🚀 go-pugleaf

I just got bitten by a bug in virtual functions with virtual base classes.
The code follow along with the segmentation error reported when run under
gdb.  The code should print out:
	four
	two
	hello]one
	two
but as one can see when examining the run output it gets to "hello]one"
before jumping to a non-existent location.  The program seems correct to
me.  I'm dead in the water until I can figure out how to correct this.
Am I doing something wrong?  If I am why, isn't the compiler telling me?
If I am not, is there a patch to fix this problem?  Help!

-Brian G. Anderson		New York University
andersnb@cs.nyu.edu

--------the code----------
#include <stream.h>

class bottom {
public:
  char* hold;
  bottom(char* txt) { hold = txt; }
  virtual void one() const = 0;
};

class leftone: public virtual bottom {
public:
  virtual void two() const = 0;
  void one() const { cout << hold << "] one\n"; two(); }
};

class lefttwo: public leftone {
public:
  void two() const { cout << "two\n"; }
};

class right: public virtual bottom {
public:
  void three() const { cout << "three\n"; one(); }
};

class top: public right, public lefttwo {
public:
  top(char* txt): bottom(txt) {};
  void four() const { cout << "four\n"; two(); one(); }
};

main() {
  top x("hello");
  x.four();
}

-------compile and run--------
(shasha)% g++ -g -v test.cc
g++ version 1.36.4 (based on GCC 1.36.93)
 /usr/src/local/usr/local/lib/gcc-cpp -+ -v -undef -D__GNUC__ -D__GNUG__ -D__cplusplus -Dsparc -Dsun -Dunix -D__sparc__ -D__sun__ -D__unix__ test.cc /usr/tmp/cca07957.cpp
GNU CPP version 1.36.92
 /usr/src/local/usr/local/lib/gcc-cc1plus /usr/tmp/cca07957.cpp -quiet -dumpbase test.cc -g -version -o /usr/tmp/cca07957.s
GNU C++ version 1.36.4 (based on GCC 1.36.93) (sparc) compiled by GNU C version 1.36.92.
default target switches: -mfpu -mepilogue
 /usr/src/local/usr/local/lib/gcc-as -o test.o /usr/tmp/cca07957.s
 /usr/src/local/usr/local/lib/gcc-ld -e start -dc -dp -Bstatic /lib/crt0.o test.o -lg++ /usr/src/local/usr/local/lib/gcc-gnulib -lg -lc
(shasha)% gdb a.out
GDB 3.4, Copyright (C) 1989 Free Software Foundation, Inc.
There is ABSOLUTELY NO WARRANTY for GDB; type "info warranty" for details.
GDB is free software and you are welcome to distribute copies of it
 under certain conditions; type "info copying" to see the conditions.
Reading symbol data from /shasha/andersnb/plinda/a.out...done.
Type "help" for a list of commands.
(gdb) run
Starting program: a.out 
four
two
hello] one

Program received signal 11, Segmentation fault
0x0 in _DYNAMIC ()
(gdb) quit
The program is running.  Quit anyway? (y or n) y
(shasha)% exit
(shasha)% 

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Brian G. Anderson                                       |
NYU Ultracomputer Research Project                     |||
715 Broadway  Rm. 1006                                |||||
New York, NY  10003                                   |||||
(212) 998-3346                                     --- //\ ---
arpa:	andersnb@cmcl2                             ----/ \----
uucp:	{ihnp4,seismo}!cmcl2!andersnb              ----   ----