Refs #11808. Add WITH_UBSAN option to cmake script.

Code/Mantid/Build/CMake/GNUSetup.cmake

@@ -14,6 +14,11 @@ elseif ( "${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang" )
   message( STATUS "clang version ${CMAKE_CXX_COMPILER_VERSION}" )
 endif()
 
+#Use the old ABI until the dust has settled and all dependencies are built with the new ABI.
+if ( CMAKE_COMPILER_IS_GNUCXX AND NOT (GCC_COMPILER_VERSION VERSION_LESS "5.1.0"))
+  add_definitions(-D_GLIBCXX_USE_CXX11_ABI=0)
+endif()
+
 # Global warning flags.
 set( GNUFLAGS "-Wall -Wextra -Wconversion -Winit-self -Wpointer-arith -Wcast-qual -Wcast-align -fno-common" )
 # Disable some warnings about deprecated headers and type conversions that
@@ -46,6 +51,20 @@ if(WITH_ASAN)
   set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} -fsanitize=address -lasan" )
 endif()
 
+option(WITH_UBSAN "Enable undefined behavior sanitizer" OFF)
+if(WITH_UBSAN)
+  message(STATUS "enabling undefined behavior sanitizers")
+  set( UBSAN_NO_RECOVER "-fno-sanitize-recover")
+  if ( CMAKE_COMPILER_IS_GNUCXX AND GCC_COMPILER_VERSION VERSION_LESS "5.1.0")
+    set( UBSAN_NO_RECOVER "")
+  endif()
+  set(SAN_FLAGS "-fno-omit-frame-pointer -fno-common -fsanitize=undefined ${UBSAN_NO_RECOVER}")
+  add_compile_options(-fno-omit-frame-pointer -fno-common -fsanitize=undefined ${UBSAN_NO_RECOVER})
+  set(CMAKE_MODULE_LINKER_FLAGS "${CMAKE_MODULE_LINKER_FLAGS} ${SAN_FLAGS}" )
+  set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} ${SAN_FLAGS}" )
+  set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} ${SAN_FLAGS}" )
+endif()
+
 # Set the options for gcc and g++
 set( CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${GNUFLAGS}" )
 # -Wno-overloaded-virtual is down here because it's not applicable to the C_FLAGS