🚀 go-pugleaf

When calling a function, the default copy constructor for an object is
not proper invoked. Here is the function argument a class (and not a
reference, as common).

Correct behaviour will invoke the copy constructor of the base classes, 
and the copy constructor of the individual members. After the function
call the destructor must be called.

g++ only calls the destructor...

The output from g++ 2.3.1 is:

A() 0
C() 0
C(copy( 0 )) 1
A(copy( 0 )) 1
A(copy( 0 )) 2
In funca 2
~A() 2
In funcb 0, 0
~C() 0  ~A() 0
~C() 1  ~A() 1
~C() 0  ~A() 0

and it should be: (sun C++ 2.1 output, ignore different place of ~A() 2)

A() 0
C() 0
A(copy( 0 )) 1
C(copy( 0 )) 1
A(copy( 0 )) 2
In funca 2
A(copy( 0 )) 3
C(copy( 0 )) 2
In funcb 3, 2
~C() 2  ~A() 3
~A() 2
~C() 1  ~A() 1
~C() 0  ~A() 0

BTW: It is better as g++ 2.2.1: This produced:

A() 0
C() 0
A(copy( 0 )) 1
C() 1
A(copy( 0 )) 2
In funca 2
~A() 2
In funcb 0, 0
~C() 0  ~A() 0
~C() 1  ~A() 1
~C() 0  ~A() 0

Which result already has been resulted.

And here is the code:

#include	<iostream.h>

struct A {
	static int	cnt;
	int		val;
	A()		: val(cnt++)	{ cout << "A() " << val << "\n"; }
	A(A & copy)	: val(cnt++)
		{ cout << "A(copy( " << copy.val << " )) " << val << "\n"; }
	virtual	~A()	{ cout << "~A() " << val << '\n'; }
};

int	A::cnt = 0;

struct C {
	static int	cnt;
	int		val;
	C()		:val(cnt++)	{ cout << "C() " << val << "\n"; }
	C(C & copy)	:val(cnt++)
		{ cout << "C(copy( " << copy.val << " )) " << val << "\n"; }
	~C()		{ cout << "~C() " << val << '\t'; }
};

int	C::cnt = 0;
	
struct B : public A {
	C		c;
};

void
funca(A a)
{
	cout << "In funca " << a.val << "\n";
}

void
func(B b)
{
	cout << "In funcb " << b.val << ", " << b.c.val << "\n";
}

main()
{
	B	b;

	B	bb(b);

	funca(b);
	func(b);

	return 0;
}

Klamer

Klamer Schutte			Tel: +31-53-892778	Fax: +31-53-340045
Faculty of electrical engineering -- University of Twente, The Netherlands
preferred: klamer@mi.el.utwente.nl     SMTP: klamer@utelmi01.el.utwente.nl