* On some compilers it's a struct and cannot be used in arithmetic
  expressions.

* On some machines this test will create core files on every
    make check
  if not disallowed with ulimit -c 0.

* Also fixes implicit type conversion.

* clang otherwise about having more cases than enum values.

* ...to wrapper of extended copy constructor.

* The control flow is too complicated for gcc to notice unitialized
  pointers will not be used.