[cfe-dev] testing the clang static code analyzer

[Anna Zaks]

On Aug 15, 2013, at 9:16 AM, Lior Brafman <liorbr at checkpoint.com> wrote:

> Hi,
>  
> I installed the Clang Static Code Analyzer and tried testing it with a very simple example:
> #include <stdio.h>
> #include <stdlib.h>
>  
> Int main(int ac, char* argv[])
> {
>                 int a;
>                 char *string;
>  
>                 string = (char*) malloc(10);
>                 string[11] = ‘X’;
>                 return *(int *)0;
> }
>  
> I expected 4 errors to be discover:
> 1.       Unused variable: a

We are warning about this one if the value is being assigned to:
                int a;
                a = 2;

Though, we do not warn when it's not being assigned to to allow code like this:
int a;
if (flag) { 
  a = 1;
  use (a);
}
// We don't want to warn here.

> 2.       Out of bound access to array string

Currently, we do not have any on-by-default checker that would catch this.

> 3.       Memory leak: string

We suppress leaks and other less critical issues if they occur on the same path as a very serious issue (such as a null ptr dereference). This is a heuristic which is supposed to show only the most important from a set of related issues. The heuristic is very simple, so it works agains us in this case. If you remove the null pointer dereference, you'll see the leak warning.

> 4.       Dereference of null pointer at the return statement
>  
> But instead only one error was discovered (error number 4)
>  
> Can you please help me figure out why I don’t get all the errors?
>  
> Thanks,
> Lior Brafman
> R&D
> CheckPoint
> _______________________________________________
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> cfe-dev at cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev

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