gpu: improve compatibility with self-hosted compiler

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

gpu/src/buffer.zig

@@ -4,7 +4,10 @@ const MapModeFlags = @import("types.zig").MapModeFlags;
 const Impl = @import("interface.zig").Impl;
 
 pub const Buffer = opaque {
-    pub const MapCallback = fn (status: MapAsyncStatus, userdata: ?*anyopaque) callconv(.C) void;
+    pub const MapCallback = if (@import("builtin").zig_backend == .stage1)
+        fn (status: MapAsyncStatus, userdata: ?*anyopaque) callconv(.C) void
+    else
+        *const fn (status: MapAsyncStatus, userdata: ?*anyopaque) callconv(.C) void;
 
     pub const BindingType = enum(u32) {
         undef = 0x00000000,

gpu/src/callbacks.zig

@@ -10,48 +10,101 @@ const Adapter = @import("adapter.zig").Adapter;
 const ComputePipeline = @import("compute_pipeline.zig").ComputePipeline;
 const RenderPipeline = @import("render_pipeline.zig").RenderPipeline;
 
-pub const CompilationInfoCallback = fn (
-    status: CompilationInfoRequestStatus,
-    compilation_info: *const CompilationInfo,
-    userdata: ?*anyopaque,
-) callconv(.C) void;
+pub const CompilationInfoCallback = if (@import("builtin").zig_backend == .stage1)
+    fn (
+        status: CompilationInfoRequestStatus,
+        compilation_info: *const CompilationInfo,
+        userdata: ?*anyopaque,
+    ) callconv(.C) void
+else
+    *const fn (
+        status: CompilationInfoRequestStatus,
+        compilation_info: *const CompilationInfo,
+        userdata: ?*anyopaque,
+    ) callconv(.C) void;
 
-pub const ErrorCallback = fn (
-    typ: ErrorType,
-    message: [*:0]const u8,
-    userdata: ?*anyopaque,
-) callconv(.C) void;
+pub const ErrorCallback = if (@import("builtin").zig_backend == .stage1)
+    fn (
+        typ: ErrorType,
+        message: [*:0]const u8,
+        userdata: ?*anyopaque,
+    ) callconv(.C) void
+else
+    *const fn (
+        typ: ErrorType,
+        message: [*:0]const u8,
+        userdata: ?*anyopaque,
+    ) callconv(.C) void;
 
-pub const LoggingCallback = fn (
-    typ: LoggingType,
-    message: [*:0]const u8,
-    userdata: ?*anyopaque,
-) callconv(.C) void;
+pub const LoggingCallback = if (@import("builtin").zig_backend == .stage1)
+    fn (
+        typ: LoggingType,
+        message: [*:0]const u8,
+        userdata: ?*anyopaque,
+    ) callconv(.C) void
+else
+    *const fn (
+        typ: LoggingType,
+        message: [*:0]const u8,
+        userdata: ?*anyopaque,
+    ) callconv(.C) void;
 
-pub const RequestDeviceCallback = fn (
-    status: RequestDeviceStatus,
-    device: *Device,
-    message: ?[*:0]const u8,
-    userdata: ?*anyopaque,
-) callconv(.C) void;
+pub const RequestDeviceCallback = if (@import("builtin").zig_backend == .stage1)
+    fn (
+        status: RequestDeviceStatus,
+        device: *Device,
+        message: ?[*:0]const u8,
+        userdata: ?*anyopaque,
+    ) callconv(.C) void
+else
+    *const fn (
+        status: RequestDeviceStatus,
+        device: *Device,
+        message: ?[*:0]const u8,
+        userdata: ?*anyopaque,
+    ) callconv(.C) void;
 
-pub const RequestAdapterCallback = fn (
-    status: RequestAdapterStatus,
-    adapter: *Adapter,
-    message: ?[*:0]const u8,
-    userdata: ?*anyopaque,
-) callconv(.C) void;
+pub const RequestAdapterCallback = if (@import("builtin").zig_backend == .stage1)
+    fn (
+        status: RequestAdapterStatus,
+        adapter: *Adapter,
+        message: ?[*:0]const u8,
+        userdata: ?*anyopaque,
+    ) callconv(.C) void
+else
+    *const fn (
+        status: RequestAdapterStatus,
+        adapter: *Adapter,
+        message: ?[*:0]const u8,
+        userdata: ?*anyopaque,
+    ) callconv(.C) void;
 
-pub const CreateComputePipelineAsyncCallback = fn (
-    status: CreatePipelineAsyncStatus,
-    compute_pipeline: *ComputePipeline,
-    message: [*:0]const u8,
-    userdata: ?*anyopaque,
-) callconv(.C) void;
+pub const CreateComputePipelineAsyncCallback = if (@import("builtin").zig_backend == .stage1)
+    fn (
+        status: CreatePipelineAsyncStatus,
+        compute_pipeline: *ComputePipeline,
+        message: [*:0]const u8,
+        userdata: ?*anyopaque,
+    ) callconv(.C) void
+else
+    *const fn (
+        status: CreatePipelineAsyncStatus,
+        compute_pipeline: *ComputePipeline,
+        message: [*:0]const u8,
+        userdata: ?*anyopaque,
+    ) callconv(.C) void;
 
-pub const CreateRenderPipelineAsyncCallback = fn (
-    status: CreatePipelineAsyncStatus,
-    pipeline: *RenderPipeline,
-    message: [*:0]const u8,
-    userdata: ?*anyopaque,
-) callconv(.C) void;
+pub const CreateRenderPipelineAsyncCallback = if (@import("builtin").zig_backend == .stage1)
+    fn (
+        status: CreatePipelineAsyncStatus,
+        pipeline: *RenderPipeline,
+        message: [*:0]const u8,
+        userdata: ?*anyopaque,
+    ) callconv(.C) void
+else
+    *const fn (
+        status: CreatePipelineAsyncStatus,
+        pipeline: *RenderPipeline,
+        message: [*:0]const u8,
+        userdata: ?*anyopaque,
+    ) callconv(.C) void;

gpu/src/device.zig

@@ -31,11 +31,18 @@ const Impl = @import("interface.zig").Impl;
 const dawn = @import("dawn.zig");
 
 pub const Device = opaque {
-    pub const LostCallback = fn (
-        reason: LostReason,
-        message: [*:0]const u8,
-        userdata: ?*anyopaque,
-    ) callconv(.C) void;
+    pub const LostCallback = if (@import("builtin").zig_backend == .stage1)
+        fn (
+            reason: LostReason,
+            message: [*:0]const u8,
+            userdata: ?*anyopaque,
+        ) callconv(.C) void
+    else
+        *const fn (
+            reason: LostReason,
+            message: [*:0]const u8,
+            userdata: ?*anyopaque,
+        ) callconv(.C) void;
 
     pub const LostReason = enum(u32) {
         undef = 0x00000000,

gpu/src/queue.zig

@@ -9,10 +9,16 @@ const CopyTextureForBrowserOptions = @import("types.zig").CopyTextureForBrowserO
 const Impl = @import("interface.zig").Impl;
 
 pub const Queue = opaque {
-    pub const WorkDoneCallback = fn (
-        status: WorkDoneStatus,
-        userdata: ?*anyopaque,
-    ) callconv(.C) void;
+    pub const WorkDoneCallback = if (@import("builtin").zig_backend == .stage1)
+        fn (
+            status: WorkDoneStatus,
+            userdata: ?*anyopaque,
+        ) callconv(.C) void
+    else
+        *const fn (
+            status: WorkDoneStatus,
+            userdata: ?*anyopaque,
+        ) callconv(.C) void;
 
     pub const WorkDoneStatus = enum(u32) {
         success = 0x00000000,

gpu/src/types.zig

@@ -17,7 +17,10 @@ pub const whole_size = 0xffffffffffffffff;
 
 /// Generic function pointer type, used for returning API function pointers. Must be
 /// cast to the right `fn (...) callconv(.C) T` type before use.
-pub const Proc = fn () callconv(.C) void;
+pub const Proc = if (@import("builtin").zig_backend == .stage1)
+    fn () callconv(.C) void
+else
+    *const fn () callconv(.C) void;
 
 pub const ComputePassTimestampWrite = extern struct {
     query_set: *QuerySet,