https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120955
--- Comment #21 from fiesh at zefix dot tv --- Ok, reduction finally done: -----8<----- template <int a> struct b { typedef int c[a]; }; template <int a> struct f { b<a>::c d; }; namespace e::detail { struct h { int g; constexpr h() : g() {} }; } // namespace e::detail namespace e { struct j { f<6> i; }; struct l { j k; }; } // namespace e struct n { e::detail::h m{}; }; struct H { e::l p{4, 8, 5, 1, 3, 4}; n o; }; void q(H &r) { r = {}; } -----8<----- results in % podman run -it -v /tmp:/tmp alpine:3.21 sh -c 'sed -i -e s/https/http/ /etc/apk/repositories && apk -q add gcc-avr && avr-g++ --version && avr-g++ -std=c++20 -Os -g0 -o /c.o -c /tmp/c.ii && avr-size -G /c.o' && podman run -it -v /tmp:/tmp alpine:3.22 sh -c 'sed -i -e s/https/http/ /etc/apk/repositories && apk -q add gcc-avr && avr-g++ --version && avr-g++ -std=c++20 -Os -g0 -o /c.o -c /tmp/c.ii && avr-size -G /c.o' avr-g++ (Alpine Linux) 14.2.0 Copyright (C) 2024 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. text data bss total filename 54 0 0 54 /c.o avr-g++ (Alpine Linux) 15.1.0 Copyright (C) 2025 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. text data bss total filename 20 14 0 34 /c.o