https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94426
--- Comment #5 from Nathan Sidwell <nathan at gcc dot gnu.org> --- Reduced testcase: template <bool> using Void = void; template <typename U> bool Init (U); template <typename> bool VAR = Init ([] {}); template <typename T> Void<false && VAR<T>> Foo (T) {} void q () { Foo ([] {}); } bug.ii: At global scope: bug.ii:5:38: internal compiler error: in mangle_decl, at cp/mangle.c:3907 5 | template <typename> bool VAR = Init ([] {});