github.com/iotexproject/iotex-core@v1.14.1-rc1/action/protocol/execution/testdata-istanbul/write-protection-005.sol (about)

     1  // SPDX-License-Identifier: MIT
     2  pragma solidity ^0.6.6;
     3  
     4  // NOTE: Deploy this contract first
     5  contract B {
     6      // NOTE: storage layout must be the same as contract A
     7      uint public num;
     8      address public sender;
     9      uint public value;
    10      mapping(uint => uint) private _a;
    11      event Done();
    12  
    13      constructor() public {
    14          _a[1] = 1;
    15          _a[2] = 2;
    16          _a[3] = 3;
    17      }
    18  
    19      function setVars(uint _num) public payable {
    20          delete _a[1];
    21          delete _a[2];
    22          num = _num;
    23          sender = msg.sender;
    24          value = msg.value;
    25          emit Done();
    26      }
    27  }
    28  
    29  contract A {
    30      uint public num;
    31      address public sender;
    32      uint public value;
    33      address private c;
    34      mapping(uint => uint) private _a;
    35      event Success(bool);
    36  
    37      function make() public {
    38          c = address(new B());
    39          _a[1] = 1;
    40          _a[2] = 2;
    41          _a[3] = 3;
    42      }
    43  
    44      function setVars(address _contract, uint _num) public returns (uint256) {
    45          if (_contract == address(0)) {
    46              _contract = c;
    47          }
    48          delete _a[1];
    49          (bool success, bytes memory _) = _contract.staticcall(
    50              abi.encodeWithSignature("setVars(uint256)", _num)
    51          );
    52          emit Success(success);
    53  
    54          return 1;
    55      }
    56  }