PR c++/22263
	* cp-tree.h (instantiate_decl): Change prototype.
	* decl2.c (mark_used): Adjust accordingly.
	* pt.c (do_decl_instantiation): Likewise.
	(instantiate_class_member): Likewise.
	(instantiate_decl): Rename undefined_ok as expl_inst_class_mem_p.
	Clear DECL_INTERFACE_KNOWN for an explicitly instantiated template
	that has no definition available.
	(instantiate_pending_templates): Adjust call to instantiate_decl.

	PR c++/22263
	* g++.dg/template/explicit7.C: New test.

From-SVN: r102133