Fix extraction of values from device_global with different template args

Signed-off-by: Larsen, Steffen <[email protected]>

Author: steffenlarsen

sycl/include/sycl/ext/oneapi/device_global/device_global.hpp

@@ -68,6 +68,19 @@ class device_global_base {
   pointer_t get_ptr() noexcept { return usmptr; }
   pointer_t get_ptr() const noexcept { return usmptr; }
 
+  template <typename, typename, typename> friend class device_global_base;
+
+#ifndef __SYCL_DEVICE_ONLY__
+  template <typename OtherT, typename OtherProps>
+  static constexpr const T &
+  ExtractInitialVal(const device_global_base<OtherT, OtherProps> &Other) {
+    if constexpr (OtherProps::template has_property<device_image_scope_key>())
+      return Other.val;
+    else
+      return Other.init_val;
+  }
+#endif // __SYCL_DEVICE_ONLY__
+
 public:
 #if __cpp_consteval
   // The SFINAE is to allow the copy constructors to take priority.
@@ -87,7 +100,7 @@ class device_global_base {
             typename = std::enable_if_t<std::is_convertible_v<OtherT, T>>>
   constexpr device_global_base(
       const device_global_base<OtherT, OtherProps> &DGB)
-      : init_val{DGB.init_val} {}
+      : init_val{ExtractInitialVal(DGB)} {}
   constexpr device_global_base(const device_global_base &DGB)
       : init_val{DGB.init_val} {}
 #else
@@ -127,6 +140,8 @@ class device_global_base<
   T *get_ptr() noexcept { return &val; }
   const T *get_ptr() const noexcept { return &val; }
 
+  template <typename, typename, typename> friend class device_global_base;
+
 public:
 #if __cpp_consteval
   // The SFINAE is to allow the copy constructors to take priority.