gpu: improve compatibility with self-hosted compiler

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

gpu/examples/sample_utils.zig

@@ -236,18 +236,31 @@ pub const AutoReleasePool = if (!@import("builtin").target.isDarwin()) opaque {
 pub fn msgSend(obj: anytype, sel_name: [:0]const u8, args: anytype, comptime ReturnType: type) ReturnType {
     const args_meta = @typeInfo(@TypeOf(args)).Struct.fields;
 
-    const FnType = switch (args_meta.len) {
+    const FnType = if (@import("builtin").zig_backend == .stage1)
+        switch (args_meta.len) {
             0 => fn (@TypeOf(obj), objc.SEL) callconv(.C) ReturnType,
             1 => fn (@TypeOf(obj), objc.SEL, args_meta[0].field_type) callconv(.C) ReturnType,
             2 => fn (@TypeOf(obj), objc.SEL, args_meta[0].field_type, args_meta[1].field_type) callconv(.C) ReturnType,
             3 => fn (@TypeOf(obj), objc.SEL, args_meta[0].field_type, args_meta[1].field_type, args_meta[2].field_type) callconv(.C) ReturnType,
             4 => fn (@TypeOf(obj), objc.SEL, args_meta[0].field_type, args_meta[1].field_type, args_meta[2].field_type, args_meta[3].field_type) callconv(.C) ReturnType,
             else => @compileError("Unsupported number of args"),
+        }
+    else
+        switch (args_meta.len) {
+            0 => *const fn (@TypeOf(obj), objc.SEL) callconv(.C) ReturnType,
+            1 => *const fn (@TypeOf(obj), objc.SEL, args_meta[0].field_type) callconv(.C) ReturnType,
+            2 => *const fn (@TypeOf(obj), objc.SEL, args_meta[0].field_type, args_meta[1].field_type) callconv(.C) ReturnType,
+            3 => *const fn (@TypeOf(obj), objc.SEL, args_meta[0].field_type, args_meta[1].field_type, args_meta[2].field_type) callconv(.C) ReturnType,
+            4 => *const fn (@TypeOf(obj), objc.SEL, args_meta[0].field_type, args_meta[1].field_type, args_meta[2].field_type, args_meta[3].field_type) callconv(.C) ReturnType,
+            else => @compileError("Unsupported number of args"),
         };
 
     // NOTE: func is a var because making it const causes a compile error which I believe is a compiler bug
-    var func = @ptrCast(FnType, objc.objc_msgSend);
+    var func = if (@import("builtin").zig_backend == .stage1)
-    const sel = objc.sel_getUid(sel_name);
+        @ptrCast(FnType, objc.objc_msgSend)
+    else
+        @ptrCast(FnType, &objc.objc_msgSend);
+    const sel = objc.sel_getUid(@ptrCast([*c]const u8, sel_name));
 
     return @call(.{}, func, .{ obj, sel } ++ args);
 }

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

gpu/src/device.zig

@@ -31,7 +31,14 @@ const Impl = @import("interface.zig").Impl;
 const dawn = @import("dawn.zig");
 
 pub const Device = opaque {
-    pub const LostCallback = fn (
+    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,

gpu/src/queue.zig

@@ -9,7 +9,13 @@ const CopyTextureForBrowserOptions = @import("types.zig").CopyTextureForBrowserO
 const Impl = @import("interface.zig").Impl;
 
 pub const Queue = opaque {
-    pub const WorkDoneCallback = fn (
+    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;

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,