Preserve balance in contract creation

Abstract

Contract addresses are deterministic. So it is possible to calculate an address of a contract before actual deployment (by having an Externally Owned Account and its Nonce). Due to this property of contract addresses, it’s also possible to send coins to an address of a future contract in advance and, as a result, make its balance positive without having any deployed contract at that address yet.

A side effect of deploying a smart contract to the address with positive balance is that the balance is being burnt and becomes zero.

Note: this side effect is only relevant in the case of contract creation via the JSON-RPC interface, not via CREATE / CREATE2 opcodes (these two opcodes do preserve balances).

Motivation

There’s no benefit of burning such funds after smart contracts creation. The funds are not being sent to any address, nor are they being re-used in the network in some other way. They simply disappear.

This RSKIP proposes to preserve the balance after contracts creation.

This will also make the network compatible with the Ethereum ecosystem, where pre-funded addresses also preserve their balances after deploying contracts at those addresses.

Implementation

The implementation should check if there’s any balance by a contract address before creation and add that amount (if any) to the contract’s balance afterwards.

    Coin oldBalance = getBalance(addr);
    newAccount = createAccount(addr);
    addBalance(addr, oldBalance);

Backwards Compatibility

This change is a hard-fork and therefore all full nodes must be updated.

Copyright

Copyright and related rights waived via CC0.