Always return the shorter Vararg length.

The type `var` might be switched during intersection.
Thus previous result looks order dependent.

In fact, we should always return the shorter `Vararg` length.
As former terms has been taken care by `intersect_tuple`.

Also fix JuliaLang#37257

src/subtype.c

@@ -2167,9 +2167,13 @@ 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))
-            v = jl_box_long(jl_unbox_long(v) + offset);
-        bb->lb = bb->ub = v;
+        jl_value_t *vnew = v;
+        if (bb->need_offset && jl_is_long(v)) {
+            vnew = jl_box_long(jl_unbox_long(v) + offset);
+            // Here we always return the smaller Varargs length.
+            if (offset < 0) v = vnew;
+        }
+        bb->lb = bb->ub = vnew;
     }
     else if (jl_is_long(v) && jl_is_long(bb->lb)) {
         long lv = jl_unbox_long(v), llb = jl_unbox_long(bb->lb);
@@ -2194,7 +2198,8 @@ 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)) {
-        if (bb->offset == 0)
+        // Here we always return the smaller Varargs length.
+        if (bb->offset <= 0)
             return bb->lb;
         if (jl_unbox_long(bb->lb) < bb->offset)
             return jl_bottom_type;

test/subtype.jl

@@ -2046,18 +2046,22 @@ let f36443(::NTuple{N}=[(f36443,),(1,2)][2],::Val{N}=Val(2)) where{N} = 0
 end
 
 let C = Tuple{Val{3},Int,Int,Int,Int},
-    Cerror = Tuple{Val{3},Int,Int,Int,Int,Int}, 
     As = (Tuple{Val{N},Int,Vararg{T,N}} where {T,N}, 
           Tuple{Val{N},Int,Vararg{T,N}} where {N,T}),
     Bs = (Tuple{Val{3},Vararg{T,N}} where {T,N}, 
           Tuple{Val{3},Vararg{T,N}} where {N,T},
           Tuple{Val{3},Vararg{T}} where {T})
-    for A in As
-        @test_broken typeintersect(A, Bs[1]) != Cerror
-        @test_broken typeintersect(A, Bs[3]) != Cerror
-        @test_broken typeintersect(A, Bs[3]) != Cerror
-
-        @test typeintersect(Bs[1], A) == C # Union{} on master
-        @testintersect(A, Bs[2], C)        # Union{} on master
+    for A in As, B in Bs
+        @testintersect(A, B, C)
     end
 end
+
+#issue #36443
+let T = Tuple{Val{N}, Any, Any, Vararg{Any,N}} where N,
+    C = Tuple{Val{1}, Any, Any, Any}
+    @testintersect(T, Tuple{Val{1}, Vararg{Any}}, C)
+    @testintersect(T, Tuple{Val{1}, Any, Vararg{Any}}, C)
+    @testintersect(T, Tuple{Val{1}, Any, Any, Vararg{Any}}, C)
+    @testintersect(T, Tuple{Val{1}, Any, Any, Any, Vararg{Any}}, C)
+    @testintersect(T, Tuple{Val{1}, Any, Any, Any, Any, Vararg{Any}}, Union{})
+end