cppcheck Misra 17.3 and UINT8_C

[Andrea Innocenti]

Hello,

I have configured cppcheck2.16.0 in order to parse misra informations.
It seems to me that everything is working correctly but I have a strange behavior related to the rule in object.

I am working with arm-none-eabi-gcc, and I am using stdint.h as a source for the types defined as integers in order to guarantee the correct int.

What I am noticing is the following:

I have this line of code that triggers the warning:

if ((size > UINT8_C(0)) && (size <= UINT8_C(7))) {<--- A function shall not be declared implicitly

while the following is accepted:

uint16_t size = data[0] & UINT8_C(0x0F);

The two lines of code are in the same source file, therefore I can exclude that they are treated in a different way.

I have different warnings and different "not warning in the same file". What I can think about is that in the first case, the one with the warning, the UINT8_C is inside an if condition, while in the second case, UINT8_C is used in an assignment to a variable.

This seems always the case except in a couple of occasions like

switch ((data[0] & UINT8_C(0xF0)) >> UINT8_C(4))

 if (minDelayMs >= UINT8_C(0xF1)) {

It seems to me a false positive. C compiler does not issue any warning for the file. Just the misra parser.

Do you see anything wrong with the use of UINT8_C in those situations?

Thank you in advance

[Andrea Innocenti]

I would like to add that refactoring the code in this way

  uint8_t seven = UINT8_C(7);
  uint8_t zero = UINT8_C(0);
if ((size > zero) && (size <= seven))

the warning disappears.
It seems a false positive to me.

What do you think?

[Daniel Marjamäki]

Thanks for the bug report. I can reproduce and I agree it's a FP. I have created this ticket:
https://trac.cppcheck.net/ticket/13370