Illegal argument error when calling block.difficulty

[maciejwitowski]

This was found as part of the Bulletproofing program

Calling this function

function getDifficulty () public view returns (uint256) {
  return block.difficulty;
}

produces this error

"message": "failed to apply message: message execution failed: exit 24, msg receipt: , reason: message failed with backtrace:\n00: f010866 (method 3844450837) -- get beacon randomness failed with an unexpected error: illegal argument (24)\n--> caused by: rand::get_beacon_randomness -- cgo extern 'get_beacon_randomness' failed with error code -3 (1: illegal argument)\n (RetCode=24)"

[maciejwitowski]

When I'm getting this error in Remix my local lotus shows this error

ERROR rand rand/rand.go:164 failed to get beacon entry as expected: cannot draw randomness from the future

[Stebalien]

Should be fixed by filecoin-project/lotus#10216, but I haven't tested it.

[Stebalien]

Basically, when estimating gas and testing messages, we were passing a chain height in the future with the wrong tipset.