Do put the VTT parameter in DECL_ARGUMENTS.

    Do put the VTT parameter in DECL_ARGUMENTS.
        * cp-tree.h (struct cp_language_function): Add x_vtt_parm.
        (current_vtt_parm): New macro.
        (struct lang_decl_flags): Add has_vtt_parm_p, remove vtt_parm.
        (DECL_HAS_VTT_PARM_P): New macro.
        (DECL_VTT_PARM): Remove.
        (FUNCTION_FIRST_USER_PARMTYPE, FUNCTION_FIRST_USER_PARM): New macros.
        * decl.c (duplicate_decls): Only copy the operator code if
        appropriate.
        (start_function): Set current_vtt_parm.
        (lang_mark_tree): Don't mark vtt_parm.
        * decl2.c (maybe_retrofit_in_chrg): Do add the VTT parm to
        DECL_ARGUMENTS.  Set DECL_HAS_VTT_PARM_P.
        * class.c (build_clone): Maybe remove the VTT parm.
        * optimize.c (maybe_clone_body): Set up the VTT parm.
        * pt.c (copy_default_args_to_explicit_spec): Preserve the VTT parm.
        * call.c (build_over_call): Just allow the VTT arg.
        * method.c (make_thunk): Don't set DECL_VTT_PARM.
        (do_build_copy_constructor): Use FUNCTION_FIRST_USER_PARM.
        (synthesize_method): Use FUNCTION_FIRST_USER_PARMTYPE.
        * decl.c (grokdeclarator, copy_args_p, grok_ctor_properties): Likewise.
        * error.c (dump_function_decl): Likewise.
        * call.c (build_user_type_conversion_1, convert_like_real): Abort
        if we try to call a constructor with in-charge or VTT parms.
        * method.c (skip_artificial_parms_for): New fn.
        * call.c (add_function_candidate, build_over_call): Call it.
        * call.c (build_new_method_call): Use current_vtt_parm.
        * init.c (expand_virtual_init): Likewise.
        * class.c (same_signature_p): No longer static.
        * cp-tree.h: Declare it.
        * search.c (look_for_overrides_r): Use it.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@39841 138bc75d-0d04-0410-961f-82ee72b054a4