feat(ui): add 'statuscolumn' option

[luukvbaal]

Problem: Unable to customize the column next to a window ('gutter').
Solution: Add 'statuscolumn' option that follows the 'statusline' syntax, allowing to customize the status column. Also supporting the %@ click execute function label. Adds new items @C and @s which will print the fold and sign columns. Line numbers and signs can be clicked, highlighted, aligned, transformed, margined etc.

Following discussion in #4941 (comment), this was ported/improved from vim/vim#11303, after it was rejected there.
Closes #6092, closes #19805, closes #20035.

A companion plugin to this option providing common number formats and click handlers is available here

[max397574]

would it be possible to define a variable or sth so the cursorline number can be treated special?

[justinmk]

Naming nit: based on existing options, I think 'numbercolumn' might be a more conventional name. That helps discoverability by grouping it with other "column" options.

Some comments from vim users and further consideration swayed me back to a 'statusline' expression approach. We get things like highlighting, alignment, clickable elements(? untested) for free.

That's good info to include in the commit message.

[luukvbaal]

would it be possible to define a variable or sth so the cursorline number can be treated special?

Not sure it's necessary, can use v:relnum == 0 for this.

[luukvbaal]

Ready for another round of review. Points of contention are:

• Whether or not to provide new 'statusline' expression format items specifically for 'cursorcolumn' by assigning unused letters or overloading existing ones, since most of them appear to be useless in the number column. Even if we do this, we still need to provide v:-vars because stl-items themselves cannot be substituted in the %{} eval block(also an option to allow that for certain items, in that case we might not need the v:-vars?).
• If we don't add new stl-items, it might be worth to add previously requested use-cases in the :h cursorcolumn docs. How many (if any) are appropriate there?
• Currently I am setting v:redraw_relnum to -1 if 'relativenumber' is unset. Does this make sense? That way users can check if it is larger than or equal to 0 but we could also always set it to the appropriate value and have users check against &rnu. That way we also have an easy way to check for the cursor line nr if 'relativenumber' is unset. I think that might be better, or even add the boolean @max397574 suggested. Not sure what will result in the most ergonomic 'numbercolumn' strings/functions.

[hrqmonteiro]

Since it closed this, could i realy use this to set something between the linenumber and the code as it was asking?

For example, set the GitSigns to be on this space instead of the extreme left of the window (as it were before)?

[luukvbaal]

Since it closed this, could i realy use this to set something between the linenumber and the code as it was asking?

Yes, IDK what "something" is but a margin between the line number and the code could be set like this:

:let &statuscolumn='%l   '

For example, set the GitSigns to be on this space instead of the extreme left of the window (as it were before)?

If "something" is supposed to be the signcolumn, a more complete 'statuscolumn' would something like this:

:let &statuscolumn='%C%l%=%s'

Meaning foldcolumn -> line number -> right aligned sign column.

Whether this should close that issue is still debatable I guess.

[hrqmonteiro]

Since it closed this, could i realy use this to set something between the linenumber and the code as it was asking?

Yes, IDK what "something" is but a margin between the line number and the code could be set like this:

:let &statuscolumn='%l   '

For example, set the GitSigns to be on this space instead of the extreme left of the window (as it were before)?

If "something" is supposed to be the signcolumn, a more complete 'statuscolumn' would something like this:

:let &statuscolumn='%C%l%=%s'

Meaning foldcolumn -> line number -> right aligned sign column.

Whether this should close that issue is still debatable I guess.

That kinda did it, actually, wow. I just tried swapping the order and i tried: :let &statuscolumn='%l=%s%C' and i got this:

Which is almost like what i wanted, wow. I wanted: line number -> signcolumn -> foldcolumn and it's very close. Just have to get the number to 'sound' right (i mean the spacing and being aligned), and the relative numbers.

Any tips on how to achieve that?

[clason]

Usage questions are better asked on Matrix or your discussion platform of choice.

[justinmk]

@luukvbaal fantastic work!

Where did we land with these items:

• With the following diff (not resetting the sign pointers in the statuscol structure for non-wrapped lines), Repeat signs across wrapped lines #12866 would be default behavior in this PR.

• Would providing the option here be sufficient to consider that issue resolved? Or would core still want to keep the issue open to provide it in the regular sign state at some point. Same question for Clickable and customizable sign area  #20447.

Tradeoff being that users that want to disable it require a re-evaluate block in their 'statuscolumn', presumably affecting redraw performance

Seems like a fine tradeoff. Can we close those 2 issues then?

[luukvbaal]

The default value is empty, meaning that it is not used. You should ask usage questions elsewhere, but the default "gutter" looks something like vim.o.statuscolumn = "%C%s%l ".