For the same reason that this:

    if (c)
        printf("Hello");
        exit(0);
    exit(1);

Produces a warning in gcc:

    test.c:7:5: warning: this ‘if’ clause does not guard... [-Wmisleading-indentation]
         if (c)
         ^~
    test.c:9:9: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the ‘if’
             exit(0);
             ^~~~

"2^32" is of course just an xor, but it makes no sense (the "exclusive" part of it is not being exercised). If you really mean 2 bits being set in a constant then "2 | 32" is much clearer. If you're dead set on xor, "32^2" won't trigger the warning.