gpu: convert Queue from enum(usize) to *opaque

Signed-off-by: Stephen Gutekanst <stephen@hexops.com>

gpu/src/device.zig

@@ -2,6 +2,7 @@ const ChainedStruct = @import("types.zig").ChainedStruct;
 const FeatureName = @import("types.zig").FeatureName;
 const RequiredLimits = @import("types.zig").RequiredLimits;
 const Queue = @import("queue.zig").Queue;
+const QueueDescriptor = @import("queue.zig").QueueDescriptor;
 
 pub const Device = *opaque {};
 
@@ -16,5 +17,5 @@ pub const DeviceDescriptor = extern struct {
     required_features_count: u32,
     required_features: [*]const FeatureName,
     required_limits: ?*const RequiredLimits = null, // nullable
-    default_queue: Queue.Descriptor,
+    default_queue: QueueDescriptor,
 };

gpu/src/queue.zig

@@ -1,20 +1,15 @@
 const ChainedStruct = @import("types.zig").ChainedStruct;
 
-pub const Queue = enum(usize) {
-    _,
+pub const Queue = *opaque {};
 
-    // TODO: verify there is a use case for nullable value of this type.
-    pub const none: Queue = @intToEnum(Queue, 0);
-
-    pub const WorkDoneStatus = enum(u32) {
-        success = 0x00000000,
-        err = 0x00000001,
-        unknown = 0x00000002,
-        device_lost = 0x00000003,
-    };
-
-    pub const Descriptor = extern struct {
-        next_in_chain: *const ChainedStruct,
-        label: ?[*:0]const u8 = null,
-    };
+pub const QueueWorkDoneStatus = enum(u32) {
+    success = 0x00000000,
+    err = 0x00000001,
+    unknown = 0x00000002,
+    device_lost = 0x00000003,
+};
+
+pub const QueueDescriptor = extern struct {
+    next_in_chain: *const ChainedStruct,
+    label: ?[*:0]const u8 = null,
 };