gpu: adopt new dawn.json policy for optionality of slice fields, default zero values

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

gpu/README.md

@@ -140,11 +140,10 @@ We make the following quality of life improvements.
 
 TODO: explain it
 
-### Nullability
+### Optionality & nullability
 
-* `label: ?[*:0]const u8` fields have a default `null` value added to them.
-* Where a struct has a slice `_count` field, with an optional pointer, if the `_count` field defaults to zero we also enforce the optional pointer defaults to `null`. Specifically we do this for:
-* `next_in_chain: *const ChainedStruct` fields, which enable optional implementation-specific extensions to the WebGPU API, default to `null`.
+* Optional values default to their zero value (either `null` or a struct constructor `.{}`) when specified as `optional` in `dawn.json`. This means things like `label`, `next_in_chain`, etc. do not need to be specified.
+* Fields representing a slice with a `_count` field are nullable pointers defaulting to null and 0 by default.
 
 ### Slice helpers
 

gpu/src/bind_group.zig

@@ -9,20 +9,19 @@ pub const BindGroup = opaque {
     pub const Entry = extern struct {
         next_in_chain: ?*const ChainedStruct = null,
         binding: u32,
-        buffer: ?*Buffer,
+        buffer: ?*Buffer = null,
         offset: u64 = 0,
         size: u64,
-        sampler: ?*Sampler,
-        texture_view: ?*TextureView,
+        sampler: ?*Sampler = null,
+        texture_view: ?*TextureView = null,
     };
 
     pub const Descriptor = extern struct {
         next_in_chain: ?*const ChainedStruct = null,
         label: ?[*:0]const u8 = null,
         layout: *BindGroupLayout,
-        entry_count: u32,
-        // TODO: file a bug on Dawn, this is not marked as nullable but in fact is.
-        entries: ?[*]const Entry,
+        entry_count: u32 = 0,
+        entries: ?[*]const Entry = null,
     };
 
     pub inline fn setLabel(bind_group: *BindGroup, label: [*:0]const u8) void {

gpu/src/bind_group_layout.zig

@@ -20,9 +20,8 @@ pub const BindGroupLayout = opaque {
     pub const Descriptor = extern struct {
         next_in_chain: ?*const ChainedStruct = null,
         label: ?[*:0]const u8 = null,
-        entry_count: u32,
-        // TODO: file a bug on Dawn, this is not marked as nullable but in fact is.
-        entries: ?[*]const Entry,
+        entry_count: u32 = 0,
+        entries: ?[*]const Entry = null,
     };
 
     pub inline fn setLabel(bind_group_layout: *BindGroupLayout, label: [*:0]const u8) void {

gpu/src/compute_pipeline.zig

@@ -8,7 +8,7 @@ pub const ComputePipeline = opaque {
     pub const Descriptor = extern struct {
         next_in_chain: ?*const ChainedStruct = null,
         label: ?[*:0]const u8 = null,
-        layout: ?*PipelineLayout,
+        layout: ?*PipelineLayout = null,
         compute: ProgrammableStageDescriptor,
     };
 

gpu/src/dawn.zig

@@ -17,9 +17,8 @@ pub const EncoderInternalUsageDescriptor = extern struct {
 /// TODO: Can be chained in gpu.Instance.Descriptor
 pub const InstanceDescriptor = extern struct {
     chain: ChainedStruct,
-    additional_runtime_search_paths_count: u32,
-    // TODO: file a bug on Dawn, this is not marked as nullable but in fact is.
-    additional_runtime_search_paths: ?[*]const u8,
+    additional_runtime_search_paths_count: u32 = 0,
+    additional_runtime_search_paths: ?[*]const u8 = null,
 };
 
 /// TODO: Can be chained in gpu.Texture.Descriptor

gpu/src/device.zig

@@ -45,9 +45,7 @@ pub const Device = opaque {
         label: ?[*:0]const u8 = null,
         required_features_count: u32 = 0,
         required_features: ?[*]const FeatureName = null,
-        required_limits: ?*const RequiredLimits,
-        // TODO: file issue on Dawn, dawn.json doesn't communicate that a zero value here is the
-        // acceptable default value due to internal nullability of Queue.Descriptor.
+        required_limits: ?*const RequiredLimits = null,
         default_queue: Queue.Descriptor = Queue.Descriptor{},
     };
 

gpu/src/external_texture.zig

@@ -18,10 +18,10 @@ pub const ExternalTexture = opaque {
         next_in_chain: ?*const ChainedStruct = null,
         label: ?[*:0]const u8 = null,
         plane0: *TextureView,
-        plane1: ?*TextureView,
+        plane1: ?*TextureView = null,
         do_yuv_to_rgb_conversion_only: bool = false,
         // TODO: dawn.json says length 12, does it mean array length?
-        yuv_to_rgb_conversion_matrix: ?[*]const f32,
+        yuv_to_rgb_conversion_matrix: ?[*]const f32 = null,
         // TODO: dawn.json says length 7, does it mean array length?
         src_transform_function_parameters: [*]const f32,
         // TODO: dawn.json says length 7, does it mean array length?

gpu/src/pipeline_layout.zig

@@ -6,9 +6,8 @@ pub const PipelineLayout = opaque {
     pub const Descriptor = extern struct {
         next_in_chain: ?*const ChainedStruct = null,
         label: ?[*:0]const u8 = null,
-        bind_group_layout_count: u32,
-        // TODO: file a bug on Dawn, this is not marked as nullable but in fact is.
-        bind_group_layouts: ?[*]const *BindGroupLayout,
+        bind_group_layout_count: u32 = 0,
+        bind_group_layouts: ?[*]const *BindGroupLayout = null,
     };
 
     pub inline fn setLabel(pipeline_layout: *PipelineLayout, label: [*:0]const u8) void {

gpu/src/query_set.zig

@@ -9,7 +9,6 @@ pub const QuerySet = opaque {
         label: ?[*:0]const u8 = null,
         type: QueryType,
         count: u32,
-        // TODO: file a bug on Dawn, this is not marked as nullable but in fact is.
         pipeline_statistics: ?[*]const PipelineStatisticName = null,
         pipeline_statistics_count: u32 = 0,
     };

gpu/src/render_bundle_encoder.zig

@@ -11,9 +11,8 @@ pub const RenderBundleEncoder = opaque {
     pub const Descriptor = extern struct {
         next_in_chain: ?*const ChainedStruct = null,
         label: ?[*:0]const u8 = null,
-        color_formats_count: u32,
-        // TODO: file a bug on Dawn, this is not marked as nullable but in fact is.
-        color_formats: ?[*]const Texture.Format,
+        color_formats_count: u32 = 0,
+        color_formats: ?[*]const Texture.Format = null,
         depth_stencil_format: Texture.Format = .undef,
         sample_count: u32 = 1,
         depth_read_only: bool = false,

gpu/src/render_pipeline.zig

@@ -12,12 +12,12 @@ pub const RenderPipeline = opaque {
     pub const Descriptor = extern struct {
         next_in_chain: ?*const ChainedStruct = null,
         label: ?[*:0]const u8 = null,
-        layout: ?*PipelineLayout,
+        layout: ?*PipelineLayout = null,
         vertex: VertexState,
-        primitive: PrimitiveState,
-        depth_stencil: ?*const DepthStencilState,
-        multisample: MultisampleState,
-        fragment: ?*const FragmentState,
+        primitive: PrimitiveState = .{},
+        depth_stencil: ?*const DepthStencilState = null,
+        multisample: MultisampleState = .{},
+        fragment: ?*const FragmentState = null,
     };
 
     pub inline fn getBindGroupLayout(render_pipeline: *RenderPipeline, group_index: u32) *BindGroupLayout {

gpu/src/texture.zig

@@ -183,8 +183,7 @@ pub const Texture = opaque {
         mip_level_count: u32 = 1,
         sample_count: u32 = 1,
         view_format_count: u32 = 0,
-        // TODO: file a bug on Dawn, this is not marked as nullable but in fact is.
-        view_formats: ?[*]const Format,
+        view_formats: ?[*]const Format = null,
     };
 
     pub inline fn createView(texture: *Texture, descriptor: ?*const TextureView.Descriptor) *TextureView {

gpu/src/types.zig

@@ -42,33 +42,27 @@ pub const RenderPassTimestampWrite = extern struct {
 };
 
 pub const RequestAdapterOptions = extern struct {
-    // TODO: file a bug on Dawn, this is not marked as nullable but in fact is.
     next_in_chain: ?*const ChainedStruct = null,
-    compatible_surface: ?*Surface,
+    compatible_surface: ?*Surface = null,
     power_preference: PowerPreference = .undef,
     force_fallback_adapter: bool = false,
 };
 
 pub const ComputePassDescriptor = extern struct {
-    // TODO: file a bug on Dawn, this is not marked as nullable but in fact is.
     next_in_chain: ?*const ChainedStruct = null,
     label: ?[*:0]const u8 = null,
     timestamp_write_count: u32 = 0,
-    // TODO: file a bug on Dawn, this is not marked as nullable but in fact is.
     timestamp_writes: ?[*]const ComputePassTimestampWrite = null,
 };
 
 pub const RenderPassDescriptor = extern struct {
-    // TODO: file a bug on Dawn, this is not marked as nullable but in fact is.
     next_in_chain: ?*const ChainedStruct = null,
     label: ?[*:0]const u8 = null,
-    color_attachment_count: u32,
-    // TODO: file a bug on Dawn, this is not marked as nullable but in fact is.
-    color_attachments: ?[*]const RenderPassColorAttachment,
-    depth_stencil_attachment: ?[*]const RenderPassDepthStencilAttachment,
+    color_attachment_count: u32 = 0,
+    color_attachments: ?[*]const RenderPassColorAttachment = null,
+    depth_stencil_attachment: ?[*]const RenderPassDepthStencilAttachment = null,
     occlusion_query_set: ?*QuerySet = null,
     timestamp_write_count: u32 = 0,
-    // TODO: file a bug on Dawn, this is not marked as nullable but in fact is.
     timestamp_writes: ?[*]const RenderPassTimestampWrite = null,
 };
 
@@ -500,7 +494,7 @@ pub const Origin3D = extern struct {
 
 pub const CompilationMessage = extern struct {
     next_in_chain: ?*const ChainedStruct = null,
-    message: ?[*:0]const u8,
+    message: ?[*:0]const u8 = null,
     type: CompilationMessageType,
     line_num: u64,
     line_pos: u64,
@@ -520,11 +514,11 @@ pub const CopyTextureForBrowserOptions = extern struct {
     needs_color_space_conversion: bool = false,
     src_alpha_mode: AlphaMode = .unpremultiplied,
     // TODO: dawn.json says length 7, does it mean array length?
-    src_transfer_function_parameters: ?*const f32,
+    src_transfer_function_parameters: ?*const f32 = null,
     // TODO: dawn.json says length 9, does it mean array length?
-    conversion_matrix: ?*const f32,
+    conversion_matrix: ?*const f32 = null,
     // TODO: dawn.json says length 7, does it mean array length?
-    dst_transfer_function_parameters: ?*const f32,
+    dst_transfer_function_parameters: ?*const f32 = null,
     dst_alpha_mode: AlphaMode = .unpremultiplied,
     internal_usage: bool = false,
 };
@@ -584,8 +578,7 @@ pub const BlendState = extern struct {
 pub const CompilationInfo = extern struct {
     next_in_chain: ?*const ChainedStruct = null,
     message_count: u32,
-    // TODO: file a bug on Dawn, this is not marked as nullable but in fact is.
-    messages: ?[*]const CompilationMessage,
+    messages: ?[*]const CompilationMessage = null,
 };
 
 pub const DepthStencilState = extern struct {
@@ -621,13 +614,12 @@ pub const ProgrammableStageDescriptor = extern struct {
     module: *ShaderModule,
     entry_point: [*:0]const u8,
     constant_count: u32 = 0,
-    // TODO: file a bug on Dawn, this is not marked as nullable but in fact is.
     constants: ?[*]const ConstantEntry = null,
 };
 
 pub const RenderPassColorAttachment = extern struct {
-    view: ?*TextureView,
-    resolve_target: ?*TextureView,
+    view: ?*TextureView = null,
+    resolve_target: ?*TextureView = null,
     load_op: LoadOp,
     store_op: StoreOp,
     /// deprecated
@@ -654,14 +646,13 @@ pub const VertexBufferLayout = extern struct {
     array_stride: u64,
     step_mode: VertexStepMode = .vertex,
     attribute_count: u32,
-    // TODO: file a bug on Dawn, this is not marked as nullable but in fact is.
-    attributes: ?[*]const VertexAttribute,
+    attributes: ?[*]const VertexAttribute = null,
 };
 
 pub const ColorTargetState = extern struct {
     next_in_chain: ?*const ChainedStruct = null,
     format: Texture.Format,
-    blend: ?*const BlendState,
+    blend: ?*const BlendState = null,
     write_mask: ColorWriteMaskFlags = ColorWriteMaskFlags.all,
 };
 
@@ -670,10 +661,8 @@ pub const VertexState = extern struct {
     module: *ShaderModule,
     entry_point: [*:0]const u8,
     constant_count: u32 = 0,
-    // TODO: file a bug on Dawn, this is not marked as nullable but in fact is.
     constants: ?[*]const ConstantEntry = null,
     buffer_count: u32 = 0,
-    // TODO: file a bug on Dawn, this is not marked as nullable but in fact is.
     buffers: ?[*]const VertexBufferLayout = null,
 };
 
@@ -682,11 +671,9 @@ pub const FragmentState = extern struct {
     module: *ShaderModule,
     entry_point: [*:0]const u8,
     constant_count: u32 = 0,
-    // TODO: file a bug on Dawn, this is not marked as nullable but in fact is.
     constants: ?[*]const ConstantEntry = null,
     target_count: u32,
-    // TODO: file a bug on Dawn, this is not marked as nullable but in fact is.
-    targets: ?[*]const ColorTargetState,
+    targets: ?[*]const ColorTargetState = null,
 };
 
 test "BackendType name" {