[SYCL][CUDA][HIP] Deprecate context interop for CUDA and HIP (#10975)

The `sycl::context` does not map clearly to a native context for CUDA
and HIP backends. This is especially true now that we are adding support
for multi device context #10737 . It
would be good to start this deprecation process. PRs to oneMKL and
oneDNN to follow

Author: hdelan

sycl/include/sycl/backend.hpp

@@ -213,7 +213,42 @@ get_native<backend::ext_oneapi_cuda, device>(const device &Obj) {
   return static_cast<backend_return_t<backend::ext_oneapi_cuda, device>>(
       Obj.getNative());
 }
-#endif
+
+#ifndef SYCL_EXT_ONEAPI_BACKEND_CUDA_EXPERIMENTAL
+template <>
+__SYCL_DEPRECATED(
+    "Context interop is deprecated for CUDA. If a native context is required,"
+    " use cuDevicePrimaryCtxRetain with a native device")
+inline backend_return_t<backend::ext_oneapi_cuda, context> get_native<
+    backend::ext_oneapi_cuda, context>(const context &Obj) {
+  if (Obj.get_backend() != backend::ext_oneapi_cuda) {
+    throw sycl::exception(make_error_code(errc::backend_mismatch),
+                          "Backends mismatch");
+  }
+  return reinterpret_cast<backend_return_t<backend::ext_oneapi_cuda, context>>(
+      Obj.getNative());
+}
+
+#endif // SYCL_EXT_ONEAPI_BACKEND_CUDA_EXPERIMENTAL
+#endif // SYCL_EXT_ONEAPI_BACKEND_CUDA
+
+#if SYCL_EXT_ONEAPI_BACKEND_HIP
+
+template <>
+__SYCL_DEPRECATED(
+    "Context interop is deprecated for HIP. If a native context is required,"
+    " use hipDevicePrimaryCtxRetain with a native device")
+inline backend_return_t<backend::ext_oneapi_hip, context> get_native<
+    backend::ext_oneapi_hip, context>(const context &Obj) {
+  if (Obj.get_backend() != backend::ext_oneapi_hip) {
+    throw sycl::exception(make_error_code(errc::backend_mismatch),
+                          "Backends mismatch");
+  }
+  return reinterpret_cast<backend_return_t<backend::ext_oneapi_hip, context>>(
+      Obj.getNative());
+}
+
+#endif // SYCL_EXT_ONEAPI_BACKEND_HIP
 
 template <backend BackendName, typename DataT, int Dimensions,
           access::mode AccessMode, access::target AccessTarget,

sycl/test/basic_tests/interop-cuda.cpp

@@ -5,11 +5,11 @@
 /// Also test the experimental CUDA interop interface
 // RUN: %clangxx %fsycl-host-only -fsyntax-only -Xclang -verify -Xclang -verify-ignore-unexpected=note -DSYCL_EXT_ONEAPI_BACKEND_CUDA_EXPERIMENTAL %s
 // RUN: %clangxx %fsycl-host-only -fsyntax-only -Xclang -verify -Xclang -verify-ignore-unexpected=note -D__SYCL_INTERNAL_API -DSYCL_EXT_ONEAPI_BACKEND_CUDA_EXPERIMENTAL %s
-// expected-no-diagnostics
 
 // Test for legacy and experimental CUDA interop API
 
 #ifdef SYCL_EXT_ONEAPI_BACKEND_CUDA_EXPERIMENTAL
+// expected-no-diagnostics
 #include <sycl/ext/oneapi/experimental/backend/cuda.hpp>
 #endif
 
@@ -59,6 +59,9 @@ int main() {
   // backend-defined and specified in the backend specification.
 
   cu_device = get_native<backend::ext_oneapi_cuda>(Device);
+#ifndef SYCL_EXT_ONEAPI_BACKEND_CUDA_EXPERIMENTAL
+  // expected-warning@+2{{'get_native<sycl::backend::ext_oneapi_cuda, sycl::context>' is deprecated: Context interop is deprecated for CUDA. If a native context is required, use cuDevicePrimaryCtxRetain with a native device}}
+#endif
   cu_context = get_native<backend::ext_oneapi_cuda>(Context);
   cu_event = get_native<backend::ext_oneapi_cuda>(Event);
   cu_queue = get_native<backend::ext_oneapi_cuda>(Queue);

sycl/test/basic_tests/interop-hip.cpp

@@ -1,7 +1,6 @@
 // REQUIRES: hip_be
 // RUN: %clangxx %fsycl-host-only -fsyntax-only -Xclang -verify -Xclang -verify-ignore-unexpected=note %s
 // RUN: %clangxx %fsycl-host-only -fsyntax-only -Xclang -verify -Xclang -verify-ignore-unexpected=note -D__SYCL_INTERNAL_API %s
-// expected-no-diagnostics
 
 // Test for HIP interop API
 
@@ -52,6 +51,7 @@ int main() {
   // backend-defined and specified in the backend specification.
 
   hip_device = get_native<backend::ext_oneapi_hip>(Device);
+  // expected-warning@+1{{'get_native<sycl::backend::ext_oneapi_hip, sycl::context>' is deprecated: Context interop is deprecated for HIP. If a native context is required, use hipDevicePrimaryCtxRetain with a native device}}
   hip_context = get_native<backend::ext_oneapi_hip>(Context);
   hip_event = get_native<backend::ext_oneapi_hip>(Event);
   hip_queue = get_native<backend::ext_oneapi_hip>(Queue);