Test gcc's -Wuninitialized

// Compile with gcc -Wuninitialized

#include <stdio.h>

int main()
{
    int a = getchar();
    int x;

    if (a <= 'Z') {
        x = 'A';
    }

    putchar(x); // Could warn, but doesn't (4.6.3)

    return 0;
}