From 7791ebc2b1219576bfe4fd6de1c7f79d27db864d Mon Sep 17 00:00:00 2001
From: Andrei Elovikov <andrei.elovikov@intel.com>
Date: Thu, 11 Sep 2025 15:59:57 -0700
Subject: [PATCH] [NFC][SYCL] Add `sycl/detail/fwd/accessor.hpp` helper

---
 sycl/include/sycl/accessor.hpp                | 15 +++----
 sycl/include/sycl/buffer.hpp                  |  4 +-
 .../include/sycl/detail/accessor_iterator.hpp | 10 +----
 sycl/include/sycl/detail/fwd/accessor.hpp     | 42 +++++++++++++++++++
 .../ext/oneapi/accessor_property_list.hpp     | 12 ++----
 sycl/include/sycl/handler.hpp                 |  3 --
 sycl/include/sycl/image.hpp                   | 17 --------
 sycl/include/sycl/multi_ptr.hpp               |  8 +---
 .../sycl/properties/accessor_properties.hpp   | 23 +---------
 sycl/include/sycl/sampler.hpp                 | 13 ++----
 sycl/test/include_deps/sycl_accessor.hpp.cpp  |  3 +-
 sycl/test/include_deps/sycl_buffer.hpp.cpp    |  3 +-
 .../include_deps/sycl_detail_core.hpp.cpp     |  3 +-
 13 files changed, 66 insertions(+), 90 deletions(-)
 create mode 100644 sycl/include/sycl/detail/fwd/accessor.hpp

diff --git a/sycl/include/sycl/accessor.hpp b/sycl/include/sycl/accessor.hpp
index af3ceb06e45ee..3f48859aefed3 100644
--- a/sycl/include/sycl/accessor.hpp
+++ b/sycl/include/sycl/accessor.hpp
@@ -221,13 +221,6 @@ namespace ext::intel::esimd::detail {
 class AccessorPrivateProxy;
 } // namespace ext::intel::esimd::detail
 
-template <typename DataT, int Dimensions = 1,
-          access::mode AccessMode = access::mode::read_write,
-          access::target AccessTarget = access::target::device,
-          access::placeholder IsPlaceholder = access::placeholder::false_t,
-          typename PropertyListT = ext::oneapi::accessor_property_list<>>
-class accessor;
-
 namespace ext::oneapi::experimental {
 template <typename, int> class dynamic_local_accessor;
 }
@@ -616,9 +609,11 @@ class __SYCL_EXPORT LocalAccessorBaseHost {
 /// \sa buffer
 ///
 /// \ingroup sycl_api_acc
-template <typename DataT, int Dimensions, access::mode AccessMode,
-          access::target AccessTarget, access::placeholder IsPlaceholder,
-          typename PropertyListT>
+template <typename DataT, int Dimensions = 1,
+          access::mode AccessMode = access::mode::read_write,
+          access::target AccessTarget = access::target::device,
+          access::placeholder IsPlaceholder = access::placeholder::false_t,
+          typename PropertyListT = ext::oneapi::accessor_property_list<>>
 class __SYCL_EBO __SYCL_SPECIAL_CLASS __SYCL_TYPE(accessor) accessor :
 #ifndef __SYCL_DEVICE_ONLY__
     public detail::AccessorBaseHost,
diff --git a/sycl/include/sycl/buffer.hpp b/sycl/include/sycl/buffer.hpp
index 004236e9b0d6a..4c0d9575c7807 100644
--- a/sycl/include/sycl/buffer.hpp
+++ b/sycl/include/sycl/buffer.hpp
@@ -14,6 +14,7 @@
 #include <sycl/detail/common.hpp>
 #include <sycl/detail/defines_elementary.hpp>
 #include <sycl/detail/export.hpp>
+#include <sycl/detail/fwd/accessor.hpp>
 #include <sycl/detail/helpers.hpp>
 #include <sycl/detail/iostream_proxy.hpp>
 #include <sycl/detail/is_device_copyable.hpp>
@@ -51,9 +52,6 @@ template <int dimensions> class range;
 template <typename DataT>
 using buffer_allocator = detail::sycl_memory_object_allocator<DataT>;
 
-template <typename DataT, int Dimensions, access::mode AccessMode>
-class host_accessor;
-
 template <typename T, int Dimensions, typename AllocatorT, typename Enable>
 class buffer;
 
diff --git a/sycl/include/sycl/detail/accessor_iterator.hpp b/sycl/include/sycl/detail/accessor_iterator.hpp
index 97c5385bf3624..e8f753173ad47 100644
--- a/sycl/include/sycl/detail/accessor_iterator.hpp
+++ b/sycl/include/sycl/detail/accessor_iterator.hpp
@@ -10,7 +10,8 @@
 
 #include <sycl/access/access.hpp> // for mode, placeholder, target
 #include <sycl/buffer.hpp>        // for range
-#include <sycl/id.hpp>            // for id
+#include <sycl/detail/fwd/accessor.hpp>
+#include <sycl/id.hpp>
 
 #include <cstddef>  // for size_t
 #include <iterator> // for random_access_iterator_tag
@@ -37,14 +38,7 @@
 
 namespace sycl {
 inline namespace _V1 {
-
-template <typename AccessorDataT, int AccessorDimensions,
-          access::mode AccessMode, access::target AccessTarget,
-          access::placeholder IsPlaceholder, typename PropertyListT>
-class accessor;
-
 namespace detail {
-
 template <typename DataT, int Dimensions> class accessor_iterator {
 public:
   using difference_type = std::ptrdiff_t;
diff --git a/sycl/include/sycl/detail/fwd/accessor.hpp b/sycl/include/sycl/detail/fwd/accessor.hpp
new file mode 100644
index 0000000000000..8cbe1fbeb1f60
--- /dev/null
+++ b/sycl/include/sycl/detail/fwd/accessor.hpp
@@ -0,0 +1,42 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#pragma once
+
+#include <sycl/access/access.hpp>
+#include <sycl/detail/defines.hpp>
+
+namespace sycl {
+inline namespace _V1 {
+
+template <typename DataT, int Dimensions, access::mode AccessMode,
+          access::target AccessTarget, access::placeholder IsPlaceholder,
+          typename PropertyListT>
+class accessor;
+template <typename DataT, int Dimensions, access::mode AccessMode>
+class host_accessor;
+template <typename DataT, int Dimensions>
+class __SYCL_EBO
+    __SYCL_SPECIAL_CLASS __SYCL_TYPE(local_accessor) local_accessor;
+
+namespace detail {
+template <typename DataT, int Dimensions, access::mode AccessMode,
+          access::target AccessTarget, access::placeholder IsPlaceholder>
+class image_accessor;
+}
+
+template <typename DataT, int Dimensions, access_mode AccessMode,
+          image_target AccessTarget>
+class unsampled_image_accessor;
+template <typename DataT, int Dimensions, image_target AccessTarget>
+class sampled_image_accessor;
+template <typename DataT, int Dimensions, access_mode AccessMode>
+class host_unsampled_image_accessor;
+template <typename DataT, int Dimensions> class host_sampled_image_accessor;
+} // namespace _V1
+} // namespace sycl
diff --git a/sycl/include/sycl/ext/oneapi/accessor_property_list.hpp b/sycl/include/sycl/ext/oneapi/accessor_property_list.hpp
index 3fd3648671cb4..aa6335bd6cda6 100644
--- a/sycl/include/sycl/ext/oneapi/accessor_property_list.hpp
+++ b/sycl/include/sycl/ext/oneapi/accessor_property_list.hpp
@@ -8,12 +8,13 @@
 
 #pragma once
 
-#include <sycl/access/access.hpp>             // for mode, placeholder, target
-#include <sycl/detail/defines.hpp>            // for __SYCL_TYPE
+#include <sycl/access/access.hpp>  // for mode, placeholder, target
+#include <sycl/detail/defines.hpp> // for __SYCL_TYPE
+#include <sycl/detail/fwd/accessor.hpp>
 #include <sycl/detail/property_helper.hpp>    // for DataLessPropKind, Prop...
 #include <sycl/detail/property_list_base.hpp> // for PropertyListBase
 #include <sycl/exception.hpp>
-#include <sycl/property_list.hpp>             // for property_list
+#include <sycl/property_list.hpp> // for property_list
 
 #include <bitset>      // for bitset
 #include <memory>      // for shared_ptr
@@ -22,11 +23,6 @@
 
 namespace sycl {
 inline namespace _V1 {
-// Forward declaration
-template <typename DataT, int Dimensions, access::mode AccessMode,
-          access::target AccessTarget, access::placeholder IsPlaceholder,
-          typename PropertyListT>
-class accessor;
 namespace detail {
 // This helper template must be specialized for nested instance template
 // of each compile-time-constant property.
diff --git a/sycl/include/sycl/handler.hpp b/sycl/include/sycl/handler.hpp
index 44b46d4960910..9c10c9486f63a 100644
--- a/sycl/include/sycl/handler.hpp
+++ b/sycl/include/sycl/handler.hpp
@@ -208,9 +208,6 @@ class queue_impl;
 class stream_impl;
 class event_impl;
 class context_impl;
-template <typename DataT, int Dimensions, access::mode AccessMode,
-          access::target AccessTarget, access::placeholder IsPlaceholder>
-class image_accessor;
 class HandlerAccess;
 class HostTask;
 
diff --git a/sycl/include/sycl/image.hpp b/sycl/include/sycl/image.hpp
index 004763c8d601d..cff83ee1efd0b 100644
--- a/sycl/include/sycl/image.hpp
+++ b/sycl/include/sycl/image.hpp
@@ -413,25 +413,8 @@ class unsampled_image_common : public image_common<Dimensions, AllocatorT> {
         });
   }
 };
-
-template <typename DataT, int Dims, access::mode AccMode,
-          access::target AccTarget, access::placeholder IsPlaceholder>
-class image_accessor;
-
 } // namespace detail
 
-template <typename DataT, int Dimensions, access_mode AccessMode,
-          image_target AccessTarget>
-class unsampled_image_accessor;
-
-template <typename DataT, int Dimensions, access_mode AccessMode>
-class host_unsampled_image_accessor;
-
-template <typename DataT, int Dimensions, image_target AccessTarget>
-class sampled_image_accessor;
-
-template <typename DataT, int Dimensions> class host_sampled_image_accessor;
-
 /// Defines a shared image data.
 ///
 /// Images can be 1-, 2-, and 3-dimensional. They have to be accessed using the
diff --git a/sycl/include/sycl/multi_ptr.hpp b/sycl/include/sycl/multi_ptr.hpp
index 4a30322ec9936..a4112edfee485 100644
--- a/sycl/include/sycl/multi_ptr.hpp
+++ b/sycl/include/sycl/multi_ptr.hpp
@@ -12,6 +12,7 @@
 #include <sycl/aliases.hpp>       // for half
 #include <sycl/detail/address_space_cast.hpp>
 #include <sycl/detail/defines_elementary.hpp> // for __SYCL2020_DEPRECATED
+#include <sycl/detail/fwd/accessor.hpp>
 #include <sycl/detail/fwd/multi_ptr.hpp>
 #include <sycl/detail/type_traits.hpp> // for const_if_const_AS
 #include <sycl/half_type.hpp>          // for BIsRepresentationT
@@ -66,13 +67,6 @@ struct LegacyReferenceTypes<ElementType,
 };
 } // namespace detail
 
-// Forward declarations
-template <typename dataT, int dimensions, access::mode accessMode,
-          access::target accessTarget, access::placeholder isPlaceholder,
-          typename PropertyListT>
-class accessor;
-template <typename dataT, int dimensions> class local_accessor;
-
 /// Provides constructors for address space qualified and non address space
 /// qualified pointers to allow interoperability between plain C++ and OpenCL C.
 ///
diff --git a/sycl/include/sycl/properties/accessor_properties.hpp b/sycl/include/sycl/properties/accessor_properties.hpp
index dd09ce3b80247..82785748b49a7 100644
--- a/sycl/include/sycl/properties/accessor_properties.hpp
+++ b/sycl/include/sycl/properties/accessor_properties.hpp
@@ -12,6 +12,7 @@
 #include <sycl/detail/common.hpp>
 #include <sycl/detail/defines.hpp>
 #include <sycl/detail/defines_elementary.hpp>
+#include <sycl/detail/fwd/accessor.hpp>
 #include <sycl/detail/property_helper.hpp>
 #include <sycl/ext/oneapi/accessor_property_list.hpp>
 #include <sycl/properties/property_traits.hpp>
@@ -91,28 +92,6 @@ struct is_compile_time_property<sycl::ext::intel::property::buffer_location>
     : std::true_type {};
 } // namespace ext::oneapi
 
-// Forward declaration
-template <typename DataT, int Dimensions, access::mode AccessMode,
-          access::target AccessTarget, access::placeholder IsPlaceholder,
-          typename PropertyListT>
-class accessor;
-template <typename DataT, int Dimensions, access::mode AccessMode>
-class host_accessor;
-template <typename DataT, int Dimensions>
-class __SYCL_EBO
-    __SYCL_SPECIAL_CLASS __SYCL_TYPE(local_accessor) local_accessor;
-template <typename DataT, int Dimensions, access::mode AccessMode,
-          access::target AccessTarget, access::placeholder IsPlaceholder>
-class image_accessor;
-template <typename DataT, int Dimensions, access_mode AccessMode,
-          image_target AccessTarget>
-class unsampled_image_accessor;
-template <typename DataT, int Dimensions, image_target AccessTarget>
-class sampled_image_accessor;
-template <typename DataT, int Dimensions, access_mode AccessMode>
-class host_unsampled_image_accessor;
-template <typename DataT, int Dimensions> class host_sampled_image_accessor;
-
 namespace detail::acc_properties {
 template <typename T> struct is_accessor : std::false_type {};
 template <typename DataT, int Dimensions, access::mode AccessMode,
diff --git a/sycl/include/sycl/sampler.hpp b/sycl/include/sycl/sampler.hpp
index dcf9286b03e54..6dd69ff4ac734 100644
--- a/sycl/include/sycl/sampler.hpp
+++ b/sycl/include/sycl/sampler.hpp
@@ -8,9 +8,10 @@
 
 #pragma once
 
-#include <sycl/access/access.hpp>     // for mode, placeholder, target
-#include <sycl/detail/defines.hpp>    // for __SYCL_SPECIAL_CLASS, __SYCL_TYPE
-#include <sycl/detail/export.hpp>     // for __SYCL_EXPORT
+#include <sycl/access/access.hpp>  // for mode, placeholder, target
+#include <sycl/detail/defines.hpp> // for __SYCL_SPECIAL_CLASS, __SYCL_TYPE
+#include <sycl/detail/export.hpp>  // for __SYCL_EXPORT
+#include <sycl/detail/fwd/accessor.hpp>
 #include <sycl/detail/impl_utils.hpp> // for getSyclObjImpl
 #include <sycl/property_list.hpp>     // for property_list
 
@@ -39,12 +40,6 @@ enum class coordinate_normalization_mode : unsigned int {
   unnormalized = 0
 };
 
-namespace detail {
-template <typename DataT, int Dimensions, access::mode AccessMode,
-          access::target AccessTarget, access::placeholder IsPlaceholder>
-class image_accessor;
-}
-
 namespace detail {
 #ifdef __SYCL_DEVICE_ONLY__
 class __SYCL_EXPORT sampler_impl {
diff --git a/sycl/test/include_deps/sycl_accessor.hpp.cpp b/sycl/test/include_deps/sycl_accessor.hpp.cpp
index ad9871ddf513b..2901a4fbc0c7a 100644
--- a/sycl/test/include_deps/sycl_accessor.hpp.cpp
+++ b/sycl/test/include_deps/sycl_accessor.hpp.cpp
@@ -18,9 +18,10 @@
 // CHECK-NEXT: stl_wrappers/cassert
 // CHECK-NEXT: stl_wrappers/assert.h
 // CHECK-NEXT: __spirv/spirv_vars.hpp
+// CHECK-NEXT: detail/fwd/accessor.hpp
+// CHECK-NEXT: detail/defines.hpp
 // CHECK-NEXT: detail/helpers.hpp
 // CHECK-NEXT: __spirv/spirv_types.hpp
-// CHECK-NEXT: detail/defines.hpp
 // CHECK-NEXT: memory_enums.hpp
 // CHECK-NEXT: detail/iostream_proxy.hpp
 // CHECK-NEXT: detail/is_device_copyable.hpp
diff --git a/sycl/test/include_deps/sycl_buffer.hpp.cpp b/sycl/test/include_deps/sycl_buffer.hpp.cpp
index d7bba03c556fe..cc4537177202d 100644
--- a/sycl/test/include_deps/sycl_buffer.hpp.cpp
+++ b/sycl/test/include_deps/sycl_buffer.hpp.cpp
@@ -17,9 +17,10 @@
 // CHECK-NEXT: stl_wrappers/cassert
 // CHECK-NEXT: stl_wrappers/assert.h
 // CHECK-NEXT: __spirv/spirv_vars.hpp
+// CHECK-NEXT: detail/fwd/accessor.hpp
+// CHECK-NEXT: detail/defines.hpp
 // CHECK-NEXT: detail/helpers.hpp
 // CHECK-NEXT: __spirv/spirv_types.hpp
-// CHECK-NEXT: detail/defines.hpp
 // CHECK-NEXT: memory_enums.hpp
 // CHECK-NEXT: detail/iostream_proxy.hpp
 // CHECK-NEXT: detail/is_device_copyable.hpp
diff --git a/sycl/test/include_deps/sycl_detail_core.hpp.cpp b/sycl/test/include_deps/sycl_detail_core.hpp.cpp
index 6fd0a7acddb0a..a87fb75117f27 100644
--- a/sycl/test/include_deps/sycl_detail_core.hpp.cpp
+++ b/sycl/test/include_deps/sycl_detail_core.hpp.cpp
@@ -19,9 +19,10 @@
 // CHECK-NEXT: stl_wrappers/cassert
 // CHECK-NEXT: stl_wrappers/assert.h
 // CHECK-NEXT: __spirv/spirv_vars.hpp
+// CHECK-NEXT: detail/fwd/accessor.hpp
+// CHECK-NEXT: detail/defines.hpp
 // CHECK-NEXT: detail/helpers.hpp
 // CHECK-NEXT: __spirv/spirv_types.hpp
-// CHECK-NEXT: detail/defines.hpp
 // CHECK-NEXT: memory_enums.hpp
 // CHECK-NEXT: detail/iostream_proxy.hpp
 // CHECK-NEXT: detail/is_device_copyable.hpp