[Bug c++/85068] New: [6/7/8 Regression] ICE with invalid covarint return types

[reichelt at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85068

            Bug ID: 85068
           Summary: [6/7/8 Regression] ICE with invalid covarint return
                    types
           Product: gcc
           Version: unknown
            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
  Target Milestone: ---

The following invalid code snippet triggers an ICE since GCC 4.0.0:

=========================
struct A;

struct B
{
  virtual A* foo();
};

struct C : virtual B
{
  virtual C* foo();
};

struct D : C
{
  virtual C* foo();
};
=========================

bug.cc:10:14: error: invalid covariant return type for 'virtual C* C::foo()'
   virtual C* foo();
              ^~~
bug.cc:5:14: error:   overriding 'virtual A* B::foo()'
   virtual A* foo();
              ^~~
bug.cc:13:8: internal compiler error: Segmentation fault
 struct D : C
        ^
0xebb63f crash_signal
        ../../gcc/gcc/toplev.c:325
0x84327d tree_check(tree_node*, char const*, int, char const*, tree_code)
        ../../gcc/gcc/tree.h:3134
0x84327d update_vtable_entry_for_fn
        ../../gcc/gcc/cp/class.c:2492
0x84327d dfs_modify_vtables
        ../../gcc/gcc/cp/class.c:2668
0x9a178d dfs_walk_all(tree_node*, tree_node* (*)(tree_node*, void*), tree_node*
(*)(tree_node*, void*), void*)
        ../../gcc/gcc/cp/search.c:1410
0x9a17e6 dfs_walk_all(tree_node*, tree_node* (*)(tree_node*, void*), tree_node*
(*)(tree_node*, void*), void*)
        ../../gcc/gcc/cp/search.c:1422
0x9a17e6 dfs_walk_all(tree_node*, tree_node* (*)(tree_node*, void*), tree_node*
(*)(tree_node*, void*), void*)
        ../../gcc/gcc/cp/search.c:1422
0x9a39c7 dfs_walk_once(tree_node*, tree_node* (*)(tree_node*, void*),
tree_node* (*)(tree_node*, void*), void*)
        ../../gcc/gcc/cp/search.c:1507
0x849b5a modify_all_vtables
        ../../gcc/gcc/cp/class.c:2696
0x849b5a finish_struct_1(tree_node*)
        ../../gcc/gcc/cp/class.c:6813
0x84ba1c finish_struct(tree_node*, tree_node*)
        ../../gcc/gcc/cp/class.c:7047
0x92eb70 cp_parser_class_specifier_1
        ../../gcc/gcc/cp/parser.c:22537
0x930b89 cp_parser_class_specifier
        ../../gcc/gcc/cp/parser.c:22791
0x930b89 cp_parser_type_specifier
        ../../gcc/gcc/cp/parser.c:16776
0x93dec6 cp_parser_decl_specifier_seq
        ../../gcc/gcc/cp/parser.c:13627
0x9435c0 cp_parser_simple_declaration
        ../../gcc/gcc/cp/parser.c:12937
0x944568 cp_parser_block_declaration
        ../../gcc/gcc/cp/parser.c:12884
0x9484c2 cp_parser_declaration
        ../../gcc/gcc/cp/parser.c:12782
0x9488d1 cp_parser_declaration_seq_opt
        ../../gcc/gcc/cp/parser.c:12658
0x948bc4 cp_parser_translation_unit
        ../../gcc/gcc/cp/parser.c:4563
Please submit a full bug report, [etc.]