Ensure serialize/deserialize work for isbits union arrays

Author: quinnj

src/dump.c

@@ -570,7 +570,8 @@ static void jl_serialize_value_(jl_serializer_state *s, jl_value_t *v, int as_li
             jl_serialize_value(s, jl_box_long(jl_array_dim(ar,i)));
         jl_serialize_value(s, jl_typeof(ar));
         if (!ar->flags.ptrarray) {
-            size_t tot = jl_array_len(ar) * ar->elsize;
+            size_t extra = jl_is_uniontype(jl_tparam0(jl_typeof(ar))) ? jl_array_len(ar) : 0;
+            size_t tot = jl_array_len(ar) * ar->elsize + extra;
             ios_write(s->s, (char*)jl_array_data(ar), tot);
         }
         else {
@@ -1347,7 +1348,8 @@ static jl_value_t *jl_deserialize_value_array(jl_serializer_state *s, jl_value_t
     jl_value_t *aty = jl_deserialize_value(s, &jl_astaggedvalue(a)->type);
     jl_set_typeof(a, aty);
     if (!a->flags.ptrarray) {
-        size_t tot = jl_array_len(a) * a->elsize;
+        size_t extra = jl_is_uniontype(jl_tparam0(aty)) ? jl_array_len(a) : 0;
+        size_t tot = jl_array_len(a) * a->elsize + extra;
         ios_read(s->s, (char*)jl_array_data(a), tot);
     }
     else {