I got an error in solidity like "TypeError: "block.blockhash()" has been deprecated in favor of "blockhash()"" - solidity

Question

I get gemini-doller contract code from etherscan through this link"https://etherscan.io/address/0x056fd409e1d7a124bd7017459dfea2f387b6d5cd#code" while test it in remix
i found some errors in line number 28 its like "TypeError: "block.blockhash()" has been deprecated in favor of "blockhash()"" can anyone please resolve it.
pragma solidity ^0.5.1;
/** #title A contract for generating unique identifiers
*
* #notice A contract that provides a identifier generation scheme,
* guaranteeing uniqueness across all contracts that inherit from it,
* as well as unpredictability of future identifiers.
*
* #dev This contract is intended to be inherited by any contract that
* implements the callback software pattern for cooperative custodianship.
*
* #author Gemini Trust Company, LLC
*/
contract LockRequestable {
// MEMBERS
/// #notice the count of all invocations of `generateLockId`.
uint256 public lockRequestCount;
// CONSTRUCTOR
constructor() public {
lockRequestCount = 0;
}
// FUNCTIONS
function generateLockId() internal returns (bytes32 lockId) {
return keccak256(abi.encodePacked(block.blockhash(block.number - 1), address(this), ++lockRequestCount));
}
}
contract CustodianUpgradeable is LockRequestable {
// TYPES
/// #dev The struct type for pending custodian changes.
struct CustodianChangeRequest {
address proposedNew;
}
// MEMBERS
/// #dev The address of the account or contract that acts as the custodian.
address public custodian;
/// #dev The map of lock ids to pending custodian changes.
mapping (bytes32 => CustodianChangeRequest) public custodianChangeReqs;
// CONSTRUCTOR
constructor(
address _custodian
)
LockRequestable()
public
{
custodian = _custodian;
}
// MODIFIERS
modifier onlyCustodian {
require(msg.sender == custodian);
_;
}
// PUBLIC FUNCTIONS
// (UPGRADE)
function requestCustodianChange(address _proposedCustodian) public returns (bytes32 lockId) {
require(_proposedCustodian != address(0));
lockId = generateLockId();
custodianChangeReqs[lockId] = CustodianChangeRequest({
proposedNew: _proposedCustodian
});
emit CustodianChangeRequested(lockId, msg.sender, _proposedCustodian);
}
function confirmCustodianChange(bytes32 _lockId) public onlyCustodian {
custodian = getCustodianChangeReq(_lockId);
delete custodianChangeReqs[_lockId];
emit CustodianChangeConfirmed(_lockId, custodian);
}
// PRIVATE FUNCTIONS
function getCustodianChangeReq(bytes32 _lockId) private view returns (address _proposedNew) {
CustodianChangeRequest storage changeRequest = custodianChangeReqs[_lockId];
// reject ‘null’ results from the map lookup
// this can only be the case if an unknown `_lockId` is received
require(changeRequest.proposedNew != 0x0000000000000000000000000000000000000000);
return changeRequest.proposedNew;
}
/// #dev Emitted by successful `requestCustodianChange` calls.
event CustodianChangeRequested(
bytes32 _lockId,
address _msgSender,
address _proposedCustodian
);
/// #dev Emitted by successful `confirmCustodianChange` calls.
event CustodianChangeConfirmed(bytes32 _lockId, address _newCustodian);
}
contract ERC20ImplUpgradeable is CustodianUpgradeable {
// TYPES
/// #dev The struct type for pending implementation changes.
struct ImplChangeRequest {
address proposedNew;
}
// MEMBERS
// #dev The reference to the active token implementation.
ERC20Impl public erc20Impl;
/// #dev The map of lock ids to pending implementation changes.
mapping (bytes32 => ImplChangeRequest) public implChangeReqs;
// CONSTRUCTOR
constructor(address _custodian) CustodianUpgradeable(_custodian) public {
erc20Impl = ERC20Impl(0x0);
}
// MODIFIERS
modifier onlyImpl {
require(msg.sender == address(erc20Impl));
_;
}
// PUBLIC FUNCTIONS
// (UPGRADE)
function requestImplChange(address _proposedImpl) public returns (bytes32 lockId) {
require(_proposedImpl != address(0));
lockId = generateLockId();
implChangeReqs[lockId] = ImplChangeRequest({
proposedNew: _proposedImpl
});
emit ImplChangeRequested(lockId, msg.sender, _proposedImpl);
}
function confirmImplChange(bytes32 _lockId) public onlyCustodian {
erc20Impl = getImplChangeReq(_lockId);
delete implChangeReqs[_lockId];
emit ImplChangeConfirmed(_lockId, address(erc20Impl));
}
// PRIVATE FUNCTIONS
function getImplChangeReq(bytes32 _lockId) private view returns (ERC20Impl _proposedNew) {
ImplChangeRequest storage changeRequest = implChangeReqs[_lockId];
// reject ‘null’ results from the map lookup
// this can only be the case if an unknown `_lockId` is received
require(changeRequest.proposedNew != address(0));
return ERC20Impl(changeRequest.proposedNew);
}
/// #dev Emitted by successful `requestImplChange` calls.
event ImplChangeRequested(
bytes32 _lockId,
address _msgSender,
address _proposedImpl
);
/// #dev Emitted by successful `confirmImplChange` calls.
event ImplChangeConfirmed(bytes32 _lockId, address _newImpl);
}
contract ERC20Interface {
function totalSupply() public view returns (uint256);
// https://github.com/ethereum/EIPs/blob/master/EIPS/eip-20.md#balanceof
function balanceOf(address _owner) public view returns (uint256 balance);
// https://github.com/ethereum/EIPs/blob/master/EIPS/eip-20.md#transfer
function transfer(address _to, uint256 _value) public returns (bool success);
// https://github.com/ethereum/EIPs/blob/master/EIPS/eip-20.md#transferfrom
function transferFrom(address _from, address _to, uint256 _value) public returns (bool success);
// https://github.com/ethereum/EIPs/blob/master/EIPS/eip-20.md#approve
function approve(address _spender, uint256 _value) public returns (bool success);
// https://github.com/ethereum/EIPs/blob/master/EIPS/eip-20.md#allowance
function allowance(address _owner, address _spender) public view returns (uint256 remaining);
// EVENTS
// https://github.com/ethereum/EIPs/blob/master/EIPS/eip-20.md#transfer-1
event Transfer(address indexed _from, address indexed _to, uint256 _value);
// https://github.com/ethereum/EIPs/blob/master/EIPS/eip-20.md#approval
event Approval(address indexed _owner, address indexed _spender, uint256 _value);
}
contract ERC20Proxy is ERC20Interface, ERC20ImplUpgradeable {
// MEMBERS
/// #notice Returns the name of the token.
string public name;
/// #notice Returns the symbol of the token.
string public symbol;
/// #notice Returns the number of decimals the token uses.
uint8 public decimals;
// CONSTRUCTOR
constructor(
string memory _name,
string memory _symbol,
uint8 _decimals,
address _custodian
)
ERC20ImplUpgradeable(_custodian)
public
{
name = _name;
symbol = _symbol;
decimals = _decimals;
}
// PUBLIC FUNCTIONS
// (ERC20Interface)
/** #notice Returns the total token supply.
*
* #return the total token supply.
*/
function totalSupply() public view returns (uint256) {
return erc20Impl.totalSupply();
}
function balanceOf(address _owner) public view returns (uint256 balance) {
return erc20Impl.balanceOf(_owner);
}
/** #dev Internal use only.
*/
function emitTransfer(address _from, address _to, uint256 _value) public onlyImpl {
emit Transfer(_from, _to, _value);
}
function transfer(address _to, uint256 _value) public returns (bool success) {
return erc20Impl.transferWithSender(msg.sender, _to, _value);
}
function transferFrom(address _from, address _to, uint256 _value) public returns (bool success) {
return erc20Impl.transferFromWithSender(msg.sender, _from, _to, _value);
}
/** #dev Internal use only.
*/
function emitApproval(address _owner, address _spender, uint256 _value) public onlyImpl {
emit Approval(_owner, _spender, _value);
}
/** #notice Allows `_spender` to withdraw from your account multiple times,
* up to the `_value` amount. If this function is called again it
* overwrites the current allowance with _value.
*
* #dev Will fire the `Approval` event.
*
* #return success true if approval completes.
*/
function approve(address _spender, uint256 _value) public returns (bool success) {
return erc20Impl.approveWithSender(msg.sender, _spender, _value);
}
function increaseApproval(address _spender, uint256 _addedValue) public returns (bool success) {
return erc20Impl.increaseApprovalWithSender(msg.sender, _spender, _addedValue);
}
function decreaseApproval(address _spender, uint256 _subtractedValue) public returns (bool success) {
return erc20Impl.decreaseApprovalWithSender(msg.sender, _spender, _subtractedValue);
}
/** #notice Returns how much `_spender` is currently allowed to spend from
* `_owner`'s balance.
*
* #return remaining the remaining allowance.
*/
function allowance(address _owner, address _spender) public view returns (uint256 remaining) {
return erc20Impl.allowance(_owner, _spender);
}
}
contract ERC20Impl is CustodianUpgradeable {
// TYPES
/// #dev The struct type for pending increases to the token supply (print).
struct PendingPrint {
address receiver;
uint256 value;
}
// MEMBERS
/// #dev The reference to the proxy.
ERC20Proxy public erc20Proxy;
/// #dev The reference to the store.
ERC20Store public erc20Store;
/// #dev The sole authorized caller of delegated transfer control ('sweeping').
address public sweeper;
bytes32 public sweepMsg;
mapping (address => bool) public sweptSet;
/// #dev The map of lock ids to pending token increases.
mapping (bytes32 => PendingPrint) public pendingPrintMap;
// CONSTRUCTOR
constructor(
address _erc20Proxy,
address _erc20Store,
address _custodian,
address _sweeper
)
CustodianUpgradeable(_custodian)
public
{
require(_sweeper != 0x0000000000000000000000000000000000000000);
erc20Proxy = ERC20Proxy(_erc20Proxy);
erc20Store = ERC20Store(_erc20Store);
sweeper = _sweeper;
sweepMsg = keccak256(abi.encodePacked(address(this), "sweep"));
}
// MODIFIERS
modifier onlyProxy {
require(msg.sender == address(erc20Proxy));
_;
}
modifier onlySweeper {
require(msg.sender == sweeper);
_;
}
function approveWithSender(
address _sender,
address _spender,
uint256 _value
)
public
onlyProxy
returns (bool success)
{
require(_spender != address(0)); // disallow unspendable approvals
erc20Store.setAllowance(_sender, _spender, _value);
erc20Proxy.emitApproval(_sender, _spender, _value);
return true;
}
/** #notice Core logic of the `increaseApproval` function.
*
* #dev This function can only be called by the referenced proxy,
* which has an `increaseApproval` function.
* Every argument passed to that function as well as the original
* `msg.sender` gets passed to this function.
* NOTE: approvals for the zero address (unspendable) are disallowed.
*
* #param _sender The address initiating the approval.
*/
function increaseApprovalWithSender(
address _sender,
address _spender,
uint256 _addedValue
)
public
onlyProxy
returns (bool success)
{
require(_spender != address(0)); // disallow unspendable approvals
uint256 currentAllowance = erc20Store.allowed(_sender, _spender);
uint256 newAllowance = currentAllowance + _addedValue;
require(newAllowance >= currentAllowance);
erc20Store.setAllowance(_sender, _spender, newAllowance);
erc20Proxy.emitApproval(_sender, _spender, newAllowance);
return true;
}
/** #notice Core logic of the `decreaseApproval` function.
*
* #dev This function can only be called by the referenced proxy,
* which has a `decreaseApproval` function.
* Every argument passed to that function as well as the original
* `msg.sender` gets passed to this function.
* NOTE: approvals for the zero address (unspendable) are disallowed.
*
* #param _sender The address initiating the approval.
*/
function decreaseApprovalWithSender(
address _sender,
address _spender,
uint256 _subtractedValue
)
public
onlyProxy
returns (bool success)
{
require(_spender != address(0)); // disallow unspendable approvals
uint256 currentAllowance = erc20Store.allowed(_sender, _spender);
uint256 newAllowance = currentAllowance - _subtractedValue;
require(newAllowance <= currentAllowance);
erc20Store.setAllowance(_sender, _spender, newAllowance);
erc20Proxy.emitApproval(_sender, _spender, newAllowance);
return true;
}
function requestPrint(address _receiver, uint256 _value) public returns (bytes32 lockId) {
require(_receiver != address(0));
lockId = generateLockId();
pendingPrintMap[lockId] = PendingPrint({
receiver: _receiver,
value: _value
});
emit PrintingLocked(lockId, _receiver, _value);
}
function confirmPrint(bytes32 _lockId) public onlyCustodian {
PendingPrint storage print = pendingPrintMap[_lockId];
// reject ‘null’ results from the map lookup
// this can only be the case if an unknown `_lockId` is received
address receiver = print.receiver;
require (receiver != address(0));
uint256 value = print.value;
delete pendingPrintMap[_lockId];
uint256 supply = erc20Store.totalSupply();
uint256 newSupply = supply + value;
if (newSupply >= supply) {
erc20Store.setTotalSupply(newSupply);
erc20Store.addBalance(receiver, value);
emit PrintingConfirmed(_lockId, receiver, value);
erc20Proxy.emitTransfer(address(0), receiver, value);
}
}
/** #notice Burns the specified value from the sender's balance.
*
* #dev Sender's balanced is subtracted by the amount they wish to burn.
*
* #param _value The amount to burn.
*
* #return success true if the burn succeeded.
*/
function burn(uint256 _value) public returns (bool success) {
uint256 balanceOfSender = erc20Store.balances(msg.sender);
require(_value <= balanceOfSender);
erc20Store.setBalance(msg.sender, balanceOfSender - _value);
erc20Store.setTotalSupply(erc20Store.totalSupply() - _value);
erc20Proxy.emitTransfer(msg.sender, address(0), _value);
return true;
}
function batchTransfer(address[] memory _tos, uint256[] memory _values) public returns (bool success) {
require(_tos.length == _values.length);
uint256 numTransfers = _tos.length;
uint256 senderBalance = erc20Store.balances(msg.sender);
for (uint256 i = 0; i < numTransfers; i++) {
address to = _tos[i];
require(to != address(0));
uint256 v = _values[i];
require(senderBalance >= v);
if (msg.sender != to) {
senderBalance -= v;
erc20Store.addBalance(to, v);
}
erc20Proxy.emitTransfer(msg.sender, to, v);
}
erc20Store.setBalance(msg.sender, senderBalance);
return true;
}
function enableSweep(uint8[] memory _vs, bytes32[] memory _rs, bytes32[] memory _ss, address _to) public onlySweeper {
require(_to != address(0));
require((_vs.length == _rs.length) && (_vs.length == _ss.length));
uint256 numSignatures = _vs.length;
uint256 sweptBalance = 0;
for (uint256 i=0; i<numSignatures; ++i) {
address from = ecrecover(sweepMsg, _vs[i], _rs[i], _ss[i]);
// ecrecover returns 0 on malformed input
if (from != address(0)) {
sweptSet[from] = true;
uint256 fromBalance = erc20Store.balances(from);
if (fromBalance > 0) {
sweptBalance += fromBalance;
erc20Store.setBalance(from, 0);
erc20Proxy.emitTransfer(from, _to, fromBalance);
}
}
}
if (sweptBalance > 0) {
erc20Store.addBalance(_to, sweptBalance);
}
}
function replaySweep(address[] memory _froms, address _to) public onlySweeper {
require(_to != address(0));
uint256 lenFroms = _froms.length;
uint256 sweptBalance = 0;
for (uint256 i=0; i<lenFroms; ++i) {
address from = _froms[i];
if (sweptSet[from]) {
uint256 fromBalance = erc20Store.balances(from);
if (fromBalance > 0) {
sweptBalance += fromBalance;
erc20Store.setBalance(from, 0);
erc20Proxy.emitTransfer(from, _to, fromBalance);
}
}
}
if (sweptBalance > 0) {
erc20Store.addBalance(_to, sweptBalance);
}
}
function transferFromWithSender(
address _sender,
address _from,
address _to,
uint256 _value
)
public
onlyProxy
returns (bool success)
{
require(_to != address(0)); // ensure burn is the cannonical transfer to 0x0
uint256 balanceOfFrom = erc20Store.balances(_from);
require(_value <= balanceOfFrom);
uint256 senderAllowance = erc20Store.allowed(_from, _sender);
require(_value <= senderAllowance);
erc20Store.setBalance(_from, balanceOfFrom - _value);
erc20Store.addBalance(_to, _value);
erc20Store.setAllowance(_from, _sender, senderAllowance - _value);
erc20Proxy.emitTransfer(_from, _to, _value);
return true;
}
function transferWithSender(
address _sender,
address _to,
uint256 _value
)
public
onlyProxy
returns (bool success)
{
require(_to != address(0)); // ensure burn is the cannonical transfer to 0x0
uint256 balanceOfSender = erc20Store.balances(_sender);
require(_value <= balanceOfSender);
erc20Store.setBalance(_sender, balanceOfSender - _value);
erc20Store.addBalance(_to, _value);
erc20Proxy.emitTransfer(_sender, _to, _value);
return true;
}
// METHODS (ERC20 sub interface impl.)
/// #notice Core logic of the ERC20 `totalSupply` function.
function totalSupply() public view returns (uint256) {
return erc20Store.totalSupply();
}
/// #notice Core logic of the ERC20 `balanceOf` function.
function balanceOf(address _owner) public view returns (uint256 balance) {
return erc20Store.balances(_owner);
}
/// #notice Core logic of the ERC20 `allowance` function.
function allowance(address _owner, address _spender) public view returns (uint256 remaining) {
return erc20Store.allowed(_owner, _spender);
}
// EVENTS
/// #dev Emitted by successful `requestPrint` calls.
event PrintingLocked(bytes32 _lockId, address _receiver, uint256 _value);
/// #dev Emitted by successful `confirmPrint` calls.
event PrintingConfirmed(bytes32 _lockId, address _receiver, uint256 _value);
}
contract ERC20Store is ERC20ImplUpgradeable {
// MEMBERS
/// #dev The total token supply.
uint256 public totalSupply;
/// #dev The mapping of balances.
mapping (address => uint256) public balances;
/// #dev The mapping of allowances.
mapping (address => mapping (address => uint256)) public allowed;
// CONSTRUCTOR
constructor(address _custodian) ERC20ImplUpgradeable(_custodian) public {
totalSupply = 0;
}
// PUBLIC FUNCTIONS
// (ERC20 Ledger)
function setTotalSupply(
uint256 _newTotalSupply
)
public
onlyImpl
{
totalSupply = _newTotalSupply;
}
function setAllowance(
address _owner,
address _spender,
uint256 _value
)
public
onlyImpl
{
allowed[_owner][_spender] = _value;
}
function setBalance(
address _owner,
uint256 _newBalance
)
public
onlyImpl
{
balances[_owner] = _newBalance;
}
function addBalance(
address _owner,
uint256 _balanceIncrease
)
public
onlyImpl
{
balances[_owner] = balances[_owner] + _balanceIncrease;
}
}
if you want more information regarding it please feel free to put comment below
Thankyou:)

Answer 1

I got an error in solidity like “TypeError: ”block.blockhash()“ has been deprecated in favor of ”blockhash()“”
It is because new changes in new compiler version '0.5.0'.
Just remove block from block.blockhash(block.number-1) like this :
blockhash(block.number-1).

Answer 2

I got an error in solidity like “Operator != not compatible with types address and int_const 0”
Because you are trying to compare address type with uint Type, See
here require(changeRequest.proposedNew != 0); in this line
proposedNew is address variable and 0 is uint.
If you want to correct it
try require(changeRequest.proposedNew !=
0x0000000000000000000000000000000000000000);
and also in require(_sweeper !=
0x0000000000000000000000000000000000000000);.