Vala fails to compile the next test case:

[test.vala]

void modify(out int n) {
        n = 5;
}

void main() {
        int[] a = new int[3];
        for(int i=0; i<a.length; i++)
                modify(out a[i]);
}

[/test.vala]


$ valac test.vala 
test.vala:8.10-8.17: error: ref and out method arguments can only be used with fields, parameters, and local variables
		modify(out a[i]);
		       ^^^^^^^^
Compilation failed: 1 error(s), 0 warning(s)