restore pair to main

Author: vinay-deshmukh

libcxx/include/__utility/pair.h

@@ -42,7 +42,6 @@
 #include <__utility/forward.h>
 #include <__utility/move.h>
 #include <__utility/piecewise_construct.h>
-#include <type_traits>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #  pragma GCC system_header
@@ -254,7 +253,6 @@ struct pair
       __enable_if_t<is_assignable<first_type&, _U1 const&>::value && is_assignable<second_type&, _U2 const&>::value,
                     int> = 0>
   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pair& operator=(pair<_U1, _U2> const& __p) {
-    // static_assert(std::is_same_v<decltype(first), decltype(__p.first)>);
     first  = __p.first;
     second = __p.second;
     return *this;