[Bug c++/84533] New: [7/8 Regression] ICE with duplicate enum value

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84533

            Bug ID: 84533
           Summary: [7/8 Regression] ICE with duplicate enum value
           Product: gcc
           Version: 8.0
            Status: UNCONFIRMED
          Keywords: ice-on-invalid-code
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: reichelt at gcc dot gnu.org
  Target Milestone: ---

The following really short invalid code snippet (compiled with "-std=c++1z")
triggers an ICE since GCC 7.1.0:

======================
enum E { e, e };
======================

bug.cc:1:13: internal compiler error: tree check: expected var_decl or
function_decl, have const_decl in redeclaration_error_message, at
cp/decl.c:2923
 enum E { e, e };
             ^
0x78a6fc tree_check_failed(tree_node const*, char const*, int, char const*,
...)
        ../../gcc/gcc/tree.c:9335
0x890e85 tree_check2(tree_node*, char const*, int, char const*, tree_code,
tree_code)
        ../../gcc/gcc/tree.h:3151
0x890e85 redeclaration_error_message
        ../../gcc/gcc/cp/decl.c:2923
0x890e85 duplicate_decls(tree_node*, tree_node*, bool)
        ../../gcc/gcc/cp/decl.c:1767
0x9007ea do_pushdecl
        ../../gcc/gcc/cp/name-lookup.c:3035
0x9007ea pushdecl(tree_node*, bool)
        ../../gcc/gcc/cp/name-lookup.c:3170
0x8935d9 build_enumerator(tree_node*, tree_node*, tree_node*, tree_node*,
unsigned int)
        ../../gcc/gcc/cp/decl.c:14644
0x929db7 cp_parser_enumerator_definition
        ../../gcc/gcc/cp/parser.c:18410
0x929db7 cp_parser_enumerator_list
        ../../gcc/gcc/cp/parser.c:18339
0x929db7 cp_parser_enum_specifier
        ../../gcc/gcc/cp/parser.c:18266
0x929db7 cp_parser_type_specifier
        ../../gcc/gcc/cp/parser.c:16726
0x936966 cp_parser_decl_specifier_seq
        ../../gcc/gcc/cp/parser.c:13612
0x93c030 cp_parser_simple_declaration
        ../../gcc/gcc/cp/parser.c:12922
0x93cfd8 cp_parser_block_declaration
        ../../gcc/gcc/cp/parser.c:12869
0x940f32 cp_parser_declaration
        ../../gcc/gcc/cp/parser.c:12767
0x941341 cp_parser_declaration_seq_opt
        ../../gcc/gcc/cp/parser.c:12643
0x941634 cp_parser_translation_unit
        ../../gcc/gcc/cp/parser.c:4559
0x941634 c_parse_file()
        ../../gcc/gcc/cp/parser.c:38866
0xa3f966 c_common_parse_file()
        ../../gcc/gcc/c-family/c-opts.c:1132
Please submit a full bug report, [etc.]