Re: c++/8279: REGRESSION: failure to find a matching function in ostream_iterator expansion

Re: c++/8279: REGRESSION: failure to find a matching function in ostream_iterator expansion

[Wolfgang Bangerth]

The following reply was made to PR c++/8279; it has been noted by GNATS.

From: Wolfgang Bangerth <bangerth@ticam.utexas.edu>
To: gcc-bugs@gcc.gnu.org, <gcc-gnats@gcc.gnu.org>, <jbuck@synopsys.com>,
   <paolo@gcc.gnu.org>
Cc:  
Subject: Re: c++/8279: REGRESSION: failure to find a matching function in
 ostream_iterator expansion
Date: Mon, 21 Oct 2002 11:04:09 -0500 (CDT)

 The testcase fails for a relatively simple reason: copying to an 
 ostream_iterator invokes ostream_iterator::operator=, which here looks 
 like this:
       ostream_iterator& 
       operator=(const _Tp& __value) 
       { 
 	*_M_stream << __value;
 	//...
 	return *this;
       }
 _M_stream is of type std::ostream, and __value of type _Tp=std::pair. So 
 the compiler looks for an operator
       std::ostream << std::pair
 
 Since the declaration of this class is in namespace std, in looks for this 
 operator in namespace std. Since both types are in namespace std, Koenig 
 lookup also does not bring in additional namespaces. It will thus not find 
 the globally declared operator of the test case.
 
 This also explains, why it is not compilable with icc6, as well as that it 
 compiled with gcc2.95, since that did not know about namespace std.
 
 I don't think there is a simple solution to work around this, short of 
 putting the respective operator in namespace std.
 
 At least, I believe the compiler is right to reject the code, and that 
 this is not a bug.
 
 Regards
   Wolfgang
 
 -------------------------------------------------------------------------
 Wolfgang Bangerth              email:           bangerth@ticam.utexas.edu
                                www: http://www.ticam.utexas.edu/~bangerth
 
 

Re: c++/8279: REGRESSION: failure to find a matching function in ostream_iterator expansion

[jbuck]

Synopsis: REGRESSION: failure to find a matching function in ostream_iterator expansion

State-Changed-From-To: feedback->closed
State-Changed-By: jbuck
State-Changed-When: Tue Oct 22 11:01:21 2002
State-Changed-Why:
    The conclusion of the language experts is that this is not
    a bug.

http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=8279

Re: c++/8279: REGRESSION: failure to find a matching function in ostream_iterator expansion

[Paolo Carlini]

The following reply was made to PR c++/8279; it has been noted by GNATS.

From: Paolo Carlini <pcarlini@unitus.it>
To: gcc-gnats@gcc.gnu.org,  gcc-prs@gcc.gnu.org,  jbuck@synopsys.com, 
 gcc-bugs@gcc.gnu.org,  paolo@gcc.gnu.org
Cc:  
Subject: Re: c++/8279: REGRESSION: failure to find a matching function in
 ostream_iterator expansion
Date: Mon, 21 Oct 2002 18:31:47 +0200

 Hi everyone,
 
 I'm tempted to agree with Wolfgang...
 
 Anyway, a quick couple of additional data points: both the widespread 
 EDG-based compilers agree with recent GCCs on this matter: Icc and 
 Comeau. Also, same behavior for Metrowerks CW8.2.
 
 Ciao, Paolo.
 
 http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=8279
 

Re: c++/8279: REGRESSION: failure to find a matching function in ostream_iterator expansion

[paolo]

Synopsis: REGRESSION: failure to find a matching function in ostream_iterator expansion

Responsible-Changed-From-To: unassigned->paolo
Responsible-Changed-By: paolo
Responsible-Changed-When: Sat Oct 19 03:58:15 2002
Responsible-Changed-Why:
    .
State-Changed-From-To: open->feedback
State-Changed-By: paolo
State-Changed-When: Sat Oct 19 03:58:15 2002
State-Changed-Why:
    The testcase doesn't compile with 3.0.4/3.1.1/Icc6 either.
    I'm not a language lawyer but what about putting the
    operator<< inside namespace std:: ??
    The following works for me (and all the compilers above):
    #include <iostream>
    #include <algorithm>
    #include <iterator>
    #include <vector>
    
    typedef std::pair<int,int> Pairtype;
    
    namespace std {
      inline std::ostream& operator<<(std::ostream& o, const Pairtype& a) {
        o << a.first << ": " << a.second;
        return o;
      }
    }
    
    int main()
    {
      std::vector<Pairtype> data;
    
      std::copy(data.begin(), data.end(),
    	    std::ostream_iterator<Pairtype>(std::cout, "\n"));
    }

http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=8279

c++/8279: REGRESSION: failure to find a matching function in ostream_iterator expansion

[jbuck]

>Number:         8279
>Category:       c++
>Synopsis:       REGRESSION: failure to find a matching function in ostream_iterator expansion
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Fri Oct 18 13:56:01 PDT 2002
>Closed-Date:
>Last-Modified:
>Originator:     Joe Buck
>Release:        gcc-3.2
>Organization:
>Environment:
both linux (red hat 7.2) and solaris (sparc 2.7)
>Description:
The attached program compiles and runs correctly under
gcc 2.95.2, but fails to compile under gcc 3.2 (including
the release branch as of 17 Oct).  The compiler complains
that it cannot find a compatible operator<< while expanding
the ostream_iterator template, even though an exact match
is present.  Defining HIDE_BUG reveals that the compiler is
perfectly capable of finding the operator<< and using it
when a loop, rather than std::copy to the ostream_iterator,
is used
>How-To-Repeat:
Do
gcc -c map_test.cpp
for comparison, try
gcc -c -DHIDE_BUG map_test.cpp
>Fix:

>Release-Note:
>Audit-Trail:
>Unformatted:
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