non-const reference to temporary (was: non-const copy ctor)

[Christian Fröbel]

Hi there,

Christian Fröbel wrote:
> I'm having problems with a non-const copy constructor.

I'd like to correct myself. This problem dosn't seem to be related to the copy 
constructor at all. The problem is that I'm not allowed to make a non-const 
reference to a temporary object. For example code like this doesn't compile:

class C {};

void foo (C& c) {}

int main (void)
{
	foo (C()); // <== problem
	return 0;
}

The error message I get here is:
conversion.cpp:48: error: invalid initialization of non-const reference of 
type ‘C&’ from a temporary of type ‘C’
conversion.cpp:42: error: in passing argument 1 of ‘void foo(C&)’

I read §5.5 in Stroustrup's C++ Programming Language regadring that topic but 
couldn't find anything of real use there. I understand that it generally 
doesn't make sense to alter a temporary object. But why forbid it? And 
sometimes it does make sense (e. g. std::auto_ptr).

Maybe someone of you can shed some light on this topic.

Also, I'd like to know if there's a general way to work around this problem.

Thanks,
  Christian