Fix for MISRA rule 4.1 to avoid false positives for octal escape sequ…

[matzeschmid]

…ences less than 3 octal digits and hexadecimal escape sequences less than 2 hexadecimal digits (ticket #9370).

Add end of sequence check for single quoted sequences.
Add compliant and non-compliant test cases for short escape sequences.

[matzeschmid]

Based on the discussion of development thread started by Richard Smith i created the changes for this pull request.
Versat opened a ticket for this (#9370).
Discussion thread: https://sourceforge.net/p/cppcheck/discussion/development/thread/7274ed3842/

[matzeschmid]

I just saw that there is another pull request #2216 with a fix for ticket #9370.
And it really looks much better than my fix.
It's not just a fix, it's a complete refactoring of MISRA 4.1 rule checker, clear structure, much easier to read and understand.

[jubnzv]

I see some problems with parsing expressions that contains 2+ digits, e.g. following examples will cause FP:

int c41_12         = '\12323';
int c41_13         = '\1232\3';

[matzeschmid]

Based on discussion on #2216 i checked the fix against the following code and got the expected result. I agree, some of the checks should be added to test file.

int c41_12        = '\12323';  // 4.1
int c41_13        = '\1232\3'; // 4.1

void misra_4_1()
{
    (void)printf("\x41g");         // 4.1
    (void)printf("\x8g");          // 4.1
    (void)printf("\x41\x42");
    (void)printf("\x41" "g");
    (void)printf("%i", '\141t');   // 4.1
    (void)printf("%i", '\141\t');
    (void)printf("%i", '\141');
    (void)printf("%i", '\0t');     // 4.1
    (void)printf("%i", '\0\t');
    (void)printf("%i", '\0');
    (void)printf("%i", '\12t');    // 4.1
    (void)printf("%i", '\12\t');
    (void)printf("%i", '\12');
    (void)printf("%i", '\12323');  // 4.1
    (void)printf("%i", '\1232\3'); // 4.1
}

[matzeschmid]

Checked fix against strings which contains simple escape sequences (especially \\) which should not lead to MISRA 4.1 false positive. Passed, got expected result.

Test lines:

const char *s41_9 = "hello\\world\n";
(void)printf("hello\\world\r\n");

[danmar]

I merged the other PR... please update this now.

[matzeschmid]

I merged the other PR... please update this now.

OK, fine.
So i just close my PR to remove it from the list, right ?

[danmar]

ok.

[danmar]

thanks for your work. if you think the other pr should be tweaked somehow let me know.