builtin: make load_builtin macro $ty optional

Author: Firestar99

crates/spirv-std/src/builtin.rs

@@ -7,11 +7,13 @@
 //!   * [GLSL reference source code](https://github.com/KhronosGroup/OpenGL-Refpages/tree/main/gl4)
 //!   * [GLSL extensions](https://github.com/KhronosGroup/GLSL/tree/main/extensions)
 
+/// Load a BuiltIn by name with optional type
 #[cfg(target_arch = "spirv")]
+#[macro_export]
 macro_rules! load_builtin {
-    ($ty:ty, $name:ident) => {
+    ($name:ident $(: $ty:ty)?) => {
         unsafe {
-            let mut result = <$ty>::default();
+            let mut result $(: $ty)? = Default::default();
             core::arch::asm! {
                 "%builtin = OpVariable typeof{result_ref} Input",
                 concat!("OpDecorate %builtin BuiltIn ", stringify!($name)),
@@ -39,7 +41,7 @@ pub mod compute {
     #[inline]
     #[gpu_only]
     pub fn local_invocation_id() -> UVec3 {
-        load_builtin!(UVec3, LocalInvocationId)
+        load_builtin!(LocalInvocationId)
     }
 
     /// The current invocation’s local invocation index,
@@ -51,7 +53,7 @@ pub mod compute {
     #[inline]
     #[gpu_only]
     pub fn local_invocation_index() -> u32 {
-        load_builtin!(u32, LocalInvocationIndex)
+        load_builtin!(LocalInvocationIndex)
     }
 
     // Global builtins, for this invocation's position in the compute grid.
@@ -65,7 +67,7 @@ pub mod compute {
     #[inline]
     #[gpu_only]
     pub fn global_invocation_id() -> UVec3 {
-        load_builtin!(UVec3, GlobalInvocationId)
+        load_builtin!(GlobalInvocationId)
     }
 
     // Subgroup builtins
@@ -78,7 +80,7 @@ pub mod compute {
     #[inline]
     #[gpu_only]
     pub fn num_subgroups() -> u32 {
-        load_builtin!(u32, NumSubgroups)
+        load_builtin!(NumSubgroups)
     }
 
     /// The subgroup ID of current invocation’s subgroup within the workgroup.
@@ -89,7 +91,7 @@ pub mod compute {
     #[inline]
     #[gpu_only]
     pub fn subgroup_id() -> u32 {
-        load_builtin!(u32, SubgroupId)
+        load_builtin!(SubgroupId)
     }
 
     /// This invocation's ID within its subgroup.
@@ -100,7 +102,7 @@ pub mod compute {
     #[inline]
     #[gpu_only]
     pub fn subgroup_invocation_id() -> u32 {
-        load_builtin!(u32, SubgroupLocalInvocationId)
+        load_builtin!(SubgroupLocalInvocationId)
     }
 
     ///  The subgroup size of current invocation’s subgroup.
@@ -111,7 +113,7 @@ pub mod compute {
     #[inline]
     #[gpu_only]
     pub fn subgroup_size() -> u32 {
-        load_builtin!(u32, SubgroupSize)
+        load_builtin!(SubgroupSize)
     }
 
     // Workgroup builtins
@@ -124,7 +126,7 @@ pub mod compute {
     #[inline]
     #[gpu_only]
     pub fn num_workgroups() -> UVec3 {
-        load_builtin!(UVec3, NumWorkgroups)
+        load_builtin!(NumWorkgroups)
     }
 
     /// The current invocation’s workgroup ID,
@@ -136,6 +138,6 @@ pub mod compute {
     #[inline]
     #[gpu_only]
     pub fn workgroup_id() -> UVec3 {
-        load_builtin!(UVec3, WorkgroupId)
+        load_builtin!(WorkgroupId)
     }
 }