Lbrack token.Pos // position of "["
		Low    Expr      // begin of slice range; or nil
		High   Expr      // end of slice range; or nil
		Max    Expr      // maximum capacity of slice; or nil
		Slice3 bool      // true if 3-index slice (2 colons present)
		Rbrack token.Pos // position of "]"
	}

	// A TypeAssertExpr node represents an expression followed by a
	// type assertion.
	//
	TypeAssertExpr struct {

			o.exprList(n.Args)
		}

		if lhs == nil || lhs.Op() != ir.ONAME && !ir.SameSafeExpr(lhs, n.Args[0]) {
			return o.copyExpr(n)
		}
		return n

	case ir.OSLICE, ir.OSLICEARR, ir.OSLICESTR, ir.OSLICE3, ir.OSLICE3ARR:
		n := n.(*ir.SliceExpr)
		n.X = o.expr(n.X, nil)
		n.Low = o.cheapExpr(o.expr(n.Low, nil))
		n.High = o.cheapExpr(o.expr(n.High, nil))
		n.Max = o.cheapExpr(o.expr(n.Max, nil))