[gcc(refs/users/wschmidt/heads/builtins3)] libstdc++: Do not set eofbit eagerly in operator>>(istream&, char(&)[N])

[William Schmidt <wschmidt@gcc.gnu.org>]

https://gcc.gnu.org/g:4e39f563c0cd25401f689c2093cb8c13692156ef

commit 4e39f563c0cd25401f689c2093cb8c13692156ef
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Thu Aug 6 19:23:14 2020 +0100

    libstdc++: Do not set eofbit eagerly in operator>>(istream&, char(&)[N])
    
    Similar to the bugs I fixed recently in istream::ignore, we incorrectly
    set eofbit too often in operator>>(istream&, string&) and
    operator>>(istream&.  char(&)[N]).
    
    We should only set eofbit if we reach EOF but would have kept going
    otherwise. If we've already extracted the maximum number of characters
    (whether that's because of the buffer size or the istream's width())
    then we should not set eofbit.
    
    libstdc++-v3/ChangeLog:
    
            * include/bits/basic_string.tcc
            (operator>>(basic_istream&, basic_string&)): Do not set eofbit
            if extraction stopped after in.width() characters.
            * src/c++98/istream-string.cc (operator>>(istream&, string&)):
            Likewise.
            * include/bits/istream.tcc (__istream_extract): Do not set
            eofbit if extraction stopped after n-1 characters.
            * src/c++98/istream.cc (__istream_extract): Likewise.
            * testsuite/21_strings/basic_string/inserters_extractors/char/13.cc: New test.
            * testsuite/21_strings/basic_string/inserters_extractors/wchar_t/13.cc: New test.
            * testsuite/27_io/basic_istream/extractors_character/char/5.cc: New test.
            * testsuite/27_io/basic_istream/extractors_character/wchar_t/5.cc: New test.

Diff:
---
 libstdc++-v3/include/bits/basic_string.tcc         |  2 +-
 libstdc++-v3/include/bits/istream.tcc              |  4 +-
 libstdc++-v3/src/c++98/istream-string.cc           |  2 +-
 libstdc++-v3/src/c++98/istream.cc                  |  3 +-
 .../basic_string/inserters_extractors/char/13.cc   | 55 ++++++++++++++++++++++
 .../inserters_extractors/wchar_t/13.cc             | 55 ++++++++++++++++++++++
 .../basic_istream/extractors_character/char/5.cc   | 54 +++++++++++++++++++++
 .../extractors_character/wchar_t/5.cc              | 54 +++++++++++++++++++++
 8 files changed, 225 insertions(+), 4 deletions(-)

diff --git a/libstdc++-v3/include/bits/basic_string.tcc b/libstdc++-v3/include/bits/basic_string.tcc
index e370f439390..75218a40610 100644
--- a/libstdc++-v3/include/bits/basic_string.tcc
+++ b/libstdc++-v3/include/bits/basic_string.tcc
@@ -1518,7 +1518,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 		}
 	      __str.append(__buf, __len);
 
-	      if (_Traits::eq_int_type(__c, __eof))
+	      if (__extracted < __n && _Traits::eq_int_type(__c, __eof))
 		__err |= __ios_base::eofbit;
 	      __in.width(0);
 	    }
diff --git a/libstdc++-v3/include/bits/istream.tcc b/libstdc++-v3/include/bits/istream.tcc
index b8f530f6ef5..022db9383e9 100644
--- a/libstdc++-v3/include/bits/istream.tcc
+++ b/libstdc++-v3/include/bits/istream.tcc
@@ -1023,7 +1023,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 		  ++__extracted;
 		  __c = __sb->snextc();
 		}
-	      if (_Traits::eq_int_type(__c, __eof))
+
+	      if (__extracted < __num - 1
+		  && _Traits::eq_int_type(__c, __eof))
 		__err |= ios_base::eofbit;
 
 	      // _GLIBCXX_RESOLVE_LIB_DEFECTS
diff --git a/libstdc++-v3/src/c++98/istream-string.cc b/libstdc++-v3/src/c++98/istream-string.cc
index c59f2ce0b34..bfd7389e2e2 100644
--- a/libstdc++-v3/src/c++98/istream-string.cc
+++ b/libstdc++-v3/src/c++98/istream-string.cc
@@ -93,7 +93,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 		    }
 		}
 
-	      if (__traits_type::eq_int_type(__c, __eof))
+	      if (__extracted < __n && __traits_type::eq_int_type(__c, __eof))
 		__err |= ios_base::eofbit;
 	      __in.width(0);
 	    }
diff --git a/libstdc++-v3/src/c++98/istream.cc b/libstdc++-v3/src/c++98/istream.cc
index 7a48779d337..79a77b8475a 100644
--- a/libstdc++-v3/src/c++98/istream.cc
+++ b/libstdc++-v3/src/c++98/istream.cc
@@ -261,7 +261,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 		    }
 		}
 
-	      if (__traits_type::eq_int_type(__c, __eof))
+	      if (__extracted < __num - 1
+		  && __traits_type::eq_int_type(__c, __eof))
 		__err |= ios_base::eofbit;
 
 	      // _GLIBCXX_RESOLVE_LIB_DEFECTS
diff --git a/libstdc++-v3/testsuite/21_strings/basic_string/inserters_extractors/char/13.cc b/libstdc++-v3/testsuite/21_strings/basic_string/inserters_extractors/char/13.cc
new file mode 100644
index 00000000000..f54042a4604
--- /dev/null
+++ b/libstdc++-v3/testsuite/21_strings/basic_string/inserters_extractors/char/13.cc
@@ -0,0 +1,55 @@
+// Copyright (C) 2020 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-do run }
+
+#include <string>
+#include <sstream>
+#include <testsuite_hooks.h>
+
+void
+test01()
+{
+  const std::string str = "1234";
+  std::istringstream in(str);
+  std::string buf;
+  in.width(4);
+  in >> buf;
+  VERIFY( !in.eof() ); // should stop after reading 4 chars
+  VERIFY( buf == str );
+}
+
+struct CT : std::char_traits<char> { };
+
+void
+test02()
+{
+  const std::basic_string<char, CT> str = "1234";
+  std::basic_istringstream<char, CT> in(str);
+  std::basic_string<char, CT> buf;
+  in.width(4);
+  in >> buf;
+  VERIFY( !in.eof() ); // should stop after reading 4 chars
+  VERIFY( buf == str );
+}
+
+int
+main()
+{
+  test01();
+  test02();
+}
diff --git a/libstdc++-v3/testsuite/21_strings/basic_string/inserters_extractors/wchar_t/13.cc b/libstdc++-v3/testsuite/21_strings/basic_string/inserters_extractors/wchar_t/13.cc
new file mode 100644
index 00000000000..f18e2cbe461
--- /dev/null
+++ b/libstdc++-v3/testsuite/21_strings/basic_string/inserters_extractors/wchar_t/13.cc
@@ -0,0 +1,55 @@
+// Copyright (C) 2020 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-do run }
+
+#include <string>
+#include <sstream>
+#include <testsuite_hooks.h>
+
+void
+test01()
+{
+  const std::wstring str = L"1234";
+  std::wistringstream in(str);
+  std::wstring buf;
+  in.width(4);
+  in >> buf;
+  VERIFY( !in.eof() ); // should stop after reading 4 chars
+  VERIFY( buf == str );
+}
+
+struct WT : std::char_traits<wchar_t> { };
+
+void
+test02()
+{
+  const std::basic_string<wchar_t, WT> str = L"1234";
+  std::basic_istringstream<wchar_t, WT> in(str);
+  std::basic_string<wchar_t, WT> buf;
+  in.width(4);
+  in >> buf;
+  VERIFY( !in.eof() ); // should stop after reading 4 chars
+  VERIFY( buf == str );
+}
+
+int
+main()
+{
+  test01();
+  test02();
+}
diff --git a/libstdc++-v3/testsuite/27_io/basic_istream/extractors_character/char/5.cc b/libstdc++-v3/testsuite/27_io/basic_istream/extractors_character/char/5.cc
new file mode 100644
index 00000000000..984f8815645
--- /dev/null
+++ b/libstdc++-v3/testsuite/27_io/basic_istream/extractors_character/char/5.cc
@@ -0,0 +1,54 @@
+// Copyright (C) 2020 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-do run }
+
+#include <sstream>
+#include <testsuite_hooks.h>
+
+void
+test01()
+{
+  const std::string str = "1234";
+  std::istringstream in(str);
+  char buf[6];
+  in.width(5);
+  in >> buf; // stops after reading 4 chars, doesn't reach EOF
+  VERIFY( !in.eof() );
+  VERIFY( buf == str );
+}
+
+struct CT : std::char_traits<char> { };
+
+void
+test02()
+{
+  const std::string str = "1234";
+  std::basic_istringstream<char, CT> in(str.c_str());
+  char buf[6];
+  in.width(5);
+  in >> buf; // stops after reading 4 chars, doesn't reach EOF
+  VERIFY( !in.eof() );
+  VERIFY( buf == str );
+}
+
+int
+main()
+{
+  test01();
+  test02();
+}
diff --git a/libstdc++-v3/testsuite/27_io/basic_istream/extractors_character/wchar_t/5.cc b/libstdc++-v3/testsuite/27_io/basic_istream/extractors_character/wchar_t/5.cc
new file mode 100644
index 00000000000..03bbcadfda5
--- /dev/null
+++ b/libstdc++-v3/testsuite/27_io/basic_istream/extractors_character/wchar_t/5.cc
@@ -0,0 +1,54 @@
+// Copyright (C) 2020 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-do run }
+
+#include <sstream>
+#include <testsuite_hooks.h>
+
+void
+test01()
+{
+  const std::string str = "1234";
+  std::istringstream in(str);
+  char buf[6];
+  in.width(5);
+  in >> buf; // stops after reading 4 chars, doesn't reach EOF
+  VERIFY( !in.eof() );
+  VERIFY( buf == str );
+}
+
+struct WT : std::char_traits<wchar_t> { };
+
+void
+test02()
+{
+  const std::wstring str = L"1234";
+  std::basic_istringstream<wchar_t, WT> in(str.c_str());
+  wchar_t buf[6];
+  in.width(5);
+  in >> buf; // stops after reading 4 chars, doesn't reach EOF
+  VERIFY( !in.eof() );
+  VERIFY( buf == str );
+}
+
+int
+main()
+{
+  test01();
+  test02();
+}