Re: c++/6257: C-library symbols enter global namespace

Re: c++/6257: C-library symbols enter global namespace

[Phil Edwards]

The following reply was made to PR c++/6257; it has been noted by GNATS.

From: Phil Edwards <phil@jaj.com>
To: marc-oliver.gewaltig@hre-ftr.f.rd.honda.co.jp
Cc: gcc-gnats@gcc.gnu.org
Subject: Re: c++/6257: C-library symbols enter global namespace
Date: Thu, 25 Apr 2002 16:46:39 -0400

 On Thu, Apr 11, 2002 at 04:16:58PM -0000, marc-oliver.gewaltig@hre-ftr.f.rd.honda.co.jp wrote:
 > >Category:       c++
 
 This should be libstdc++, but GNATs won't let me fix that.  Hmmm.
 
 > >Release:        unknown-1.0
 
 This makes a difference.  Lots of stuff changed between 2.x and 3.x.
 
 > >Description:
 > The C++ standard states that 
 > - all C++ header files define their symbols in namespace std
 > - all C header files, used in the form <c*> define their symbol in
 >   namespace std (Annex D 5.2,3).
 > 
 > However, g++ puts C symbols in the global namespace,
 > even if included via <c**> headers.
 
 We know.  Interoperating with an arbitrary C library (which is what we are
 required to do) is quite difficult.  As yet very few people have volunteered
 to work on a solution, and those that have volunteered have very little time.
 Some of the partial solutions are in the source tree and can be turned on
 with the appropriate --enable options.
 
 To use your two examples, making this work on Linux should be much easier
 than on Solaris.
 
 
 > >Fix:
 > Put all C symbols in the namespace std, if included
 > by <c*> headers.
 
 You realize, of course, that this is completely useless?  "Fix the problem"
 is an implied answer.  If you'd like to help us work on an actual patch,
 we'd be very grateful.
 

Re: c++/6257: C-library symbols enter global namespace

[Marc-Oliver Gewaltig]

The following reply was made to PR c++/6257; it has been noted by GNATS.

From: Marc-Oliver Gewaltig <marc-oliver.gewaltig@hre-ftr.f.rd.honda.co.jp>
To: Phil Edwards <phil@jaj.com>, gcc-gnats@gcc.gnu.org
Cc:  
Subject: Re: c++/6257: C-library symbols enter global namespace
Date: Fri, 12 Apr 2002 09:44:33 +0200

 Phil Edwards wrote:
 
 > You need to give an actual version number here...  the situation is better
 > with GCC 3.x but is still problematic.  If you are using 2.x then the library
 > is very outdated.
 
 Sorry, I think I put this somewhere.
 I had this problem on 
 g++ 3.0.{2,3,4}
 
 > However, g++ puts C symbols in the global namespace,
 > > even if included via <c**> headers.
 > 
 > Yes, we know.  The problem is almost impossible to solve without control
 > over the C library.  Since we don't provide a C library -- your system
 > vendor gives you that -- we cannot control its contents.
 
 Actually, this issue was a problem for me on Linux, where string.h
 defines a number of functions which are not part of standard C.
 In particular char* index() gives me a headache, since it collides
 with a typedef in my code.
 
 My original problem was, that on Linux (with g++ 3.0.{2,3,4}, the
 following does NOT compile, though it should. And on Linux, there is
 at least some control over the C library, since it comes from GNU.
 
 #include <iostream>
 
 namespace test
 {
    typedef unsigned int index;
 }
 
 using test::index;
 
 int main()
 {
   index i=5;
 
   return 0;
 }
  
 
 Isn't it at least possible to threat code correctly which does not explicitly
 include C headers?
 
 > 
 > Various ideas have been proposed, but nobody has had time to implement them.
 
 
 I had the naive idea that if
 1. all c++ headers included only <c*> headers and
 2. all <c*> headers wrap the <*.h> includes in namespace std
 the problem should be solved, but maybe I am missing something...
 
 > > >Fix:
 > > Put all C symbols in the namespace std, if included
 > > by <c*> headers.
 > 
 > You do realize that this answer was completely useless?  "Fix the problem"
 > is an obvious and unhelpful response to "How to fix?"
 
 Sorry, it was meant constructive (see above). As I said, I am
 probably not deep enough in the matters.
 
 > 
 > Now, if you have a /patch/, then that would be very helpful.  :-)
 > 
 Sorry again, but I will have a look... ;-)
 
 Oliver
 
 -- 
 Dr. Marc-Oliver Gewaltig  
 Future Technology Research  
 
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Re: c++/6257: C-library symbols enter global namespace

[Phil Edwards]

The following reply was made to PR c++/6257; it has been noted by GNATS.

From: Phil Edwards <phil@jaj.com>
To: marc-oliver.gewaltig@hre-ftr.f.rd.honda.co.jp
Cc: gcc-gnats@gcc.gnu.org
Subject: Re: c++/6257: C-library symbols enter global namespace
Date: Thu, 11 Apr 2002 15:35:31 -0400

 On Thu, Apr 11, 2002 at 04:16:58PM -0000, marc-oliver.gewaltig@hre-ftr.f.rd.honda.co.jp wrote:
 > >Originator:     marc-oliver.gewaltig@hre-ftr.f.rd.honda.co.jp
 > >Release:        unknown-1.0
 
 You need to give an actual version number here...  the situation is better
 with GCC 3.x but is still problematic.  If you are using 2.x then the library
 is very outdated.
 
 
 > However, g++ puts C symbols in the global namespace,
 > even if included via <c**> headers.
 
 Yes, we know.  The problem is almost impossible to solve without control
 over the C library.  Since we don't provide a C library -- your system
 vendor gives you that -- we cannot control its contents.
 
 Various ideas have been proposed, but nobody has had time to implement them.
 
 
 > >Fix:
 > Put all C symbols in the namespace std, if included
 > by <c*> headers.
 
 You do realize that this answer was completely useless?  "Fix the problem"
 is an obvious and unhelpful response to "How to fix?"
 
 Now, if you have a /patch/, then that would be very helpful.  :-)
 
 
 Phil
 
 -- 
 If ye love wealth greater than liberty, the tranquility of servitude greater
 than the animating contest for freedom, go home and leave us in peace.  We seek
 not your counsel, nor your arms.  Crouch down and lick the hand that feeds you;
 and may posterity forget that ye were our countrymen.            - Samuel Adams

c++/6257: C-library symbols enter global namespace

[marc-oliver.gewaltig]

>Number:         6257
>Category:       c++
>Synopsis:       C-library symbols enter global namespace
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Thu Apr 11 09:26:00 PDT 2002
>Closed-Date:
>Last-Modified:
>Originator:     marc-oliver.gewaltig@hre-ftr.f.rd.honda.co.jp
>Release:        unknown-1.0
>Organization:
>Environment:
Linux (Suse 6.2), Solaris 8, probably all
>Description:
The C++ standard states that 
- all C++ header files define their symbols in namespace std
- all C header files, used in the form <c*> define their symbol in
  namespace std (Annex D 5.2,3).

However, g++ puts C symbols in the global namespace,
even if included via <c**> headers.

>How-To-Repeat:
The following version of hello-world should NOT compile
with an ISO-14882 compliant compiler

#include <cstdio>

int main()
{
  // should not work, because printf is in std::
  printf("Hello world.\n");

  return 0;
}
>Fix:
Put all C symbols in the namespace std, if included
by <c*> headers.
>Release-Note:
>Audit-Trail:
>Unformatted: