Solidity Type Conversion – Explicit Type Conversion Not Allowed from ‘int_const -1’ to ‘uint128’

soliditysolidity-0.8.x

I am compiling using sol 0.8.0 and the following line is producing the error in the title:

uint256 public constant MASK = uint128(~0);

Error:

Explicit type conversion not allowed from "int_const -1" to "uint128".

When changing the variable to this:

uint256 public constant MASK = ~0;

The error changes to:

Type int_const -1 is not implicitly convertible to expected type uint256. Cannot implicitly convert signed literal to unsigned type.

Best Answer

Changed it to this:

uint256 public constant MASK = type(uint128).max;

New restrictions in 0.8.0

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Solidity Errors – How to Solve Explicit Type Conversion Not Allowed from int_const 11111 to bytes32

First, convert int_const to uint256 then convert it to bytes32.

diff = bytes32 (uint256(11111));

and there is another problem with your contract.

You are using msg.sender and msg.value in your constructor. For that you need to mark your constructor as payable.

constructor() payable public

solidity – Resolving Error When Returning an Array from a Function: Return Argument Type uint256[2] is Not Implicitly Convertible

Fixed length arrays (e.g. uint[2] memory) and dynamic length arrays (e.g. uint[] memory) are stored in memory differently, as the dynamic length array has to also store the length.

From the docs:

The length of a dynamic array is stored at the first slot of the array and followed by the array elements.

Due to this difference it is not possible to convert them automatically. More info is available in the Solidity docs on the internals:

Edit: An alternative for your example would be the usage of a tuple as the return type:

function length() public view returns(uint fixedLength, uint dynamicLength) { 
  return (fixedArr.length, dynamicArr.length); 
}

Best Answer

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Solidity Errors – How to Solve Explicit Type Conversion Not Allowed from int_const 11111 to bytes32

solidity – Resolving Error When Returning an Array from a Function: Return Argument Type uint256[2] is Not Implicitly Convertible

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