From a62b2206004e1931833da43292e77b4edf406326 Mon Sep 17 00:00:00 2001
From: aelovikov-intel <andrei.elovikov@intel.com>
Date: Tue, 24 Dec 2024 08:24:38 -0800
Subject: [PATCH] [SYCL] Use explicit return type in `get_vec_idx` helper
 (#16464)

Apparently, some versions of MSVC (e.g. 14.29.30133) fail to compile it

```
error C3779: 'sycl::_V1::detail::SwizzleOp<VecT,OperationLeftT,OperationRightT,OperationCurrentT,Indexes...>::get_vec_idx': a function that returns 'auto' cannot be used before it is defined
```

when used with `-fsycl-host-compiler`. This has been caught by the
existing `bit_cast_win.cpp` test in a downstream environment.
---
 sycl/include/sycl/vector.hpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sycl/include/sycl/vector.hpp b/sycl/include/sycl/vector.hpp
index 82ce6b676eb75..3c5e7c3a305b6 100644
--- a/sycl/include/sycl/vector.hpp
+++ b/sycl/include/sycl/vector.hpp
@@ -1181,7 +1181,7 @@ class SwizzleOp : public detail::NamedSwizzlesMixinBoth<
   }
 
 private:
-  static constexpr auto get_vec_idx(int idx) {
+  static constexpr int get_vec_idx(int idx) {
     int counter = 0;
     int result = -1;
     ((result = counter++ == idx ? Indexes : result), ...);