https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84181
--- Comment #1 from Benjamin Buch <benni.buch at gmail dot com> --- Same with: template < int ... I > struct A{}; template < typename T > void f(){ [](auto ... i){ return A< decltype(i)::x ... >{}; }; } int main(){ f< int >(); } $ g++ -std=c++14 main2.cpp main2.cpp: In instantiation of 'void f() [with T = int]': main2.cpp:12:14: required from here main2.cpp:7:40: internal compiler error: in strip_typedefs_expr, at cp/tree.c:1690 return A< decltype(i)::x ... >{}; ^ 0x63696d strip_typedefs_expr(tree_node*, bool*) ../../gcc/gcc/cp/tree.c:1690 0x997709 strip_typedefs_expr(tree_node*, bool*) ../../gcc/gcc/cp/tree.c:1795 0x90f33c canonicalize_expr_argument ../../gcc/gcc/cp/pt.c:7489 0x9477db canonicalize_expr_argument ../../gcc/gcc/cp/pt.c:7486 0x9477db convert_template_argument ../../gcc/gcc/cp/pt.c:7823 0x945ada coerce_template_parameter_pack ../../gcc/gcc/cp/pt.c:7971 0x945ada coerce_template_parms ../../gcc/gcc/cp/pt.c:8191 0x93f2b6 lookup_template_class_1 ../../gcc/gcc/cp/pt.c:8818 0x93f2b6 lookup_template_class(tree_node*, tree_node*, tree_node*, tree_node*, int, int) ../../gcc/gcc/cp/pt.c:9167 0x940d5a tsubst_aggr_type ../../gcc/gcc/cp/pt.c:12073 0x93b27e tsubst(tree_node*, tree_node*, int, tree_node*) ../../gcc/gcc/cp/pt.c:13706 0x926e14 tsubst_copy_and_build(tree_node*, tree_node*, int, tree_node*, bool, bool) ../../gcc/gcc/cp/pt.c:18153 0x934e49 tsubst_copy_and_build(tree_node*, tree_node*, int, tree_node*, bool, bool) ../../gcc/gcc/cp/pt.c:17100 0x934e49 tsubst_expr(tree_node*, tree_node*, int, tree_node*, bool) ../../gcc/gcc/cp/pt.c:16838 0x932ea0 tsubst_expr(tree_node*, tree_node*, int, tree_node*, bool) ../../gcc/gcc/cp/pt.c:16055 0x931f61 tsubst_expr(tree_node*, tree_node*, int, tree_node*, bool) ../../gcc/gcc/cp/pt.c:16322 0x931f61 tsubst_expr(tree_node*, tree_node*, int, tree_node*, bool) ../../gcc/gcc/cp/pt.c:16322 0x925b9b tsubst_expr(tree_node*, tree_node*, int, tree_node*, bool) ../../gcc/gcc/cp/pt.c:16030 0x925b9b tsubst_lambda_expr(tree_node*, tree_node*, int, tree_node*) ../../gcc/gcc/cp/pt.c:17056 0x927498 tsubst_copy_and_build(tree_node*, tree_node*, int, tree_node*, bool, bool) ../../gcc/gcc/cp/pt.c:18346 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.