Core ERC-20/WETH state transitions, allowance logic, events, and payable deposit/withdraw operations are largely preserved, but important constructor, fallback, event-indexing, and arithmetic-semantics details are missing or inaccurate.
The source initializes name to "Wrapped Ether", symbol to "WETH", and decimals to 18; the decompiled output omits these initialization values.
The source has a payable fallback function that calls deposit(), allowing plain Ether transfers to mint WETH. The decompiled output omits the fallback, so direct transfers without calldata are not represented.
Approval and Transfer events have indexed address parameters in the source, but the decompiled event declarations omit indexed attributes, changing the emitted log topics and event filtering behavior.
The original Solidity 0.4.18 arithmetic wraps on uint256 overflow, whereas the decompiled Solidity 0.8-style arithmetic would revert on overflow in balance additions and other unchecked operations if compiled as shown.
withdraw() includes an undefined require(success) after transfer(). The source uses address.transfer, which directly reverts on failure and has no separate success value; this representation is invalid or potentially introduces an inaccurate additional condition.
Candidate
Score: 82/100
Core ERC-20/WETH state transitions, allowance logic, events, withdrawals, deposits, and return values are accurately represented, but the fallback deposit path and constructor-initialized metadata are omitted. The Solidity 0.8 pragma also changes arithmetic overflow behavior if treated as compilable source.
The payable fallback function is missing. In the original, receiving Ether with empty calldata automatically calls deposit() and credits balanceOf[msg.sender]; the decompiled contract does not represent this behavior.
Constructor initialization of name, symbol, and decimals is omitted. The original deploys with "Wrapped Ether", "WETH", and 18, whereas the decompiled declarations leave these values uninitialized.
The decompiled Solidity uses pragma >=0.8.0, which implies checked arithmetic, while the original Solidity 0.4.18 bytecode uses wrapping arithmetic on overflows. This affects overflow cases in deposits, transfers, and destination balance increases.
withdraw includes an unexplained require(success) after transfer. The original transfer operation itself reverts on failure and does not expose a separate success value; this is either an invalid artifact or an inaccurately represented redundant check.
Diff
Decompiled output is identical between baseline and candidate.