[null-ls] typechecking error: read .../undodir/%home%user%Projects%APIs%Go%main.go: unexpected NUL in input

[KorcakDaniel]

I've some difficulties with null-ls trying to format the undo file while opening the project file.

I've followed this thread #879, but the warning stated in the title shows every time I open the go project file.
The issue seems to be related to the golangci_lint built-in diagnostics, since python project using flake8 built-in diagnostics doesn't trigger this message. Any help is appreciated.

Here is my configuration:

    { "jose-elias-alvarez/null-ls.nvim",
        dependencies = { "nvim-lua/plenary.nvim" },
        config = function()
            local null_ls = require("null-ls")

            local augroup = vim.api.nvim_create_augroup("LspFormatting", {})

            null_ls.setup({
                sources = {
                    null_ls.builtins.diagnostics.eslint_d.with({
                        diagnostics_format = '[eslint] #{m}\n(#{c})'
                    }),
                    null_ls.builtins.formatting.black,
                    null_ls.builtins.diagnostics.flake8,
                    null_ls.builtins.diagnostics.golangci_lint,
                },
                on_attach = function(client, bufnr)
                    if client.supports_method("textDocument/formatting") then
                        vim.api.nvim_buf_create_user_command(bufnr, "LspFormatting", function()
                            -- or vim.lsp.buf.formatting(bufnr) on 0.8
                            vim.lsp.buf.format({ bufnr = bufnr })
                        end, {})

                        -- you can leave this out if your on_attach is unique to null-ls,
                        -- but if you share it with multiple servers, you'll want to keep it
                        vim.api.nvim_clear_autocmds({
                            group = augroup,
                            buffer = bufnr,
                        })

                        vim.api.nvim_create_autocmd("BufWritePre", {
                            group = augroup,
                            buffer = bufnr,
                            command = "undojoin | LspFormatting",
                        })
                    end
                end,
                },

                vim.api.nvim_create_user_command(
                  'DisableLspFormatting',
                  function()
                    vim.api.nvim_clear_autocmds({ group = augroup, buffer = 0 })
                  end,
                  { nargs = 0 }
                )
            )
        end,
    }

This is what's in the log, when I enable debugging:
[WARN Wed Feb 22 01:13:20 2023] ....nvim/lua/null-ls/builtins/diagnostics/golangci_lint.lua:34: typechecking error: read /home/user/Projects/APIs/Go/lua/undodir/%home%user%Projects%APIs%Go%main.go: unexpected NUL in input

[jose-elias-alvarez]

I don't think this has to do with #879. What is creating /home/user/Projects/APIs/Go/lua/undodir/%home%user%Projects%APIs%Go%main.go?

[KorcakDaniel]

Neovim's functionality of undodir itself, which can be allowed in the settings. The Neovim keeps the changes even after closing the buffer, so the changes can be undone after reopening the file again.

vim.o.undodir = os.getenv("HOME") .. "/.config/nvim/undodir"
vim.o.undofile = true

Neovim docs - undodir

[KorcakDaniel]

I've now noticed that it's more of a misconfiguration on my part, since it creates the undo directory in the project folder itself, and the built-in diagnostics is trying to parse it. After removing it, the diagnostics works.

I also fixed the undodir to not create the file in the project directory again

vim.o.undodir = vim.fn.stdpath('config') .. "/undodir"
vim.o.undofile = true

[jose-elias-alvarez]

Makes sense, glad you figured this out!