https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92745
--- Comment #5 from Jakub Jelinek <jakub at gcc dot gnu.org> --- Better testcase: template <typename a, int b> struct c { typedef a d[b]; }; template <typename a, int b> struct array { typename c<a, b>::d e; a operator[](long); }; template<class T> using vec4_t __attribute__((vector_size(4*sizeof(T)))) = float; auto transpose(array<vec4_t<float>, 4> col) { array<vec4_t<float>, 4> ret{vec4_t<float>{col[0][0], col[1][0], col[2][0], col[3][0]}, vec4_t<float>{col[0][1], col[1][1], col[2][1], col[3][1]}, vec4_t<float>{col[0][2], col[1][2], col[2][2], col[3][2]}, vec4_t<float>{col[0][3], col[1][3], col[2][3], col[3][3]}}; return ret; }