http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58871
Bug ID: 58871 Summary: [4.7/4.8/4.9 Regression] [c++11] ICE with defaulted copy constructor in broken template class hierarchy 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" or "-std=c++0x" for older compilers) triggers an ICE since GCC 4.6.0: ======================================================== template<typename T> struct A : virtual T { A(); A(const A&); }; template<typename T> A<T>::A(const A<T>&) = default; A<int> a = A<int>(); ======================================================== bug.cc: In instantiation of 'struct A<int>': bug.cc:9:8: required from here bug.cc:1:29: error: base type 'int' fails to be a struct or class type template<typename T> struct A : virtual T ^ bug.cc:7:22: internal compiler error: in implicitly_declare_fn, at cp/method.c:1660 template<typename T> A<T>::A(const A<T>&) = default; ^ 0x6b0bd0 implicitly_declare_fn(special_function_kind, tree_node*, bool, tree_node*, tree_node*) ../../gcc/gcc/cp/method.c:1660 0x6b470e defaulted_late_check(tree_node*) ../../gcc/gcc/cp/method.c:1780 0x5cc4f4 tsubst_decl ../../gcc/gcc/cp/pt.c:10537 0x5b9634 tsubst(tree_node*, tree_node*, int, tree_node*) ../../gcc/gcc/cp/pt.c:11323 0x5e75db instantiate_class_template_1 ../../gcc/gcc/cp/pt.c:8927 0x5e75db instantiate_class_template(tree_node*) ../../gcc/gcc/cp/pt.c:9236 0x6784eb complete_type(tree_node*) ../../gcc/gcc/cp/typeck.c:132 0x561589 start_decl_1(tree_node*, bool) ../../gcc/gcc/cp/decl.c:4679 0x58b2f1 start_decl(cp_declarator const*, cp_decl_specifier_seq*, int, tree_node*, tree_node*, tree_node**) ../../gcc/gcc/cp/decl.c:4642 0x663dba cp_parser_init_declarator ../../gcc/gcc/cp/parser.c:16526 0x66569f cp_parser_simple_declaration ../../gcc/gcc/cp/parser.c:11066 0x6495e0 cp_parser_block_declaration ../../gcc/gcc/cp/parser.c:10947 0x6708fe cp_parser_declaration ../../gcc/gcc/cp/parser.c:10844 0x66f61a cp_parser_declaration_seq_opt ../../gcc/gcc/cp/parser.c:10730 0x670f36 cp_parser_translation_unit ../../gcc/gcc/cp/parser.c:3990 0x670f36 c_parse_file() ../../gcc/gcc/cp/parser.c:30999 0x78e183 c_common_parse_file() ../../gcc/gcc/c-family/c-opts.c:1046 Please submit a full bug report, [etc.]