I have to study a software that compiles under v6.3.2 with no errors.

The problem is that when try to compile it under v6.5.0 several compiler errors occur, for example: 'comma at end of 
enumerator list'.

In other forums I see that the upwritten error can be avoided with the compiler option '-std=c99', but when I try to use
 it the qcc give me the following error:
cc: unknown option: '-std=c99'

I tried also to compile using the command line outside Momentics, but the error is the same so this error is not related
 to the makefile.

Can you help me?