Made oneDPL work with a modern DPC++ / old GCC combination.

Upgraded to the very latest version of oneDPL to make it
compatible with the latest oneAPI / DPC++ versions.

Updated the TBB build to make find_package(TBB) calls
functional, so that the oneDPL build/configuration would
find the TBB version built by the project.

Moved the oneDPL includes at the beginning of the test source
file, as they are very sensitive to include orders when using
GCC 9 as it turns out.

Author: krasznaa

extern/dpl/CMakeLists.txt

@@ -18,13 +18,20 @@ message( STATUS "Building oneDPL as part of the TRACCC project" )
 
 # Declare where to get DPL from.
 set( TRACCC_DPL_SOURCE
-   "URL;https://github.com/oneapi-src/oneDPL/archive/refs/tags/oneDPL-2022.0.0-release.tar.gz;URL_MD5;46b60bd87325042df716d1df4686eb3b"
+   "URL;https://github.com/oneapi-src/oneDPL/archive/refs/tags/oneDPL-2022.2.0-rc1.tar.gz;URL_MD5;e63a3903873636b464db6ee7a9364055"
    CACHE STRING "Source for DPL, when built as part of this project" )
 mark_as_advanced( TRACCC_DPL_SOURCE )
 FetchContent_Declare( DPL ${TRACCC_DPL_SOURCE} )
 
-# Exclude TBB
-set( ONEDPL_BACKEND dpcpp_only )
+# Set the default oneDPL threading backend.
+set( ONEDPL_BACKEND "dpcpp" CACHE STRING "oneDPL threading backend" )
 
 # Get it into the current directory.
 FetchContent_MakeAvailable( DPL )
+
+# Treat the oneDPL headers as "system headers", to avoid getting warnings from
+# them.
+get_target_property( _incDirs oneDPL INTERFACE_INCLUDE_DIRECTORIES )
+target_include_directories( oneDPL
+   SYSTEM INTERFACE ${_incDirs} )
+unset( _incDirs )

extern/tbb/CMakeLists.txt

@@ -1,6 +1,6 @@
 # TRACCC library, part of the ACTS project (R&D line)
 #
-# (c) 2022 CERN for the benefit of the ACTS project
+# (c) 2022-2023 CERN for the benefit of the ACTS project
 #
 # Mozilla Public License Version 2.0
 
@@ -27,5 +27,23 @@ FetchContent_Declare( TBB ${TRACCC_TBB_SOURCE} )
 set( TBB_TEST FALSE CACHE BOOL "Turn off the TBB tests" )
 set( TBB_STRICT FALSE CACHE BOOL "Do not throw errors on compiler warnings" )
 
-# Get it into the current directory.
+# Get it into the current directory. Setting TBB_DIR locally to an empty string
+# is necessary so that incremental rebuilds would not get confused about the
+# TBB_DIR cache variable set a little further down in this file. (The TBB CMake
+# configuration is plenty weird...)
+set( TBB_DIR "" )
 FetchContent_MakeAvailable( TBB )
+
+# Make CMake pick up a no-op TBBConfig.cmake file in any possible
+# find_package(TBB) call. (Mostly needed in case other externals also need
+# TBB.)
+include( CMakePackageConfigHelpers )
+configure_file( "${CMAKE_CURRENT_SOURCE_DIR}/TBBConfig.cmake.in"
+   "${CMAKE_CURRENT_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/TBBConfig.cmake"
+   @ONLY )
+write_basic_package_version_file(
+   "${CMAKE_CURRENT_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/TBBConfig-version.cmake"
+   VERSION "2021.7.0"
+   COMPATIBILITY "AnyNewerVersion" )
+set( TBB_DIR "${CMAKE_CURRENT_BINARY_DIR}${CMAKE_FILES_DIRECTORY}" CACHE PATH
+   "TBBConfig.cmake location" )

extern/tbb/TBBConfig.cmake.in

@@ -0,0 +1,10 @@
+# TRACCC library, part of the ACTS project (R&D line)
+#
+# (c) 2023 CERN for the benefit of the ACTS project
+#
+# Mozilla Public License Version 2.0
+
+# Dummy file for making find_package(TBB) calls a no-op when the TRACCC
+# project is building TBB itself.
+
+message( "Woo Hoo!!!" )

tests/sycl/test_dpl.sycl

@@ -5,6 +5,10 @@
  * Mozilla Public License Version 2.0
  */
 
+// DPL include(s).
+#include <oneapi/dpl/algorithm>
+#include <oneapi/dpl/execution>
+
 // SYCL include(s).
 #include <CL/sycl.hpp>
 
@@ -15,10 +19,6 @@
 #include <vecmem/memory/sycl/device_memory_resource.hpp>
 #include <vecmem/utils/sycl/copy.hpp>
 
-// DPL include(s).
-#include <oneapi/dpl/algorithm>
-#include <oneapi/dpl/execution>
-
 // GTest include(s).
 #include <gtest/gtest.h>