[Bug libstdc++/56282] New: [4.8 regression] std::basic_ios<char> broken with -std=c++11 (undefined reference)

[Bug libstdc++/56282] New: [4.8 regression] std::basic_ios<char> broken with -std=c++11 (undefined reference)

[daniel at constexpr dot org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56282

             Bug #: 56282
           Summary: [4.8 regression] std::basic_ios<char> broken with
                    -std=c++11 (undefined reference)
    Classification: Unclassified
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: daniel@constexpr.org


Simple enough:

$ echo -e '#include <iostream>\n int main() { std::cout << "Hello World!\\n";
return bool(std::cout); }' | g++-4.8.0-pre9999 -x c++ - -std=c++11
/tmp/cc4QaOVU.o: In function `main':
:(.text+0x19): undefined reference to `std::basic_ios<char,
std::char_traits<char> >::operator bool() const'
collect2: error: ld returned 1 exit status

Broken by this commit:
http://gcc.gnu.org/git/?p=gcc.git;a=commitdiff;h=9d8eb68081f898e225727d69da8212813f27e199

The offending commit adds the correct test operator for C++11:

+#if __cplusplus >= 201103L
+      explicit operator bool() const
+      { return !this->fail(); }
+#else
       operator void*() const
       { return this->fail() ? 0 : const_cast<basic_ios*>(this); }
+#endif

However, std::basic_ios<char> is explicitly instantiated in libstdc++.so (from
basic_ios.tcc):
#if _GLIBCXX_EXTERN_TEMPLATE
  extern template class basic_ios<char>;

#ifdef _GLIBCXX_USE_WCHAR_T
  extern template class basic_ios<wchar_t>;
#endif
#endif

So the gcc doesn't instantiate explicit operator bool for std::basic_ios<char>
and instead tries to use the instantiation in libstdc++.so, which only has the
operator void*.


$ g++-4.8.0-pre9999 -v
Using built-in specs.
COLLECT_GCC=g++-4.8.0-pre9999
COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-pc-linux-gnu/4.8.0-pre9999/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with:
/var/tmp/portage/sys-devel/gcc-4.8.0_pre9999/work/gcc-4.8.0-9999/configure
--prefix=/usr --bindir=/usr/x86_64-pc-linux-gnu/gcc-bin/4.8.0-pre9999
--includedir=/usr/lib/gcc/x86_64-pc-linux-gnu/4.8.0-pre9999/include
--datadir=/usr/share/gcc-data/x86_64-pc-linux-gnu/4.8.0-pre9999
--mandir=/usr/share/gcc-data/x86_64-pc-linux-gnu/4.8.0-pre9999/man
--infodir=/usr/share/gcc-data/x86_64-pc-linux-gnu/4.8.0-pre9999/info
--with-gxx-include-dir=/usr/lib/gcc/x86_64-pc-linux-gnu/4.8.0-pre9999/include/g++-v4
--host=x86_64-pc-linux-gnu --build=x86_64-pc-linux-gnu --disable-altivec
--disable-fixed-point --with-ppl --with-cloog --disable-ppl-version-check
--with-cloog-include=/usr/include/cloog-ppl --enable-lto --enable-nls
--without-included-gettext --with-system-zlib --enable-obsolete
--disable-werror --enable-secureplt --enable-multilib
--with-multilib-list=m32,m64 --enable-libmudflap --disable-libssp
--enable-libgomp
--with-python-dir=/share/gcc-data/x86_64-pc-linux-gnu/4.8.0-pre9999/python
--enable-checking=release --disable-libgcj --enable-libstdcxx-time
--enable-languages=c,c++,fortran --enable-shared --enable-threads=posix
--enable-__cxa_atexit --enable-clocale=gnu --enable-targets=all
--with-bugurl=http://bugs.gentoo.org/ --with-pkgversion='Gentoo 4.8.0_pre9999'
Thread model: posix
gcc version 4.8.0-pre9999 20130211 (experimental) commit
37db34b1d053392f4d8899178a7f647bb70f400e (Gentoo 4.8.0_pre9999)

[Bug libstdc++/56282] [4.8 regression] std::basic_ios<char> broken with -std=c++11 (undefined reference)

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56282

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |4.8.0

[Bug libstdc++/56282] [4.8 regression] std::basic_ios<char> broken with -std=c++11 (undefined reference)

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56282

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P1
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2013-02-11
                 CC|                            |jakub at gcc dot gnu.org
     Ever Confirmed|0                           |1

--- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> 2013-02-11 09:04:00 UTC ---
Guess we need a new export and instantiate this operator from some C++11 source
too?

[Bug libstdc++/56282] [4.8 regression] std::basic_ios<char> broken with -std=c++11 (undefined reference)

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56282

--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> 2013-02-11 09:53:38 UTC ---
Created attachment 29415
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=29415
Instantiate and export new operator

Something like this, although putting it in fstream-inst.cc is a bit of a hack,
it just happens to be compiled as C++11

I'm not sure the wildcard patterns are right yet though...

[Bug libstdc++/56282] [4.8 regression] std::basic_ios<char> broken with -std=c++11 (undefined reference)

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56282

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
  Attachment #29415|0                           |1
        is obsolete|                            |

--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> 2013-02-11 10:03:31 UTC ---
Created attachment 29416
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=29416
fix exports

I think this is right now

[Bug libstdc++/56282] [4.8 regression] std::basic_ios<char> broken with -std=c++11 (undefined reference)

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56282

Paolo Carlini <paolo.carlini at oracle dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
         AssignedTo|unassigned at gcc dot       |paolo.carlini at oracle dot
                   |gnu.org                     |com

--- Comment #4 from Paolo Carlini <paolo.carlini at oracle dot com> 2013-02-11 10:09:05 UTC ---
Nahh, let's revert the whole thing.

[Bug libstdc++/56282] [4.8 regression] std::basic_ios<char> broken with -std=c++11 (undefined reference)

[paolo at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56282

--- Comment #5 from paolo at gcc dot gnu.org <paolo at gcc dot gnu.org> 2013-02-11 10:30:50 UTC ---
Author: paolo
Date: Mon Feb 11 10:30:43 2013
New Revision: 195939

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=195939
Log:
2013-02-11  Paolo Carlini  <paolo.carlini@oracle.com>

    PR libstdc++/56282
    Revert:
    2013-02-06  Edward Smith-Rowland  <3dw4rd@verizon.net>

    PR libstdc++/56193
    * include/bits/basic_ios.h: Replace operator void*() const
    with explicit operator bool() const in C++11 and greater.
    * testsuite/27_io/basic_ios/pr56193.cc: New file.

Removed:
    trunk/libstdc++-v3/testsuite/27_io/basic_ios/pr56193.cc
Modified:
    trunk/libstdc++-v3/ChangeLog
    trunk/libstdc++-v3/include/bits/basic_ios.h

[Bug libstdc++/56282] [4.8 regression] std::basic_ios<char> broken with -std=c++11 (undefined reference)

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56282

Paolo Carlini <paolo.carlini at oracle dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|                            |FIXED

--- Comment #6 from Paolo Carlini <paolo.carlini at oracle dot com> 2013-02-11 10:32:55 UTC ---
Fixed.