PR c++/27094
	* pt.c (tsubst_default_argument): Increment function_depth around
	call to tsubst_expr.
	* parser.c (cp_parser_parameter_declaration): Likewise.
	* decl2.c (mark_used): Tidy.
	PR c++/27094
	* g++.dg/template/defarg8.C: New test.

From-SVN: r113399