Hi @onsails,
Thank you for your plugin. I use it with the sample config:

lua require("diaglist").init({
    debug = false, 
    debounce_ms = 150,
})

I noticed the quickfix only populated after I call lua require('diaglist').open_all_diagnostics() which sets the window title and in this way lets the vim.fn.getqflist{ title = 0 }.title ~= check to pass.
So currently, I always get the print('foreign quickfix, not populating') message for using :copen.
I'm wondering why does it work like this? Should the README point it out?

Forgive me if I'm missing something obvious, but is there an easy way when using this plugin to have the quickfix list open automatically when there are errors? Something like neomake's behavior?

As reported here:

LeonHeidelbach/trailblazer.nvim#37

As stated in the title, these lines in loclist.lua

  if warnings + errors > 0 then

and quickfix.lua

  if #all_diagnostics > 0 then

prevent the lists from updating when there are no errors/warnings left.
Screenshot:

Then I comment the incorrect line and the windows closes, but another :copen shows the errors still there:

Edit: I have created a PR with a possible simple solution. Let me know what you think.

Using the latest LSP and Neovim.

Hello. I am always grateful for this plugin. Sorry for my poor English.

Why don't you export the local function populate_qflist() in lua/diaglist/quickfix.lua publicly?

In my case, I want to add a diaglist to the quickfix list on LspAttach events (or equivalent timing: e.g. nvim-lspconfig callback function), but I do not want to display the quickfix window at that time.

The plugin sets a flag on QuickFixCmdPre to signify that the quickfix has been populated by something other than the diagnostics. This unfortunatelly conflicts with non-builtin functions utilizing quickfix (like vim.lsp.buf.workspace_symbol() or vim.lsp.buf.references()).

Both this and the current issue of not respecting foregin location lists can be fixed using setqflist() (and getqflist(), setloclist(), getloclist()), perhaps by specifying the lists' ID or even just the title. The lsp_diagnostic_hook can then check if current quickfix list has a specific title (say "Diagnostics") and only then update. If the user wants to force the update they can do so with open_all_diagnostics() or open_buffer_diagnostics().

I would try making a PR myself, but the above are vimscript functions and I have no clue how to nicely use them from lua.

Excellent plugin!
One small annoyance I've noticed is that when I leave the quickfix window, it no longer maintains the current selection and the top item is selected instead.

$ nvim --version
NVIM v0.6.0-dev+274-g6188926e0
Build type: RelWithDebInfo
LuaJIT 2.1.0-beta3

After installing diaglist, here's what happens when I enter a buffer with an LSP attached to it:

Basically, the diaglist window appears and steals focus. If I try to go to another buffer, focus immediately goes back to diaglist.

I've set up diaglist with just:

require("diaglist").init({})

On NVIM v0.5.1, diaglist works just fine!

When I'm using Neovim V0.5, errors show saying that LSP events are not valid events. After switching to Neovim V0.6, deprecation warnings are popping up.