misra check crashing during misra_20_9 check

[Peter Schops]

when you have the following in the code, the misra check crashes in the misra_20_9 check

#define bad_define
#define correct_define 1

#if bad_define
  printf ("will crash the misra check\n");
#endif

#if correct_define
   printf ("Hello\n");
#endif

I managed to fix the code by adding an extra escape in misra.py. This way we don't try to access s[0] after the cond.E.split

    def misra_20_9(self, cfg):
        for cond in cfg.preprocessor_if_conditions:
            if cond.E is (None or u""):
                continue

I found it also strange that misra_20_8 is not flagging this line. bad_define is assinged no value. So how can cond.result evaluate to 0 or 1. (0 in this case)
To get the attention I added some extra condition to set misra_20_8, which is probably not totally correct.

    def misra_20_8(self, cfg):
        for cond in cfg.preprocessor_if_conditions:
            if cond.E is (None or u""):
                self.reportError(cond, 20, 8)
            if cond.result and cond.result not in (0,1):
                self.reportError(cond, 20, 8)

[Daniel Marjamäki]

Feel free to create a PR. I will not do any more active work on misra.py.. but will be happy to review/merge PRs that fix misra.py bugs.

We provide better Misra checking in Cppcheck Premium.