gpu: update TODOs, give all chain fields default values

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

gpu/src/dawn.zig

@@ -4,25 +4,25 @@ pub const Interface = @import("dawn_impl.zig").Interface;
 
 /// TODO: Can be chained in gpu.Device.Descriptor
 pub const CacheDeviceDescriptor = extern struct {
-    chain: ChainedStruct,
+    chain: ChainedStruct = .{ .next = null, .s_type = .dawn_cache_device_descriptor },
     isolation_key: [*:0]const u8 = "",
 };
 
 /// TODO: Can be chained in gpu.CommandEncoder.Descriptor
 pub const EncoderInternalUsageDescriptor = extern struct {
-    chain: ChainedStruct,
+    chain: ChainedStruct = .{ .next = null, .s_type = .dawn_encoder_internal_usage_descriptor },
     use_internal_usages: bool = false,
 };
 
 /// TODO: Can be chained in gpu.Instance.Descriptor
 pub const InstanceDescriptor = extern struct {
-    chain: ChainedStruct,
+    chain: ChainedStruct = .{ .next = null, .s_type = .dawn_instance_descriptor },
     additional_runtime_search_paths_count: u32 = 0,
     additional_runtime_search_paths: ?[*]const u8 = null,
 
     /// Provides a slightly friendlier Zig API to initialize this structure.
     pub inline fn init(v: struct {
-        chain: ChainedStruct,
+        chain: ChainedStruct = .{ .next = null, .s_type = .dawn_instance_descriptor },
         additional_runtime_search_paths: ?[]const u8 = null,
     }) InstanceDescriptor {
         return .{
@@ -35,13 +35,13 @@ pub const InstanceDescriptor = extern struct {
 
 /// TODO: Can be chained in gpu.Texture.Descriptor
 pub const TextureInternalUsageDescriptor = extern struct {
-    chain: ChainedStruct,
+    chain: ChainedStruct = .{ .next = null, .s_type = .dawn_texture_internal_usage_descriptor },
     internal_usage: Texture.UsageFlags = Texture.UsageFlags.none,
 };
 
 /// TODO: Can be chained in gpu.Device.Descriptor
 pub const TogglesDeviceDescriptor = extern struct {
-    chain: ChainedStruct,
+    chain: ChainedStruct = .{ .next = null, .s_type = .dawn_toggles_device_descriptor },
     force_enabled_toggles_count: u32 = 0,
     force_enabled_toggles: ?[*]const u8 = null,
     force_disabled_toggles_count: u32 = 0,
@@ -49,7 +49,7 @@ pub const TogglesDeviceDescriptor = extern struct {
 
     /// Provides a slightly friendlier Zig API to initialize this structure.
     pub inline fn init(v: struct {
-        chain: ChainedStruct,
+        chain: ChainedStruct = .{ .next = null, .s_type = .dawn_toggles_device_descriptor },
         force_enabled_toggles: ?[]const u8 = null,
         force_disabled_toggles: ?[]const u8 = null,
     }) TogglesDeviceDescriptor {

gpu/src/dawn_impl.zig

@@ -108,7 +108,7 @@ pub const Interface = struct {
         procs.bufferDestroy.?(@ptrCast(c.WGPUBuffer, buffer));
     }
 
-    // TODO: file a bug on Dawn docstrings, this returns null but is not documented as such.
+    // TODO: dawn: return value not marked as nullable in dawn.json but in fact is.
     pub inline fn bufferGetConstMappedRange(buffer: *gpu.Buffer, offset: usize, size: usize) ?*const anyopaque {
         return procs.bufferGetConstMappedRange.?(
             @ptrCast(c.WGPUBuffer, buffer),
@@ -117,7 +117,7 @@ pub const Interface = struct {
         );
     }
 
-    // TODO: file a bug on Dawn docstrings, this returns null but is not documented as such.
+    // TODO: dawn: return value not marked as nullable in dawn.json but in fact is.
     pub inline fn bufferGetMappedRange(buffer: *gpu.Buffer, offset: usize, size: usize) ?*anyopaque {
         return procs.bufferGetMappedRange.?(
             @ptrCast(c.WGPUBuffer, buffer),

gpu/src/external_texture.zig

@@ -5,13 +5,13 @@ const Impl = @import("interface.zig").Impl;
 pub const ExternalTexture = opaque {
     /// TODO: Can be chained in gpu.BindGroup.Entry
     pub const BindingEntry = extern struct {
-        chain: ChainedStruct,
+        chain: ChainedStruct = .{ .next = null, .s_type = .external_texture_binding_entry },
         external_texture: *ExternalTexture,
     };
 
     /// TODO: Can be chained in gpu.BindGroupLayout.Entry
     pub const BindingLayout = extern struct {
-        chain: ChainedStruct,
+        chain: ChainedStruct = .{ .next = null, .s_type = .external_texture_binding_layout },
     };
 
     pub const Descriptor = extern struct {

gpu/src/interface.zig

@@ -333,8 +333,6 @@ pub fn Export(comptime T: type) type {
             return T.bufferGetUsage(buffer);
         }
 
-        // TODO: Zig cannot currently export a packed struct gpu.MapModeFlags, so we use a u32 for
-        // now.
         // WGPU_EXPORT void wgpuBufferMapAsync(WGPUBuffer buffer, WGPUMapModeFlags mode, size_t offset, size_t size, WGPUBufferMapCallback callback, void * userdata);
         export fn wgpuBufferMapAsync(buffer: *gpu.Buffer, mode: u32, offset: usize, size: usize, callback: gpu.Buffer.MapCallback, userdata: ?*anyopaque) void {
             T.bufferMapAsync(buffer, @bitCast(gpu.MapModeFlags, mode), offset, size, callback, userdata);
@@ -1115,8 +1113,6 @@ pub fn Export(comptime T: type) type {
             T.surfaceRelease(surface);
         }
 
-        // TODO: Zig cannot currently export a packed struct gpu.Texture.UsageFlags, so we use a u32
-        // for now.
         // WGPU_EXPORT void wgpuSwapChainConfigure(WGPUSwapChain swapChain, WGPUTextureFormat format, WGPUTextureUsageFlags allowedUsage, uint32_t width, uint32_t height);
         export fn wgpuSwapChainConfigure(swap_chain: *gpu.SwapChain, format: gpu.Texture.Format, allowed_usage: u32, width: u32, height: u32) void {
             T.swapChainConfigure(swap_chain, format, @bitCast(gpu.Texture.UsageFlags, allowed_usage), width, height);
@@ -1322,7 +1318,7 @@ pub const StubInterface = Interface(struct {
         unreachable;
     }
 
-    // TODO: file a bug on Dawn docstrings, this returns null but is not documented as such.
+    // TODO: dawn: return value not marked as nullable in dawn.json but in fact is.
     pub inline fn bufferGetConstMappedRange(buffer: *gpu.Buffer, offset: usize, size: usize) ?*const anyopaque {
         _ = buffer;
         _ = offset;
@@ -1330,7 +1326,7 @@ pub const StubInterface = Interface(struct {
         unreachable;
     }
 
-    // TODO: file a bug on Dawn docstrings, this returns null but is not documented as such.
+    // TODO: dawn: return value not marked as nullable in dawn.json but in fact is.
     pub inline fn bufferGetMappedRange(buffer: *gpu.Buffer, offset: usize, size: usize) ?*anyopaque {
         _ = buffer;
         _ = offset;

gpu/src/queue.zig

@@ -30,7 +30,7 @@ pub const Queue = opaque {
         Impl.queueCopyTextureForBrowser(queue, source, destination, copy_size, options);
     }
 
-    // TODO: is it not possible to *unset* this callback? Presumably it should be nullable?
+    // TODO: presumably callback should be nullable for unsetting
     pub inline fn onSubmittedWorkDone(
         queue: *Queue,
         signal_value: u64,

gpu/src/types.zig

@@ -466,13 +466,13 @@ pub const ShaderStageFlags = packed struct {
 };
 
 pub const ChainedStruct = extern struct {
-    // TODO: file a bug on Dawn, this is not marked as nullable but in fact is.
+    // TODO: dawn: not marked as nullable in dawn.json but in fact is.
     next: ?*const ChainedStruct = null,
     s_type: SType,
 };
 
 pub const ChainedStructOut = extern struct {
-    // TODO: file a bug on Dawn, this is not marked as nullable but in fact is.
+    // TODO: dawn: not marked as nullable in dawn.json but in fact is.
     next: ?*ChainedStructOut = null,
     s_type: SType,
 };
@@ -573,7 +573,7 @@ pub const MultisampleState = extern struct {
 
 /// TODO: Can be chained in gpu.PrimitiveState
 pub const PrimitiveDepthClipControl = extern struct {
-    chain: ChainedStruct,
+    chain: ChainedStruct = .{ .next = null, .s_type = .primitive_depth_clip_control },
     unclipped_depth: bool = false,
 };
 
@@ -587,7 +587,7 @@ pub const PrimitiveState = extern struct {
 
 /// TODO: Can be chained in gpu.RenderPassDescriptor
 pub const RenderPassDescriptorMaxDrawCount = extern struct {
-    chain: ChainedStruct,
+    chain: ChainedStruct = .{ .next = null, .s_type = .render_pass_descriptor_max_draw_count },
     max_draw_count: u64 = 50000000,
 };