Avoid set var's bounds if offset != 0

if `offset != 0`, then these 2 var should have different value, thus it's invalid to set bounds.

src/subtype.c

@@ -2165,15 +2165,15 @@ static jl_value_t *set_var_to_const(jl_varbinding_t *bb, jl_value_t *v JL_MAYBE_
         offset = -othervar->offset;
     assert(!othervar || othervar->offset == -offset);
     if (bb->lb == jl_bottom_type && bb->ub == (jl_value_t*)jl_any_type) {
-        if (jl_is_long(v)) {
+        if (offset == 0)
+            bb->lb = bb->ub = v;
+        else if (jl_is_long(v)) {
             size_t iv = jl_unbox_long(v);
             v = jl_box_long(iv + offset);
             bb->lb = bb->ub = v;
             // Here we always return the shorter `Vararg`'s length.
             if (offset > 0) return jl_box_long(iv);
         }
-        else
-            bb->lb = bb->ub = v;
     }
     else if (jl_is_long(v) && jl_is_long(bb->lb)) {
         if (jl_unbox_long(v) + offset != jl_unbox_long(bb->lb))
@@ -2194,11 +2194,12 @@ static jl_value_t *bound_var_below(jl_tvar_t *tv, jl_varbinding_t *bb, jl_stenv_
         return jl_bottom_type;
     record_var_occurrence(bb, e, 2);
     if (jl_is_long(bb->lb)) {
+        size_t blb = jl_unbox_long(bb->lb);
+        if (blb < bb->offset || blb < 0)
+            return jl_bottom_type;
         // Here we always return the shorter `Vararg`'s length.
         if (bb->offset <= 0)
             return bb->lb;
-        if (jl_unbox_long(bb->lb) < bb->offset)
-            return jl_bottom_type;
         return jl_box_long(jl_unbox_long(bb->lb) - bb->offset);
     }
     return (jl_value_t*)tv;
@@ -3041,14 +3042,14 @@ static jl_value_t *intersect(jl_value_t *x, jl_value_t *y, jl_stenv_t *e, int pa
                     lb = ylb;
                 else
                     lb = simple_join(xlb, ylb);
-                if (yy) {
+                if (yy && yy->offset == 0) {
                     yy->lb = lb;
                     if (!reachable_var(ub, (jl_tvar_t*)y, e))
                         yy->ub = ub;
                     assert(yy->ub != y);
                     assert(yy->lb != y);
                 }
-                if (xx && !reachable_var(y, (jl_tvar_t*)x, e)) {
+                if (xx && xx->offset == 0 && !reachable_var(y, (jl_tvar_t*)x, e)) {
                     xx->lb = y;
                     xx->ub = y;
                     assert(xx->ub != x);