Fix unsound MTLPackedFloat3

crates/header-translator/src/stmt.rs

@@ -314,6 +314,7 @@ fn parse_struct(entity: &Entity<'_>, context: &Context<'_>) -> (bool, Vec<(Strin
         EntityKind::ObjCBoxable => {
             boxable = true;
         }
+        EntityKind::UnionDecl => error!("can't handle unions in structs yet"),
         _ => warn!("unknown"),
     });
 
@@ -782,17 +783,17 @@ impl Stmt {
                 }]
             }
             EntityKind::UnionDecl => {
-                // debug!(
-                //     "union: {:?}, {:?}, {:#?}, {:#?}",
-                //     entity.get_display_name(),
-                //     entity.get_name(),
-                //     entity.has_attributes(),
-                //     entity.get_children(),
-                // );
+                error!(
+                    name = ?entity.get_name(),
+                    has_attributes = ?entity.has_attributes(),
+                    children = ?entity.get_children(),
+                    "union",
+                );
                 vec![]
             }
             _ => {
-                panic!("Unknown: {entity:?}")
+                error!("unknown");
+                vec![]
             }
         }
     }

crates/header-translator/translation-config.toml

@@ -777,3 +777,9 @@ newRenderPipelineStateWithDescriptor_options_reflection_error = { skipped = true
 newComputePipelineStateWithFunction_options_reflection_error = { skipped = true }
 newComputePipelineStateWithDescriptor_options_reflection_error = { skipped = true }
 newRenderPipelineStateWithTileDescriptor_options_reflection_error = { skipped = true }
+
+# Uses unions internally
+[struct.MTLPackedFloat3]
+skipped = true
+[fn.MTLPackedFloat3Make]
+skipped = true

crates/icrate/src/Metal/fixes.rs

@@ -1,6 +1,7 @@
-use std::os::raw::c_double;
+use core::fmt;
 
-use objc2::ffi::NSUInteger;
+use crate::common::*;
+use objc2::encode::Encoding;
 
 pub type CFTimeInterval = c_double;
 
@@ -12,3 +13,56 @@ pub const MTLResourceStorageModeMask: NSUInteger = 0xf << MTLResourceStorageMode
 
 pub const MTLResourceHazardTrackingModeShift: NSUInteger = 8;
 pub const MTLResourceHazardTrackingModeMask: NSUInteger = 0x3 << MTLResourceHazardTrackingModeShift;
+
+// TODO: Investigate the need for this helper struct?
+//
+// I'm fairly sure that just replacing `MTLPackedFloat3` with this struct has
+// the same effect in Rust as doing the trick with putting it in a union?
+//
+// Or is the intention actually to create something similar to `#[packed]`?
+//
+// <https://users.rust-lang.org/t/mapping-nested-packed-union-from-c-to-rust/87334>
+
+#[repr(C)]
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub struct __MTLPackedFloat3 {
+    x: c_float,
+    y: c_float,
+    z: c_float,
+}
+
+#[repr(C)]
+#[derive(Clone, Copy)]
+pub union MTLPackedFloat3 {
+    struct_: __MTLPackedFloat3,
+    elements: [c_float; 3],
+}
+
+impl PartialEq for MTLPackedFloat3 {
+    fn eq(&self, other: &Self) -> bool {
+        unsafe { self.struct_ == other.struct_ }
+    }
+}
+
+impl fmt::Debug for MTLPackedFloat3 {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        unsafe { self.struct_.fmt(f) }
+    }
+}
+
+impl_encode! {
+    MTLPackedFloat3 = Encoding::Struct(
+        "_MTLPackedFloat3",
+        &[Encoding::Union(
+            "?",
+            &[Encoding::Struct(
+                "?",
+                &[c_float::ENCODING, c_float::ENCODING, c_float::ENCODING],
+            ),
+            Encoding::Array(
+                3,
+                &c_float::ENCODING,
+            )],
+        )],
+    );
+}