macos: Make "Settings…" menu item open config file in Application Sup… (#2895)

…port

...unless ~/.config/ghostty/config already exists, then that is opened.
(Or whatever $XDG_CONFIG_HOME points to.)

If both files exists, ghostty reads first the one in
~/.config/ghostty/config and then the one in Application Support, and
merges the settings. In that case, the menu item opens the file at
~/.config.

Fixes #2890.

Author: mitchellh

src/config/edit.zig

@@ -1,12 +1,30 @@
 const std = @import("std");
+const builtin = @import("builtin");
 const Allocator = std.mem.Allocator;
 const internal_os = @import("../os/main.zig");
 
 /// Open the configuration in the OS default editor according to the default
 /// paths the main config file could be in.
 pub fn open(alloc_gpa: Allocator) !void {
     // default location
-    const config_path = try internal_os.xdg.config(alloc_gpa, .{ .subdir = "ghostty/config" });
+    const config_path = config_path: {
+        const xdg_config_path = try internal_os.xdg.config(alloc_gpa, .{ .subdir = "ghostty/config" });
+
+        if (comptime builtin.os.tag == .macos) macos: {
+            // On macOS, use the application support path if the XDG path doesn't exists.
+            if (std.fs.accessAbsolute(xdg_config_path, .{})) {
+                break :macos;
+            } else |err| switch (err) {
+                error.BadPathName, error.FileNotFound => {},
+                else => break :macos,
+            }
+
+            alloc_gpa.free(xdg_config_path);
+            break :config_path try internal_os.macos.appSupportDir(alloc_gpa, "config");
+        }
+
+        break :config_path xdg_config_path;
+    };
     defer alloc_gpa.free(config_path);
 
     // Create config directory recursively.