[libc++][spaceship] P1614R2: Removed ops from `complex`

[H-G-Hristov]

Summary

Implements parts of P1614R2:

• Removed ops from complex

[Mordante]

In general LGTM, modulo one nit. I would like to land D152297 first and directly update the status page.

libcxx/include/complex

153

We keep all information.

[H-G-Hristov]

@Mordante Thank you for the review. I'll update the patches and do more of them after we land D152297.

libcxx/include/complex

153

Thank you for letting me know, I haven't seen this before.

[H-G-Hristov]

Addressed comments

[Mordante]

LGTM!

libcxx/include/complex

153

It's not that common, but we want to know that the difference in our implementation between versions is.

libcxx/docs/Status/SpaceshipProjects.csv

 | `[range.join.sentinel] <https://wg21.link/range.join.sentinel>`_,| remove ops `join_view::sentinel`,None,Unassigned,|Not Started|
 | `[range.split.outer] <https://wg21.link/range.split.outer>`_,| remove ops `split_view::outer_iterator`,None,Unassigned,|Not Started|
 | `[range.split.inner] <https://wg21.link/range.split.inner>`_,| remove ops `split_view::inner_iterator`,None,Unassigned,|Not Started|
 - `5.10 Clause 25: Algorithms library <https://wg21.link/p1614r2#clause-25-algorithms-library>`_,,,,
 "| `[algorithm.syn] <https://wg21.link/algorithm.syn>`_
 | `[alg.three.way] <https://wg21.link/alg.three.way>`_",| `lexicographical_compare_three_way <https://reviews.llvm.org/D131395>`_,[comparisons.three.way],Adrian Vogelsgesang,|Complete|
 - `5.11 Clause 26: Numerics library <https://wg21.link/p1614r2#clause-26-numerics-library>`_,,,,
 "| `[complex.syn] <https://wg21.link/complex.syn>`_
-| `[complex.ops] <https://wg21.link/complex.ops>`_",| remove ops `complex <https://reviews.llvm.org/D152615>`_,None,Hristo Hristov,|In Progress|
+| `[complex.ops] <https://wg21.link/complex.ops>`_",| remove ops `complex <https://reviews.llvm.org/D152615>`_,None,Hristo Hristov,|Complete|
 "| `[class.slice.overview] <https://wg21.link/class.slice.overview>`_
 | `[slice.ops] <https://wg21.link/slice.ops>`_",| `slice <https://reviews.llvm.org/D152617>`_,None,Hristo Hristov,|Complete|
 - `5.12 Clause 27: Time library <https://wg21.link/p1614r2#clause-27-time-library>`_,,,,
 | `[time.syn] <https://wg21.link/time.syn>`_,|,None,Unassigned,|Not Started|
 | `[time.duration.comparisons] <https://wg21.link/time.duration.comparisons>`_, `chrono::duration <https://reviews.llvm.org/D145881>`_, None, Hristo Hristov, |Complete|
 | `[time.point.comparisons] <https://wg21.link/time.point.comparisons>`_, `chrono::time_point <https://reviews.llvm.org/D146250>`_, None, Hristo Hristov, |Complete|
 "| `[time.cal.day.nonmembers] <https://wg21.link/time.cal.day.nonmembers>`_
 | `[time.cal.month.nonmembers] <https://wg21.link/time.cal.month.nonmembers>`_

libcxx/include/complex

 template<class T> complex<T> operator*(const complex<T>&, const complex<T>&); // constexpr in C++20
 template<class T> complex<T> operator*(const complex<T>&, const T&);          // constexpr in C++20
 template<class T> complex<T> operator*(const T&, const complex<T>&);          // constexpr in C++20
 template<class T> complex<T> operator/(const complex<T>&, const complex<T>&); // constexpr in C++20
 template<class T> complex<T> operator/(const complex<T>&, const T&);          // constexpr in C++20
 template<class T> complex<T> operator/(const T&, const complex<T>&);          // constexpr in C++20
 template<class T> complex<T> operator+(const complex<T>&);                    // constexpr in C++20
 template<class T> complex<T> operator-(const complex<T>&);                    // constexpr in C++20
-template<class T> bool operator==(const complex<T>&, const complex<T>&); // constexpr in C++14
-template<class T> bool operator==(const complex<T>&, const T&); // constexpr in C++14
-template<class T> bool operator==(const T&, const complex<T>&); // constexpr in C++14
-template<class T> bool operator!=(const complex<T>&, const complex<T>&); // constexpr in C++14
-template<class T> bool operator!=(const complex<T>&, const T&); // constexpr in C++14
-template<class T> bool operator!=(const T&, const complex<T>&); // constexpr in C++14
+template<class T> bool operator==(const complex<T>&, const complex<T>&);      // constexpr in C++14
+template<class T> bool operator==(const complex<T>&, const T&);               // constexpr in C++14
+template<class T> bool operator==(const T&, const complex<T>&);               // constexpr in C++14, removed in C++20
+template<class T> bool operator!=(const complex<T>&, const complex<T>&);      // constexpr in C++14, removed in C++20
+template<class T> bool operator!=(const complex<T>&, const T&);               // constexpr in C++14, removed in C++20
+template<class T> bool operator!=(const T&, const complex<T>&);               // constexpr in C++14, removed in C++20
 
 template<class T, class charT, class traits>
   basic_istream<charT, traits>&
   operator>>(basic_istream<charT, traits>&, complex<T>&);
 template<class T, class charT, class traits>
   basic_ostream<charT, traits>&
   operator<<(basic_ostream<charT, traits>&, const complex<T>&);
 

 template<class _Tp>
 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
 bool
 operator==(const complex<_Tp>& __x, const _Tp& __y)
 {
     return __x.real() == __y && __x.imag() == 0;
 }
 
+#if _LIBCPP_STD_VER <= 17
+
 template<class _Tp>
 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
 bool
 operator==(const _Tp& __x, const complex<_Tp>& __y)
 {
     return __x == __y.real() && 0 == __y.imag();
 }
 

 template<class _Tp>
 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX14
 bool
 operator!=(const _Tp& __x, const complex<_Tp>& __y)
 {
     return !(__x == __y);
 }
 
+#endif
+
 // 26.3.7 values:
 
 template <class _Tp, bool = is_integral<_Tp>::value,
                      bool = is_floating_point<_Tp>::value
                      >
 struct __libcpp_complex_overload_traits {};
 
 // Integral Types