Fix encode []any to array

https://github.com/jackc/pgx/issues/1488

pgtype/array_codec.go

@@ -60,7 +60,9 @@ func (c *ArrayCodec) PlanEncode(m *Map, oid uint32, format int16, value any) Enc
 
 	elementEncodePlan := m.PlanEncode(c.ElementType.OID, format, elementType)
 	if elementEncodePlan == nil {
-		return nil
+		if reflect.TypeOf(elementType) != nil {
+			return nil
+		}
 	}
 
 	switch format {

pgtype/array_codec_test.go

@@ -103,7 +103,7 @@ func TestArrayCodecArray(t *testing.T) {
 	})
 }
 
-func TestArrayCodecAnySlice(t *testing.T) {
+func TestArrayCodecNamedSliceType(t *testing.T) {
 	defaultConnTestRunner.RunTest(context.Background(), t, func(ctx context.Context, t testing.TB, conn *pgx.Conn) {
 		type _int16Slice []int16
 
@@ -126,6 +126,29 @@ func TestArrayCodecAnySlice(t *testing.T) {
 	})
 }
 
+// https://github.com/jackc/pgx/issues/1488
+func TestArrayCodecAnySliceArgument(t *testing.T) {
+	defaultConnTestRunner.RunTest(context.Background(), t, func(ctx context.Context, t testing.TB, conn *pgx.Conn) {
+		type _int16Slice []int16
+
+		for i, tt := range []struct {
+			arg      any
+			expected []int16
+		}{
+			{[]any{1, 2, 3}, []int16{1, 2, 3}},
+		} {
+			var actual []int16
+			err := conn.QueryRow(
+				ctx,
+				"select $1::smallint[]",
+				tt.arg,
+			).Scan(&actual)
+			assert.NoErrorf(t, err, "%d", i)
+			assert.Equalf(t, tt.expected, actual, "%d", i)
+		}
+	})
+}
+
 // https://github.com/jackc/pgx/issues/1442
 func TestArrayCodecAnyArray(t *testing.T) {
 	defaultConnTestRunner.RunTest(context.Background(), t, func(ctx context.Context, t testing.TB, conn *pgx.Conn) {