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Fix Wrong Input Length - ERC165 Example (#1640)
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* Wrong input size - noThrowCall ERC165

Input should be 36 bytes (4 signature bytes + 32 bytes parameter)

Solidity 5 validates the length of msg.data, reverting on the 32 bytes input, all contracts using the broken 'doesContractImplementInterface' will not be able to read an ERC165 implementation targetting Solidity 5.

A legacy-compatible strategy should be defined to make all the "ERC165 readers" sending a 32 bytes sized data compatible with ERC165 contracts compiled targeting this new version of the compiler.

A possible solution could be to add a keyword on Solidity to disable the validation of the calldata length.

* Add version history section to EIP165

* EIP 1640 -> PR 1640
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Agustin Aguilar authored and Arachnid committed May 22, 2019
1 parent 6366821 commit 7c10d58
Showing 1 changed file with 6 additions and 1 deletion.
7 changes: 6 additions & 1 deletion EIPS/eip-165.md
Original file line number Diff line number Diff line change
Expand Up @@ -151,7 +151,7 @@ contract ERC165Query {
30000, // 30k gas
_contract, // To addr
x, // Inputs are stored at location x
0x20, // Inputs are 32 bytes long
0x24, // Inputs are 36 bytes long
x, // Store output over input (saves space)
0x20) // Outputs are 32 bytes long
Expand Down Expand Up @@ -225,6 +225,11 @@ contract Homer is ERC165, Simpson {

With three or more supported interfaces (including ERC165 itself as a required supported interface), the mapping approach (in every case) costs less gas than the pure approach (at worst case).

## Version history
* PR 1640, finalized 2019-01-23 -- This corrects the noThrowCall test case to use 36 bytes rather than the previous 32 bytes. The previous code was an error that still silently worked in Solidity 0.4.x but which was broken by new behavior introduced in Solidity 0.5.0. This change was discussed at [#1640](https://github.com/ethereum/EIPs/pull/1640).

* EIP 165, finalized 2018-04-20 -- Original published version.

## Copyright

Copyright and related rights waived via [CC0](https://creativecommons.org/publicdomain/zero/1.0/).

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