[BUG] -Wuninitialized: initialize variable with itself

[Alejandro Colomar via Gcc]

Hi,





    int main(void)
    {
        int i = i;
        return i;
    }


It seems obvious that it should give a warning, and in Clang it does:


    $ clang --version | head -n1
    Debian clang version 14.0.6

    $ clang -Wall -Wextra foo.c

            int i = i;
                ~   ^
    1 warning generated.


But for GCC it looks fine:

    $ gcc --version | head -n1
    gcc (Debian 12.2.0-9) 12.2.0

    $ gcc -Wall -Wextra foo.c
    $


Until you enable the analyzer, which catches the uninitialized use:


    $ gcc -fanalyzer foo.c
    foo.c: In function ‘main’:

        3 |         int i = i;
          |             ^
      ‘main’: events 1-2
        |
        |    3 |         int i = i;
        |      |             ^
        |      |             |
        |      |             (1) region created on stack here
        |      |             (2) use of uninitialized value ‘i’ here
        |





Cheers,
Alex

--
<http://www.alejandro-colomar.es/>

While discussing some idea for a new feature, I tested the following example program: foo.c:3:10: warning: variable 'i' is uninitialized when used within its own initialization [-Wuninitialized] foo.c:3:13: warning: use of uninitialized value ‘i’ [CWE-457] [-Wanalyzer-use-of-uninitialized-value] I expect that GCC should be able to detect this bug with a simple warning. The analyzer is quite unreadable compared to normal warnings.

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