🚀 go-pugleaf

The following program gives the output `I'm an LR' instead of the
correct output `I'm an LR2'.  The problem, which appears to be due to
the virtual table for LR2 being wrongly set up, disappears if either the
virtual destructor for class L is removed, or if a virtual destructor is
added to class R.

Environment: g++ 2.2.2 on Sparc running SunOS 4.

Script started on Tue Aug 11 09:49:52 1992
vtblbug% cat -n vtblbug.cc
     1	// vtblbug.cc
     2	
     3	#include <iostream.h>
     4	
     5	class L {
     6	public:
     7	    virtual ~L() {}
     8	    virtual void whatami(ostream& stream = cout) const
     9	       {stream << "I'm an L" << endl;}
    10	};
    11	
    12	class R {
    13	public:
    14	    virtual void whatami(ostream& stream = cout) const
    15	       {stream << "I'm an R" << endl;}
    16	};
    17	
    18	class LR : public L, public R {
    19	public:
    20	    void whatami(ostream& stream = cout) const
    21	       {stream << "I'm an LR" << endl;}
    22	};
    23	
    24	class LR2 : public LR {
    25	public:
    26	    void whatami(ostream& stream = cout) const
    27	       {stream << "I'm an LR2" << endl;}
    28	};
    29	
    30	main()
    31	   {LR2 node;
    32	    L *node_ptr = &node;
    33	    node_ptr->whatami();}
vtblbug% make vtblbug
rm -f vtblbug.o
g++ -c -g -v -Wall vtblbug.cc
Reading specs from /usr/local/lib/gcc-lib/sparc-sun-sunos4.1/2.2.2/specs
gcc version 2.2.2
 /usr/local/lib/gcc-lib/sparc-sun-sunos4.1/2.2.2/cpp -lang-c++ -v -undef -D__GNUC__=2 -D__GNUG__=2 -D__cplusplus -Dsparc -Dsun -Dunix -D__sparc__ -D__sun__ -D__unix__ -D__sparc -D__sun -D__unix -g -Wall vtblbug.cc /usr/tmp/cca19588.i
GNU CPP version 2.2.2 (sparc)
 /usr/local/lib/gcc-lib/sparc-sun-sunos4.1/2.2.2/cc1plus /usr/tmp/cca19588.i -quiet -dumpbase vtblbug.cc -g -Wall -version -o /usr/tmp/cca19588.s
GNU C++ version 2.2.2 (sparc) compiled by GNU C version 2.2.2.
 as -o vtblbug.o /usr/tmp/cca19588.s
g++ -g  -v -o vtblbug vtblbug.o
Reading specs from /usr/local/lib/gcc-lib/sparc-sun-sunos4.1/2.2.2/specs
gcc version 2.2.2
 /usr/local/lib/gcc-lib/sparc-sun-sunos4.1/2.2.2/ld -e start -dc -dp -o vtblbug /lib/crt0.o -L/usr/local/lib/gcc-lib/sparc-sun-sunos4.1/2.2.2 -L/usr/local/lib vtblbug.o -lg++ -lgcc -lc -lg -lgcc
vtblbug% !$
vtblbug
I'm an LR
vtblbug% exit
vtblbug% 
script done on Tue Aug 11 09:51:26 1992