> For the complete documentation index, see [llms.txt](https://docs.megaeth.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.megaeth.com/spec/megaevm/selfdestruct.md). # SELFDESTRUCT This page specifies the availability and semantics of the `SELFDESTRUCT` opcode in MegaETH. It defines the current behavior and records the earlier MiniRex restriction. ## Motivation Ethereum deprecated the legacy `SELFDESTRUCT` behavior because it breaks assumptions about contract permanence and state growth, and it interacts poorly with modern state-management and witness-generation requirements. MegaETH inherits the same motivation. The protocol therefore needs to specify whether `SELFDESTRUCT` is disabled entirely or, when enabled, which restricted semantics apply. ## Specification ### Stable Behavior `SELFDESTRUCT` MUST follow [EIP-6780](https://eips.ethereum.org/EIPS/eip-6780) semantics. If the executing contract was created in the same transaction, `SELFDESTRUCT` MUST: * transfer the remaining balance to the target address, and * remove the contract's code and storage. If the executing contract was not created in the same transaction, `SELFDESTRUCT` MUST: * transfer the remaining balance to the target address, and * preserve the contract's code and storage. `SELFDESTRUCT` targeting the [beneficiary](/spec/reference/glossary.md#beneficiary) MUST trigger beneficiary [gas detention](/spec/megaevm/gas-detention.md). ### Beneficiary Account Creation When `SELFDESTRUCT` transfers a non-zero balance to a target address that does not yet exist in state, the value transfer creates a new account. A node MUST meter this account creation identically to account creation by any other means: * charge the account-creation [storage gas](/spec/reference/glossary.md#storage-gas) (`ACCOUNT_CREATION_STORAGE_GAS_BASE × (multiplier − 1)`, where `multiplier` is the target's [SALT bucket](/spec/reference/glossary.md#salt-bucket) multiplier), and * record the creation against the [data size](/spec/megaevm/resource-accounting.md#data-size) (`+SELFDESTRUCT_BENEFICIARY_DATA_BYTES`), [KV updates](/spec/megaevm/resource-accounting.md#kv-updates) (`+1`), and [state growth](/spec/megaevm/resource-accounting.md#state-growth) (`+1`) resource lanes. A `SELFDESTRUCT` whose transferred balance is zero MUST NOT incur any of these charges, because a zero-value transfer does not create the target account. A `SELFDESTRUCT` whose target already exists in state MUST NOT incur these charges. ### State Growth Refund When a contract that was created in the same transaction executes `SELFDESTRUCT` ([EIP-6780](https://eips.ethereum.org/EIPS/eip-6780) semantics), the node MUST apply a [state growth](/spec/megaevm/resource-accounting.md#state-growth) refund: * `-1` for the account itself (reversing the `+1` from `CREATE`/`CREATE2`). * `-1` for each storage slot whose original value was zero and current value is non-zero (reversing each `+1` from `SSTORE`). This refund MUST only be applied on the **first** effective destruction. If the same account is the target of `SELFDESTRUCT` more than once in the same transaction, subsequent destructions MUST NOT produce additional refunds. This refund MUST NOT be applied when `SELFDESTRUCT` targets a pre-existing account (one not created in the current transaction), because pre-existing accounts do not have their code and storage removed under EIP-6780. The refund is frame-aware: if the call frame that performed the `SELFDESTRUCT` reverts, the refund MUST be discarded together with the destruction effect. ## Constants | Constant | Value | Description | | ------------------------------------- | ------ | ---------------------------------------------------------------------------------- | | `ACCOUNT_CREATION_STORAGE_GAS_BASE` | 25,000 | Base storage gas charged when a value transfer creates a previously empty account | | `SELFDESTRUCT_BENEFICIARY_DATA_BYTES` | 40 | Data-size bytes recorded for the beneficiary account write on beneficiary creation | ## Rationale **Why disable SELFDESTRUCT before Rex2?** MegaETH initially disabled `SELFDESTRUCT` to avoid inheriting destructive account-lifecycle behavior before the protocol defined the intended stable semantics. **Why adopt EIP-6780 in stable behavior?** EIP-6780 is the post-Cancun Ethereum behavior and provides a widely understood baseline. Adopting it restores compatibility while avoiding legacy full-destruction behavior for long-lived contracts. **Why meter beneficiary account creation?** A value-carrying `SELFDESTRUCT` to a non-existent target creates an account exactly as a value-transferring `CALL` to an empty address does. Charging the same account-creation storage gas and recording the same resource-lane usage closes a path by which state could be grown at compute-gas cost only, without going through the metered account-creation surcharge. ## Security Considerations **If `SELFDESTRUCT` targeting the** [**beneficiary**](/spec/reference/glossary.md#beneficiary) **does not trigger gas detention**, contracts can use it to access beneficiary balance without being detained, creating an unmitigated conflict hotspot for parallel execution. **If `SELFDESTRUCT` does not charge new-account costs when it creates its target**, an attacker can create accounts and grow state through `SELFDESTRUCT` at compute-gas cost only, bypassing the account-creation storage gas and resource-lane accounting that every other account-creation path pays. ## Spec History * [MiniRex](/spec/network-upgrades/minirex.md), [Rex](/spec/network-upgrades/rex.md), and [Rex1](/spec/network-upgrades/rex1.md) disable `SELFDESTRUCT`; executing it halts with `InvalidFEOpcode`. * [Rex2](/spec/network-upgrades/rex2.md) re-enables `SELFDESTRUCT` with [EIP-6780](https://eips.ethereum.org/EIPS/eip-6780) semantics. * [Rex4](/spec/network-upgrades/rex4.md) — added beneficiary-triggered volatile-access behavior for SELFDESTRUCT, and [state growth refund](#state-growth-refund) for same-transaction-created accounts destroyed by `SELFDESTRUCT`. * [Rex5](/spec/network-upgrades/rex5.md) — charged account-creation storage gas and recorded data-size, KV-update, and state-growth usage when a value-carrying `SELFDESTRUCT` creates a previously non-existent beneficiary account. --- # Agent Instructions This documentation is published with GitBook. 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