[BUG] Assertion failed. /solidity/libsolidity/analysis/TypeChecker.cpp(2344)

[Jizhou-Chen]

Description

Error:

Internal compiler error:
/solidity/libsolidity/analysis/TypeChecker.cpp(2344): Throw in function void solidity::frontend::TypeChecker::typeCheckStringConcatFunction(const solidity::frontend::FunctionCall&, const solidity::frontend::FunctionType*)
Dynamic exception type: boost::wrapexcept<solidity::langutil::InternalCompilerError>
std::exception::what: Solidity assertion failed
[solidity::util::tag_comment*] = Solidity assertion failed

Environment

• Compiler version: Version: 0.8.28-develop.2025.1.19+commit.7893614a.mod.Linux.g++
• Compilation pipeline (legacy, IR, EOF):
• Target EVM version (as per compiler settings):
• Framework/IDE (e.g. Foundry, Hardhat, Remix):
• EVM execution environment / backend / blockchain client:
• Operating system: Ubuntu 22.04

Steps to Reproduce

poc.sol (fuzzer-generated):

contract C {
    int immutable x = x = 0xabc;
    modifier m() {
        for (uint256 i = 3; x == 0; i++) {
            _;
            _;
            return;
        }
    }

    function f() public m m m returns (uint) {
        string.concat({x: .3, y: "abc", z: true});
    }
}

To reproduce:
solc --bin -o poc poc.sol