cp:
PR 21903
	* cp-tree.def (DEFAULT_ARG): Document TREE_CHAIN use.
	* parser.c (cp_parser_late_parsing_default_args): Propagate parsed
	argument to any early instantiations.
	* pt.c (tsubst_arg_types): Chain early instantiation of default arg.
testsuite:
	PR 21903
	* g++.dg/parse/defarg9.C: New.

From-SVN: r100669