Is there any MISRA rule to find this sideeffect??

[dg1980]

Hi
Isn't there a rule to ensure that comparison is perform on same object type?

Check the table in MISRA C 2012 Appendix D.1: both operands are essentially unsigned.
The table in rule 10.1 poses no restrictions on operator < for essentially unsigned operands.
If both operands are supposed to be of the same essential type (not just the same essential type category): that is not clearly stated IMHO.
IMHO, currently the bug would be catched only if there is a narrowing assignment which is prohibited by rule 10.3 (see below).
Anyhow, an official clarification would be nice.

Code:

#include

int main(void)
{
  unsigned char var1 = 0;
  unsigned short var2 =  300;
  const unsigned char cmp = var2;/*Expression assigned to a narrower or different essential type [MISRA 2012 Rule 10.3, required]*/

  while (var1 <  cmp)
  {
    var1++;
  }
  (void)printf("program completed \n ");
  return 0;
}