Scope of MISRA conformance checker

[Rob Arthan]

According to the MISRA feature matrix, the MISRA add-on for cppcheck should check rule 5.3, which states that an identifier declared in an inner scope shall not hide an identifier declared in an outer scope. However, I don't get any issues reported when I check the following code:

extern int a;
int a;
static int f(void)
{
    int a;
    return 0;
}

I am running this using:

cppcheck --addon=misra.json t.c

where my misra.json file looks like this:

{
    "script": "misra.py",
    "args": [
        "--rule-texts=/Users/rda/git/pp-pro/src/qcz/misra.txt"
    ]
}

Am I not running the add-on correctly?

[Daniel Marjamäki]

Can you add the --enable=style please this particular warning is provided by core cppcheck and I think the message id is shadowVariable.

[CHR]

Looks like there has been a regression in cppcheck since https://github.com/chrchr-github/cppcheck/commit/3ef1212448aab2197ca8b58099b86fee68665c36

[Natalia Tejedor]

I have checked also your file, t.c, with option --enable=style:

 ./cppcheck --language=c --enable=style --addon=misra.json  t.c 

and it returns just:

../t.c:5:9: style: Unused variable: a [unusedVariable]
    int a;
        ^

Being "misra.jon":

{
  "script": "misra.py",
  "args": [
    "--suppress-rules 1.2,15.2,15.3,21.6,21.8,21.9,21.10"
  ]
}

Regarding 5.3 rule, this is not checked by Misra addon, it is checked by cppcheck itself, as it states here: http://cppcheck.net/misra.php

BTW, I take a pure example from MISRA pdf:

void fn1 (void)
{
  int16_t i;
  {
    int16_t i;
    i = 3;
  }
}

And, running the same command, it returns:

t-misra.c:5:13: style: Local variable 'i' shadows outer variable [shadowVariable]
    int16_t i;
            ^
t-misra.c:3:11: note: Shadowed declaration
  int16_t i;
          ^
t-misra.c:5:13: note: Shadow variable
    int16_t i;
            ^
t-misra.c:6:7: style: Variable 'i' is assigned a value that is never used. [unreadVariable]
    i = 3;
      ^
t-misra.c:3:11: style: Unused variable: i [unusedVariable]
  int16_t i;
          ^
t-misra.c:1:6: style: misra violation (use --rule-texts=<file> to get proper output) [misra-c2012-8.4]
void fn1 (void)
     ^

It seems the first 3 comments refers to this rule, 5.3, and last comment refers to other rule, and it seems to be ok.

[CHR]

The problem in cppcheck has been fixed with https://github.com/danmar/cppcheck/pull/4079

[Daniel Marjamäki]

Thanks CHR!