#2024: Fix CI issue with empty CXX standard variable

CMakeLists.txt

@@ -39,7 +39,7 @@ set(CMAKE_CXX_EXTENSIONS OFF)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
 
 if(NOT CMAKE_CXX_STANDARD)
-  set(CMAKE_CXX_STANDARD 14 CACHE STRING "The C++ standard to use")
+  set(CMAKE_CXX_STANDARD 14 CACHE STRING "The C++ standard to use" FORCE)
 endif()
 message(STATUS "CMAKE_CXX_STANDARD: ${CMAKE_CXX_STANDARD}")
 

ci/build_cpp.sh

@@ -154,7 +154,7 @@ cmake -G "${CMAKE_GENERATOR:-Ninja}" \
       -Dvt_debug_verbose="${VT_DEBUG_VERBOSE:-}" \
       -Dvt_tests_num_nodes="${VT_TESTS_NUM_NODES:-}" \
       -Dvt_no_color_enabled="${VT_NO_COLOR_ENABLED:-0}" \
-      -DCMAKE_CXX_STANDARD="${CMAKE_CXX_STANDARD}" \
+      -DCMAKE_CXX_STANDARD="${CMAKE_CXX_STANDARD:-14}" \
       -DBUILD_SHARED_LIBS="${BUILD_SHARED_LIBS:-0}" \
       "$VT"
 cmake_conf_ret=$?

ci/build_vt_sample.sh

@@ -51,7 +51,7 @@ then
       -Dvt_trace_only="1" \
       -DVT_BUILD_EXAMPLES="0" \
       -DVT_BUILD_TESTS="0" \
-      -DCMAKE_CXX_STANDARD="${CMAKE_CXX_STANDARD}" \
+      -DCMAKE_CXX_STANDARD="${CMAKE_CXX_STANDARD:-14}" \
       -DCMAKE_EXPORT_COMPILE_COMMANDS=1 \
       -DCMAKE_BUILD_TYPE="${CMAKE_BUILD_TYPE:-Release}" \
       -DCMAKE_CXX_COMPILER="${CXX:-c++}" \