PR c++/59012
	* parser.c (cp_parser_std_attribute_list): Handle attribute expansion.
	(cp_parser_std_attribute_spec): Handle alignas pack expansion.
	* decl2.c (is_late_template_attribute): An attribute exp is dependent.
	* pt.c (make_pack_expansion): Allow TREE_LIST for attribute expansion.
	(apply_late_template_attributes): Handle attribute pack expansion.

From-SVN: r222902