nvim-lint

An asynchronous linter plugin for Neovim (>= 0.6.0) complementary to the built-in Language Server Protocol support.

Motivation & Goals

With ale we already got an asynchronous linter, why write yet another one?

Because ale reports diagnostics with its own home grown solution and even includes its own language server client.

nvim-lint instead uses the vim.diagnostic module to present diagnostics in the same way the language client built into neovim does. nvim-lint is meant to fill the gaps for languages where either no language server exists, or where standalone linters provide better results than the available language server do.

Installation

• Requires Neovim >= 0.6.0
• nvim-lint is a plugin. Install it like any other Neovim plugin.
  • If using vim-plug: Plug 'mfussenegger/nvim-lint'
  • If using packer.nvim: use 'mfussenegger/nvim-lint'

Usage

Configure the linters you want to run per file type. For example:

require('lint').linters_by_ft = {
  markdown = {'vale',}
}

Then setup a autocmd to trigger linting. For example:

au BufWritePost * lua require('lint').try_lint()

or with Lua autocmds (requires 0.7):

vim.api.nvim_create_autocmd({ "BufWritePost" }, {
  callback = function()
    require("lint").try_lint()
  end,
})

Some linters require a file to be saved to disk, others support linting stdin input. For such linters you could also define a more aggressive autocmd, for example on the InsertLeave or TextChanged events.

If you want to customize how the diagnostics are displayed, read :help vim.diagnostic.config.

Available Linters

There is a generic linter called compiler that uses the makeprg and errorformat options of the current buffer.

Other dedicated linters that are built-in are:

Custom Linters

You can register custom linters by adding them to the linters table, but please consider contributing a linter if it is missing.

require('lint').linters.your_linter_name = {
  cmd = 'linter_cmd',
  stdin = true, -- or false if it doesn't support content input via stdin. In that case the filename is automatically added to the arguments.
  append_fname = true, -- Automatically append the file name to `args` if `stdin = false` (default: true)
  args = {}, -- list of arguments. Can contain functions with zero arguments that will be evaluated once the linter is used.
  stream = nil, -- ('stdout' | 'stderr' | 'both') configure the stream to which the linter outputs the linting result.
  ignore_exitcode = false, -- set this to true if the linter exits with a code != 0 and that's considered normal.
  env = nil, -- custom environment table to use with the external process. Note that this replaces the *entire* environment, it is not additive.
  parser = your_parse_function
}

Instead of declaring the linter as a table, you can also declare it as a function which returns the linter table in case you want to dynamically generate some of the properties.

your_parse_function can be a function which takes two arguments:

• output
• bufnr

The output is the output generated by the linter command. The function must return a list of diagnostics as specified in :help diagnostic-structure.

You can override the environment that the linting process runs in by setting the env key, e.g.

env = { ["FOO"] = "bar" }

Note that this completely overrides the environment, it does not add new environment variables. The one exception is that the PATH variable will be preserved if it is not explicitly set.

You can generate a parse function from a Lua pattern or from an errorformat using the function in the lint.parser module:

from_errorformat

parser = require('lint.parser').from_errorformat(errorformat)

The function takes a single argument which is the errorformat.

from_pattern

parser = require('lint.parser').from_pattern(pattern, groups, severity_map, defaults, opts)

The function allows to parse the linter's output using a Lua regular expression pattern.

• pattern: The regular expression pattern applied on each line of the output
• groups: The groups specified by the pattern

Available groups:

• lnum
• end_lnum
• col
• end_col
• message
• file
• severity
• code

The order of the groups must match the order of the captures within the pattern. An example:

local pattern = '[^:]+:(%d+):(%d+):(%w+):(.+)'
local groups = { 'lnum', 'col', 'code', 'message' }

• severity: A mapping from severity codes to diagnostic codes

default_severity = {
['error'] = vim.diagnostic.severity.ERROR,
['warning'] = vim.diagnostic.severity.WARN,
['information'] = vim.diagnostic.severity.INFO,
['hint'] = vim.diagnostic.severity.HINT,
}

• defaults: The defaults diagnostic values

defaults = {["source"] = "mylint-name"}

• opts: Additional options

  • end_col_offset: offset added to end_col. Defaults to -1, assuming that the end-column position is exclusive.

Customize built-in linter parameters

You can import a linter and modify its properties. An example:

local phpcs = require('lint').linters.phpcs
phpcs.args = {
  '-q',
  -- <- Add a new parameter here
  '--report=json',
  '-'
}

Alternatives

• Ale
• efm-langserver
• diagnostic-languageserver

Development ☢️

Run tests

Running tests requires busted.

See neorocks or Using Neovim as Lua interpreter with Luarocks for installation instructions.

busted tests/