Editor highlighting of conditional statements based on the __cplusplus symbol is incorrect in CCSv9.x. It always shows that it is defined, even if it is not. The compiler handles the condition correctly. The issue seems to be with the Language Mapping. When specifying C source files to map to the default "TI GNU C", the issue occurs. When explicitly mapping it to "GNU C", the issue goes away. There is something related to the "TI GNU C" mapping.