[Bug c++/85133] New: [7/8 Regression] [concepts] ICE with invalid concept used in variadic template

[reichelt at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85133

            Bug ID: 85133
           Summary: [7/8 Regression] [concepts] ICE with invalid concept
                    used in variadic template
           Product: gcc
           Version: 8.0
            Status: UNCONFIRMED
          Keywords: error-recovery, ice-on-invalid-code
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: reichelt at gcc dot gnu.org
            Blocks: 67491
  Target Milestone: ---

The following invalid code snippet (compiled with "-fconcepts")
triggers an ICE since GCC 7.1.0:

===========================================
template<typename> concept bool C;

template<C...> struct A {};

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

bug.cc:1:33: error: variable concept has no initializer
 template<typename> concept bool C;
                                 ^
bug.cc:5:6: internal compiler error: in iterative_hash_template_arg, at
cp/pt.c:1713
 A<int> a;
      ^
0x64ed6f iterative_hash_template_arg(tree_node*, unsigned int)
        ../../gcc-7.1.0/gcc/cp/pt.c:1713
0x64e280 iterative_hash_template_arg(tree_node*, unsigned int)
        ../../gcc-7.1.0/gcc/cp/pt.c:1732
0x65826d concept_spec_hasher::hash(concept_spec_entry*)
        ../../gcc-7.1.0/gcc/cp/pt.c:25880
0x65826d hash_table<concept_spec_hasher,
xcallocator>::find_slot(concept_spec_entry* const&, insert_option)
        ../../gcc-7.1.0/gcc/hash-table.h:414
0x65826d memoize_concept_satisfaction(tree_node*, tree_node*, tree_node*)
        ../../gcc-7.1.0/gcc/cp/pt.c:25941
0x85af29 satisfy_check_constraint
        ../../gcc-7.1.0/gcc/cp/constraint.cc:2058
0x85af29 satisfy_constraint_1
        ../../gcc-7.1.0/gcc/cp/constraint.cc:2247
0x85b460 satisfy_constraint
        ../../gcc-7.1.0/gcc/cp/constraint.cc:2302
0x85b866 constraints_satisfied_p(tree_node*, tree_node*)
        ../../gcc-7.1.0/gcc/cp/constraint.cc:2414
0x66579c gen_elem_of_pack_expansion_instantiation
        ../../gcc-7.1.0/gcc/cp/pt.c:11048
0x66579c tsubst_pack_expansion(tree_node*, tree_node*, int, tree_node*)
        ../../gcc-7.1.0/gcc/cp/pt.c:11504
0x85a6d8 satisfy_pack_expansion
        ../../gcc-7.1.0/gcc/cp/constraint.cc:1983
0x85a6d8 satisfy_constraint_1
        ../../gcc-7.1.0/gcc/cp/constraint.cc:2274
0x85b460 satisfy_constraint
        ../../gcc-7.1.0/gcc/cp/constraint.cc:2302
0x85b553 satisfy_associated_constraints
        ../../gcc-7.1.0/gcc/cp/constraint.cc:2326
0x85b896 constraints_satisfied_p(tree_node*, tree_node*)
        ../../gcc-7.1.0/gcc/cp/constraint.cc:2416
0x699158 lookup_template_class_1
        ../../gcc-7.1.0/gcc/cp/pt.c:8707
0x699158 lookup_template_class(tree_node*, tree_node*, tree_node*, tree_node*,
int, int)
        ../../gcc-7.1.0/gcc/cp/pt.c:9009
0x7af3dd finish_template_type(tree_node*, tree_node*, int)
        ../../gcc-7.1.0/gcc/cp/semantics.c:3151
0x736c44 cp_parser_template_id
        ../../gcc-7.1.0/gcc/cp/parser.c:15495
Please submit a full bug report, [etc.]


Referenced Bugs:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67491
[Bug 67491] [meta-bug] concepts issues