. See screenshots below:

Default:

Workaround:

[lukas-reineke]

There is some discussion about the underline color in #686

[cd-a]

I was hoping it would work like in version 2 with highlight groups

[siduck]

@lukas-reineke it works but if i set highlight group with my colorscheme which would happen before ibl.setup then ibl overrides it, shouldnt it be better to keep hlgroup untouched if its already set?

[lukas-reineke]

The @ibl highlight groups are internal. I will not officially support setting them manually, or add code to handle the case someone does.

[siduck]

The @ibl highlight groups are internal. I will not officially support setting them manually, or add code to handle the case someone does.

oh, how do colorscheme plugins handle this then? most hlgroups load by default..

[lukas-reineke]

Setting a custom highlight group for scope start and end is not currently supported, that's why the issue is still open.

It's a compromise between making the setup that most people want as easy as possible, and supporting full customization.
I chose to make scope a single list of highlight groups, and the plugin creates all the necessary @ibl highlight groups automatically. This makes the setup much easier for the vast majority of users.
But this makes it currently hard to change the highlight to something other than underline.

Like I said, I'm not against adding support for this, if someone has a good idea how. Without compromising the simple setup.