fmt.Fprintf(s, "[%v]", n.Index)

	case OSLICE, OSLICESTR, OSLICEARR, OSLICE3, OSLICE3ARR:
		n := n.(*SliceExpr)
		exprFmt(n.X, s, nprec)
		fmt.Fprint(s, "[")
		if n.Low != nil {
			fmt.Fprint(s, n.Low)
		}
		fmt.Fprint(s, ":")
		if n.High != nil {
			fmt.Fprint(s, n.High)
		}
		if n.Op().IsSlice3() {
			fmt.Fprint(s, ":")
			if n.Max != nil {
				fmt.Fprint(s, n.Max)
			}
		}

	} else {
		n.SetType(types.NewPtr(t.Elem()))
	}
	return n
}

// tcSlice typechecks an OSLICE or OSLICE3 node.
func tcSlice(n *ir.SliceExpr) ir.Node {
	n.X = DefaultLit(Expr(n.X), nil)
	n.Low = indexlit(Expr(n.Low))
	n.High = indexlit(Expr(n.High))
	n.Max = indexlit(Expr(n.Max))
	hasmax := n.Op().IsSlice3()
	l := n.X
	if l.Type() == nil {
		n.SetType(nil)
		return n
	}
	if l.Type().IsArray() {

	case nil:
		check.errorf(x, NonSliceableOperand, invalidOp+"cannot slice %s: %s has no core type", x, x.typ)
		x.mode = invalid
		return

	case *Basic:
		if isString(u) {
			if e.Slice3 {
				at := e.Max
				if at == nil {
					at = e // e.Index[2] should be present but be careful
				}
				check.error(at, InvalidSliceExpr, invalidOp+"3-index slice of string")
				x.mode = invalid
				return

		}
	}
}

func TestUpsertSlice(t *testing.T) {
	langs := []Language{
		{Code: "upsert-slice1", Name: "Upsert-slice1"},
		{Code: "upsert-slice2", Name: "Upsert-slice2"},
		{Code: "upsert-slice3", Name: "Upsert-slice3"},
	}
	DB.Clauses(clause.OnConflict{DoNothing: true}).Create(&langs)

	var langs2 []Language
	if err := DB.Find(&langs2, "code LIKE ?", "upsert-slice%").Error; err != nil {

		default:
			base.FatalfAt(n.Pos(), "mayCall %+v", n)

		case ir.OCALLFUNC, ir.OCALLINTER,
			ir.OUNSAFEADD, ir.OUNSAFESLICE:
			return true

		case ir.OINDEX, ir.OSLICE, ir.OSLICEARR, ir.OSLICE3, ir.OSLICE3ARR, ir.OSLICESTR,
			ir.ODEREF, ir.ODOTPTR, ir.ODOTTYPE, ir.ODYNAMICDOTTYPE, ir.ODIV, ir.OMOD,
			ir.OSLICE2ARR, ir.OSLICE2ARRPTR:
			// These ops might panic, make sure they are done

		n := n.(*ir.SliceHeaderExpr)
		return walkSliceHeader(n, init)

	case ir.OSTRINGHEADER:
		n := n.(*ir.StringHeaderExpr)
		return walkStringHeader(n, init)

	case ir.OSLICE, ir.OSLICEARR, ir.OSLICESTR, ir.OSLICE3, ir.OSLICE3ARR:
		n := n.(*ir.SliceExpr)
		return walkSlice(n, init)

	case ir.ONEW:
		n := n.(*ir.UnaryExpr)
		return walkNew(n, init)

	case ir.OADDSTR:

// Unfortunate: x doesn't need to escape to heap, just to result.
func slice2(x string) string { // ERROR "leaking param: x$"
	v := reflect.ValueOf(x) // ERROR "x escapes to heap"
	return v.Slice(1, 2).String()
}

func slice3(x [10]byte) []byte {
	v := reflect.ValueOf(x) // ERROR "x escapes to heap"
	return v.Slice(1, 2).Bytes()
}

func elem1(x *int) int { // ERROR "x does not escape"
	v := reflect.ValueOf(x)

		return item.Slice(idx[0], idx[1]), nil
	}
	// given item[i:j:k], make sure i <= j <= k.
	if idx[1] > idx[2] {
		return reflect.Value{}, fmt.Errorf("invalid slice index: %d > %d", idx[1], idx[2])
	}
	return item.Slice3(idx[0], idx[1], idx[2]), nil
}

// Length

// length returns the length of the item, with an error if it has no defined length.
func length(item reflect.Value) (int, error) {
	item, isNil := indirect(item)

	{name: "dot", format: "package main; var x = «x.»x"},
	{name: "index", format: "package main; var x = x«[1]»"},
	{name: "slice", format: "package main; var x = x«[1:2]»"},
	{name: "slice3", format: "package main; var x = x«[1:2:3]»"},
	{name: "dottype", format: "package main; var x = x«.(any)»"},
	{name: "callseq", format: "package main; var x = x«()»"},

	case ir.OSTRINGHEADER:
		n := n.(*ir.StringHeaderExpr)
		return tcStringHeader(n)

	case ir.OMAKESLICECOPY:
		n := n.(*ir.MakeExpr)
		return tcMakeSliceCopy(n)

	case ir.OSLICE, ir.OSLICE3:
		n := n.(*ir.SliceExpr)
		return tcSlice(n)

	// call and call like
	case ir.OCALL:
		n := n.(*ir.CallExpr)
		return tcCall(n, top)

	case ir.OCAP, ir.OLEN:
		n := n.(*ir.UnaryExpr)