Add support for ~/.config/lazygit without setting XDG_CONFIG_HOME

Currently lazygit looks for its config file in `XDG_CONFIG_HOME` if it's
available, but if not it falls back to the defaults defined by the
[xdg](https://github.com/adrg/xdg) package. Unfortunately the defaults
the package falls back to isn't what CLI applications commonly fall back
to on macOS. Specifically, it looks in `~/Library/Application Support`
instead of `~/.config`.

This updates the app config logic to:

- Look for `~/.config/lazygit` first if `XDG_CONFIG_HOME` is not set
  and we're on macOS.
- Fallback to the existing `xdg` package location if the configuration
  file exists there.
- Default to `~/.config/lazygit/config.yml` if `XDG_CONFIG_HOME` is not
  set, we're on macOS, and there is no existing configuration file.

This change did feel a bit like having to thread a needle and I didn't
see any existing tests for this behavior (which is reasonable, since it's
complicated and OS dependent) so I did test a few variations of the
configuration locally by building with this change included and running
a `brew` installed lazygit.

It seemed to work properly, falling back to the existing location when
`XDG_CONFIG_HOME` isn't set, using `~/.config/lazygit` when `config.yml`
is present, and creating `~/.config/lazygit/config.yml` when it's not.

I think this should resolve https://github.com/jesseduffield/lazygit/issues/1341

docs/Config.md

@@ -3,7 +3,7 @@
 Default path for the global config file:
 
 - Linux: `~/.config/lazygit/config.yml`
-- MacOS: `~/Library/Application\ Support/lazygit/config.yml`
+- MacOS: `~/.config/lazygit/config.yml` (previously `~/Library/Application\ Support/lazygit/config.yml`)
 - Windows: `%LOCALAPPDATA%\lazygit\config.yml` (default location, but it will also be found in `%APPDATA%\lazygit\config.yml`
 
 For old installations (slightly embarrassing: I didn't realise at the time that you didn't need to supply a vendor name to the path so I just used my name):
@@ -12,10 +12,6 @@ For old installations (slightly embarrassing: I didn't realise at the time that
 - MacOS: `~/Library/Application\ Support/jesseduffield/lazygit/config.yml`
 - Windows: `%APPDATA%\jesseduffield\lazygit\config.yml`
 
-If you want to change the config directory:
-
-- MacOS: `export XDG_CONFIG_HOME="$HOME/.config"`
-
 In addition to the global config file you can create repo-specific config files in `<repo>/.git/lazygit.yml`. Settings in these files override settings in the global config file. In addition, files called `.lazygit.yml` in any of the parent directories of a repo will also be loaded; this can be useful if you have settings that you want to apply to a group of repositories.
 
 JSON schema is available for `config.yml` so that IntelliSense in Visual Studio Code (completion and error checking) is automatically enabled when the [YAML Red Hat][yaml] extension is installed. However, note that automatic schema detection only works if your config file is in one of the standard paths mentioned above. If you override the path to the file, you can still make IntelliSense work by adding

pkg/config/app_config.go

@@ -417,13 +417,34 @@ func findConfigFile(filename string) (exists bool, path string) {
 		return true, legacyConfigPath
 	}
 
+	// if on macOs, default to looking in ~/.config/lazygit first since that's
+	// the most common location for CLI apps to store configuration when
+	// `XDG_CONFIG_HOME` is not set. The `xdg` package uses `~/Library/Application\ Support`
+	// as the default directory for macOS, so we have to handle this case manually.
+	if overrideXdgConfigHome && os.Getenv("XDG_CONFIG_HOME") == "" {
+		homeConfigFilePath, err := findHomeConfigFile(filename)
+		if err == nil {
+			return true, homeConfigFilePath
+		}
+	}
+
 	// look for lazygit/filename in XDG_CONFIG_HOME and XDG_CONFIG_DIRS
 	configFilepath, err := xdg.SearchConfigFile(filepath.Join("lazygit", filename))
 	if err == nil {
 		return true, configFilepath
 	}
 
-	return false, filepath.Join(xdg.ConfigHome, "lazygit", filename)
+	configHome := xdg.ConfigHome
+	// If we're on macOS and XDG_CONFIG_HOME is not set, we use
+	// ~/.config/lazygit instead of the default `~/Library/Application\ Support`
+	// directory the `xdg` package uses.
+	if overrideXdgConfigHome && os.Getenv("XDG_CONFIG_HOME") == "" {
+		if homeDir, err := os.UserHomeDir(); err == nil {
+			return false, filepath.Join(homeDir, ".config", "lazygit", filename)
+		}
+	}
+
+	return false, filepath.Join(configHome, "lazygit", filename)
 }
 
 var ConfigFilename = "config.yml"
@@ -562,3 +583,17 @@ func LogPath() (string, error) {
 
 	return stateFilePath("development.log")
 }
+
+func findHomeConfigFile(filename string) (string, error) {
+	home, err := os.UserHomeDir()
+	if err != nil {
+		return "", err
+	}
+
+	path := filepath.Join(home, ".config", "lazygit", filename)
+	if _, err = os.Stat(path); err != nil {
+		return "", err
+	}
+
+	return path, nil
+}

pkg/config/xdg.go

@@ -0,0 +1,5 @@
+//go:build !darwin
+
+package config
+
+const overrideXdgConfigHome = false

pkg/config/xdg_darwin.go

@@ -0,0 +1,5 @@
+//go:build darwin
+
+package config
+
+const overrideXdgConfigHome = true