fix(#1976): support non-standard $GIT_DIR (#2012)

* Improve $GIT_DIR handling

- Retrieve $GIT_DIR using `git rev-parse --absolute-git-dir`
- Move $GIT_DIR ignore in the project exploration part

Resolves #1976

* Code review

- move norm_path to utils.lua
- fix comment #2012

* add comments for utils.norm_path

* get_git_directory use norm_path from utils

* watcher improvements

---------

Co-authored-by: Alexander Courtis <alex@courtis.org>

lua/nvim-tree/explorer/watch.lua

@@ -4,11 +4,7 @@ local Watcher = require("nvim-tree.watcher").Watcher
 
 local M = {}
 
-local function is_git(path)
-  return vim.fn.fnamemodify(path, ":t") == ".git"
-end
-
-local IGNORED_PATHS = {
+M.ignore_dirs = {
   -- disable watchers on kernel filesystems
   -- which have a lot of unwanted events
   "/sys",
@@ -16,13 +12,11 @@ local IGNORED_PATHS = {
   "/dev",
 }
 
-local function is_folder_ignored(path)
-  for _, folder in ipairs(IGNORED_PATHS) do
-    if vim.startswith(path, folder) then
-      return true
-    end
-  end
+function M.ignore_dir(path)
+  table.insert(M.ignore_dirs, path)
+end
 
+local function is_folder_ignored(path)
   for _, ignore_dir in ipairs(M.ignore_dirs) do
     if vim.fn.match(path, ignore_dir) ~= -1 then
       return true
@@ -44,7 +38,7 @@ function M.create_watcher(node)
     path = node.absolute_path
   end
 
-  if is_git(path) or is_folder_ignored(path) then
+  if is_folder_ignored(path) then
     return nil
   end
 
@@ -74,7 +68,7 @@ end
 function M.setup(opts)
   M.enabled = opts.filesystem_watchers.enable
   M.debounce_delay = opts.filesystem_watchers.debounce_delay
-  M.ignore_dirs = opts.filesystem_watchers.ignore_dirs
+  M.ignore_dirs = vim.tbl_extend("force", M.ignore_dirs, opts.filesystem_watchers.ignore_dirs)
   M.uid = 0
 end
 

lua/nvim-tree/git/init.lua

@@ -2,6 +2,7 @@ local log = require "nvim-tree.log"
 local utils = require "nvim-tree.utils"
 local git_utils = require "nvim-tree.git.utils"
 local Runner = require "nvim-tree.git.runner"
+local Watch = require "nvim-tree.explorer.watch"
 local Watcher = require("nvim-tree.watcher").Watcher
 local Iterator = require "nvim-tree.iterators.node-iterator"
 local explorer_node = require "nvim-tree.explorer.node"
@@ -164,22 +165,34 @@ function M.load_project_status(cwd)
   }
 
   local watcher = nil
+
   if M.config.filesystem_watchers.enable then
     log.line("watcher", "git start")
 
-    local callback = function(w)
-      log.line("watcher", "git event scheduled '%s'", w.project_root)
-      utils.debounce("git:watcher:" .. w.project_root, M.config.filesystem_watchers.debounce_delay, function()
-        if w.destroyed then
-          return
-        end
-        reload_tree_at(w.project_root)
-      end)
-    end
+    local git_directory = git_utils.get_git_directory(project_root)
 
-    watcher = Watcher:new(utils.path_join { project_root, ".git" }, WATCHED_FILES, callback, {
-      project_root = project_root,
-    })
+    if git_directory == nil then
+      log.line("watcher", "could not found the location of .git folder")
+    else
+      local callback = function(w)
+        log.line("watcher", "git event scheduled '%s'", w.project_root)
+        utils.debounce("git:watcher:" .. w.project_root, M.config.filesystem_watchers.debounce_delay, function()
+          if w.destroyed then
+            return
+          end
+          reload_tree_at(w.project_root)
+        end)
+      end
+
+      -- Add GIT_DIR to the list of directory to ignore
+      -- local base_gitdir = utils.path_basename(git_directory)
+      -- Watch.ignore_dir(base_gitdir)
+      Watch.ignore_dir(git_directory)
+
+      watcher = Watcher:new(git_directory, WATCHED_FILES, callback, {
+        project_root = project_root,
+      })
+    end
   end
 
   M.projects[project_root] = {

lua/nvim-tree/git/utils.lua

@@ -1,7 +1,6 @@
 local M = {}
 local log = require "nvim-tree.log"
-
-local has_cygpath = vim.fn.executable "cygpath" == 1
+local utils = require "nvim-tree.utils"
 
 function M.get_toplevel(cwd)
   local profile = log.profile_start("git toplevel %s", cwd)
@@ -18,16 +17,9 @@ function M.get_toplevel(cwd)
     return nil
   end
 
-  -- git always returns path with forward slashes
-  if vim.fn.has "win32" == 1 then
-    -- msys2 git support
-    if has_cygpath then
-      toplevel = vim.fn.system("cygpath -w " .. vim.fn.shellescape(toplevel))
-      if vim.v.shell_error ~= 0 then
-        return nil
-      end
-    end
-    toplevel = toplevel:gsub("/", "\\")
+  toplevel = utils.norm_path(toplevel)
+  if toplevel == nil then
+    return nil
   end
 
   -- remove newline
@@ -94,4 +86,28 @@ function M.file_status_to_dir_status(status, cwd)
   return r
 end
 
+function M.get_git_directory(cwd)
+  local profile = log.profile_start("git directory %s", cwd)
+
+  local cmd = { "git", "-C", cwd, "rev-parse", "--absolute-git-dir" }
+  log.line("git", vim.inspect(cmd))
+
+  local git_dir = vim.fn.system(cmd)
+
+  log.raw("git", git_dir)
+  log.profile_end(profile)
+
+  if vim.v.shell_error ~= 0 or not git_dir or #git_dir == 0 or git_dir:match "fatal" then
+    return nil
+  end
+
+  git_dir = utils.norm_path(git_dir)
+  if git_dir == nil then
+    return nil
+  end
+
+  -- remove newline
+  return git_dir:sub(0, -2)
+end
+
 return M

lua/nvim-tree/utils.lua

@@ -5,10 +5,11 @@ local M = {
   debouncers = {},
 }
 
+local has_cygpath = vim.fn.executable "cygpath" == 1
+
 M.is_unix = vim.fn.has "unix" == 1
 M.is_macos = vim.fn.has "mac" == 1 or vim.fn.has "macunix" == 1
 M.is_wsl = vim.fn.has "wsl" == 1
--- false for WSL
 M.is_windows = vim.fn.has "win32" == 1 or vim.fn.has "win32unix" == 1
 
 function M.str_find(haystack, needle)
@@ -38,6 +39,26 @@ function M.path_split(path)
   return path:gmatch("[^" .. path_separator .. "]+" .. path_separator .. "?")
 end
 
+--- Normalise a path:
+---  windows: replace slashes with backslashes
+---   cygwin: resolve path first via cygpath
+--- @param path string
+--- @return string|nil nil on cygpath failure
+function M.norm_path(path)
+  if M.is_windows then
+    -- msys2 git support
+    if has_cygpath then
+      path = vim.fn.system("cygpath -w " .. vim.fn.shellescape(path))
+      if vim.v.shell_error ~= 0 then
+        return nil
+      end
+    end
+    path = path:gsub("/", "\\")
+  end
+
+  return path
+end
+
 ---Get the basename of the given path.
 ---@param path string
 ---@return string