reflect: Value.Set: fix direction of assignment check

src/reflect/value.go

@@ -907,7 +907,7 @@ func (it *MapIter) Next() bool {
 
 func (v Value) Set(x Value) {
 	v.checkAddressable()
-	if !v.typecode.AssignableTo(x.typecode) {
+	if !x.typecode.AssignableTo(v.typecode) {
 		panic("reflect: cannot set")
 	}
 

src/reflect/value_test.go

@@ -504,6 +504,15 @@ func TestTinyNumMethods(t *testing.T) {
 	}
 }
 
+func TestAssignableTo(t *testing.T) {
+	var a any
+	refa := ValueOf(&a).Elem()
+	refa.Set(ValueOf(4))
+	if got, want := refa.Interface().(int), 4; got != want {
+		t.Errorf("AssignableTo / Set failed, got %v, want %v", got, want)
+	}
+}
+
 func equal[T comparable](a, b []T) bool {
 	if len(a) != len(b) {
 		return false