Need help configuring a new builtin diagnostic source

[craigmac]

I'm trying to create a new source in builtins/diagnostics called 'markdownlin2.lua', based on the cli tool found here. It works differently than the standard markdownlint-cli tool, in that it doesn't accept flags or seem to accept stdin (see writeup about differences here).

This is what I've come up with so far in the lua file:

local h = require("null-ls.helpers")
local methods = require("null-ls.methods")

local DIAGNOSTICS = methods.internal.DIAGNOSTICS

return h.make_builtin({
    method = DIAGNOSTICS,
    filetypes = { "markdown", "liquid" },
    generator_opts = {
        command = "markdownlint-cli2",
        args = {},
        to_stdin = false,
        from_stderr = false,
        format = "line",
        to_temp_file = true,
        check_exit_code = function(code)
            return code <= 1
        end,
        on_output = h.diagnostics.from_patterns({
            {
                pattern = [[:(%d+):(%d+) ([%w-/]+) (.*)]],
                groups = { "row", "col", "code", "message" },
            },
            {
                pattern = [[:(%d+) ([%w-/]+) (.*)]],
                groups = { "row", "code", "message" },
            },
        }),
    },
    factory = h.generator_factory,
})

I don't see anything anything in the log when using :NullLsLog and when I open a known bad markdownfile (checked with same cli on the command line like this markdownlint-cli2 quick-start.md) I don't get any diagnostics. When I check :NullLsInfo it does report that markdownlint-cli2 is a source active in the buffer, along with 'vale' (which works as expected). Any ideas? I've tried playing with turning on/off to_temp_file and the stderr but no combination has worked so far. The output on the cli matches the same output as the markdownlint-cli tool MOSTLY except it adds 5 lines of heading stats before the output. I've asked the maintainer and he said that the output out stderr is the same so to get the exact same output to the console I need to do markdownlint-cli2 quick-start.md 1>/dev/null to get rid of the stdout header stuff. Any ideas of what else to try or how to debug further?

[syphar]

Configuring a builtin is actually slightly different than configuring your own custom source.

I have some custom diagnostic sources in my dotfiles.

Also, did you add the custom source to your .setup(sources={}) table?

[jose-elias-alvarez]

Did you enable debug logging? Turning it on shows that the CLI is outputting a help dialog, meaning it likely isn't receiving the correct arguments. Setting args = { "$FILENAME" } and from_stderr = true seems to work, though I haven't tested it thoroughly.

[craigmac]

That worked, thank you! I guess I just assumed FILENAME was passed automatically. I'll have to look into the debug logging in the future. I'm not a programmer by trade, so thanks for the kind response.

[jose-elias-alvarez]

Glad it worked! Feel free to open a PR with the new built-in if you think it might be useful to others.