solc produce Different Bytcode in multiple contracts after an equivalent expression change about solidity HOT 5 CLOSED

Thanks for reporting, @chamitro, but I believe this is not a bug. The string expressions are indeed equivalent; the difference in the bytecode is due to metadata. If you compare the Yul code generated by both, they should be equal.

Please see the following warning in our documentation about contract metadata:

Since the bytecode of the resulting contract contains the metadata hash by default, any change to the metadata
might result in a change of the bytecode. This includes changes to a filename or path, and 
since the metadata includes a hash of all the sources used, a single whitespace change results 
in different metadata, and different bytecode.

For instance, the contracts below will generate different bytecode due to metadata divergence, although f() will produce the same output for both (i.e., ManofDevelopingIndia):

• a.sol:

contract A {
    string private _name = "ManofDevelopingIndia";
    function f() public view returns (string memory) {
        return _name;
    }
}

• b.sol

contract A {
    string private _name = "Man" "of" "Developing" "India";
    function f() public view returns (string memory) {
        return _name;
    }
}

You can check the generated Yul by doing

solc --ir a.sol > a.yul
solc --ir b.sol > b.yul
diff a.yul b.yul

You will see that only the metadata hash and some source locations will be different, like:

<         data ".metadata" hex"a2646970667358221220fef6372fd6d9f1584086e88f921cc5f73d7c76d9ff3f0f3913e4fb9b6805dad164736f6c63430008170033"
---
>         data ".metadata" hex"a2646970667358221220ee7e0fb2c94e6b02415895ae48c4229bfae8191cff9bf875a305caccc0d6116664736f6c63430008170033"

from solidity.

Thank you for the information! My question is that while the change is in the ManOfDevelopingIndia contract's source code, the bytecode of : IERC20, IDexRouter, IDexFactory and Context contracts is not changing, while the bytecode of Utils and SafeMath is changing. I was expecting that there wouldl be changes only in the ManOfDevelopingIndia contract.

from solidity.

Thank you for the information! My question is that while the change is in the ManOfDevelopingIndia contract's source code, the bytecode of : IERC20, IDexRouter, IDexFactory and Context contracts is not changing, while the bytecode of Utils and SafeMath is changing. I was expecting that there wouldl be changes only in the ManOfDevelopingIndia contract.

the behavior you're observing is a result of how Solidity handles metadata and bytecode generation. While the logical functionality of certain contracts remains unchanged, metadata changes can propagate to affect other parts of the bytecode.

from solidity.

Ok thank you for the informations!

from solidity.

Thank you for the information! My question is that while the change is in the ManOfDevelopingIndia contract's source code, the bytecode of : IERC20, IDexRouter, IDexFactory and Context contracts is not changing, while the bytecode of Utils and SafeMath is changing. I was expecting that there wouldl be changes only in the ManOfDevelopingIndia contract.

Hi @chamitro, as @max-clinch mentioned, such metadata changes can propagate when compiling multiple contracts together. If you execute the commands below, you should only observe changes in source locations and metadata information. Therefore, I don't believe this is a bug, and I will be closing this issue.

solc --ir standard.sol > 1.yul
solc --ir standard2.sol > 2.yul
diff 1.yul 2.yul

Please feel free to reopen if there are additional points to address. Pinging @cameel in case I misunderstood something and this is indeed a bug ;)

from solidity.