add mh_lint

[ayoubelmhamdi]

Matlab linter form miss_hit can work with Octave too

This PR use the output from mh_lint, but can do better if we use json that officially supported by mh_lint

[jose-elias-alvarez]

This looks good to me, is there anything you wanted me to check before merging it?

[ayoubelmhamdi]

if mh_lint is not merged, how i can use it, from dotfiles?

I'm trying this config but something is not correcte

local null_ls = require 'null-ls'
local helpers = require 'null-ls.helpers'

local mh_lint = {
  method = null_ls.methods.DIAGNOSTICS,
  filetypes = { 'matlab', 'octave' },
  generator = null_ls.generator ({
    command = 'mh_lint',
    args = { '--brief', '$FILENAME' },
    to_stdin = false,
    from_stderr = true,
    format = 'line',
    on_output = helpers.diagnostics.from_pattern ({
      {
        pattern = [[(%d+):(%d+): (%w+): (.*)]],
        groups = { "row", "col", "severity", "message" },
      },
    }),
  }),
}

null_ls.register(mh_lint)

null_ls.setup {
  sources = {
    null_ls.builtins.diagnostics.mh_lint,
  },
}

log

[TRACE Sat 05 Nov 2022 05:04:26 AM CET] ...im/site/pack/packer/opt/null-ls.nvim/lua/null-ls/rpc.lua:123: received LSP request for method shutdown
[TRACE Sat 05 Nov 2022 05:04:26 AM CET] ...im/site/pack/packer/opt/null-ls.nvim/lua/null-ls/rpc.lua:148: received LSP notification for method exit
[WARN  Sat 05 Nov 2022 05:04:29 AM CET] ...ck/packer/opt/null-ls.nvim/lua/null-ls/builtins/init.lua:17: failed to load builtin mh_lint for method diagnostics; please check your config
[WARN  Sat 05 Nov 2022 05:04:30 AM CET] .../pack/packer/opt/null-ls.nvim/lua/null-ls/generators.lua:92: failed to run generator: ...ker/opt/null-ls.nvim/lua/null-ls/helpers/diagnostics.lua:100: bad argument #1 to 'match' (string expected, got table)

[jose-elias-alvarez]

Yes, you can test it out from your config or from a local branch. Your specific error comes from a mismatched signature for from_pattern - see the source for the correct usage.