gpu: add TODOs regarding nullability

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

gpu/src/Buffer.zig

@@ -3,6 +3,7 @@ const std = @import("std");
 pub const Buffer = enum(usize) {
     _,
 
+    // TODO: verify there is a use case for nullable value of this type.
     pub const none: Buffer = @intToEnum(Buffer, 0);
 
     pub const BindingType = enum(u32) {

gpu/src/Device.zig

@@ -1,6 +1,7 @@
 pub const Device = enum(usize) {
     _,
 
+    // TODO: verify there is a use case for nullable value of this type.
     pub const none: Device = @intToEnum(Device, 0);
 
     pub const LostReason = enum(u32) {

gpu/src/Instance.zig

@@ -1,5 +1,6 @@
 pub const Instance = enum(usize) {
     _,
 
+    // TODO: verify there is a use case for nullable value of this type.
     pub const none: Instance = @intToEnum(Instance, 0);
 };

gpu/src/Queue.zig

@@ -1,6 +1,7 @@
 pub const Queue = enum(usize) {
     _,
 
+    // 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) {

gpu/src/Sampler.zig

@@ -1,6 +1,7 @@
 pub const Sampler = enum(usize) {
     _,
 
+    // TODO: verify there is a use case for nullable value of this type.
     pub const none: Sampler = @intToEnum(Sampler, 0);
 
     pub const AddressMode = enum(u32) {

gpu/src/Surface.zig

@@ -1,5 +1,6 @@
 pub const Surface = enum(usize) {
     _,
 
+    // TODO: verify there is a use case for nullable value of this type.
     pub const none: Surface = @intToEnum(Surface, 0);
 };

gpu/src/Texture.zig

@@ -3,6 +3,7 @@ const std = @import("std");
 pub const Texture = enum(usize) {
     _,
 
+    // TODO: verify there is a use case for nullable value of this type.
     pub const none: Texture = @intToEnum(Texture, 0);
 
     pub const Aspect = enum(u32) {

gpu/src/adapter.zig

@@ -4,6 +4,7 @@ const ChainedStructOut = @import("types.zig").ChainedStructOut;
 pub const Adapter = enum(usize) {
     _,
 
+    // TODO: verify there is a use case for nullable value of this type.
     pub const none: Adapter = @intToEnum(Adapter, 0);
 
     pub const Type = enum(u32) {

gpu/src/bind_group.zig

@@ -1,5 +1,6 @@
 pub const BindGroup = enum(usize) {
     _,
 
+    // TODO: verify there is a use case for nullable value of this type.
     pub const none: BindGroup = @intToEnum(BindGroup, 0);
 };

gpu/src/bind_group_layout.zig

@@ -1,5 +1,6 @@
 pub const BindGroupLayout = enum(usize) {
     _,
 
+    // TODO: verify there is a use case for nullable value of this type.
     pub const none: BindGroupLayout = @intToEnum(BindGroupLayout, 0);
 };

gpu/src/command_buffer.zig

@@ -1,5 +1,6 @@
 pub const CommandBuffer = enum(usize) {
     _,
 
+    // TODO: verify there is a use case for nullable value of this type.
     pub const none: CommandBuffer = @intToEnum(CommandBuffer, 0);
 };

gpu/src/command_encoder.zig

@@ -1,5 +1,6 @@
 pub const CommandEncoder = enum(usize) {
     _,
 
+    // TODO: verify there is a use case for nullable value of this type.
     pub const none: CommandEncoder = @intToEnum(CommandEncoder, 0);
 };

gpu/src/compute_pass_encoder.zig

@@ -1,5 +1,6 @@
 pub const ComputePassEncoder = enum(usize) {
     _,
 
+    // TODO: verify there is a use case for nullable value of this type.
     pub const none: ComputePassEncoder = @intToEnum(ComputePassEncoder, 0);
 };

gpu/src/compute_pipeline.zig

@@ -1,5 +1,6 @@
 pub const ComputePipeline = enum(usize) {
     _,
 
+    // TODO: verify there is a use case for nullable value of this type.
     pub const none: ComputePipeline = @intToEnum(ComputePipeline, 0);
 };

gpu/src/external_texture.zig

@@ -1,5 +1,6 @@
 pub const ExternalTexture = enum(usize) {
     _,
 
+    // TODO: verify there is a use case for nullable value of this type.
     pub const none: ExternalTexture = @intToEnum(ExternalTexture, 0);
 };

gpu/src/pipeline_layout.zig

@@ -1,5 +1,6 @@
 pub const PipelineLayout = enum(usize) {
     _,
 
+    // TODO: verify there is a use case for nullable value of this type.
     pub const none: PipelineLayout = @intToEnum(PipelineLayout, 0);
 };

gpu/src/query_set.zig

@@ -1,5 +1,6 @@
 pub const QuerySet = enum(usize) {
     _,
 
+    // TODO: verify there is a use case for nullable value of this type.
     pub const none: QuerySet = @intToEnum(QuerySet, 0);
 };

gpu/src/render_bundle.zig

@@ -1,5 +1,6 @@
 pub const RenderBundle = enum(usize) {
     _,
 
+    // TODO: verify there is a use case for nullable value of this type.
     pub const none: RenderBundle = @intToEnum(RenderBundle, 0);
 };

gpu/src/render_bundle_encoder.zig

@@ -1,5 +1,6 @@
 pub const RenderBundleEncoder = enum(usize) {
     _,
 
+    // TODO: verify there is a use case for nullable value of this type.
     pub const none: RenderBundleEncoder = @intToEnum(RenderBundleEncoder, 0);
 };

gpu/src/render_pass_encoder.zig

@@ -1,5 +1,6 @@
 pub const RenderPassEncoder = enum(usize) {
     _,
 
+    // TODO: verify there is a use case for nullable value of this type.
     pub const none: RenderPassEncoder = @intToEnum(RenderPassEncoder, 0);
 };

gpu/src/render_pipeline.zig

@@ -1,5 +1,6 @@
 pub const RenderPipeline = enum(usize) {
     _,
 
+    // TODO: verify there is a use case for nullable value of this type.
     pub const none: RenderPipeline = @intToEnum(RenderPipeline, 0);
 };

gpu/src/shader_module.zig

@@ -1,5 +1,6 @@
 pub const ShaderModule = enum(usize) {
     _,
 
+    // TODO: verify there is a use case for nullable value of this type.
     pub const none: ShaderModule = @intToEnum(ShaderModule, 0);
 };

gpu/src/swap_chain.zig

@@ -1,5 +1,6 @@
 pub const SwapChain = enum(usize) {
     _,
 
+    // TODO: verify there is a use case for nullable value of this type.
     pub const none: SwapChain = @intToEnum(SwapChain, 0);
 };

gpu/src/texture_view.zig

@@ -1,6 +1,7 @@
 pub const TextureView = enum(usize) {
     _,
 
+    // TODO: verify there is a use case for nullable value of this type.
     pub const none: TextureView = @intToEnum(TextureView, 0);
 
     pub const Dimension = enum(u32) {