[Bug c++/60187] New: [4.7/4.8/4.9 Regression] [c++11] ICE with parameter pack as underlying type for enum

[reichelt at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60187

            Bug ID: 60187
           Summary: [4.7/4.8/4.9 Regression] [c++11] ICE with parameter
                    pack as underlying type for enum
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: reichelt at gcc dot gnu.org

The following invalid code snippet (compiled with "-std=c++11")
triggers an ICE since GCC 4.6.0:

==================================================
template<typename... T> struct A
{
  enum E : T {};
};

A<int> a;
==================================================

bug.cc: In instantiation of 'struct A<int>':
bug.cc:6:8:   required from here
bug.cc:3:8: internal compiler error: in dependent_type_p, at cp/pt.c:20283
   enum E : T {};
        ^
0x5ff408 dependent_type_p(tree_node*)
        ../../gcc/gcc/cp/pt.c:20283
0x5d1e29 start_enum(tree_node*, tree_node*, tree_node*, bool, bool*)
        ../../gcc/gcc/cp/decl.c:12604
0x624e54 lookup_template_class_1
        ../../gcc/gcc/cp/pt.c:7518
0x624e54 lookup_template_class(tree_node*, tree_node*, tree_node*, tree_node*,
int, int)
        ../../gcc/gcc/cp/pt.c:7725
0x629673 tsubst_aggr_type
        ../../gcc/gcc/cp/pt.c:10031
0x61b9f1 tsubst(tree_node*, tree_node*, int, tree_node*)
        ../../gcc/gcc/cp/pt.c:11436
0x62e0d3 tsubst_decl
        ../../gcc/gcc/cp/pt.c:10824
0x61be9f tsubst(tree_node*, tree_node*, int, tree_node*)
        ../../gcc/gcc/cp/pt.c:11357
0x64a34a instantiate_class_template_1
        ../../gcc/gcc/cp/pt.c:9010
0x64a34a instantiate_class_template(tree_node*)
        ../../gcc/gcc/cp/pt.c:9274
0x6db973 complete_type(tree_node*)
        ../../gcc/gcc/cp/typeck.c:134
0x5c4f38 start_decl_1(tree_node*, bool)
        ../../gcc/gcc/cp/decl.c:4719
0x5ede67 start_decl(cp_declarator const*, cp_decl_specifier_seq*, int,
tree_node*, tree_node*, tree_node**)
        ../../gcc/gcc/cp/decl.c:4682
0x6c7e9e cp_parser_init_declarator
        ../../gcc/gcc/cp/parser.c:16680
0x6c9929 cp_parser_simple_declaration
        ../../gcc/gcc/cp/parser.c:11205
0x6acc13 cp_parser_block_declaration
        ../../gcc/gcc/cp/parser.c:11086
0x6d3ec2 cp_parser_declaration
        ../../gcc/gcc/cp/parser.c:10983
0x6d2bb8 cp_parser_declaration_seq_opt
        ../../gcc/gcc/cp/parser.c:10869
0x6d445a cp_parser_translation_unit
        ../../gcc/gcc/cp/parser.c:4014
0x6d445a c_parse_file()
        ../../gcc/gcc/cp/parser.c:31536
Please submit a full bug report, [etc.]

The code was correctly rejected by GCC 4.4.0
and wrongly accepted by GCC 4.4.1-4.5.3.