https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84098
Bug ID: 84098 Summary: [8 Regression] ICE when using a lambda in a in-class static member initialization Product: gcc Version: 8.0.1 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ Assignee: unassigned at gcc dot gnu.org Reporter: benni.buch at gmail dot com Target Milestone: --- struct A{}; template < typename > struct Test{ static constexpr auto var = []{}; }; int main(){ (void)Test< A >::var; } $ g++ -std=c++11 main.cpp main.cpp: In instantiation of 'struct Test<A>': main.cpp:9:20: required from here main.cpp:5:34: internal compiler error: in lookup_template_class_1, at cp/pt.c:8957 static constexpr auto var = []{}; ^ 0x612d1c lookup_template_class_1 ../../gcc/gcc/cp/pt.c:8957 0x612d1c lookup_template_class(tree_node*, tree_node*, tree_node*, tree_node*, int, int) ../../gcc/gcc/cp/pt.c:9167 0x94017a tsubst_aggr_type ../../gcc/gcc/cp/pt.c:12035 0x93a69e tsubst(tree_node*, tree_node*, int, tree_node*) ../../gcc/gcc/cp/pt.c:13668 0x9412b2 tsubst_decl ../../gcc/gcc/cp/pt.c:12965 0x93a7af tsubst(tree_node*, tree_node*, int, tree_node*) ../../gcc/gcc/cp/pt.c:13586 0x958cea instantiate_class_template_1 ../../gcc/gcc/cp/pt.c:10635 0x958cea instantiate_class_template(tree_node*) ../../gcc/gcc/cp/pt.c:10920 0x999afd complete_type(tree_node*) ../../gcc/gcc/cp/typeck.c:136 0x8f833a cp_parser_nested_name_specifier_opt ../../gcc/gcc/cp/parser.c:6441 0x8f9e45 cp_parser_simple_type_specifier ../../gcc/gcc/cp/parser.c:17111 0x8faf57 cp_parser_postfix_expression ../../gcc/gcc/cp/parser.c:6945 0x8fbbc0 cp_parser_unary_expression ../../gcc/gcc/cp/parser.c:8281 0x8dc73f cp_parser_cast_expression ../../gcc/gcc/cp/parser.c:9049 0x8dc901 cp_parser_cast_expression ../../gcc/gcc/cp/parser.c:9001 0x8dcf4a cp_parser_binary_expression ../../gcc/gcc/cp/parser.c:9150 0x8de714 cp_parser_assignment_expression ../../gcc/gcc/cp/parser.c:9437 0x8dee28 cp_parser_expression ../../gcc/gcc/cp/parser.c:9606 0x8e0ad8 cp_parser_expression_statement ../../gcc/gcc/cp/parser.c:11075 0x8e683d cp_parser_statement ../../gcc/gcc/cp/parser.c:10879 Please submit a full bug report, with preprocessed source if appropriate. Please include the complete backtrace with any bug report. See <https://gcc.gnu.org/bugs/> for instructions. $ g++ --version g++ (GCC) 8.0.1 20180129 (experimental) Copyright (C) 2018 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. Known to work with g++-5 and g++6, both give an error message but don't run into an ICE, clang accepts the code. $ g++-6 -std=c++11 main.cpp main.cpp:5:27: error: 'constexpr const Test<A>::<lambda()> Test<A>::var', declared using local type 'const Test<A>::<lambda()>', is used but never defined [-fpermissive] static constexpr auto var = []{}; ^~~ $ g++-6 --version g++-6 (Ubuntu/Linaro 6.3.0-18ubuntu2~16.04) 6.3.0 20170519 Copyright (C) 2016 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. $ g++-5 --version g++-5 (Ubuntu 5.4.1-2ubuntu1~16.04) 5.4.1 20160904 Copyright (C) 2015 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.