[Bug c++/84770] [8 Regression] ICE with parameter pack involving typedef

["msebor at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84770

--- Comment #2 from Martin Sebor <msebor at gcc dot gnu.org> ---
The ICE is due the assert below failing:

            gcc_assert (strip_typedefs_expr (arg, NULL) == arg);

arg is

<nontype_argument_pack 0x7fffefc2de00 constant
    arg:0 <tree_vec 0x7fffefc2dd80 length:1
        elt:0 <indirect_ref 0x7fffefc2dde0 type <integer_type 0x7fffefc1a9d8 T>

            arg:0 <nop_expr 0x7fffefc2ddc0 type <reference_type 0x7fffefc1ad20>
                constant
                arg:0 <addr_expr 0x7fffefc2dda0 type <pointer_type
0x7fffefae5a80>
                    constant arg:0 <var_decl 0x7ffff7ff5d80 i>>>>>>

but strip_typedefs_expr() returns

<nontype_argument_pack 0x7fffefc2de80 constant
    arg:0 <tree_vec 0x7fffefc2de60 length:1
        elt:0 <indirect_ref 0x7fffefc2de40 type <integer_type 0x7fffefc1a9d8 T>

            arg:0 <nop_expr 0x7fffefc2de20 type <reference_type 0x7fffefc30000>
                constant
                arg:0 <addr_expr 0x7fffefc2dda0 type <pointer_type
0x7fffefae5a80>
                    constant arg:0 <var_decl 0x7ffff7ff5d80 i>>>>>>