    function execTransactionFromModule(
        address to,
        uint256 value,
        bytes memory data,
        Enum.Operation operation
    ) public virtual returns (bool success) {
        // Only whitelisted modules are allowed.
        require(msg.sender != SENTINEL_MODULES && modules[msg.sender] != address(0), "GS104");
        // Execute transaction without further confirmations.
        address guard = getGuard();

        bytes32 guardHash;
        if (guard != address(0)) {
@>          guardHash = Guard(guard).checkModuleTransaction(to, value, data, operation, msg.sender);
        }
        success = execute(to, value, data, operation, type(uint256).max);

        if (guard != address(0)) {
            Guard(guard).checkAfterExecution(guardHash, success);
        }
        if (success) emit ExecutionFromModuleSuccess(msg.sender);
        else emit ExecutionFromModuleFailure(msg.sender);
    }
    function checkModuleTransaction(
        address to,
        uint256 value,
        bytes memory data,
        Enum.Operation operation,
        address module
    ) external;
// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

interface WithoutReturn {
      function checkModuleTransaction() external;
}

interface WithReturn {
      function checkModuleTransaction() external returns(bytes32);
}

contract Test {

  function test() external returns(bytes32) {

    address calledContract = address(new ContractWithoutReturn());

    // Reverts on decoding
    bytes32 result = WithReturn(calledContract).checkModuleTransaction();
    return result;
  }
}

contract ContractWithoutReturn is WithoutReturn {

  function checkModuleTransaction() external {}

}
    function checkModuleTransaction(
        address to,
        uint256 value,
        bytes memory data,
        Enum.Operation operation,
        address module
-   ) external;
+   ) external returns(bytes32);
