Test implicit packing of struct members.

reference/shaders-msl-no-opt/packing/struct-packing.comp

@@ -0,0 +1,27 @@
+#include <metal_stdlib>
+#include <simd/simd.h>
+
+using namespace metal;
+
+struct Foo
+{
+    packed_float3 a;
+};
+
+struct Bar
+{
+    packed_float3 a;
+};
+
+struct SSBOScalar
+{
+    Foo foo;
+    Bar bar;
+};
+
+kernel void main0(device SSBOScalar& buffer_scalar [[buffer(0)]])
+{
+    buffer_scalar.foo.a[0u] = 10.0;
+    buffer_scalar.bar.a[0u] = 20.0;
+}
+

shaders-msl-no-opt/packing/struct-packing.comp

@@ -0,0 +1,27 @@
+#version 450
+#extension GL_EXT_scalar_block_layout : require
+layout(local_size_x = 1) in;
+
+// Foo will be marked packed_float3 because offset of bar is just 12 bytes after foo.
+struct Foo
+{
+	vec3 a;
+};
+
+// Bar will be marked as packed due to alignment of the struct itself cannot work without packed.
+struct Bar
+{
+	vec3 a;
+};
+
+layout(scalar, set = 0, binding = 0) buffer SSBOScalar
+{
+	Foo foo;
+	Bar bar;
+} buffer_scalar;
+
+void main()
+{
+	buffer_scalar.foo.a.x = 10.0;
+	buffer_scalar.bar.a.x = 20.0;
+}