cpp: define isl::managed_copy() overload

[ftynse]

I found myself writing
isl::manage(isl_whatever_copy(o)); // manage releases!
multiple times.

Can we generate an overloaded function

isl::whatever managed_copy(__isl_keep isl_whatever *w) {
  return isl::manage(isl_whatever_copy(w));
}

as a shortcut for these cases?

[ftynse]

While the idea of the C++ interface is not to use raw pointers, other isl-dependent libraries (read ppcg) may use raw pointers and feature no C++ interface.

[tobiasgrosser]

Sounds very reasonable. Should be a rather simple change and this is indeed a pattern that arises often. Would be glad to see a PR.

[ftynse]

This hack may work, but it will break the consistency of __isl_keep/__isl_take because manage is __take.

template <typename T>
auto managed_copy(__isl_keep T t) -> decltype(isl::manage(t)) {
  auto x = isl::manage(t);
  auto copy = x;
  x.release();
  return copy;
}

[tobiasgrosser]

I would just extend the generator. Should only be a couple of lines and
can follow precisely the pattern isl::manage is generated.

Best,
Tobias

[tobiasgrosser]

This issue has been resolved.