* cp-tree.h (DECL_PARM_LEVEL): New.
(struct lang_decl_parm): Add level field.
* name-lookup.c (function_parm_depth): New fn.
* name-lookup.h: Declare it.
* parser.c (cp_parser_parameter_declaration_list): Use it.
* mangle.c (struct globals): Add parm_depth field.
(write_bare_function_type): Adjust it.
(write_expression): Include the level delta in PARM_DECL mangling
for abi >= 6.
* semantics.c (finish_decltype_type): Remove shortcut for decltype
of id-expression.
* mangle.c (write_type) [DECLTYPE_TYPE]: Strip it here for abi < 6.
From-SVN: r170459
