False Uninitialized variable

[Martin Poupě]

Hello,
have a code:

#include <stdint.h>

static uint8_t GetValue(uint8_t n)
{
    uint8_t i,buf[10];
    for(i = 0; i < n; i++)
    {
        buf[i] = i;
    }
    return buf[n / 2];
}

uint8_t Test(uint8_t k)
{
    return GetValue((k & 7) + 1);
}

cppcheck 2.14 says:
tmp.c:10:12: warning: Uninitialized variable: buf [uninitvar]
return buf[n / 2];
^
tmp.c:6:18: note: Assuming condition is false
for(i = 0; i < n; i++)
^
tmp.c:10:12: note: Uninitialized variable: buf
return buf[n / 2];
^
However n is always at least 1, so the used part of the buf is always set.
I know, it requires global analysis :-)

[CHR]

So GetValue() must not be called with n == 0, which is dangerous at best.
We also warn for

int f(int i) {
    int a;
    if (i != 42)
        a = 7;
    return a;
}

[Martin Poupě]

Yes, it is dangerous to call GetValue(0), however this case will never happen. The function is static, so not callable from outside of this source and the only place of call is safe, because routine Test() always calls with n at least 1.