regression: XlibSurfaceCreateInfoKHR stores a `Window` rather than `*Window`

[andrewrk]

after upgrading:

-            .url = "git+https://github.com/Snektron/vulkan-zig.git#06dae6c9201863837a92064e2e7814aa71064067",
-            .hash = "1220edeb3fc7dfc40e6fde705a108edce0a3cc76d165a7c9919d1fb037eccec43372",
+            .url = "git+https://github.com/Snektron/vulkan-zig.git#42e7a8409b8150e1cbd57a8ff8cec219114bac74",
+            .hash = "vulkan-0.0.0-r7Ytx2dUAwDhoUvuIqliqPUbyDZZi0bl_CQIwspUpHs_",

this error occurred:

.zig-cache/o/e2e0f6bfe6b8da13ec6138c94e67b2b5/vk.zig:2054:13: error: extern structs cannot contain fields of type 'WaylandWindow'
    window: Window,
            ^~~~~~
.zig-cache/o/e2e0f6bfe6b8da13ec6138c94e67b2b5/vk.zig:2054:13: note: only extern structs and ABI sized packed structs are extern compatible
src/WaylandWindow.zig:1:1: note: struct declared here
const WaylandWindow = @This();
^~~~~

in my root source file I have:

pub const Window = switch (config.window_lib) {
    .x11 => @import("XcbWindow.zig"),
    .wayland => @import("WaylandWindow.zig"),
};

in vk.zig:2054:

pub const XlibSurfaceCreateInfoKHR = extern struct {
    s_type: StructureType = .xlib_surface_create_info_khr,
    p_next: ?*const anyopaque = null,
    flags: XlibSurfaceCreateFlagsKHR = .{},
    dpy: *Display,
    window: Window,
};

Looks like that should be

-    window: Window,
+    window: *Window,

?

[andrewrk]

I suppose I can put the * on the application side. I'll leave this open for you to decide if that's how you intend it to be. It's a little awkward since I have to do this:

pub const MyWindow = switch (config.window_lib) {
    .x11 => @import("XcbWindow.zig"),
    .wayland => @import("WaylandWindow.zig"),
};
/// For vulkan
pub const Window = *MyWindow;

and then reference MyWindow everywhere.

[Snektron]

Are you sure that this problem is caused by Vulkan-zig? Both versions that you mention have the same definition, with the Window directly a member of that. Judging from the Vulkan specification for VkXlibSurfaceCreateinfoKHR that looks to be correct.

From this sketchy code browser I found that Window should just be typedefed to an XID, and I can see that the Window type is used as non-opaque type in various places over Xlib.h. Perhaps your Zig definition of Window is not correct?

[andrewrk]

I thought that was basically just a type-safe *anyopaque?

I mean if we look at the definition:

pub const Window = if (@hasDecl(root, "Window")) root.Window else c_ulong;

that's just a userdata / context type.

[Snektron]

See the X11 headers that I linked, the Window type itself is a non-opaque type.

[andrewrk]

OK I dug around more and I think what happened is that I got confused because I created Window in my root source file not knowing that it was going to be noticed by vk.zig. It's a name collision. I did that as part of adding Wayland support, in which case there is no compile error so I didn't notice. But when going back to X11, months later, while updating dependencies, I incorrectly assumed that I did that intentionally, and that caused me to misunderstand the situation.

Might be a good idea to namespace these root source file overrides...

[andrewrk]

https://codeberg.org/andrewrk/daw/commit/32b53414cbdc5271a6986b62f879ed06054eb677

[Snektron]

Yes, namespacing those overrides is a good idea.

[andrewrk]

Title and original description of the issue are wrong; feel free to do as you please with this