PR c++/28860
	* cp-tree.h (maybe_process_partial_specialization): Return
	tree instead of void.
	* parser.c (cp_parser_class_head): Use return value of
	maybe_process_partial_specialization.
	* pt.c (maybe_process_partial_specialization): Return error_mark_node
	for broken specializations, TYPE otherwise.  Check for template
	template parameters.

	* g++.dg/template/ttp22.C: New test.

From-SVN: r116541