From 3ebad06bd4ef95530b10ea47c0b26f9c43aeceba Mon Sep 17 00:00:00 2001
From: James Price <j.price@bristol.ac.uk>
Date: Wed, 11 May 2016 22:22:20 +0100
Subject: [PATCH] [SYCL] Fix detection of CL/sycl.hpp for C++14 versions

---
 CMakeLists.txt | 20 +++++++++++++++-----
 1 file changed, 15 insertions(+), 5 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 34847ba..8d10c40 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -7,6 +7,7 @@ set(CMAKE_CXX_STANDARD_REQUIRED ON)
 project(gpu-stream)
 
 include(CheckIncludeFileCXX)
+include(CheckCXXCompilerFlag)
 
 set(gpu-stream_VERSION_MAJOR 2)
 set(gpu-stream_VERSION_MINOR 0)
@@ -110,22 +111,31 @@ endif ()
 #-------------------------------------------------------------------------------
 # SYCL
 #-------------------------------------------------------------------------------
-set(CMAKE_REQUIRED_FLAGS "-std=c++11")
+if ("${CMAKE_CXX_COMPILER_ID}" MATCHES "Clang" OR
+    "${CMAKE_CXX_COMPILER_ID}" MATCHES "GNU")
+  # Use C++14 if available, otherwise drop back to C++11
+  check_cxx_compiler_flag("-std=c++14" CXX14)
+  if (CXX14)
+    set(CMAKE_REQUIRED_FLAGS "-std=c++14")
+  else()
+    set(CMAKE_REQUIRED_FLAGS "-std=c++11")
+  endif()
+endif()
+
 check_include_file_cxx("CL/sycl.hpp" HAS_SYCL)
 if (HAS_SYCL)
+  add_executable(gpu-stream-sycl main.cpp SYCLStream.cpp)
+  target_compile_definitions(gpu-stream-sycl PUBLIC SYCL)
+
   find_program(COMPUTECPP "compute++")
   if (COMPUTECPP)
     message(STATUS "Using ComputeCpp for SYCL compilation")
     add_custom_target(SYCLStream.sycl COMMAND ${COMPUTECPP} ${CMAKE_CURRENT_SOURCE_DIR}/SYCLStream.cpp -sycl -no-serial-memop -O2 -emit-llvm -c)
-    add_executable(gpu-stream-sycl main.cpp SYCLStream.cpp)
     add_dependencies(gpu-stream-sycl SYCLStream.sycl)
-    target_compile_definitions(gpu-stream-sycl PUBLIC SYCL)
     target_compile_options(gpu-stream-sycl PUBLIC -include SYCLStream.sycl)
     target_link_libraries(gpu-stream-sycl SYCL OpenCL)
   else()
     message(STATUS "Using header-only SYCL implementation")
-    add_executable(gpu-stream-sycl main.cpp SYCLStream.cpp)
-    target_compile_definitions(gpu-stream-sycl PUBLIC SYCL)
     set_property(TARGET gpu-stream-sycl PROPERTY CXX_STANDARD 14)
   endif(COMPUTECPP)
 else ()