libstdc++-v3/testsuite/27_io/basic_istringstream/rdbuf/wchar_t/2832.cc

   1 // Copyright (C) 2004-2020 Free Software Foundation, Inc.
   2 //
   3 // This file is part of the GNU ISO C++ Library.  This library is free
   4 // software; you can redistribute it and/or modify it under the
   5 // terms of the GNU General Public License as published by the
   6 // Free Software Foundation; either version 3, or (at your option)
   7 // any later version.
   8
   9 // This library is distributed in the hope that it will be useful,
  10 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 // GNU General Public License for more details.
  13
  14 // You should have received a copy of the GNU General Public License along
  15 // with this library; see the file COPYING3.  If not see
  16 // <http://www.gnu.org/licenses/>.
  17
  18 // 27.7.2.2 member functions (istringstream_members)
  19
  20 #include <sstream>
  21 #include <testsuite_hooks.h>
  22
  23 void
  24 redirect_buffer(std::wios& stream, std::wstreambuf* new_buf)
  25 { stream.rdbuf(new_buf); }
  26
  27 std::wstreambuf*
  28 active_buffer(std::wios& stream)
  29 { return stream.rdbuf(); }
  30
  31 // libstdc++/2832
  32 void test02()
  33 {
  34   const wchar_t* strlit01 = L"fuck war";
  35   const std::wstring str00;
  36   const std::wstring str01(strlit01);
  37   std::wstring str02;
  38   std::wstringbuf sbuf(str01);
  39   std::wstreambuf* pbasebuf0 = &sbuf;
  40
  41   std::wistringstream sstrm1;
  42   VERIFY( sstrm1.str() == str00 );
  43   // derived rdbuf() always returns original streambuf, even though
  44   // it's no longer associated with the stream.
  45   std::wstringbuf* const buf1 = sstrm1.rdbuf();
  46   // base rdbuf() returns the currently associated streambuf
  47   std::wstreambuf* pbasebuf1 = active_buffer(sstrm1);
  48   redirect_buffer(sstrm1, &sbuf);
  49   std::wstringbuf* const buf2 = sstrm1.rdbuf();
  50   std::wstreambuf* pbasebuf2 = active_buffer(sstrm1);
  51   VERIFY( buf1 == buf2 );
  52   VERIFY( pbasebuf1 != pbasebuf2 );
  53   VERIFY( pbasebuf2 == pbasebuf0 );
  54
  55   // derived rdbuf() returns the original buf, so str() doesn't change.
  56   VERIFY( sstrm1.str() != str01 );
  57   VERIFY( sstrm1.str() == str00 );
  58   // however, casting the active streambuf to a stringbuf shows what's up:
  59   std::wstringbuf* psbuf = dynamic_cast<std::wstringbuf*>(pbasebuf2);
  60   str02 = psbuf->str();
  61   VERIFY( str02 == str01 );
  62
  63   // How confusing and non-intuitive is this?
  64   // These semantics are a joke, a serious defect, and incredibly lame.
  65 }
  66
  67 int main()
  68 {
  69   test02();
  70   return 0;
  71 }