[Bug c++/71465] New: ICE on invalid C++ code (with duplicate base) on x86_64-linux-gnu: in dfs_build_secondary_vptr_vtt_inits, at cp/class.c:9075

[su at cs dot ucdavis.edu]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71465

            Bug ID: 71465
           Summary: ICE on invalid C++ code (with duplicate base) on
                    x86_64-linux-gnu: in
                    dfs_build_secondary_vptr_vtt_inits, at cp/class.c:9075
           Product: gcc
           Version: 7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: su at cs dot ucdavis.edu
  Target Milestone: ---

The following code causes an ICE when compiled with the current gcc trunk on
x86_64-linux-gnu in both 32-bit and 64-bit modes.

This is a regression from 6.1.x. 


$ g++-trunk -v
Using built-in specs.
COLLECT_GCC=g++-trunk
COLLECT_LTO_WRAPPER=/usr/local/gcc-trunk/libexec/gcc/x86_64-pc-linux-gnu/7.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../gcc-source-trunk/configure --enable-languages=c,c++,lto
--prefix=/usr/local/gcc-trunk --disable-bootstrap
Thread model: posix
gcc version 7.0.0 20160608 (experimental) [trunk revision 237196] (GCC) 
$ 
$ g++-6.1 -c small.cpp
small.cpp:4:18: error: duplicate base type ‘C’ invalid
 struct D : C, B, C {};
                  ^
$  
$ g++-trunk -c small.cpp
small.cpp:4:18: error: duplicate base type ‘C’ invalid
 struct D : C, B, C {};
                  ^
small.cpp:4:8: internal compiler error: in dfs_build_secondary_vptr_vtt_inits,
at cp/class.c:9075
 struct D : C, B, C {};
        ^
0x74907e dfs_build_secondary_vptr_vtt_inits
        ../../gcc-source-trunk/gcc/cp/class.c:9075
0x80472e dfs_walk_all(tree_node*, tree_node* (*)(tree_node*, void*), tree_node*
(*)(tree_node*, void*), void*)
        ../../gcc-source-trunk/gcc/cp/search.c:1798
0x804774 dfs_walk_all(tree_node*, tree_node* (*)(tree_node*, void*), tree_node*
(*)(tree_node*, void*), void*)
        ../../gcc-source-trunk/gcc/cp/search.c:1810
0x804774 dfs_walk_all(tree_node*, tree_node* (*)(tree_node*, void*), tree_node*
(*)(tree_node*, void*), void*)
        ../../gcc-source-trunk/gcc/cp/search.c:1810
0x807b88 dfs_walk_once(tree_node*, tree_node* (*)(tree_node*, void*),
tree_node* (*)(tree_node*, void*), void*)
        ../../gcc-source-trunk/gcc/cp/search.c:1895
0x7492cd build_vtt_inits
        ../../gcc-source-trunk/gcc/cp/class.c:9022
0x74d216 build_vtt
        ../../gcc-source-trunk/gcc/cp/class.c:8907
0x74d216 finish_struct_1(tree_node*)
        ../../gcc-source-trunk/gcc/cp/class.c:7070
0x74edb4 finish_struct(tree_node*, tree_node*)
        ../../gcc-source-trunk/gcc/cp/class.c:7265
0x78875c cp_parser_class_specifier_1
        ../../gcc-source-trunk/gcc/cp/parser.c:21368
0x78875c cp_parser_class_specifier
        ../../gcc-source-trunk/gcc/cp/parser.c:21596
0x78875c cp_parser_type_specifier
        ../../gcc-source-trunk/gcc/cp/parser.c:15836
0x79d223 cp_parser_decl_specifier_seq
        ../../gcc-source-trunk/gcc/cp/parser.c:12758
0x7aa711 cp_parser_simple_declaration
        ../../gcc-source-trunk/gcc/cp/parser.c:12299
0x7aab61 cp_parser_block_declaration
        ../../gcc-source-trunk/gcc/cp/parser.c:12246
0x7b3f40 cp_parser_declaration
        ../../gcc-source-trunk/gcc/cp/parser.c:12143
0x7b2a14 cp_parser_declaration_seq_opt
        ../../gcc-source-trunk/gcc/cp/parser.c:12022
0x7b2d48 cp_parser_translation_unit
        ../../gcc-source-trunk/gcc/cp/parser.c:4324
0x7b2d48 c_parse_file()
        ../../gcc-source-trunk/gcc/cp/parser.c:37502
0x9162f2 c_common_parse_file()
        ../../gcc-source-trunk/gcc/c-family/c-opts.c:1064
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
See <http://gcc.gnu.org/bugs.html> for instructions.
$ 


-------------------------------------


struct A { virtual void foo () {} };
struct B : virtual A {};
struct C : virtual A {}; 
struct D : C, B, C {};