cp:
	PR c++/9978, c++/9708
	* cp-tree.h (instantiate_template): Add tsubst_flags parameter.
	* call.c (add_template_candidate_real): Adjust
	instantiate_template call.
	* class.c (resolve_address_of_overloaded_function): Likewise.
	* decl.c (build_enumerator): Set TREE_CONSTANT.
	* pt.c (check_instantiated_args): New.
	(push_inline_template_parms_recursive): Set TREE_CONSTANT,
	TREE_READONLY.
	(build_template_parm_index): Copy TREE_CONSTANT, TREE_READONLY.
	(reduce_template_parm_level): Likewise.
	(process_template_parm): Likewise.
	(check_explicit_specialization): Adjust instantiate_template call.
	(convert_template_argument): Don't check non-type argument here.
	(lookup_template_class): Check them here.
	(tsubst_friend_function): Adjust instantiate_template call.
	(instantiate_template): Add tsubst_flags parameter, use it. Check
	instantiated args.
testsuite:
	PR c++/9978, c++/9708
	* g++.dg/ext/vlm1.C: Adjust expected error.
	* g++.dg/ext/vla2.C: New test.
	* g++.dg/template/arg1.C: New test.
	* g++.dg/template/arg2.C: New test.

From-SVN: r64714