https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96104
--- Comment #2 from Marek Polacek <mpolacek at gcc dot gnu.org> --- Reduced: // PR c++/96104 template <typename T> void fn(T &); class E {}; struct F { template <typename T> void mfn(T t) { t, fn(E()); } // { dg-error "cannot bind non-const lvalue reference" } }; int main() { E e; F f; f.mfn(e); }