[libc++][NFC] Explicitly delete assignment operator in tuple (#90604)

Author: philnik777

libcxx/include/tuple

@@ -304,7 +304,7 @@ class __tuple_leaf {
 #  endif
   }
 
-  _LIBCPP_CONSTEXPR_SINCE_CXX14 __tuple_leaf& operator=(const __tuple_leaf&);
+  _LIBCPP_CONSTEXPR_SINCE_CXX14 __tuple_leaf& operator=(const __tuple_leaf&) = delete;
 
 public:
   _LIBCPP_HIDE_FROM_ABI constexpr __tuple_leaf() _NOEXCEPT_(is_nothrow_default_constructible<_Hp>::value) : __value_() {
@@ -380,7 +380,7 @@ public:
 
 template <size_t _Ip, class _Hp>
 class __tuple_leaf<_Ip, _Hp, true> : private _Hp {
-  _LIBCPP_CONSTEXPR_SINCE_CXX14 __tuple_leaf& operator=(const __tuple_leaf&);
+  _LIBCPP_CONSTEXPR_SINCE_CXX14 __tuple_leaf& operator=(const __tuple_leaf&) = delete;
 
 public:
   _LIBCPP_HIDE_FROM_ABI constexpr __tuple_leaf() _NOEXCEPT_(is_nothrow_default_constructible<_Hp>::value) {}
@@ -1375,22 +1375,22 @@ inline _LIBCPP_HIDE_FROM_ABI constexpr _Tp __make_from_tuple_impl(_Tuple&& __t,
 }
 #else
 template <class _Tp, class _Tuple, size_t... _Idx>
-inline _LIBCPP_HIDE_FROM_ABI constexpr _Tp __make_from_tuple_impl(_Tuple&& __t, __tuple_indices<_Idx...>, 
+inline _LIBCPP_HIDE_FROM_ABI constexpr _Tp __make_from_tuple_impl(_Tuple&& __t, __tuple_indices<_Idx...>,
     enable_if_t<is_constructible_v<_Tp, decltype(std::get<_Idx>(std::forward<_Tuple>(__t)))...>> * = nullptr)
     _LIBCPP_NOEXCEPT_RETURN(_Tp(std::get<_Idx>(std::forward<_Tuple>(__t))...))
 #endif // _LIBCPP_STD_VER >= 20
 
-template <class _Tp, class _Tuple, 
+template <class _Tp, class _Tuple,
           class _Seq = typename __make_tuple_indices<tuple_size_v<remove_reference_t<_Tuple>>>::type, class = void>
 inline constexpr bool __can_make_from_tuple = false;
 
 template <class _Tp, class _Tuple, size_t... _Idx>
-inline constexpr bool __can_make_from_tuple<_Tp, _Tuple, __tuple_indices<_Idx...>, 
+inline constexpr bool __can_make_from_tuple<_Tp, _Tuple, __tuple_indices<_Idx...>,
     enable_if_t<is_constructible_v<_Tp, decltype(std::get<_Idx>(std::declval<_Tuple>()))...>>> = true;
 
-// Based on LWG3528(https://wg21.link/LWG3528) and http://eel.is/c++draft/description#structure.requirements-9, 
-// the standard allows to impose requirements, we constraint std::make_from_tuple to make std::make_from_tuple 
-// SFINAE friendly and also avoid worse diagnostic messages. We still keep the constraints of std::__make_from_tuple_impl 
+// Based on LWG3528(https://wg21.link/LWG3528) and http://eel.is/c++draft/description#structure.requirements-9,
+// the standard allows to impose requirements, we constraint std::make_from_tuple to make std::make_from_tuple
+// SFINAE friendly and also avoid worse diagnostic messages. We still keep the constraints of std::__make_from_tuple_impl
 // so that std::__make_from_tuple_impl will have the same advantages when used alone.
 #if _LIBCPP_STD_VER >= 20
 template <class _Tp, class _Tuple>