Working tree buffer is a 'real' buffer with LSP server(s) attached

[gegoune]

Hi there,
this is more of a request for assistance than a bug report but discussions are disabled here, hope you don't mind.

I have long struggled with various issues related to LSP functionality and Diffview, which I believe all come from the fact that working tree diff buffer (right hand side one) is a real, live, buffer rather than URI scheme prefixed with diffview://.

Please note that all LSP features are enabled through callback function of LspAttach autocommand.

1. Opening Diffview on newly started Neovim (without any buffer loaded yet) will cause topmost file on the file panel to be loaded. If LSP folding feature is enabled with:

vim.wo[win][0].foldmethod = 'expr'
vim.wo[win][0].foldexpr = 'v:lua.vim.lsp.foldexpr()'

this will cause right hand buffer to fold quite aggressively when LSP server attaches (with foldlevel=0 as opposed to my default foldlevel=99). It is the case for yaml-language-server at least (but likely all servers supporting FoldingRange will behave like this). Important distinction is that if I open the same buffer prior to opening Diffview, no such folding takes place. It's only an issue when Diffview opens the buffer.

2. With the nature of representation of code lenses (at least on nightly) being on separate line above targetted definition the result is misaligned buffers due to virtual lines.

I tried various autocommands, Diffview hooks, to enable and disable LSP features but didn't manage to get it to work satisfactorily.

Do you think, perhaps being quite a fundamental change, Diffview could also treat right hand side buffer (working tree) as a special buffer for which all LSP functionalities are disabled the same way left hand side buffer is?

Thanks.

[dlyongemallo]

The rationale for why the buffers behave as they do in terms of LSPs is given in the TIPS.md file.

You can fix the folding problem by either setting the (global) view.foldlevel = 99, or by using a hook:

hooks = {
  diff_buf_win_enter = function(bufnr, winid, ctx)
    if ctx.symbol == "b" and not vim.api.nvim_buf_get_name(bufnr):match("^diffview://") then
      vim.wo[winid].foldlevel = 99
    end
  end,
}

[dlyongemallo]

Can you try view.default.disable_diagnostics = true? I don't use nightly so I'm not sure whether this works or not. (It will turn off virt_lines from diagnostics.)

[gegoune]

Diagnostics are not a problem. Disabling them (as per your suggestion, which I had enabled already) works well. It's the other LSP functionalities that are causing problems.

As for the foldlevel, I have found that setting any window-local options within Diffview hooks occasionally causes those settings to 'leak' past Diffview views to actual buffers (when using gf, or just closing or changing away from Diffview tabpage). I had this problem when setting custom statuscolumn for Diffview views. But will try your solution (thanks!) and see if the same issue occurs. One thing I noticed already though is that with fold level 99, I lose Diffview's "smart" folding off non-diffing parts.

And yes, indeed, this doc mentions LSP behaviour in diffview:// buffer, and the fact that 'b' buffer differs. Which was part of my reasoning behind 'b' buffer also being prefixed rather than reusing 'actual' buffer (sorry if my wording isn't correct here).