Re: libstdc++/6642: Constness prevents substraction of iterators

Re: libstdc++/6642: Constness prevents substraction of iterators

[Paolo Carlini]

The following reply was made to PR libstdc++/6642; it has been noted by GNATS.

From: Paolo Carlini <pcarlini@unitus.it>
To: gcc-gnats@gcc.gnu.org,  gcc-prs@gcc.gnu.org,  ofv@wanadoo.es, 
 gcc-bugs@gcc.gnu.org
Cc:  
Subject: Re: libstdc++/6642: Constness prevents substraction of iterators
Date: Tue, 02 Jul 2002 21:56:58 +0200

 Patch applied to trunk:
 
     http://gcc.gnu.org/ml/gcc-patches/2002-07/msg00080.html
 
 Paolo.
 
 http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=6642 
 
 

Re: libstdc++/6642: Constness prevents substraction of iterators

[paolo]

Synopsis: Constness prevents substraction of iterators

State-Changed-From-To: analyzed->closed
State-Changed-By: paolo
State-Changed-When: Thu Jul 25 04:36:13 2002
State-Changed-Why:
    Fixed for 3.2 and 3.3 together with the related 6503 and
    7186.

http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=6642

Re: libstdc++/6642: Constness prevents substraction of iterators

[paolo]

Synopsis: Constness prevents substraction of iterators

Responsible-Changed-From-To: unassigned->paolo
Responsible-Changed-By: paolo
Responsible-Changed-When: Wed May 29 02:44:32 2002
Responsible-Changed-Why:
    Working on it
State-Changed-From-To: open->analyzed
State-Changed-By: paolo
State-Changed-When: Wed May 29 02:44:32 2002
State-Changed-Why:
    Confirmed. See DR179 <Ready>.

http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=6642

libstdc++/6642: Constness prevents substraction of iterators

[ofv]

>Number:         6642
>Category:       libstdc++
>Synopsis:       Constness prevents substraction of iterators
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          rejects-legal
>Submitter-Id:   net
>Arrival-Date:   Sun May 12 22:26:00 PDT 2002
>Closed-Date:
>Last-Modified:
>Originator:     Oscar Fuentes
>Release:        gcc version 3.1 20020510 (prerelease)
>Organization:
>Environment:
Reading specs from t:\msys\1.0\mingw\bin\..\lib\gcc-lib\i686-pc-mingw32\3.1\specs
Configured with: ../gcc-3.1-20020510/configure --enable-languages=c,c++ --enable-threads=win32 --enable-sjlj-exceptions --prefix=t:/msys/1.0/mingw
Thread model: win32
gcc version 3.1 20020510 (prerelease)
>Description:
Substraction of iterators being the first operand 'non-const' and the second 'const' are not possible.
>How-To-Repeat:
#include <string>

class MyClass {
private:
  std::string s;
  std::string::iterator it;
public:
  unsigned pos() const {
    return it - s.begin();
  }
};

Gives

t:/msys/1.0/mingw/include/g++-v3/bits/stl_iterator.h: In constructor 
   `__gnu_cxx::__normal_iterator<_Iterator, 
   _Container>::__normal_iterator(const __gnu_cxx::__normal_iterator<_Iter, 
   _Container>&) [with _Iter = const char*, _Iterator = char*, _Container = 
   std::basic_string<char, std::char_traits<char>, std::allocator<char> >]':
case.cpp:9:   instantiated from here
t:/msys/1.0/mingw/include/g++-v3/bits/stl_iterator.h:589: invalid conversion 
   from `const char* const' to `char*'

>Fix:
-(s.begin() - it) works :-)
>Release-Note:
>Audit-Trail:
>Unformatted: