TIP-6780: SELFDESTRUCT only in same transaction

[raymondliu0711]

tip: 6780
title: SELFDESTRUCT only in same transaction
author: lei19942016@hotmail.com
status: Draft
type: Standards Track
category: VM
created: 2025-05-29

Summary

Ethereum has incorporated EIP-6780 in the Cancun upgrade, modifying the behavior of the SELFDESTRUCT opcode. To maintain compatibility with Ethereum's implementation of this opcode modification, TRON needs to introduce this TIP and correspondingly update the SELFDESTRUCT opcode behavior in the TVM.

Abstract

This TIP changes the functionality of the SELFDESTRUCT opcode. The new functionality will be only to send all TRX in the account to the target, except that the current behaviour is preserved when SELFDESTRUCT is called in the same transaction a contract was created.

Motivation

To maintain compatibility with Ethereum EVM instruction modifications, we are implementing corresponding changes to the SELFDESTRUCT opcode behavior in TRON.

Original motivation from EIP-6780:

The SELFDESTRUCT opcode requires large changes to the state of an account, in particular removing all code and storage. This will not be possible in the future with Verkle trees: Each account will be stored in many different account keys, which will not be obviously connected to the root account.

This EIP implements this change. Applications that only use SELFDESTRUCT to retrieve funds will still work. Applications that only use SELFDESTRUCT in the same transaction as they created a contract will also continue to work without any changes.

Specification

The behaviour of SELFDESTRUCT is changed in the following way:

1. When SELFDESTRUCT is executed in a transaction that is not the same as the contract calling SELFDESTRUCT was created:

   • The current execution frame halts.
   • SELFDESTRUCT does not delete any data (including storage keys, code, or the account itself).
   • SELFDESTRUCT transfers the entire account assets(TRX, Staked TRX, TRC10) to the target.
   • Note that if the target is the same as the contract calling SELFDESTRUCT there is no net change in balances. Unlike the prior specification, assets will not be burnt in this case.

2. When SELFDESTRUCT is executed in the same transaction as the contract was created:

   • SELFDESTRUCT continues to behave as it did prior to this TIP, this includes the following actions
     • The current execution frame halts.
     • SELFDESTRUCT deletes data as previously specified.
     • SELFDESTRUCT transfers the entire account assets(TRX, Staked TRX, TRC10) to the target
     • The account balance of the contract calling SELFDESTRUCT is set to 0.
   • Note that if the target is the same as the contract calling SELFDESTRUCT that assets will be burnt.

A contract is considered created at the beginning of a create transaction or when a CREATE series operation begins execution (CREATE, CREATE2, and other operations that deploy contracts in the future). If a balance exists at the contract's new address it is still considered to be a contract creation.

The SELFDESTRUCT opcode remains deprecated as specified in TIP-652. Any use in newly deployed contracts is strongly discouraged even if this new behaviour is taken into account, and future changes to the TVM might further reduce the functionality of the opcode.

Rationale

Getting rid of the SELFDESTRUCT opcode has been considered in the past, and there are currently no strong reasons to use it. This TIP implements a behavior that will attempt to leave some common uses of SELFDESTRUCT working, while reducing the complexity of the change on TVM implementations that would come from contract versioning.

Handling the account creation and contract creation as two distinct and possibly separate events is needed for use cases such as counterfactual accounts. By allowing the SELFDESTRUCT to delete the account at contract creation time it will not result in stubs of counterfactually instantiated contracts that never had any on-chain state other than a balance prior to the contract creation. These accounts would never have any storage and thus the trie updates to delete the account would be limited to the account node, which is the same impact a regular transfer of TRX would have.

Backwards Compatibility

This TIP requires a hard fork, since it modifies consensus rules.

Contracts that depended on re-deploying contracts at the same address using CREATE2 (after a SELFDESTRUCT) will no longer function properly if the created contract does not call SELFDESTRUCT within the same transaction.

Previously it was possible to burn TRX by calling SELFDESTRUCT targeting the executing contract as the beneficiary. If the contract existed prior to the transaction the TRX will not be burned. If the contract was newly created in the transaction the TRX will be burned, as before.

Test Cases

Test cases for this TIP can reference EIP-6780 test cases eip6780_selfdestruct.

Security Considerations

The following applications of SELFDESTRUCT will be broken and applications that use it in this way are not safe anymore:

1. Where CREATE2 is used to redeploy a contract in the same place in order to make a contract upgradable. This is not supported anymore and other types of proxy contracts should be used instead.

2. Where a contract depended on burning TRX via a SELFDESTRUCT with the contract as beneficiary, in a contract not created within the same transaction.

Copyright

Copyright and related rights waived via CC0.

[lxcmyf]

What are the differences between the SELFDESTRUCT in this tip and the SELFDESTRUCT in the EIP?

[raymondliu0711]

What are the differences between the SELFDESTRUCT in this tip and the SELFDESTRUCT in the EIP?

This TIP-6780 aims to maintain compatibility with Ethereum's EIP-6780 implementation. The core logic and behavior of SELFDESTRUCT are the same.

The goal is that contracts expecting EIP-6780 behavior will work the same way on TRON after this TIP is implemented.

[yanghang8612]

What to do with staked TRX in contract accounts instead?

[raymondliu0711]

What to do with staked TRX in contract accounts instead?

Staked TRX and trc10 assets in contract will follow the same transfer logic as TRX balance:

1. When SELFDESTRUCT is called in a different transaction (not same as contract creation):

   • All staked TRX will be transferred to the target address along with the TRX balance
   • If the target is the same as the contract, there is no change.

2. When SELFDESTRUCT is called in the same transaction as contract creation:

   • Behaves as before this TIP - all staked TRX will be transferred to the target address
   • If target is the same contract, staked TRX will be burnt

This ensures that all assets are handled consistently with the new SELFDESTRUCT behavior.

[Sunny6889]

Since the new action will be All staked TRX will be transferred to the target address instead of delete, is there any security risk of users misunderstanding the new behavior and accidentally leaving funds in contracts they believe will be deleted?

[raymondliu0711]

Since the new action will be All staked TRX will be transferred to the target address instead of delete, is there any security risk of users misunderstanding the new behavior and accidentally leaving funds in contracts they believe will be deleted?

Users have already been notified in TIP-652​​ that the behavior of SELFDESTRUCT will change, and this TIP outlines the specific behavior logic.

If users miss these notifications, the behavior of SELFDESTRUCT will differ when contract calls SELFDESTRUCT not in same transaction with creation:

• targeting itself: assets remain in contract (no transfer occurs). The contract can perform as before in functionalities.
• targeting another address: assets will be transfer to target. Contract with empty assets can carry minimum risk.

I believe the risks associated with these changes are minimal.