Also save signature triggering the invalidation

Author: timholy

src/gf.c

@@ -1739,6 +1739,9 @@ JL_DLLEXPORT void jl_method_table_insert(jl_methtable_t *mt, jl_method_t *method
             for (i = 1; i < na; i += 2) {
                 jl_value_t *backedgetyp = backedges[i - 1];
                 if (!jl_has_empty_intersection(backedgetyp, (jl_value_t*)type)) {
+                    if (_jl_debug_method_invalidation) {
+                        jl_array_ptr_1d_push(_jl_debug_method_invalidation, (jl_value_t*)backedgetyp);
+                    }
                     jl_method_instance_t *backedge = (jl_method_instance_t*)backedges[i];
                     invalidate_method_instance(backedge, max_world, 0);
                     invalidated = 1;