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 āCā invalid struct D : C, B, C {}; ^ $ $ g++-trunk -c small.cpp small.cpp:4:18: error: duplicate base type āCā 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 {};