text: //===----------------------------------------------------------------------===//
  //
  //                     The LLVM Compiler Infrastructure
  //
  // This file is dual licensed under the MIT and the University of Illinois Open
  // Source Licenses. See LICENSE.TXT for details.
  //
  //===----------------------------------------------------------------------===//
  
  // <istream>
  
  // template<class charT, class traits>
  //   basic_istream<charT,traits>& operator>>(basic_istream<charT,traits>&& in, charT* s);
  
  #include <istream>
  #include <cassert>
  
  template <class CharT>
  struct testbuf
      : public std::basic_streambuf<CharT>
  {
      typedef std::basic_string<CharT> string_type;
      typedef std::basic_streambuf<CharT> base;
  private:
      string_type str_;
  public:
  
      testbuf() {}
      testbuf(const string_type& str)
          : str_(str)
      {
          base::setg(const_cast<CharT*>(str_.data()),
                     const_cast<CharT*>(str_.data()),
                     const_cast<CharT*>(str_.data()) + str_.size());
      }
  
      CharT* eback() const {return base::eback();}
      CharT* gptr() const {return base::gptr();}
      CharT* egptr() const {return base::egptr();}
  };
  
  int main()
  {
      {
          testbuf<char> sb("   abcdefghijk    ");
          std::istream is(&sb);
          char s[20];
          is >> s;
          assert(!is.eof());
          assert(!is.fail());
          assert(std::string(s) == "abcdefghijk");
      }
  #if TEST_STD_VER > 17
      {
          testbuf<char> sb("   abcdefghijk    ");
          std::istream is(&sb);
          char s[4];
          is >> s;
          assert(!is.eof());
          assert(!is.fail());
          assert(std::string(s) == "abc");
      }
  #endif
      {
          testbuf<wchar_t> sb(L"   abcdefghijk    ");
          std::wistream is(&sb);
          is.width(4);
          wchar_t s[20];
          is >> s;
          assert(!is.eof());
          assert(!is.fail());
          assert(std::wstring(s) == L"abc");
          assert(is.width() == 0);
      }
      {
          testbuf<wchar_t> sb(L"   abcdefghijk");
          std::wistream is(&sb);
          wchar_t s[20];
          is >> s;
          assert( is.eof());
          assert(!is.fail());
          assert(std::wstring(s) == L"abcdefghijk");
          assert(is.width() == 0);
      }
  #if TEST_STD_VER > 17
      {
          testbuf<wchar_t> sb(L"   abcdefghijk");
          std::wistream is(&sb);
          wchar_t s[4];
          is >> s;
          assert(!is.eof());
          assert(!is.fail());
          assert(std::wstring(s) == L"abc");
      }
  #endif
      {
          testbuf<char> sb("   abcdefghijk");
          std::istream is(&sb);
          char s[20];
          is.width(1);
          is >> s;
          assert(!is.eof());
          assert( is.fail());
          assert(std::string(s) == "");
          assert(is.width() == 0);
      }
  #if TEST_STD_VER > 17
      {
          testbuf<char> sb("   abcdefghijk");
          std::istream is(&sb);
          char s[1];
          is >> s;
          assert(!is.eof());
          assert( is.fail());
          assert(std::string(s) == "");
      }
  #endif
  }
  