From a037165124e0021025bd4d2194a76d1decda1d04 Mon Sep 17 00:00:00 2001
From: Dmitriy Sobolev <Dmitriy.Sobolev@intel.com>
Date: Wed, 6 Nov 2024 13:11:19 +0000
Subject: [PATCH] Allow passing a non-trivially-copyable comparator to sort
 (#1932)

Signed-off-by: Dmitriy Sobolev <dmitriy.sobolev@intel.com>
---
 .../dpcpp/parallel_backend_sycl_merge_sort.h       |  1 +
 include/oneapi/dpl/pstl/hetero/dpcpp/sycl_traits.h | 10 ++++++++++
 .../device_copyable.pass.cpp                       | 14 ++++++++++++++
 3 files changed, 25 insertions(+)

diff --git a/include/oneapi/dpl/pstl/hetero/dpcpp/parallel_backend_sycl_merge_sort.h b/include/oneapi/dpl/pstl/hetero/dpcpp/parallel_backend_sycl_merge_sort.h
index db55edc37d..0765f8ef7b 100644
--- a/include/oneapi/dpl/pstl/hetero/dpcpp/parallel_backend_sycl_merge_sort.h
+++ b/include/oneapi/dpl/pstl/hetero/dpcpp/parallel_backend_sycl_merge_sort.h
@@ -24,6 +24,7 @@
 #include <type_traits> // std::decay_t, std::integral_constant
 
 #include "sycl_defs.h"                   // __dpl_sycl::__local_accessor, __dpl_sycl::__group_barrier
+#include "sycl_traits.h"                 // SYCL traits specialization for some oneDPL types.
 #include "../../utils.h"                 // __dpl_bit_floor, __dpl_bit_ceil
 #include "../../utils_ranges.h"          // __difference_t
 #include "parallel_backend_sycl_merge.h" // __find_start_point, __serial_merge
diff --git a/include/oneapi/dpl/pstl/hetero/dpcpp/sycl_traits.h b/include/oneapi/dpl/pstl/hetero/dpcpp/sycl_traits.h
index f498a58750..2d0e88fd34 100644
--- a/include/oneapi/dpl/pstl/hetero/dpcpp/sycl_traits.h
+++ b/include/oneapi/dpl/pstl/hetero/dpcpp/sycl_traits.h
@@ -257,6 +257,9 @@ struct __write_to_id_if_else;
 template <typename _ExecutionPolicy, typename _Pred>
 struct __early_exit_find_or;
 
+template <typename _Range, typename _Compare>
+struct __leaf_sorter;
+
 } // namespace oneapi::dpl::__par_backend_hetero
 
 template <typename _UnaryOp>
@@ -313,6 +316,13 @@ struct sycl::is_device_copyable<_ONEDPL_SPECIALIZE_FOR(oneapi::dpl::__par_backen
 {
 };
 
+template <typename _Range, typename _Compare>
+struct sycl::is_device_copyable<_ONEDPL_SPECIALIZE_FOR(oneapi::dpl::__par_backend_hetero::__leaf_sorter, _Range,
+                                                       _Compare)>
+    : oneapi::dpl::__internal::__are_all_device_copyable<_Range, _Compare>
+{
+};
+
 namespace oneapi::dpl::unseq_backend
 {
 
diff --git a/test/general/implementation_details/device_copyable.pass.cpp b/test/general/implementation_details/device_copyable.pass.cpp
index 8b137cc33e..9b1b09e8c2 100644
--- a/test/general/implementation_details/device_copyable.pass.cpp
+++ b/test/general/implementation_details/device_copyable.pass.cpp
@@ -190,6 +190,15 @@ test_device_copyable()
             oneapi::dpl::__par_backend_hetero::__early_exit_find_or<policy_non_device_copyable, noop_device_copyable>>,
         "__early_exit_find_or is not device copyable with device copyable types");
 
+    // __leaf_sorter
+    // Note that the use of noop_device_copyable/noop_non_device_copyable is valid in this context because
+    // sycl::is_device_copyable specialization for __leaf_sorter does not require instantiation of
+    // __leaf_sorter with the provided types. See [temp.inst]/1 of C++17 spec for the details.
+    static_assert(
+        sycl::is_device_copyable_v<oneapi::dpl::__par_backend_hetero::__leaf_sorter<noop_device_copyable,
+                                                                                    noop_device_copyable>>,
+        "__leaf_sorter is not device copyable with device copyable types");
+
     //__not_pred
     static_assert(sycl::is_device_copyable_v<oneapi::dpl::__internal::__not_pred<noop_device_copyable>>,
                   "__not_pred is not device copyable with device copyable types");
@@ -423,6 +432,11 @@ test_non_device_copyable()
                                                                                             noop_non_device_copyable>>,
         "__early_exit_find_or is device copyable with non device copyable types");
 
+    // __leaf_sorter
+    static_assert(!sycl::is_device_copyable_v<oneapi::dpl::__par_backend_hetero::__leaf_sorter<noop_device_copyable,
+                                                                                               noop_non_device_copyable>>,
+                  "__leaf_sorter is device copyable with non device copyable types");
+
     //__not_pred
     static_assert(!sycl::is_device_copyable_v<oneapi::dpl::__internal::__not_pred<noop_non_device_copyable>>,
                   "__not_pred is device copyable with non device copyable types");