[Bug c++/41216] New: G++ failed to correctly resolve the template parameters.

[yimingli0126 at 163 dot com]

y(_InputIterator,
_InputIterator, _ForwardIterator) [with _InputIterator = Inner*,
_ForwardIterator = Inner*, bool  = false]'
d:\mingw-5.1.4\bin\../lib/gcc/mingw32/4.4.1/include/c++/bits/stl_uninitialized.h:117:
  instantiated from '_ForwardIterator std::uninitialized_copy(_InputIterator,
_InputIterator, _ForwardIterator) [with _InputIterator = Inner*,
_ForwardIterator = Inner*]'
d:\mingw-5.1.4\bin\../lib/gcc/mingw32/4.4.1/include/c++/bits/stl_uninitialized.h:257:
  instantiated from '_ForwardIterator
std::__uninitialized_copy_a(_InputIterator, _InputIterator, _ForwardIterator,
std::allocator<_Tp>&) [with _InputIterator = Inner*, _ForwardIterator = Inner*,
_Tp = Inner]'
d:\mingw-5.1.4\bin\../lib/gcc/mingw32/4.4.1/include/c++/bits/stl_uninitialized.h:267:
  instantiated from '_ForwardIterator
std::__uninitialized_move_a(_InputIterator, _InputIterator, _ForwardIterator,
_Allocator&) [with _InputIterator = Inner*, _ForwardIterator = Inner*,
_Allocator = std::allocator]'
d:\mingw-5.1.4\bin\../lib/gcc/mingw32/4.4.1/include/c++/bits/vector.tcc:338:  
instantiated from 'void std::vector<_Tp,
_Alloc>::_M_insert_aux(__gnu_cxx::__normal_iterator::_Tp_alloc_type::pointer, std::vector<_Tp,
_Alloc> >, const _Tp&) [with _Tp = Inner, _Alloc = std::allocator]'
d:\mingw-5.1.4\bin\../lib/gcc/mingw32/4.4.1/include/c++/bits/stl_vector.h:741: 
 instantiated from 'void std::vector<_Tp, _Alloc>::push_back(const _Tp&) [with
_Tp = Inner, _Alloc = std::allocator]'
..\Src\TestMinGW.cpp:24:   instantiated from 'Outter::Outter(IStream&) [with
IStream = std::istream]'
..\Src\TestMinGW.cpp:40:   instantiated from here
..\Src\TestMinGW.cpp:16: error: no match for 'operator>>' in 'in >>
inner->Inner::data'
Build error occurred, build is stopped
Time consumed: 500  ms.


-- 
   Summary: G++ failed to correctly resolve the template parameters.
   Product: gcc
   Version: 4.4.1
Status: UNCONFIRMED
  Severity: major
  Priority: P3
 Component: c++
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: yimingli0126 at 163 dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41216

[Bug c++/41216] G++ failed to correctly resolve the template parameters.

[yimingli0126 at 163 dot com]

--- Comment #1 from yimingli0126 at 163 dot com  2009-09-01 16:16 ---
Created an attachment (id=18462)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=18462&action=view)
The source file rising the compilation failure.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41216

[Bug libstdc++/41216] G++ failed to correctly resolve the template parameters.

[yimingli0126 at 163 dot com]

--- Comment #5 from yimingli0126 at 163 dot com  2009-09-02 06:59 ---
(In reply to comment #4)
> Actually, a library issue, invalid, still library.

Many thanks for your reply.

Yes, it could be a library issue and this problem occurred since v4.3.x.

MSVC 8.0/9.0 doesn't have this problem.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41216

[Bug libstdc++/41216] G++ failed to correctly resolve the template parameters.

[yimingli0126 at 163 dot com]

--- Comment #7 from yimingli0126 at 163 dot com  2009-09-02 10:33 ---
Thanks.

I have added explicit copy constructors both Inner(Inner const&) and
Inner(Inner&) to the class Inner, which are superior to template < class
IStream > Inner (IStream&) when the complier decides which should be called, so
that now the codes work well.

Here are the new sample codes:

struct Inner {
  template < class IStream > friend IStream& operator >> ( IStream& in, Inner&
inner );

  Inner() : data(0) {}
  Inner( Inner const& inner ) : data(inner.data) {} // Make the class
copy-constructable.
  Inner( Inner& );  // Only declaration is necessary fo gcc.
  template < class IStream > explicit Inner( IStream& in ) { operator >>
(in,*this); }

  int data;
};

template < class IStream >
IStream& operator >> ( IStream& in, Inner& inner )
{
  in >> inner.data;
  return in;
}

struct Outter {
  template < class IStream > friend IStream& operator >> ( IStream& in, Outter&
outter );

  Outter() {}
  Outter( Outter const& outter) {}  // Make the class copy-constructable.
  Outter( Outter& );  // Only declaration is necessary.
  template < class IStream > explicit Outter( IStream& in ) { operator >>
(in,*this); }

  std::vector inners;
};

template < class IStream >
IStream& operator >> ( IStream& in, Outter& outter )
{
  outter.inners.push_back(Inner(in));
  return in;
}

int main ( int argc, char* argv[] )
{
  Inner inner(std::cin);
  Outter outter(std::cin);
  return 0;
}

Actually, becuase there is a delcaration of Inner(Inner&), the instance of
template < class IStream > Outter( IStream& ) with IStream = Inner is
suppressed.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41216