SafeMath .add() imposes infinite gas

Question

When I use add() function from Solidity SafeMath library, I get infinite gas requirement in remix (and this reflects in transactions that wont go through).

Simplified example:

function someFunction() internal view returns (bool) {
    uint256 a = 23;
    uint256 b = 48;
    return (a.add(1) > b);
}

SafeMath is included.

What is wrong?

Here is paste of SafeMath included:

https://pastebin.com/C4FVyBFa

Version used:

pragma solidity ^0.4.24;

Answer 1

I meant we really need to see the whole contract that is causing the issue so we might spot something.

Here's a slightly modified version of your function (so it's callable from outside) which is working as expected in a super basic shell of a contract.

// File: zeppelin-solidity/contracts/math/SafeMath.sol

/**
 * @title SafeMath
 * @dev Math operations with safety checks that throw on error
 */
library SafeMath {

  /**
  * @dev Multiplies two numbers, throws on overflow.
  */
  function mul(uint256 _a, uint256 _b) internal pure returns (uint256 c) {
    // Gas optimization: this is cheaper than asserting 'a' not being zero, but the
    // benefit is lost if 'b' is also tested.
    // See: https://github.com/OpenZeppelin/openzeppelin-solidity/pull/522
    if (_a == 0) {
      return 0;
    }

    c = _a * _b;
    assert(c / _a == _b);
    return c;
  }

  /**
  * @dev Integer division of two numbers, truncating the quotient.
  */
  function div(uint256 _a, uint256 _b) internal pure returns (uint256) {
    // assert(_b > 0); // Solidity automatically throws when dividing by 0
    // uint256 c = _a / _b;
    // assert(_a == _b * c + _a % _b); // There is no case in which this doesn't hold
    return _a / _b;
  }

  /**
  * @dev Subtracts two numbers, throws on overflow (i.e. if subtrahend is greater than minuend).
  */
  function sub(uint256 _a, uint256 _b) internal pure returns (uint256) {
    assert(_b <= _a);
    return _a - _b;
  }

  /**
  * @dev Adds two numbers, throws on overflow.
  */
  function add(uint256 _a, uint256 _b) internal pure returns (uint256 c) {
    c = _a + _b;
    assert(c >= _a);
    return c;
  }
}

contract Try {

  using SafeMath for uint256;

  function someFunction() public view returns (bool) {
    uint256 a = 23;
    uint256 b = 48;
    return (a.add(1) > b);
  }

}

It returns false, as expected.

We need to see something that compiles but doesn't work as intended.

Hope it helps.