nvim-custom-diagnostic-highlight

A simple plugin to apply a highlight group to unused variables and functions similar to what coc-nvim does.

It can also apply any custom highlight to other diagnostics

Note that the unused fields are darkened and other diagnostics are not changed.

By default it works for unused fields, but the plugin is configurable for whatever diagnostics you want

Installation

Simply import the plugin with your favorite package manager and call .setup on it

-- Packer
use {
  'Kasama/nvim-custom-diagnostic-highlight',
  config = function()
    require('nvim-custom-diagnostic-highlight').setup {}
  end
}

-- Plug
Plug 'Kasama/nvim-custom-diagnostic-highlight'
require('nvim-custom-diagnostic-highlight').setup {}

-- ...etc

Basic Usage

By default this plugin registers a diagnostics handler to highlight unused-diagnosed variables, functions, imports, etc.

The most basic usage is to have require('nvim-custom-diagnostic-highlight').setup {} in your configurations.

Configuration

The most up-to-date default configuration can be found at ./lua/nvim-custom-diagnostic-highlight.lua

The default configuration includes:

local final_opts = {
  register_handler = true,                                    -- Wether to register the handler automatically
  handler_name = 'kasama/nvim-custom-diagnostic-highlight',   -- The name of the handler to be registered (has no effect if register_handler = false)
  highlight_group = 'Conceal',                                -- The Highlight group to set at the diagnostic
  patterns_override = {                                       -- Lua patterns to be tested against the diagnostic message. Overrides default behavior
    '%sunused', '^unused', 'not used', 'never used',
    'not read', 'never read', 'empty block', 'not accessed'
  },
  extra_patterns = {},                                        -- Extra lua patterns to add. Does NOT override and will be added to the above
  diagnostic_handler_namespace = 'unused_hl_ns',              -- Name of the handler namespace that will contain the highlight (needs to be unique)
  defer_until_n_lines_away = false,                           -- If set to a number, then highlighting is deferred until the cursor is N lines away from
                                                              -- diagnostics. Useful to avoid unwanted highlights in the currently edited position.
  defer_highlight_update_events = {'CursorHold', 'CursorHoldI'}, -- Events on which deferred highlights will be updated (passed to nvim_create_autocmd)
}

Note that both handler_name and diagnostic_handler_namespace must be unique values

Advanced usage

This plugin by default is setup to highlight unused variables, but it can be used to add any highlight to any diagnostic.

It can also be used multiple times. The example below sets up once with the default behavior and another highlighting import related diagnostics with a custom highlight group.

local unused_handler = require('nvim-custom-diagnostic-highlight').setup {
  register_handler = false,
  diagnostic_handler_namespace = 'unused_handler'
}
local import_handler = require('nvim-custom-diagnostic-highlight').setup {
  register_handler = false,
  highlight_group = 'MyCustomHighlightGroup',
  patterns_override = { 'import' },
  diagnostic_handler_namespace = 'import_handler'
}

vim.cmd [[highlight MyCustomHighlightGroup ctermfg=168 ctermbg=16 guifg=#e06c75 guibg=#282c34]]

vim.diagnostic.handlers['my/unused'] = unused_handler
vim.diagnostic.handlers['my/import'] = import_handler

There are many possibilities.