fix(msl-out): use namer for <fun>{Input,Output} structs

CHANGELOG.md

@@ -118,6 +118,7 @@ By @bradwerth [#6216](https://github.com/gfx-rs/wgpu/pull/6216).
 - Added `gl_DrawID` to glsl and `DrawIndex` to spv. By @ChosenName in [#6325](https://github.com/gfx-rs/wgpu/pull/6325).
 - Matrices can now be indexed by value (#4337), and indexing arrays by value no longer causes excessive spilling (#6358). By @jimblandy in [#6390](https://github.com/gfx-rs/wgpu/pull/6390).
 - Add support for `textureQueryLevels` to the GLSL parser. By @magcius in [#6325](https://github.com/gfx-rs/wgpu/pull/6415).
+- Fix unescaped identifiers in the Metal backend shader I/O structures causing shader miscompilation. By @ErichDonGubler in [#6438](https://github.com/gfx-rs/wgpu/pull/6438).
 
 #### General
 

naga/src/back/msl/writer.rs

@@ -5063,7 +5063,7 @@ template <typename A>
             // a struct type named `<fun>Input` to hold them. If we are doing
             // vertex pulling, we instead update our attribute mapping to
             // note the types, names, and zero values of the attributes.
-            let stage_in_name = format!("{fun_name}Input");
+            let stage_in_name = self.namer.call(&format!("{fun_name}Input"));
             let varyings_member_name = self.namer.call("varyings");
             let mut has_varyings = false;
             if !flattened_arguments.is_empty() {
@@ -5115,7 +5115,7 @@ template <typename A>
 
             // Define a struct type named for the return value, if any, named
             // `<fun>Output`.
-            let stage_out_name = format!("{fun_name}Output");
+            let stage_out_name = self.namer.call(&format!("{fun_name}Output"));
             let result_member_name = self.namer.call("member");
             let result_type_name = match fun.result {
                 Some(ref result) => {

naga/tests/out/msl/6438-conflicting-idents.msl

@@ -12,19 +12,19 @@ struct OurVertexShaderOutput {
 struct vsInput {
     metal::float2 xy [[attribute(0)]];
 };
-struct vsOutput {
+struct vsOutput_1 {
     metal::float4 position [[position]];
     metal::float2 texcoord [[user(loc0), center_perspective]];
 };
-vertex vsOutput vs(
+vertex vsOutput_1 vs(
   vsInput varyings [[stage_in]]
 ) {
     const auto xy = varyings.xy;
     OurVertexShaderOutput vsOutput = {};
     vsOutput.position = metal::float4(xy, 0.0, 1.0);
     OurVertexShaderOutput _e6 = vsOutput;
     const auto _tmp = _e6;
-    return vsOutput { _tmp.position, _tmp.texcoord };
+    return vsOutput_1 { _tmp.position, _tmp.texcoord };
 }