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Update EIP-7702: Clarify CODE* operations behavior #9250

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Feb 13, 2025
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Update EIP-7702: Clarify CODE* operations behavior #9250

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2 changes: 2 additions & 0 deletions EIPS/eip-7702.md
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Expand Up @@ -91,6 +91,8 @@ The delegation designation uses the banned opcode `0xef` from [EIP-3541](./eip-3

For example, `EXTCODESIZE` would return `23` (the size of `0xef0100 || address`), `EXTCODEHASH` would return `keccak256(0xef0100 || address)`, and `CALL` would load the code from `address` and execute it in the context of `authority`.

`CODESIZE` and `CODECOPY` instructions operate on executable code, as before. *Note that in a delegated execution `CODESIZE` and `CODECOPY` produce different result comparing to `EXTCODESIZE` and `EXTCODECOPY` of execution target.*
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I did not realize this before, but this is the first time we have a case where CODECOPY/CODESIZE vs EXTCODECOPY/EXTCODESIZE on itself (ADDRESS) returns something different, right? (Except in the context of a contract creation frame)

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Yes, but it also answers the question "Am I being run as a delegate" - which is a useful security feature.

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I don't think this is true. CODECOPY copies the code that is dynamically running whereas EXTCODECOPY on ADDRESS copies the account code, these can already differ prior to EIP-7702 due to DELEGATECALL or CALLCODE.


In case a delegation designator points to a precompile address, retrieved code is considered empty and `CALL`, `CALLCODE`, `STATICCALL`, `DELEGATECALL` instructions targeting this account will execute empty code, i.e. succeed with no execution given enough gas.

In case a delegation designator points to another designator, creating a potential chain or loop of designators, clients must retrieve only the first code and then stop following the designator chain.
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