diff --git a/src/writer/msl/generator_impl.cc b/src/writer/msl/generator_impl.cc
index 077beae..ddb3f17 100644
--- a/src/writer/msl/generator_impl.cc
+++ b/src/writer/msl/generator_impl.cc
@@ -2378,12 +2378,12 @@
       TextBuffer b;
       TINT_DEFER(helpers_.Append(b));
       line(&b) << R"(template<typename T, int N, int M>
-inline auto operator*(matrix<T, N, M> lhs, packed_vec<T, N> rhs) {
+inline vec<T, M> operator*(matrix<T, N, M> lhs, packed_vec<T, N> rhs) {
   return lhs * vec<T, N>(rhs);
 }
 
 template<typename T, int N, int M>
-inline auto operator*(packed_vec<T, M> lhs, matrix<T, N, M> rhs) {
+inline vec<T, N> operator*(packed_vec<T, M> lhs, matrix<T, N, M> rhs) {
   return vec<T, M>(lhs) * rhs;
 }
 )";
diff --git a/test/buffer/storage/dynamic_index/read.wgsl.expected.msl b/test/buffer/storage/dynamic_index/read.wgsl.expected.msl
index 6e5de18..a9e2537 100644
--- a/test/buffer/storage/dynamic_index/read.wgsl.expected.msl
+++ b/test/buffer/storage/dynamic_index/read.wgsl.expected.msl
@@ -3,12 +3,12 @@
 using namespace metal;
 
 template<typename T, int N, int M>
-inline auto operator*(matrix<T, N, M> lhs, packed_vec<T, N> rhs) {
+inline vec<T, M> operator*(matrix<T, N, M> lhs, packed_vec<T, N> rhs) {
   return lhs * vec<T, N>(rhs);
 }
 
 template<typename T, int N, int M>
-inline auto operator*(packed_vec<T, M> lhs, matrix<T, N, M> rhs) {
+inline vec<T, N> operator*(packed_vec<T, M> lhs, matrix<T, N, M> rhs) {
   return vec<T, M>(lhs) * rhs;
 }
 
diff --git a/test/buffer/storage/dynamic_index/write.wgsl.expected.msl b/test/buffer/storage/dynamic_index/write.wgsl.expected.msl
index 363bd47..ad1753b 100644
--- a/test/buffer/storage/dynamic_index/write.wgsl.expected.msl
+++ b/test/buffer/storage/dynamic_index/write.wgsl.expected.msl
@@ -3,12 +3,12 @@
 using namespace metal;
 
 template<typename T, int N, int M>
-inline auto operator*(matrix<T, N, M> lhs, packed_vec<T, N> rhs) {
+inline vec<T, M> operator*(matrix<T, N, M> lhs, packed_vec<T, N> rhs) {
   return lhs * vec<T, N>(rhs);
 }
 
 template<typename T, int N, int M>
-inline auto operator*(packed_vec<T, M> lhs, matrix<T, N, M> rhs) {
+inline vec<T, N> operator*(packed_vec<T, M> lhs, matrix<T, N, M> rhs) {
   return vec<T, M>(lhs) * rhs;
 }
 
diff --git a/test/buffer/storage/static_index/read.wgsl.expected.msl b/test/buffer/storage/static_index/read.wgsl.expected.msl
index 2e9124f..d60818e 100644
--- a/test/buffer/storage/static_index/read.wgsl.expected.msl
+++ b/test/buffer/storage/static_index/read.wgsl.expected.msl
@@ -3,12 +3,12 @@
 using namespace metal;
 
 template<typename T, int N, int M>
-inline auto operator*(matrix<T, N, M> lhs, packed_vec<T, N> rhs) {
+inline vec<T, M> operator*(matrix<T, N, M> lhs, packed_vec<T, N> rhs) {
   return lhs * vec<T, N>(rhs);
 }
 
 template<typename T, int N, int M>
-inline auto operator*(packed_vec<T, M> lhs, matrix<T, N, M> rhs) {
+inline vec<T, N> operator*(packed_vec<T, M> lhs, matrix<T, N, M> rhs) {
   return vec<T, M>(lhs) * rhs;
 }
 
diff --git a/test/buffer/storage/static_index/write.wgsl.expected.msl b/test/buffer/storage/static_index/write.wgsl.expected.msl
index b263ba8..bae3fcd 100644
--- a/test/buffer/storage/static_index/write.wgsl.expected.msl
+++ b/test/buffer/storage/static_index/write.wgsl.expected.msl
@@ -3,12 +3,12 @@
 using namespace metal;
 
 template<typename T, int N, int M>
-inline auto operator*(matrix<T, N, M> lhs, packed_vec<T, N> rhs) {
+inline vec<T, M> operator*(matrix<T, N, M> lhs, packed_vec<T, N> rhs) {
   return lhs * vec<T, N>(rhs);
 }
 
 template<typename T, int N, int M>
-inline auto operator*(packed_vec<T, M> lhs, matrix<T, N, M> rhs) {
+inline vec<T, N> operator*(packed_vec<T, M> lhs, matrix<T, N, M> rhs) {
   return vec<T, M>(lhs) * rhs;
 }
 
diff --git a/test/buffer/uniform/dynamic_index/read.wgsl.expected.msl b/test/buffer/uniform/dynamic_index/read.wgsl.expected.msl
index 0b2cafe..fb6344f 100644
--- a/test/buffer/uniform/dynamic_index/read.wgsl.expected.msl
+++ b/test/buffer/uniform/dynamic_index/read.wgsl.expected.msl
@@ -3,12 +3,12 @@
 using namespace metal;
 
 template<typename T, int N, int M>
-inline auto operator*(matrix<T, N, M> lhs, packed_vec<T, N> rhs) {
+inline vec<T, M> operator*(matrix<T, N, M> lhs, packed_vec<T, N> rhs) {
   return lhs * vec<T, N>(rhs);
 }
 
 template<typename T, int N, int M>
-inline auto operator*(packed_vec<T, M> lhs, matrix<T, N, M> rhs) {
+inline vec<T, N> operator*(packed_vec<T, M> lhs, matrix<T, N, M> rhs) {
   return vec<T, M>(lhs) * rhs;
 }
 
diff --git a/test/buffer/uniform/static_index/read.wgsl.expected.msl b/test/buffer/uniform/static_index/read.wgsl.expected.msl
index a1e8385..670ba5d 100644
--- a/test/buffer/uniform/static_index/read.wgsl.expected.msl
+++ b/test/buffer/uniform/static_index/read.wgsl.expected.msl
@@ -3,12 +3,12 @@
 using namespace metal;
 
 template<typename T, int N, int M>
-inline auto operator*(matrix<T, N, M> lhs, packed_vec<T, N> rhs) {
+inline vec<T, M> operator*(matrix<T, N, M> lhs, packed_vec<T, N> rhs) {
   return lhs * vec<T, N>(rhs);
 }
 
 template<typename T, int N, int M>
-inline auto operator*(packed_vec<T, M> lhs, matrix<T, N, M> rhs) {
+inline vec<T, N> operator*(packed_vec<T, M> lhs, matrix<T, N, M> rhs) {
   return vec<T, M>(lhs) * rhs;
 }
 
diff --git a/test/bug/chromium/1273230.wgsl.expected.msl b/test/bug/chromium/1273230.wgsl.expected.msl
index 7633307..c8e38ab 100644
--- a/test/bug/chromium/1273230.wgsl.expected.msl
+++ b/test/bug/chromium/1273230.wgsl.expected.msl
@@ -23,12 +23,12 @@
 using namespace metal;
 
 template<typename T, int N, int M>
-inline auto operator*(matrix<T, N, M> lhs, packed_vec<T, N> rhs) {
+inline vec<T, M> operator*(matrix<T, N, M> lhs, packed_vec<T, N> rhs) {
   return lhs * vec<T, N>(rhs);
 }
 
 template<typename T, int N, int M>
-inline auto operator*(packed_vec<T, M> lhs, matrix<T, N, M> rhs) {
+inline vec<T, N> operator*(packed_vec<T, M> lhs, matrix<T, N, M> rhs) {
   return vec<T, M>(lhs) * rhs;
 }
 
diff --git a/test/bug/chromium/1273451.wgsl.expected.msl b/test/bug/chromium/1273451.wgsl.expected.msl
new file mode 100644
index 0000000..5d5fcf6
--- /dev/null
+++ b/test/bug/chromium/1273451.wgsl.expected.msl
@@ -0,0 +1,15 @@
+#include <metal_stdlib>
+
+using namespace metal;
+struct A {
+  int a;
+};
+struct B {
+  int b;
+};
+
+B f(A a) {
+  B const tint_symbol = {};
+  return tint_symbol;
+}
+
diff --git a/test/bug/tint/1113.wgsl.expected.msl b/test/bug/tint/1113.wgsl.expected.msl
index 6a102ec..21d92de 100644
--- a/test/bug/tint/1113.wgsl.expected.msl
+++ b/test/bug/tint/1113.wgsl.expected.msl
@@ -3,12 +3,12 @@
 using namespace metal;
 
 template<typename T, int N, int M>
-inline auto operator*(matrix<T, N, M> lhs, packed_vec<T, N> rhs) {
+inline vec<T, M> operator*(matrix<T, N, M> lhs, packed_vec<T, N> rhs) {
   return lhs * vec<T, N>(rhs);
 }
 
 template<typename T, int N, int M>
-inline auto operator*(packed_vec<T, M> lhs, matrix<T, N, M> rhs) {
+inline vec<T, N> operator*(packed_vec<T, M> lhs, matrix<T, N, M> rhs) {
   return vec<T, M>(lhs) * rhs;
 }
 
diff --git a/test/bug/tint/1121.wgsl.expected.msl b/test/bug/tint/1121.wgsl.expected.msl
index 2fc032d..6497723 100644
--- a/test/bug/tint/1121.wgsl.expected.msl
+++ b/test/bug/tint/1121.wgsl.expected.msl
@@ -3,12 +3,12 @@
 using namespace metal;
 
 template<typename T, int N, int M>
-inline auto operator*(matrix<T, N, M> lhs, packed_vec<T, N> rhs) {
+inline vec<T, M> operator*(matrix<T, N, M> lhs, packed_vec<T, N> rhs) {
   return lhs * vec<T, N>(rhs);
 }
 
 template<typename T, int N, int M>
-inline auto operator*(packed_vec<T, M> lhs, matrix<T, N, M> rhs) {
+inline vec<T, N> operator*(packed_vec<T, M> lhs, matrix<T, N, M> rhs) {
   return vec<T, M>(lhs) * rhs;
 }
 
diff --git a/test/bug/tint/948.wgsl.expected.msl b/test/bug/tint/948.wgsl.expected.msl
index a249fab..d4659c5 100644
--- a/test/bug/tint/948.wgsl.expected.msl
+++ b/test/bug/tint/948.wgsl.expected.msl
@@ -3,12 +3,12 @@
 using namespace metal;
 
 template<typename T, int N, int M>
-inline auto operator*(matrix<T, N, M> lhs, packed_vec<T, N> rhs) {
+inline vec<T, M> operator*(matrix<T, N, M> lhs, packed_vec<T, N> rhs) {
   return lhs * vec<T, N>(rhs);
 }
 
 template<typename T, int N, int M>
-inline auto operator*(packed_vec<T, M> lhs, matrix<T, N, M> rhs) {
+inline vec<T, N> operator*(packed_vec<T, M> lhs, matrix<T, N, M> rhs) {
   return vec<T, M>(lhs) * rhs;
 }
 
diff --git a/test/bug/tint/949.wgsl.expected.msl b/test/bug/tint/949.wgsl.expected.msl
index 6180838..3f023d0 100644
--- a/test/bug/tint/949.wgsl.expected.msl
+++ b/test/bug/tint/949.wgsl.expected.msl
@@ -3,12 +3,12 @@
 using namespace metal;
 
 template<typename T, int N, int M>
-inline auto operator*(matrix<T, N, M> lhs, packed_vec<T, N> rhs) {
+inline vec<T, M> operator*(matrix<T, N, M> lhs, packed_vec<T, N> rhs) {
   return lhs * vec<T, N>(rhs);
 }
 
 template<typename T, int N, int M>
-inline auto operator*(packed_vec<T, M> lhs, matrix<T, N, M> rhs) {
+inline vec<T, N> operator*(packed_vec<T, M> lhs, matrix<T, N, M> rhs) {
   return vec<T, M>(lhs) * rhs;
 }
 
diff --git a/test/bug/tint/980.wgsl.expected.msl b/test/bug/tint/980.wgsl.expected.msl
index 499b542..6261f54 100644
--- a/test/bug/tint/980.wgsl.expected.msl
+++ b/test/bug/tint/980.wgsl.expected.msl
@@ -3,12 +3,12 @@
 using namespace metal;
 
 template<typename T, int N, int M>
-inline auto operator*(matrix<T, N, M> lhs, packed_vec<T, N> rhs) {
+inline vec<T, M> operator*(matrix<T, N, M> lhs, packed_vec<T, N> rhs) {
   return lhs * vec<T, N>(rhs);
 }
 
 template<typename T, int N, int M>
-inline auto operator*(packed_vec<T, M> lhs, matrix<T, N, M> rhs) {
+inline vec<T, N> operator*(packed_vec<T, M> lhs, matrix<T, N, M> rhs) {
   return vec<T, M>(lhs) * rhs;
 }
 
diff --git a/test/expressions/binary/mul/mat3x2-vec3/f32.wgsl.expected.msl b/test/expressions/binary/mul/mat3x2-vec3/f32.wgsl.expected.msl
index 6d656c9..31add65 100644
--- a/test/expressions/binary/mul/mat3x2-vec3/f32.wgsl.expected.msl
+++ b/test/expressions/binary/mul/mat3x2-vec3/f32.wgsl.expected.msl
@@ -3,12 +3,12 @@
 using namespace metal;
 
 template<typename T, int N, int M>
-inline auto operator*(matrix<T, N, M> lhs, packed_vec<T, N> rhs) {
+inline vec<T, M> operator*(matrix<T, N, M> lhs, packed_vec<T, N> rhs) {
   return lhs * vec<T, N>(rhs);
 }
 
 template<typename T, int N, int M>
-inline auto operator*(packed_vec<T, M> lhs, matrix<T, N, M> rhs) {
+inline vec<T, N> operator*(packed_vec<T, M> lhs, matrix<T, N, M> rhs) {
   return vec<T, M>(lhs) * rhs;
 }
 
diff --git a/test/expressions/binary/mul/mat3x3-vec3/f32.wgsl.expected.msl b/test/expressions/binary/mul/mat3x3-vec3/f32.wgsl.expected.msl
index afbe420..40ec533 100644
--- a/test/expressions/binary/mul/mat3x3-vec3/f32.wgsl.expected.msl
+++ b/test/expressions/binary/mul/mat3x3-vec3/f32.wgsl.expected.msl
@@ -3,12 +3,12 @@
 using namespace metal;
 
 template<typename T, int N, int M>
-inline auto operator*(matrix<T, N, M> lhs, packed_vec<T, N> rhs) {
+inline vec<T, M> operator*(matrix<T, N, M> lhs, packed_vec<T, N> rhs) {
   return lhs * vec<T, N>(rhs);
 }
 
 template<typename T, int N, int M>
-inline auto operator*(packed_vec<T, M> lhs, matrix<T, N, M> rhs) {
+inline vec<T, N> operator*(packed_vec<T, M> lhs, matrix<T, N, M> rhs) {
   return vec<T, M>(lhs) * rhs;
 }
 
diff --git a/test/expressions/binary/mul/vec3-mat3x3/f32.wgsl.expected.msl b/test/expressions/binary/mul/vec3-mat3x3/f32.wgsl.expected.msl
index b4412e9..a5da864 100644
--- a/test/expressions/binary/mul/vec3-mat3x3/f32.wgsl.expected.msl
+++ b/test/expressions/binary/mul/vec3-mat3x3/f32.wgsl.expected.msl
@@ -3,12 +3,12 @@
 using namespace metal;
 
 template<typename T, int N, int M>
-inline auto operator*(matrix<T, N, M> lhs, packed_vec<T, N> rhs) {
+inline vec<T, M> operator*(matrix<T, N, M> lhs, packed_vec<T, N> rhs) {
   return lhs * vec<T, N>(rhs);
 }
 
 template<typename T, int N, int M>
-inline auto operator*(packed_vec<T, M> lhs, matrix<T, N, M> rhs) {
+inline vec<T, N> operator*(packed_vec<T, M> lhs, matrix<T, N, M> rhs) {
   return vec<T, M>(lhs) * rhs;
 }
 
diff --git a/test/expressions/binary/mul/vec3-mat4x3/f32.wgsl.expected.msl b/test/expressions/binary/mul/vec3-mat4x3/f32.wgsl.expected.msl
index 5a320cf..36412ba 100644
--- a/test/expressions/binary/mul/vec3-mat4x3/f32.wgsl.expected.msl
+++ b/test/expressions/binary/mul/vec3-mat4x3/f32.wgsl.expected.msl
@@ -3,12 +3,12 @@
 using namespace metal;
 
 template<typename T, int N, int M>
-inline auto operator*(matrix<T, N, M> lhs, packed_vec<T, N> rhs) {
+inline vec<T, M> operator*(matrix<T, N, M> lhs, packed_vec<T, N> rhs) {
   return lhs * vec<T, N>(rhs);
 }
 
 template<typename T, int N, int M>
-inline auto operator*(packed_vec<T, M> lhs, matrix<T, N, M> rhs) {
+inline vec<T, N> operator*(packed_vec<T, M> lhs, matrix<T, N, M> rhs) {
   return vec<T, M>(lhs) * rhs;
 }
 
diff --git a/test/expressions/swizzle/read/packed_vec3/f32.wgsl.expected.msl b/test/expressions/swizzle/read/packed_vec3/f32.wgsl.expected.msl
index 070734e..9f40be1 100644
--- a/test/expressions/swizzle/read/packed_vec3/f32.wgsl.expected.msl
+++ b/test/expressions/swizzle/read/packed_vec3/f32.wgsl.expected.msl
@@ -3,12 +3,12 @@
 using namespace metal;
 
 template<typename T, int N, int M>
-inline auto operator*(matrix<T, N, M> lhs, packed_vec<T, N> rhs) {
+inline vec<T, M> operator*(matrix<T, N, M> lhs, packed_vec<T, N> rhs) {
   return lhs * vec<T, N>(rhs);
 }
 
 template<typename T, int N, int M>
-inline auto operator*(packed_vec<T, M> lhs, matrix<T, N, M> rhs) {
+inline vec<T, N> operator*(packed_vec<T, M> lhs, matrix<T, N, M> rhs) {
   return vec<T, M>(lhs) * rhs;
 }
 
diff --git a/test/expressions/swizzle/write/packed_vec3/f32.wgsl.expected.msl b/test/expressions/swizzle/write/packed_vec3/f32.wgsl.expected.msl
index e726778..2e63ec7 100644
--- a/test/expressions/swizzle/write/packed_vec3/f32.wgsl.expected.msl
+++ b/test/expressions/swizzle/write/packed_vec3/f32.wgsl.expected.msl
@@ -3,12 +3,12 @@
 using namespace metal;
 
 template<typename T, int N, int M>
-inline auto operator*(matrix<T, N, M> lhs, packed_vec<T, N> rhs) {
+inline vec<T, M> operator*(matrix<T, N, M> lhs, packed_vec<T, N> rhs) {
   return lhs * vec<T, N>(rhs);
 }
 
 template<typename T, int N, int M>
-inline auto operator*(packed_vec<T, M> lhs, matrix<T, N, M> rhs) {
+inline vec<T, N> operator*(packed_vec<T, M> lhs, matrix<T, N, M> rhs) {
   return vec<T, M>(lhs) * rhs;
 }