re PR c++/3820 (GCC 3.0 crashes with empty base class)

re PR c++/3820 (GCC 3.0 crashes with empty base class)

cp:
	PR c++/3820
	Stop using TYPE_NONCOPIED_PARTS.
	* call.c (build_over_call): Be careful when copy constructing
	or assigning to an empty class.
	* class.c (check_bases_and_members): It has a
	COMPLEX_ASSIGN_REF if it has a vptr.
	(layout_class_type): Don't add empty class padding to
	TYPE_NONCOPIED_PARTS.
	(finish_struct_1): Don't add the VFIELD either.
	* cp-tree.h (TYPE_HAS_TRIVIAL_INIT_REF): Mention _copy_
	initialization.
testsuite:
	* g++.dg/abi/empty4.C: New test.

From-SVN: r44691