🚀 go-pugleaf

Given the following little test program in C++:

	class Object {
	public:
		virtual ~Object();
	};

	class OutputStream : public Object {
	public:
		OutputStream( Object & );
		virtual int foo (void) = 0;
		virtual operator int();
	};

	OutputStream &
	flush( OutputStream & stream )
	{
		return (stream);
	}

GCC 2.1 produces the error message

	stdin: In function `class OutputStream& flush (class OutputStream&)':
	stdin:14: cannot allocate an object of type `OutputStream'
	stdin:14: since the following virtual functions are abstract:
	stdin:8: int  OutputStream::foo ()
	stdin:8: int  OutputStream::foo ()
	stdin:14: in conversion to type `OutputStream'

and then dumps core (memory fault).  The compiler does not notice that
the idea is to convert to type `OutputStream &' and not to `OutputStream'.

If the member function declaration

		virtual operator int();

is deleted from class OutputStream, then everything works fine.  There is
no error message and no core dump.

If the constructor OutputStream::OutputStream is omitted instead, we
get the error message

	stdin: In function `class OutputStream& flush (class OutputStream&)':
	stdin:15: conversion to non-scalar type requested

followed by a core dump (memory fault).  If we omit the abstract member
function OutputStream::foo, the compiler says:

	stdin: In function `class OutputStream& flush (class OutputStream&)':
	stdin:15: bad argument 0 for function
		  `OutputStream::OutputStream (class Object&)' (type was int )
	stdin:15: in conversion to type `OutputStream'

followed by the usual core dump.

Now we leave class OutputStream untouched, but we remove the virtual
destructor of class Object.  That is class Object becomes

	class Object { };

Instead of a core dump, the result is an endless loop of error messages:

	stdin: In function `class OutputStream& flush (class OutputStream&)':
	stdin:14: cannot allocate an object of type `OutputStream'
	stdin:14: since the following virtual functions are abstract:
	stdin:7: int  OutputStream::foo ()
	stdin:14: in conversion to type `OutputStream'
	stdin:14: cannot allocate an object of type `OutputStream'
	stdin:14: since type `OutputStream' has abstract virtual functions
	stdin:14: in conversion to type `OutputStream'
	stdin:14: cannot allocate an object of type `OutputStream'
	stdin:14: since type `OutputStream' has abstract virtual functions
	stdin:14: in conversion to type `OutputStream'
	stdin:14: ...

--Gerald