Add support for AdaptiveCpp to C++ Standard Parallelism

src/std/STDStream.cpp

@@ -149,7 +149,7 @@ template <class T>
 void STDStream<T>::nstream()
 {
   //  a[i] += b[i] + scalar * c[i];
-#if defined(DATA17) || defined(DATA23) // Until we can require GCC 14.1
+#if defined(DATA17)
   //  Need to do in two round-trips with C++17 STL.
   //  1: a[i] += b[i]
   //  2: a[i] += scalar * c[i];
@@ -160,6 +160,7 @@ void STDStream<T>::nstream()
   auto as = std::ranges::subrange(a, a + array_size);
   auto bs = std::ranges::subrange(b, b + array_size);
   auto cs = std::ranges::subrange(c, c + array_size);
+  auto r = std::views::zip(as, bs, cs);
   std::transform(exe_policy, r.begin(), r.end(), a, [](auto vs) {
       auto [a, b, c] = vs;
       return a + b + startScalar * c;

src/std/model.cmake

@@ -20,6 +20,10 @@ register_flag_optional(NVHPC_OFFLOAD
            ccnative - Compiles for compute capability of current device"
 	"")
 
+register_flag_optional(ACPP_OFFLOAD
+        "Enable offloading support (via the non-standard `-acpp-stdpar`) for AdaptiveCpp."
+	"OFF")
+
 register_flag_optional(USE_TBB
         "No-op if ONE_TBB_DIR is set. Link against an in-tree oneTBB via FetchContent_Declare, see top level CMakeLists.txt for details."
         "OFF")
@@ -59,8 +63,17 @@ macro(setup)
         register_append_cxx_flags(ANY ${NVHPC_FLAGS})
         register_append_link_flags(${NVHPC_FLAGS})
     endif ()
+    if (ACPP_OFFLOAD)
+        set(ACPP_FLAGS --acpp-stdpar)
+        register_append_cxx_flags(ANY ${ACPP_FLAGS})
+        register_append_link_flags(${ACPP_FLAGS})      
+    endif ()
     if (USE_TBB)
-      register_link_library(TBB::tbb)
+      if (FETCH_TBB)
+	register_link_library(TBB::tbb)
+      else ()
+	register_link_library(tbb)
+      endif ()
     endif ()
     if (USE_ONEDPL)
         register_definitions(USE_ONEDPL)