bug: custom plugin rtp docs don't work

[strager]

Did you check docs and existing issues?

• I have read all the lazy.nvim docs
• I have searched the existing issues of lazy.nvim
• I have searched the existing issues of plugins related to this issue

Neovim version (nvim -v)

v0.9.5

Operating system/version

macOS 14.2.1

Describe the bug

A plugin exists inside a Git repo. The plugin isn't at the root of the Git repo; it's in the plugin/vim/quick-lint-js.vim subdirectory.

Following the docs, it looks like I should use the config hook: https://github.com/folke/lazy.nvim/tree/main?tab=readme-ov-file#-migration-guide

However, the config hook executed after the Git repo is added to runtimepath and after lazy.nvim executes files in the Git repo which don't belong to the plugin (!).

• Bug: Instructions in the docs for setting runtimepath using config add to runtimepath and don't replace the runtimepath entry.
• Bug: lazy.nvim loads scripts in the Git repo which aren't part of the plugin. (In particular, lazy.nvim executes a test script which ends with :qall!, causing Neovim to exit on startup. Adding quick-lint-js to my LazyVim config causes vim to stop working. quick-lint/quick-lint-js#1195)

Steps To Reproduce

Create ~/.config/nvim/lua/plugins/quick-lint-js.lua:

return {
  "quick-lint/quick-lint-js",
  tag = "3.1.0",
  config = function(plugin)
    vim.opt.rtp:append(plugin.dir .. "/plugin/vim/quick-lint-js.vim")

    require("lspconfig/quick_lint_js").setup {}
  end
}

Open Neovim. Observe that Neovim exits on startup because lazy.nvim executes <quick-lint-js>/plugin/vim/test.vim which is outside the Vim plugin's directory (<quick-lint-js>/plugin/vim/quick-lint-js.vim).

Expected Behavior

Neovim doesn't exit on startup. The quick-lint-js plugin is loaded without error like in other package managers which support an rtp option.

Repro

No response

[strager]

Related issues: #183, #756, #1262

[strager]

I found a hacky workaround. The cond hook executes before anything is added to runtimepath, so I can edit plugin.dir in a cond hook to get the behavior I want:

return {
  "quick-lint/quick-lint-js",
  tag = "3.1.0",
  cond = function(plugin)
    -- TODO(strager): Don't make this happen multiple times.
    plugin.dir = plugin.dir .. "/plugin/vim/quick-lint-js.vim"
    return true
  end,
  config = function(_plugin)
    require("lspconfig/quick_lint_js").setup {}
  end,
}

(This workaround probably breaks upgrading and some other flows. I haven't tested it well.)

[strager]

@folke Would you accept a patch to fix this bug?