[oneDPL][ranges] + a fix: ranges::transform algo requires the all 3 ranges to be sized (according to p3179r4)

Author: MikeDvorskiy

include/oneapi/dpl/pstl/glue_algorithm_ranges_impl.h

@@ -99,35 +99,32 @@ struct __transform_fn
         return {std::ranges::begin(__r) + __size, std::ranges::begin(__out_r) +  __size};
     }
 
-    template<typename _ExecutionPolicy, std::ranges::random_access_range _R1, std::ranges::random_access_range _R2,
-             std::ranges::random_access_range _OutRange, std::copy_constructible _F, typename _Proj1 = std::identity,
-             typename _Proj2 = std::identity>
-    requires oneapi::dpl::is_execution_policy_v<std::remove_cvref_t<_ExecutionPolicy>> && (std::ranges::sized_range<_R1>
-        || std::ranges::sized_range<_R2>) && std::ranges::sized_range<_OutRange>
-        && std::indirectly_writable<std::ranges::iterator_t<_OutRange>,
-            std::indirect_result_t<_F&, std::projected<std::ranges::iterator_t<_R1>, _Proj1>,
-            std::projected<std::ranges::iterator_t<_R2>, _Proj2>>>
-
-    std::ranges::binary_transform_result<std::ranges::borrowed_iterator_t<_R1>, std::ranges::borrowed_iterator_t<_R2>,
-        std::ranges::borrowed_iterator_t<_OutRange>>
-    operator()(_ExecutionPolicy&& __exec, _R1&& __r1, _R2&& __r2, _OutRange&& __out_r, _F __binary_op,
-               _Proj1 __proj1 = {}, _Proj2 __proj2 = {}) const
+    template <typename _ExecutionPolicy, std::ranges::random_access_range _R1, std::ranges::random_access_range _R2,
+              std::ranges::random_access_range _OutRange, std::copy_constructible _F, typename _Proj1 = std::identity,
+              typename _Proj2 = std::identity>
+    requires oneapi::dpl::is_execution_policy_v<std::remove_cvref_t<_ExecutionPolicy>>&& std::ranges::sized_range<_R1>&&
+        std::ranges::sized_range<_R2>&& std::ranges::sized_range<_OutRange>&&
+            std::indirectly_writable<std::ranges::iterator_t<_OutRange>,
+                                     std::indirect_result_t<_F&, std::projected<std::ranges::iterator_t<_R1>, _Proj1>,
+                                                            std::projected<std::ranges::iterator_t<_R2>, _Proj2>>>
+
+                std::ranges::binary_transform_result<std::ranges::borrowed_iterator_t<_R1>,
+                                                     std::ranges::borrowed_iterator_t<_R2>,
+                                                     std::ranges::borrowed_iterator_t<_OutRange>>
+                operator()(_ExecutionPolicy&& __exec, _R1&& __r1, _R2&& __r2, _OutRange&& __out_r, _F __binary_op,
+                           _Proj1 __proj1 = {}, _Proj2 __proj2 = {}) const
     {
         const auto __dispatch_tag = oneapi::dpl::__ranges::__select_backend(__exec);
 
         using _Size = std::common_type_t<oneapi::dpl::__internal::__range_size_t<_R1>,
             oneapi::dpl::__internal::__range_size_t<_R2>, std::ranges::range_size_t<_OutRange>>;
-        _Size __size = std::ranges::size(__out_r);
-        if constexpr(std::ranges::sized_range<_R1>)
-            __size = std::ranges::min(__size, (_Size)std::ranges::size(__r1));
-        if constexpr(std::ranges::sized_range<_R2>)
-            __size = std::ranges::min(__size, (_Size)std::ranges::size(__r2));
+        const _Size __size = std::ranges::min((_Size)std::ranges::size(__r1), (_Size)std::ranges::size(__r2),
+                                              (_Size)std::ranges::size(__out_r));
 
-        //take_view doesn't make unsized range sized, so subrange is used below
-        oneapi::dpl::__internal::__ranges::__pattern_transform(__dispatch_tag, std::forward<_ExecutionPolicy>(__exec),
-            std::ranges::subrange(std::ranges::begin(__r1), std::ranges::begin(__r1) + __size),
-            std::ranges::subrange(std::ranges::begin(__r2), std::ranges::begin(__r2) + __size),
-            std::ranges::take_view(__out_r, __size), __binary_op, __proj1, __proj2);
+        oneapi::dpl::__internal::__ranges::__pattern_transform(
+            __dispatch_tag, std::forward<_ExecutionPolicy>(__exec), std::ranges::take_view(__r1, __size),
+            std::ranges::take_view(__r2, __size), std::ranges::take_view(__out_r, __size), __binary_op, __proj1,
+            __proj2);
 
         return {std::ranges::begin(__r1) + __size, std::ranges::begin(__r2) + __size, std::ranges::begin(__out_r) + __size};
     }

test/parallel_api/ranges/std_ranges_transform_iota.pass.cpp

@@ -21,11 +21,12 @@ main()
 #if _ENABLE_STD_RANGES_TESTING
     using namespace test_std_ranges;
     namespace dpl_ranges = oneapi::dpl::ranges;
-    const char* err_msg = "Wrong effect algo transform with unsized ranges.";
+    const char* err_msg = "Wrong effect algo ranges::transform.";
 
-    const int n = medium_size;
-    std::ranges::iota_view view1(0, n); //size range
-    std::ranges::iota_view view2(0, std::unreachable_sentinel_t{}); //unsized
+    const int n1 = medium_size;
+    const int n2 = medium_size/2;
+    std::ranges::iota_view view1(0, n1);
+    std::ranges::iota_view view2(0, n2);
 
     std::vector<int> res(n), expected(n);
     std::ranges::transform(view1, view2, expected.begin(), binary_f, proj, proj);