ABI is different for functions defined in libraries as compared to contracts.

[bmarwritescode]

Description

When compiling a function which takes an interface as an argument, if that function is defined in a contract, the ABI indicates that the type of that interface argument is address (additional information that it is a contract is stored in the internalType field). However, when the same function which takes an interface as an argument is defined in a library, the ABI indicates that the type of that interface argument is the name of the interface (and not address) -- the internalType field remains unchanged.

Environment

• Compiler version: 0.8.24+commit.e11b9ed9.Darwin.appleclang
• Target EVM version (as per compiler settings): whatever default is (I believe shanghai)
• Framework/IDE (e.g. Truffle or Remix): N/A (compilinig command line)
• EVM execution environment / backend / blockchain client: N/A
• Operating system: macOS Monterey (version 12.3)

Steps to Reproduce

Consider the following contract Example:

// SPDX-License-Identifier: GPL-3.0
pragma solidity ^0.8.10;

import "./Library.sol";

contract Example {
    function baz(InterfaceExample i) external pure returns (uint) {
        return 0;
    }
}

along with the following library implementation:

// SPDX-License-Identifier: GPL-3.0
pragma solidity ^0.8.10;

interface InterfaceExample {}

library Library {
    function bar(InterfaceExample i) external pure returns (uint) {
        return 0;
    }
}

When we run solc Example.sol --combined-json abi the following is output:

{"contracts":{"Example.sol:Example":{"abi":[{"inputs":[{"internalType":"contract InterfaceExample","name":"i","type":"address"}],"name":"baz","outputs":[{"internalType":"uint256","name":"","type":"uint256"}],"stateMutability":"pure","type":"function"}]},"Library.sol:InterfaceExample":{"abi":[]},"Library.sol:Library":{"abi":[{"inputs":[{"internalType":"contract InterfaceExample","name":"i","type":"InterfaceExample"}],"name":"bar","outputs":[{"internalType":"uint256","name":"","type":"uint256"}],"stateMutability":"pure","type":"function"}]}},"version":"0.8.24+commit.e11b9ed9.Darwin.appleclang"}

As shown in the above results, the type for the argument of baz in the contract is {"internalType":"contract InterfaceExample","name":"i","type":"address"} but the argument of bar in the library is {"internalType":"contract InterfaceExample","name":"i","type":"InterfaceExample"}.