[Bug c++/26512] New: g++ doesn't recognize user-defined operator<<(ostream, const pair<int, double> &)

[Bug c++/26512] New: g++ doesn't recognize user-defined operator<<(ostream, const pair<int, double> &)

[olaf dot dietsche at gfa-net dot de]

g++ doesn't recognize a user-defined

operator<<(ostream, const pair<int, double> &)

although it recognizes

struct A {};
operator<<(ostream, const pair<int, A> &)

Regards, Olaf.

$ cat gccbug.cpp
#include <algorithm>
#include <iostream>
#include <iterator>
#include <map>

typedef std::map<int, double> M;
extern std::ostream &operator <<(std::ostream &f, const M::value_type &p);

void f()
{
        M m;
        std::copy(m.begin(), m.end(),
std::ostream_iterator<M::value_type>(std::cout));
}

This one compiles without problems:
#include <algorithm>
#include <iostream>
#include <iterator>
#include <map>

struct A {
        double d;
};

typedef std::map<int, A> M;
extern std::ostream &operator <<(std::ostream &f, const M::value_type &p);

void f()
{
        M m;
        std::copy(m.begin(), m.end(),
std::ostream_iterator<M::value_type>(std::cout));
}

Putting the operator<<() in namespace std, cirucmvents the compile error too:
#include <algorithm>
#include <iostream>
#include <iterator>
#include <map>

typedef std::map<int, double> M;
namespace std {
extern std::ostream &operator <<(std::ostream &f, const M::value_type &p);
};

void f()
{
        M m;
        std::copy(m.begin(), m.end(),
std::ostream_iterator<M::value_type>(std::cout));
}

And here is the output of the g++ call:
$ d:/programme/mingw/bin/g++ -v -c -Wall -save-temps gccbug.cpp
Reading specs from
d:/programme/mingw/bin/../lib/gcc/i686-pc-mingw32/4.0.2/specs
Target: i686-pc-mingw32
Configured with: ../gcc-4.0.2/configure --with-gcc --prefix=/mingw
--enable-threads --disable-nls --enable-languages=c,c++
--disable-win32-registry --disable-shared --enable-sjlj-exceptions --without-x
--enable-libstdcxx-debug
Thread model: win32
gcc version 4.0.2
 d:/programme/mingw/bin/../libexec/gcc/i686-pc-mingw32/4.0.2/cc1plus.exe -E
-quiet -v -iprefix d:\programme\mingw\bin\../lib/gcc/i686-pc-mingw32/4.0.2/
gccbug.cpp -mtune=pentiumpro -Wall -fpch-preprocess -o gccbug.ii
ignoring nonexistent directory "/mingw/include"
ignoring nonexistent directory "d:/programme/mingw/i686-pc-mingw32/include"
ignoring nonexistent directory "/mingw/include"
#include "..." search starts here:
#include <...> search starts here:
 d:/programme/mingw/bin/../lib/gcc/i686-pc-mingw32/4.0.2/include
 d:/programme/mingw/include/c++/4.0.2
 d:/programme/mingw/include/c++/4.0.2/i686-pc-mingw32
 d:/programme/mingw/include/c++/4.0.2/backward
 d:/programme/mingw/include
 d:/programme/mingw/lib/gcc/i686-pc-mingw32/4.0.2/include
End of search list.
 d:/programme/mingw/bin/../libexec/gcc/i686-pc-mingw32/4.0.2/cc1plus.exe
-fpreprocessed gccbug.ii -quiet -dumpbase gccbug.cpp -mtune=pentiumpro -auxbase
gccbug -Wall -version -o gccbug.s
GNU C++ version 4.0.2 (i686-pc-mingw32)
        compiled by GNU C version 4.0.2.
GGC heuristics: --param ggc-min-expand=99 --param ggc-min-heapsize=129918
d:/programme/mingw/include/c++/4.0.2/bits/stream_iterator.h: In member function
'std::ostream_iterator<_Tp, _CharT, _Traits>& std::ostream_iterator<_Tp,
_CharT, _Traits>::operator=(const _Tp&) [with _Tp = std::pair<const int,
double>, _CharT = char, _Traits = std::char_traits<char>]':
d:/programme/mingw/include/c++/4.0.2/bits/stl_algobase.h:270:   instantiated
from 'static _OI std::__copy<<anonymous>, <template-parameter-1-2> >::copy(_II,
_II, _OI) [with _II = std::_Rb_tree_iterator<std::pair<const int, double> >,
_OI = std::ostream_iterator<std::pair<const int, double>, char,
std::char_traits<char> >, bool <anonymous> = false, <template-parameter-1-2> =
std::bidirectional_iterator_tag]'
d:/programme/mingw/include/c++/4.0.2/bits/stl_algobase.h:317:   instantiated
from '_OI std::__copy_aux(_II, _II, _OI) [with _II =
std::_Rb_tree_iterator<std::pair<const int, double> >, _OI =
std::ostream_iterator<std::pair<const int, double>, char,
std::char_traits<char> >]'
d:/programme/mingw/include/c++/4.0.2/bits/stl_algobase.h:326:   instantiated
from 'static _OI std::__copy_normal<<anonymous>, <anonymous> >::copy_n(_II,
_II, _OI) [with _II = std::_Rb_tree_iterator<std::pair<const int, double> >,
_OI = std::ostream_iterator<std::pair<const int, double>, char,
std::char_traits<char> >, bool <anonymous> = false, bool <anonymous> = false]'
d:/programme/mingw/include/c++/4.0.2/bits/stl_algobase.h:387:   instantiated
from '_OutputIterator std::copy(_InputIterator, _InputIterator,
_OutputIterator) [with _InputIterator = std::_Rb_tree_iterator<std::pair<const
int, double> >, _OutputIterator = std::ostream_iterator<std::pair<const int,
double>, char, std::char_traits<char> >]'
gccbug.cpp:12:   instantiated from here
d:/programme/mingw/include/c++/4.0.2/bits/stream_iterator.h:196: error: no
match for 'operator<<' in '*((std::ostream_iterator<std::pair<const int,
double>, char, std::char_traits<char>
>*)this)->std::ostream_iterator<std::pair<const int, double>, char,
std::char_traits<char> >::_M_stream << __value'
d:/programme/mingw/include/c++/4.0.2/bits/ostream.tcc:67: note: candidates are:
std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT,
_Traits>::operator<<(std::basic_ostream<_CharT, _Traits>&
(*)(std::basic_ostream<_CharT, _Traits>&)) [with _CharT = char, _Traits =
std::char_traits<char>]
d:/programme/mingw/include/c++/4.0.2/bits/ostream.tcc:78: note:                
std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT,
_Traits>::operator<<(std::basic_ios<_CharT, _Traits>&
(*)(std::basic_ios<_CharT, _Traits>&)) [with _CharT = char, _Traits =
std::char_traits<char>]
d:/programme/mingw/include/c++/4.0.2/bits/ostream.tcc:90: note:                
std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT,
_Traits>::operator<<(std::ios_base& (*)(std::ios_base&)) [with _CharT = char,
_Traits = std::char_traits<char>]
d:/programme/mingw/include/c++/4.0.2/bits/ostream.tcc:125: note:               
 std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT,
_Traits>::operator<<(long int) [with _CharT = char, _Traits =
std::char_traits<char>]
d:/programme/mingw/include/c++/4.0.2/bits/ostream.tcc:159: note:               
 std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT,
_Traits>::operator<<(long unsigned int) [with _CharT = char, _Traits =
std::char_traits<char>]
d:/programme/mingw/include/c++/4.0.2/bits/ostream.tcc:102: note:               
 std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT,
_Traits>::operator<<(bool) [with _CharT = char, _Traits =
std::char_traits<char>]
d:/programme/mingw/include/c++/4.0.2/ostream:176: note:                
std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT,
_Traits>::operator<<(short int) [with _CharT = char, _Traits =
std::char_traits<char>]
d:/programme/mingw/include/c++/4.0.2/ostream:187: note:                
std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT,
_Traits>::operator<<(short unsigned int) [with _CharT = char, _Traits =
std::char_traits<char>]
d:/programme/mingw/include/c++/4.0.2/ostream:191: note:                
std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT,
_Traits>::operator<<(int) [with _CharT = char, _Traits =
std::char_traits<char>]
d:/programme/mingw/include/c++/4.0.2/ostream:202: note:                
std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT,
_Traits>::operator<<(unsigned int) [with _CharT = char, _Traits =
std::char_traits<char>]
d:/programme/mingw/include/c++/4.0.2/bits/ostream.tcc:183: note:               
 std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT,
_Traits>::operator<<(long long int) [with _CharT = char, _Traits =
std::char_traits<char>]
d:/programme/mingw/include/c++/4.0.2/bits/ostream.tcc:218: note:               
 std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT,
_Traits>::operator<<(long long unsigned int) [with _CharT = char, _Traits =
std::char_traits<char>]
d:/programme/mingw/include/c++/4.0.2/bits/ostream.tcc:242: note:               
 std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT,
_Traits>::operator<<(double) [with _CharT = char, _Traits =
std::char_traits<char>]
d:/programme/mingw/include/c++/4.0.2/ostream:217: note:                
std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT,
_Traits>::operator<<(float) [with _CharT = char, _Traits =
std::char_traits<char>]
d:/programme/mingw/include/c++/4.0.2/bits/ostream.tcc:265: note:               
 std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT,
_Traits>::operator<<(long double) [with _CharT = char, _Traits =
std::char_traits<char>]
d:/programme/mingw/include/c++/4.0.2/bits/ostream.tcc:288: note:               
 std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT,
_Traits>::operator<<(const void*) [with _CharT = char, _Traits =
std::char_traits<char>]
d:/programme/mingw/include/c++/4.0.2/bits/ostream.tcc:311: note:               
 std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT,
_Traits>::operator<<(std::basic_streambuf<_CharT, _Traits>*) [with _CharT =
char, _Traits = std::char_traits<char>]
d:/programme/mingw/include/c++/4.0.2/ostream:447: note:                
std::basic_ostream<_CharT, _Traits>& std::operator<<(std::basic_ostream<_CharT,
_Traits>&, char) [with _CharT = char, _Traits = std::char_traits<char>]
d:/programme/mingw/include/c++/4.0.2/bits/ostream.tcc:509: note:               
 std::basic_ostream<char, _Traits>& std::operator<<(std::basic_ostream<char,
_Traits>&, char) [with _Traits = std::char_traits<char>]
d:/programme/mingw/include/c++/4.0.2/ostream:458: note:                
std::basic_ostream<char, _Traits>& std::operator<<(std::basic_ostream<char,
_Traits>&, signed char) [with _Traits = std::char_traits<char>]
d:/programme/mingw/include/c++/4.0.2/ostream:463: note:                
std::basic_ostream<char, _Traits>& std::operator<<(std::basic_ostream<char,
_Traits>&, unsigned char) [with _Traits = std::char_traits<char>]
d:/programme/mingw/include/c++/4.0.2/bits/ostream.tcc:571: note:               
 std::basic_ostream<_CharT, _Traits>&
std::operator<<(std::basic_ostream<_CharT, _Traits>&, const char*) [with _CharT
= char, _Traits = std::char_traits<char>]
d:/programme/mingw/include/c++/4.0.2/bits/ostream.tcc:616: note:               
 std::basic_ostream<char, _Traits>& std::operator<<(std::basic_ostream<char,
_Traits>&, const char*) [with _Traits = std::char_traits<char>]
d:/programme/mingw/include/c++/4.0.2/ostream:497: note:                
std::basic_ostream<char, _Traits>& std::operator<<(std::basic_ostream<char,
_Traits>&, const signed char*) [with _Traits = std::char_traits<char>]
d:/programme/mingw/include/c++/4.0.2/ostream:502: note:                
std::basic_ostream<char, _Traits>& std::operator<<(std::basic_ostream<char,
_Traits>&, const unsigned char*) [with _Traits = std::char_traits<char>]


-- 
           Summary: g++ doesn't recognize user-defined operator<<(ostream,
                    const pair<int, double> &)
           Product: gcc
           Version: 4.0.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: olaf dot dietsche at gfa-net dot de


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26512

[Bug c++/26512] g++ doesn't recognize user-defined operator<<(ostream, const pair<int, double> &)

[olaf dot dietsche at gfa-net dot de]

------- Comment #1 from olaf dot dietsche at gfa-net dot de  2006-03-01 14:35 -------
Created an attachment (id=10946)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=10946&action=view)
Preprocessed gccbug.cpp


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26512

[Bug c++/26512] g++ doesn't recognize user-defined operator<<(ostream, const pair<int, double> &)

[pinskia at gcc dot gnu dot org]

------- Comment #2 from pinskia at gcc dot gnu dot org  2006-03-01 14:37 -------
This is how Agrument dependent namelookup works, well there is DR report about
fundamental types which is what is being exposed here.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26512

[Bug c++/26512] g++ doesn't recognize user-defined operator<<(ostream, const pair<int, double> &)

[pinskia at gcc dot gnu dot org]

------- Comment #3 from pinskia at gcc dot gnu dot org  2006-03-01 14:40 -------
Which is DR 225.
http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_active.html


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26512

[Bug c++/26512] g++ doesn't recognize user-defined operator<<(ostream, const pair<int, double> &)

[olaf dot dietsche at gfa-net dot de]

------- Comment #4 from olaf dot dietsche at gfa-net dot de  2006-03-03 22:57 -------
I looked at your link and at issue 197. I don't see how this applies to my bug
report, especially in connection with _user defined_ types. What I don't
understand is, why does g++ handle builtin types different than user defined
types. e.g:

operator<<(ostream, const pair<int, double> &)
vs.
operator<<(ostream, const pair<int, struct A> &)


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26512

[Bug c++/26512] g++ doesn't recognize user-defined operator<<(ostream, const pair<int, double> &)

[pinskia at gcc dot gnu dot org]

------- Comment #5 from pinskia at gcc dot gnu dot org  2006-03-03 23:10 -------
(In reply to comment #4)
> I looked at your link and at issue 197. I don't see how this applies to my bug
> report, especially in connection with _user defined_ types. What I don't
> understand is, why does g++ handle builtin types different than user defined
> types. e.g:

This does not match what you have in the source:
extern std::ostream &operator <<(std::ostream &f, const M::value_type &p);
M::value_type here is either an user defined type, A or a fundamental type.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26512

[Bug c++/26512] g++ doesn't recognize user-defined operator<<(ostream, const pair<int, double> &)

[olaf dot dietsche at gfa-net dot de]

------- Comment #6 from olaf dot dietsche at gfa-net dot de  2006-03-05 14:21 -------
Sorry, if my example wasn't clear enough :-(. I'll try to clarify.

M::value_type is std::map<int, double>::value_type, which is std::map<int,
double>::pair<int, double> in my first example.

g++ doesn't recognize the user defined
operator <<(std::ostream &f, const M::value_type &), which is
operator<<(ostream &, const pair<int, double> &)

If I change double to struct A, g++ _does_ recognize the user defined
operator <<(std::ostream &f, const M::value_type &), which is
- in my second example - operator<<(ostream, const pair<int, struct A> &)

And this is my problem: the difference in ignoring the user defined
operator<<() in the first case and recognizing the user defined operator<<()
in the second case.

I hope, this makes my problem a bit more understandable.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26512

[Bug c++/26512] g++ doesn't recognize user-defined operator<<(ostream, const pair<int, double> &)

[pinskia at gcc dot gnu dot org]

------- Comment #7 from pinskia at gcc dot gnu dot org  2006-03-05 15:43 -------
Comeau C++ does the same thing as GCC does (at least in strict mode).


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26512

[Bug c++/26512] g++ doesn't recognize user-defined operator<<(ostream, const pair<int, double> &)

[olaf dot dietsche at gfa-net dot de]

------- Comment #8 from olaf dot dietsche at gfa-net dot de  2006-03-05 16:22 -------
Which doesn't make this inconsistent behaviour any better. I don't know Comeau
C++, is it some sort of reference implementation?


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26512

[Bug c++/26512] g++ doesn't recognize user-defined operator<<(ostream, const pair<int, double> &)

[pinskia at gcc dot gnu dot org]

------- Comment #9 from pinskia at gcc dot gnu dot org  2006-03-05 16:26 -------
(In reply to comment #8)
> Which doesn't make this inconsistent behaviour any better. I don't know Comeau
> C++, is it some sort of reference implementation?

It is just another implementation to compare against.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26512

[Bug c++/26512] g++ doesn't recognize user-defined operator<<(ostream, const pair<int, double> &)

[bangerth at dealii dot org]

------- Comment #10 from bangerth at dealii dot org  2006-03-08 04:43 -------
(In reply to comment #4)
> I looked at your link and at issue 197. I don't see how this applies to my bug
> report, especially in connection with _user defined_ types. What I don't
> understand is, why does g++ handle builtin types different than user defined
> types. e.g:
> 
> operator<<(ostream, const pair<int, double> &)
> vs.
> operator<<(ostream, const pair<int, struct A> &)

Because user defined types are associated with a namespace (in which the
compiler can then lookup functions, if one of its arguments is from that
namespace), whereas builtin types have no associated namespace.

W.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26512

[Bug c++/26512] g++ doesn't recognize user-defined operator<<(ostream, const pair<int, double> &)

[bangerth at dealii dot org]

------- Comment #11 from bangerth at dealii dot org  2006-03-08 04:49 -------
This is indeed invalid under the present rules:
---------------
typedef std::map<int, double> M;
namespace std {
extern std::ostream &operator <<(std::ostream &f, const M::value_type &p);
};

void f()
{
        M m;
        std::copy(m.begin(), m.end(),
                  std::ostream_iterator<M::value_type>(std::cout));
}
---------------
When inside std::copy, the compiler needs to lookup an operator<< for
its arguments. It does so in the present namespace (i.e. std::) as well
as the namespaces of all arguments. The arguments are std::ofstream and
std::pair (and possibly the template arguments of two classes, though
I'm not sure about that). All these arguments are from namespace std::
or are builtin types that have no associated namespace. Lookup therefore
has to fail.

The solution is to put your own definition of operator<< into namespace
std:: -- not pretty, but a solution that we have discussed several times
here in this database...

W.


-- 

bangerth at dealii dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |bangerth at dealii dot org
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|                            |INVALID


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26512