I am trying to compile the following contract on Remix IDE.

pragma solidity ^0.5.1;

contract ProofofExistence{
   event ProofCreated(
      uint256  indexed id,
      bytes32 documentHash);//an event can be listened by any client

   address public owner;//getters are already generated for public variables
   mapping  (uint => bytes32) hashesById;

   modifier onlyOwner() {
      require(msg.sender == owner);

   modifier noHashExistsYet(uint256 id) {
      require(hashesById[id] == "");
   }//The modifeir can be prepended to any function

   constructor() public {//constructor is executed when the contract s created 
      owner = msg.sender;

   function notarizeHash(uint256 id, bytes32 documentHash) onlyOwner noHashExistsYet(id) public{
      hashesById[id] = documentHash;
      emit ProofCreated(id, documentHash);//Proof created event is emited to the block chain
   }//The core function of this contract allows its owner
   //to confirm a document id with a certain content

   function doesProofExist(uint256 id, bytes32 documentHash) public view returns (bool) {
      return hashesById[id] == documentHash;
   }//view/constant functions are read-only and do not cost gas

I am getting following warning message:

Use assert(x) if you never ever want x to be false, not in any circumstance (apart from a bug in your code). Use require(x) if x can be false, due to e.g. invalid input or a failing external component.

Can somebody please guide me how to get rid of the above warning message?


1 Answer 1


Can somebody please guide me how to get rid of the above warning message?

I can think of two ways to get rid of the warning:

  1. Remove all requires from your code.
  2. Disable the warning by unchecking the "Guard Conditions" checkbox in the "analysis" tab.

I advise against both.

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