🚀 go-pugleaf

I would like to construct an instance of a derived class using an
instance of its base class.  The plan is to use the base class's copy
constructor (a.k.a. "X(X&)") to initialize the inherited portions, and
initialize the rest explicitly.  Thus:

	struct Base
	{
	  int b;
	};

	struct Derived : public Base
	{
	  int d;
  
	  Derived(const Base &shared)
	  : Base(shared),
	    d(1)
	    {
	    }
	};

G++ 2.2.2 reports the following errors:

	try.cc: In method `Derived::Derived (const struct Base&)':
	try.cc:13: no constructor found for initialization of `Base'

I had thought that *all* structures/classes/types had a default copy
constructor defined for themselves.  This error seems to hint
otherwise.  Am I confused or is G++?

If I do explicitly define a copy constructor for the base class, the
errors disappear.  However, doing so in the real code I'm working on
is not a feasible solution.

Any ideas?
--
Ben Liblit   -----   "Fais que tes reves soient plus longs que la nuit."
liblit@cs.psu.edu   --   brl102@psuvm.psu.edu   --   brl102@psuvm.bitnet