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Article #1405

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#1405
From: David J. Braunegg
Date: Sat, 23 Jan 1993 02:49
52 lines
1667 bytes
This is a bug report for g++ (gcc) version 2.3.3, running on a Sun
Sparcstation, OS 4.1.


Your declaration of

        ostream& operator<<(void *p);

in iostream.h is in error.  Unless you have truly defined operator<<
on void* pointers so that it modifies the pointer, the declaration
should instead be

        ostream& operator<<(const void *p);



For example, the following program should *not* issue the const
violation warning that it does.



#include <iostream.h>

int main()
{
  const char *foo = "stuff";

  cout << (const void *)foo << endl;

  return 0;
}




djb@bambam>g++ -g -Wall test.cc
test.cc: In function `int  main ()':
test.cc:7: warning: argument passing of non-`const *' pointer from `const *'
test.cc:7: warning: argument passing of non-`const *' pointer from `const *'



I have encountered this warning frequently, because in my code I am
often writing out the address of an object to help identify it.  If
foo is `const <class> *', then I must cast it to `const void *' and
*not* to `void *' when printing its address in order to avoid a const
violation.


Please contact me if you have any further questions.

Dave
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Message-ID: <9301222229.AA06362@bambam.mitre.org>
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Path: arc1-ca.pugleaf.net!sparky!uunet!paladin.american.edu!howland.reston.ans.net!zaphod.mps.ohio-state.edu!pacific.mps.ohio-state.edu!cis.ohio-state.edu!babypuss.mitre.org!djb
From: djb@babypuss.mitre.org (David J. Braunegg)
Newsgroups: gnu.g++.bug
Subject: (none)
Date: 22 Jan 1993 21:49:39 -0500
Organization: GNUs Not Usenet
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