https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84518
--- Comment #1 from Volker Reichelt <reichelt at gcc dot gnu.org> --- A modified testcase produces a slightly different stack-trace: ==================================== template<typename T> void foo() { T x[=]; [&x]{}; } ==================================== bug.cc: In function 'void foo()': bug.cc:3:7: error: expected primary-expression before '=' token T x[=]; ^ bug.cc:3:8: error: expected primary-expression before ']' token T x[=]; ^ bug.cc: In lambda function: bug.cc:4:6: internal compiler error: in is_normal_capture_proxy, at cp/lambda.c:289 [&x]{}; ^ 0x614602 is_normal_capture_proxy(tree_node*) ../../gcc/gcc/cp/lambda.c:289 0x8d4918 is_capture_proxy_with_ref(tree_node*) ../../gcc/gcc/cp/lambda.c:301 0x8d49ad insert_capture_proxy(tree_node*) ../../gcc/gcc/cp/lambda.c:311 0x8d546f build_capture_proxy(tree_node*, tree_node*) ../../gcc/gcc/cp/lambda.c:474 0x8d8596 start_lambda_function(tree_node*, tree_node*) ../../gcc/gcc/cp/lambda.c:1374 0x91daad cp_parser_lambda_body ../../gcc/gcc/cp/parser.c:10662 0x91daad cp_parser_lambda_expression ../../gcc/gcc/cp/parser.c:10182 0x91daad cp_parser_primary_expression ../../gcc/gcc/cp/parser.c:5257 0x93043c cp_parser_postfix_expression ../../gcc/gcc/cp/parser.c:7026 0x931010 cp_parser_unary_expression ../../gcc/gcc/cp/parser.c:8318 0x91139f cp_parser_cast_expression ../../gcc/gcc/cp/parser.c:9086 0x911baa cp_parser_binary_expression ../../gcc/gcc/cp/parser.c:9187 0x9133e4 cp_parser_assignment_expression ../../gcc/gcc/cp/parser.c:9482 0x913af8 cp_parser_expression ../../gcc/gcc/cp/parser.c:9651 0x9157b8 cp_parser_expression_statement ../../gcc/gcc/cp/parser.c:11118 0x91bb2d cp_parser_statement ../../gcc/gcc/cp/parser.c:10922 0x91d040 cp_parser_statement_seq_opt ../../gcc/gcc/cp/parser.c:11261 0x91d117 cp_parser_compound_statement ../../gcc/gcc/cp/parser.c:11215 0x933890 cp_parser_function_body ../../gcc/gcc/cp/parser.c:21756 0x933890 cp_parser_ctor_initializer_opt_and_function_body ../../gcc/gcc/cp/parser.c:21793 Please submit a full bug report, [etc.]