From 9f1775aa7c150cc8a069e9487e5c6b0e28b630cd Mon Sep 17 00:00:00 2001
From: Stephen Gutekanst <stephen@hexops.com>
Date: Fri, 18 Mar 2022 20:03:38 -0700
Subject: [PATCH] gpu: correct feature storage location

Signed-off-by: Stephen Gutekanst <stephen@hexops.com>
---
 gpu/src/Adapter.zig        |  1 +
 gpu/src/Device.zig         |  3 +++
 gpu/src/NativeInstance.zig | 22 ++++++++++++----------
 3 files changed, 16 insertions(+), 10 deletions(-)

diff --git a/gpu/src/Adapter.zig b/gpu/src/Adapter.zig
index bad044b6..ef54bfc8 100644
--- a/gpu/src/Adapter.zig
+++ b/gpu/src/Adapter.zig
@@ -27,6 +27,7 @@ const Adapter = @This();
 
 /// The features which can be used to create devices on this adapter.
 features: []Feature,
+_features: [std.enums.values(Feature).len]Feature = undefined,
 
 /// The best limits which can be used to create devices on this adapter.
 ///
diff --git a/gpu/src/Device.zig b/gpu/src/Device.zig
index ec98ee0d..cb0dc156 100644
--- a/gpu/src/Device.zig
+++ b/gpu/src/Device.zig
@@ -6,6 +6,8 @@
 //!
 //! https://gpuweb.github.io/gpuweb/#devices
 //! https://gpuweb.github.io/gpuweb/#gpuadapter
+const std = @import("std");
+
 const Feature = @import("enums.zig").Feature;
 const ErrorType = @import("enums.zig").ErrorType;
 const ErrorFilter = @import("enums.zig").ErrorFilter;
@@ -34,6 +36,7 @@ const Device = @This();
 
 /// The features supported by the device (i.e. the ones with which it was created).
 features: []Feature,
+_features: [std.enums.values(Feature).len]Feature = undefined,
 
 /// The limits supported by the device (which are exactly the ones with which it was created).
 limits: Limits,
diff --git a/gpu/src/NativeInstance.zig b/gpu/src/NativeInstance.zig
index 80bf8bd1..0e0aa89b 100644
--- a/gpu/src/NativeInstance.zig
+++ b/gpu/src/NativeInstance.zig
@@ -225,14 +225,11 @@ fn wrapAdapter(adapter: c.WGPUAdapter) Adapter {
         .backend_type = @intToEnum(Adapter.BackendType, c_props.backendType),
     };
 
-    var features: [std.enums.values(Feature).len]c.WGPUFeatureName = undefined;
-    const features_len = c.wgpuAdapterEnumerateFeatures(adapter.?, &features[0]);
-
     var supported_limits: c.WGPUSupportedLimits = undefined;
     if (!c.wgpuAdapterGetLimits(adapter.?, &supported_limits)) @panic("failed to get adapter limits (this is a bug in mach/gpu)");
 
-    return .{
-        .features = @bitCast([]Feature, features[0..features_len]),
+    var wrapped = Adapter{
+        .features = undefined,
         .limits = @bitCast(Limits, supported_limits.limits),
         .properties = properties,
 
@@ -242,6 +239,10 @@ fn wrapAdapter(adapter: c.WGPUAdapter) Adapter {
         .ptr = adapter.?,
         .vtable = &adapter_vtable,
     };
+
+    const features_len = c.wgpuAdapterEnumerateFeatures(adapter.?, @ptrCast(*c.WGPUFeatureName, &wrapped._features[0]));
+    wrapped.features = wrapped._features[0..features_len];
+    return wrapped;
 }
 
 const adapter_vtable = Adapter.VTable{
@@ -303,18 +304,19 @@ const adapter_vtable = Adapter.VTable{
 };
 
 fn wrapDevice(device: c.WGPUDevice) Device {
-    var features: [std.enums.values(Feature).len]c.WGPUFeatureName = undefined;
-    const features_len = c.wgpuDeviceEnumerateFeatures(device.?, &features[0]);
-
     var supported_limits: c.WGPUSupportedLimits = undefined;
     if (!c.wgpuDeviceGetLimits(device.?, &supported_limits)) @panic("failed to get device limits (this is a bug in mach/gpu)");
 
-    return .{
-        .features = @bitCast([]Feature, features[0..features_len]),
+    var wrapped = Device{
+        .features = undefined,
         .limits = @bitCast(Limits, supported_limits.limits),
         .ptr = device.?,
         .vtable = &device_vtable,
     };
+
+    const features_len = c.wgpuDeviceEnumerateFeatures(device.?, @ptrCast(*c.WGPUFeatureName, &wrapped._features[0]));
+    wrapped.features = wrapped._features[0..features_len];
+    return wrapped;
 }
 
 const device_vtable = Device.VTable{