G++ bug in 971215: Extra temporary for method arguments

[chip at atlantic dot net]

G++ in egcs-971217 creates an extra temporary for member function
arguments that are declared as a base value but are given a derived
value instead.  What's really interesting is that this extra temporary
doesn't show up on regular functions calls, but only on member
function calls....

I'd look into it, but G++ is big and I haven't been into its guts in
years....   Any clues, oh G++ hackers?

Here's a test program that demonstrates the extra temporary:

-----------------------------------------------------------------------
#include <iostream>

class B {
  public:
    B()			{ cout << "B::B()" << endl; }
    B(const B&)		{ cout << "B::B(const B&)" << endl; }
    ~B()		{ cout << "B::~B()" << endl; }
};

class D : public B {
  public:
    D()			 { cout << "D::D()" << endl; }
    D(const D &d) : B(d) { cout << "D::D(const D&)" << endl; }
    ~D()		 { cout << "D::~D()" << endl; }
};

class Foo {
  public:
    void foo(B b) {}
};

int
main(int, char **)
{
    D d;
    Foo *f = new Foo;
    f->foo(d);
}
-----------------------------------------------------------------------

-- 
Chip Salzenberg             - a.k.a. -              <chip@pobox.com>
               "All you need is a toxic landfill /
            A cycle and a sidecar and an urge to kill"  // MST3K