bug: viewing diff with diffview.nvim not working

[kuntau]

Did you check docs and existing issues?

• I have read all the lazy docs
• I have searched the existing issues of lazy
• I have searched the exsiting issues of the plugin I have a problem with

Neovim version (nvim -v)

NVIM v0.9.0-dev-cb9d68fe

Operating system/version

MacOS 10.15.7

Describe the bug

On first start diffview open with empty file. Subsequent open will give error

[Diffview.nvim] Not a repo (or any parent), or no supported VCS adapter!

Steps To Reproduce

1. Open lazy window
2. Update/log
3. Press d on any git hash

Expected Behavior

Actual diff is shown.

Repro

-- DO NOT change the paths and don't remove the colorscheme
local root = vim.fn.fnamemodify("./.repro", ":p")

-- set stdpaths to use .repro
for _, name in ipairs({ "config", "data", "state", "cache" }) do
  vim.env[("XDG_%s_HOME"):format(name:upper())] = root .. "/" .. name
end

-- bootstrap lazy
local lazypath = root .. "/plugins/lazy.nvim"
if not vim.loop.fs_stat(lazypath) then
  vim.fn.system({
    "git",
    "clone",
    "--filter=blob:none",
    "--single-branch",
    "https://github.com/folke/lazy.nvim.git",
    lazypath,
  })
end
vim.opt.runtimepath:prepend(lazypath)

-- install plugins
local plugins = {
  "folke/tokyonight.nvim",
  "sindrets/diffview.nvim",
  "nvim-lua/plenary.nvim",
  -- add any other plugins here
}
require("lazy").setup(plugins, {
  root = root .. "/plugins",
  checker = {
	-- automatically check for plugin updates
	enabled = false,
	concurrency = 1, ---@type number? set to 1 to check for updates very slowly
	notify = true, -- get a notification when new updates are found
	frequency = 3600*2, -- check for updates every hour
  },
  diff = { cmd = "diffview.nvim" },
})

vim.cmd.colorscheme("tokyonight")
vim.g.mapleader = [[ ]]
vim.keymap.set('n','gol','<cmd>Lazy<cr>')
-- add anything else here

[kuntau]

Thank you for the fix @folke, but diffview still not fully working.

After Lazy check and you get updates. Press d on hash did show diffview correctly.

But if you go to Log view and press d on hash, diffview still give empty window.

Edit: Weird, sometimes it work and sometimes not...

[folke]

You need to press <d> on the actual commit hash. If you press <d> anywhere else, an updated diff is shown. If there's no updates, that woyld be empty. Is that the issue?

[kuntau]

I'll to screen record... Yes, I press d on actual commit hash.

If I repeat the same action with other diff value it works just fine. I've tried git, terminal_git all show the actual diff

[kuntau]

Asciinema recording

[folke]

I can't reproduce this. Do be aware that you need internet connection and need to wait a bit for the diff to load, since lazy uses partial commits. When showing a single commit for which git does not yet have the blobs, they will be downloaded on demand.

[sindrets]

lazy.nvim/lua/lazy/view/diff.lua

Lines 27 to 29 in e77be3c

	if diff.commit then
	args = ("-C=%s"):format(plugin.dir) .. " " .. diff.commit
	else

Diffview always treats git revs the same way as git-diff, so the equivalent to doing git show <commit>, would be :DiffviewOpen <commit>^!.

The notation <rev>^! explicitly describes the range of a single commit. Using non-range revs have different meanings for different git commands. In this case, git diff <commit> will compare the commit against the working tree. Whereas git diff <commit>^! will show only the changes introduced in the given commit. Which is what I assume was the intention here?

[folke]

@sindrets updated, thanks!

[kuntau]

Diffview always treats git revs the same way as git-diff, so the equivalent to doing git show <commit>, would be :DiffviewOpen <commit>^!.

Thank you. Changing those line as suggested fix the issue

diff --git a/lua/lazy/view/diff.lua b/lua/lazy/view/diff.lua
index 24955b8..f4fe5af 100644
--- a/lua/lazy/view/diff.lua
+++ b/lua/lazy/view/diff.lua
@@ -25,7 +25,7 @@ M.handlers = {
   ["diffview.nvim"] = function(plugin, diff)
     local args
     if diff.commit then
-      args = ("-C=%s"):format(plugin.dir) .. " " .. diff.commit
+      args = ("-C=%s"):format(plugin.dir) .. " " .. diff.commit .. "^!"
     else
       args = ("-C=%s"):format(plugin.dir) .. " " .. diff.from .. ".." .. diff.to
     end

[kuntau]

Ops... @folke is too fast 🥂