Test case:

class Test {
  public static void foo(char[] bar) {
    GLib.stdout.printf("%d\n", bar.length);
  }

  public static char[] bar() {
    return new char[16];
  }

  public static int main(string[] args) {
    var baz = bar();
    foo(baz);
    foo(bar());

    return 0;
  }
}

nemequ@desktop:~$ ./test
16
0

Generated C:

    test_foo ((_tmp3 = test_bar (&_tmp2)), _tmp2);

Instead, the C code should be as follows, as C doesn't guarantee that function arguments are evaluated in a specific order:

    ((_tmp3 = test_bar (&_tmp2)), test_foo (_tmp3, _tmp2));