mini.statusline: How to Enable icons for Warning, Error, Hint, etc. ?

[mezeirobert0]

To avoid repeating myself, I will link my Reddit post on Neovim sub:
https://www.reddit.com/r/neovim/comments/1f1lafg/need_to_help_with_customizing_ministatusline/

[echasnovski]

Customizing statusline content is expected by creating a function and setting it to config.content.active. Like this:

local my_active_content = function()
  -- Your code goes here
end
require('mini.statusline').setup({ content = { active = my_active_content } })

Here is an example function used for default content. Copy paste it as my_active_content body as a start and tweak it until you have your final result.

---

As you pointed in Reddit post, indeed using signs argument in MiniStatusline.section_diagnostics() is the suggested way to customize its signs. So it will be something like this:

local diag_signs = { ERROR = '!', WARN = '?', INFO = '@', HINT = '*' }
local my_active_content = function()
  -- ...
  local diagnostics = MiniStatusline.section_diagnostics({ trunc_width = 75, signs = diag_signs })
  -- ...
end

---

Adding colors is a bit tricky (which is more or less by design because 'mini.statusline' and 'mini.tabline' are intentionally "colorless"), but doable. The return string of active content is essentially used as 'statusline' value, so any special statusline items (see :h statusline) are treated as such. Including the construct of %#HLname# setting the highlight group for characters to the right.

This can be utilized by setting more complicated diagnostic signs. For example, like so:

local diag_signs = {
  ERROR = '%#DiagnosticError#!%#MiniStatuslineDevinfo#',
  WARN = '%#DiagnosticWarn#?%#MiniStatuslineDevinfo#',
  INFO = '%#DiagnosticInfo#@%#MiniStatuslineDevinfo#',
  HINT = '%#DiagnosticHint#*%#MiniStatuslineDevinfo#',
}
-- ...

The DiagnosticXxx highlight groups can not play nicely with its surrounding background color, so you may have to define your own highlight groups. But that part is left for homework.

Hope this helps.