RE: c++/1843

["Steven Belbin" <steven dot belbin at sympatico dot ca>]

The following reply was made to PR c++/1843; it has been noted by GNATS.

From: "Steven Belbin" <steven.belbin@sympatico.ca>
To: <rodrigc@mediaone.net>
Cc:  
Subject: RE: c++/1843
Date: Sun, 18 Feb 2001 19:20:52 -0500

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 Hi Craig,
 
 I included a sample with the GNAT bug report, regardless here is a sample
 that provokes a segmentation fault.
 
 ============= gcc_bug_1843.cpp =======================
 
 #include <string.h>
 #include <iostream.h>
 
 char * StringAllocate( const char * text )
 {
   int size = ( text ) ? strlen( text ) : 0;
   char * result = new char [ size + 1 ];
   if ( text )
     strncpy( result , text , size );
 
   result[ size ] = '\0';
 
   return result;
 }
 
 class error
 {
   private:
     char * m_text;
 
   public:
     error() :
       m_text( StringAllocate( NULL ) )
     {}
 
     error( const char * text ) :
       m_text( StringAllocate( text ) )
     {}
 
     error( const error & other ) :
       m_text( StringAllocate( other.m_text ) )
     {}
 
     virtual ~error()
     { delete [] m_text; }
 
     const char * text() const
     { return m_text; }
 };
 
 ostream & operator <<( ostream & output , const error & err )
 {
   return output << err.text();
 }
 
 class fatal_error :
   virtual public error
 {
   public:
     fatal_error()
     {}
 
     fatal_error( const char * text ) :
       error( text )
     {}
 
     virtual ~fatal_error()
     {}
 };
 
 int main( int argc , char * argv[] )
 {
   try
   {
     throw fatal_error( "Throwing a fatal error." );
   }
   catch( const error & err )
   {
     cerr << endl << err << endl;
   }
 
   return 0;
 }
 
 ============================================================
 
 As you can see it is straight forward example.
 
 Notes:
 I have even tried using the C++ string class for the error::m_text variable
 (without the delete [] m_text in the destructor) and a segmentation fault
 still occurs.
 
 When error is not virtual within the fatal_error the segmentation fault does
 not occur.
 
 The case that triggered this issue is more complex than the sample, in which
 virtual inherence is required of a class that can be thrown as an exception.
 
 P.S.
 
 Please, try not to reply with the typical doctor-patient shoulder reponse.
 
 [ Patient ] - Doctor, my shoulder hurts when I move it.
 [ Doctor  ] - Then don't move it.
 
 -----Original Message-----
 From: rodrigc@mediaone.net [mailto:rodrigc@mediaone.net]
 Sent: February 17, 2001 03:53 PM
 To: gcc-gnats@gcc.gnu.org; xavier.oriol@delta-tek.com;
 nobody@gcc.gnu.org; steven.belbin@delta-tek.com; rodrigc@mediaone.net
 Subject: Re: c++/1843
 
 
 http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view&pr=1843&database=gcc
 
 There is no attached file associated with this report.
 Can you submit a test case?
 
 --
 Craig Rodrigues
 http://www.gis.net/~craigr
 rodrigc@mediaone.net
 
 
 
 
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 #include <string.h>
 #include <iostream.h>
 
 char * StringAllocate( const char * text )
 {
   int size = ( text ) ? strlen( text ) : 0;
   char * result = new char [ size + 1 ];
   if ( text )
     strncpy( result , text , size );
 
   result[ size ] = '\0';
 
   return result;
 }
 
 class error
 {
   private:
     char * m_text;
 
   public:
     error() :
       m_text( StringAllocate( NULL ) )
     {}
 
     error( const char * text ) :
       m_text( StringAllocate( text ) )
     {}
 
     error( const error & other ) :
       m_text( StringAllocate( other.m_text ) )
     {}
 
     virtual ~error()
     { delete [] m_text; }
 
     const char * text() const
     { return m_text; }
 };
 
 ostream & operator <<( ostream & output , const error & err )
 {
   return output << err.text();
 }
 
 class fatal_error :
   virtual public error
 {
   public:
     fatal_error()
     {}
 
     fatal_error( const char * text ) :
       error( text )
     {}
 
     virtual ~fatal_error()
     {}
 };
 
 int main( int argc , char * argv[] )
 {
   try
   {
     throw fatal_error( "Throwing a fatal error." );
   }
   catch( const error & err )
   {
     cerr << endl << err << endl;
   }
 
   return 0;
 }
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