Add c++ standard flag before loading BLT

Author: davidbeckingsale

CMakeLists.txt

@@ -92,6 +92,34 @@ if (ENABLE_CUDA)
   endif ()
 endif()
 
+# Detect C++ standard and add appropriate flag _before_ loading BLT
+set(COMPILERS_KNOWN_TO_CMAKE33 AppleClang Clang GNU MSVC)
+
+include(CheckCXXCompilerFlag)
+if(RAJA_CXX_STANDARD_FLAG MATCHES default)
+  if("cxx_std_17" IN_LIST CMAKE_CXX_KNOWN_FEATURES)
+    #TODO set BLT_CXX_STANDARD
+    set(CMAKE_CXX_STANDARD 17)
+  elseif("cxx_std_14" IN_LIST CMAKE_CXX_KNOWN_FEATURES)
+    set(CMAKE_CXX_STANDARD 14)
+  elseif("${CMAKE_CXX_COMPILER_ID}" IN_LIST COMPILERS_KNOWN_TO_CMAKE33)
+    set(CMAKE_CXX_STANDARD 14)
+  else() #cmake has no idea what to do, do it ourselves...
+    foreach(flag_var "-std=c++17" "-std=c++1z" "-std=c++14" "-std=c++1y" "-std=c++11")
+      CHECK_CXX_COMPILER_FLAG(${flag_var} COMPILER_SUPPORTS_${flag_var})
+      if(COMPILER_SUPPORTS_${flag_var})
+        set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${flag_var}")
+        break()
+      endif()
+    endforeach(flag_var)
+  endif()
+else(RAJA_CXX_STANDARD_FLAG MATCHES default)
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${RAJA_CXX_STANDARD_FLAG}")
+  message("Using C++ standard flag: ${RAJA_CXX_STANDARD_FLAG}")
+endif(RAJA_CXX_STANDARD_FLAG MATCHES default)
+
+set(CMAKE_CXX_EXTENSIONS OFF)
+
 if (NOT BLT_LOADED)
   if (DEFINED BLT_SOURCE_DIR)
     if (NOT EXISTS ${BLT_SOURCE_DIR}/SetupBLT.cmake)
@@ -110,7 +138,6 @@ if (NOT BLT_LOADED)
   endif ()
 
   include(${BLT_SOURCE_DIR}/SetupBLT.cmake)
-
 endif()
 
 # Setup basic CMake options

cmake/SetupCompilers.cmake

@@ -5,34 +5,6 @@
 # SPDX-License-Identifier: (BSD-3-Clause)
 ###############################################################################
 
-set(COMPILERS_KNOWN_TO_CMAKE33 AppleClang Clang GNU MSVC)
-
-include(CheckCXXCompilerFlag)
-if(RAJA_CXX_STANDARD_FLAG MATCHES default)
-  if("cxx_std_17" IN_LIST CMAKE_CXX_KNOWN_FEATURES)
-    #TODO set BLT_CXX_STANDARD
-    set(CMAKE_CXX_STANDARD 17)
-  elseif("cxx_std_14" IN_LIST CMAKE_CXX_KNOWN_FEATURES)
-    set(CMAKE_CXX_STANDARD 14)
-  elseif("${CMAKE_CXX_COMPILER_ID}" IN_LIST COMPILERS_KNOWN_TO_CMAKE33)
-    set(CMAKE_CXX_STANDARD 14)
-  else() #cmake has no idea what to do, do it ourselves...
-    foreach(flag_var "-std=c++17" "-std=c++1z" "-std=c++14" "-std=c++1y" "-std=c++11")
-      CHECK_CXX_COMPILER_FLAG(${flag_var} COMPILER_SUPPORTS_${flag_var})
-      if(COMPILER_SUPPORTS_${flag_var})
-        set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${flag_var}")
-        break()
-      endif()
-    endforeach(flag_var)
-  endif()
-else(RAJA_CXX_STANDARD_FLAG MATCHES default)
-  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${RAJA_CXX_STANDARD_FLAG}")
-  message("Using C++ standard flag: ${RAJA_CXX_STANDARD_FLAG}")
-endif(RAJA_CXX_STANDARD_FLAG MATCHES default)
-
-
-set(CMAKE_CXX_EXTENSIONS OFF)
-
 set(CMAKE_CXX_FLAGS_RELEASE "${CMAKE_CXX_FLAGS_RELEASE} -O3" CACHE STRING "")
 set(CMAKE_CXX_FLAGS_RELWITHDEBINFO "${CMAKE_CXX_FLAGS_RELWITHDEBINFO} -O3" CACHE STRING "")
 set(CMAKE_CXX_FLAGS_DEBUG "${CMAKE_CXX_FLAGS_DEBUG} -O0" CACHE STRING "")