Deprecate the CALLCODE opcode
EIP-2488 proposes to deprecate the CALLCODE opcode in Ethereum by making it always return failure in a backwards compatible way. The rationale is that CALLCODE was never utilized and puts a burden on EVM implementations, and disabling it would help light clients or clients planning to sync from a later point in time. This is a breaking change with the potential to break contracts, but the author expects no contracts of any value should be affected.
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Original
Abstract
Deprecate CALLCODE in a somewhat backwards compatible way, by making it always return failure.
Motivation
CALLCODE was part of the Frontier release of Ethereum. In the first few weeks/months it became clear
that it cannot accomplish its intended design goal. This was rectified with introducing DELEGATECALL
(EIP-7) in the Homestead update (early 2016).
CALLCODE became never utilized, but it still puts a burden on EVM implementations.
Disabling it will not improve the situation for any client whose goal is to sync from genesis, but would help light clients or clients planning to sync from a later point in time.
Specification
If block.number >= FORK_BLOCK, the CALLCODE (0xf2) instruction always returns 0, which signals failure.
Rationale
It would be possible just to remove the opcode and exceptionally abort if it is encountered. However, by returning failure, the contract has a chance to act on it and potentially recover.
Backwards Compatibility
This is a breaking change and has a potential to break contracts. The author expects no contracts of any value should be affected.
TODO: validate this claim.
Security Considerations
TBA
Test Cases
TBA
Implementation
TBA
Copyright
Copyright and related rights waived via CC0.
Adopted by projects
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