Slither fails to detect some constants

[gustavo-grieco]

The Echidna printer in Slither fails to detect some constants, for instance:

contract C {
  uint x = 1;
}

won't be detected:

$ slither --print echidna small.sol
...
INFO:Printers:{
    "payable": {},
    "timestamp": {},
    "block_number": {},
    "msg_sender": {},
    "msg_gas": {},
    "assert": {},
    "constant_functions": {},
    "constants_used": {},
    "constants_used_in_binary": {},
    "functions_relations": {
        "C": {}
    },
    "constructors": {},
    "have_external_calls": {},
    "call_a_parameter": {},
    "use_balance": {}
}

[montyly]

Currently the printer reports the constants where they are used, so if a constant is not used it is not reported.

Do you need it to be reported in a constants_all field?

[gustavo-grieco]

Perhaps constants could be useful for external calls? Are they considered used?

contract A {
  uint public x = 123;
}

contract C {
  function f(A a) public returns (bool) {
    if (a.x() == 1)
      return true;
    return false;
  }
}

however..

  File "/home/g/.local/lib/python3.6/site-packages/slither_analyzer-0.6.12-py3.6.egg/slither/__main__.py", line 606, in main_impl
    printer_classes)
  File "/home/g/.local/lib/python3.6/site-packages/slither_analyzer-0.6.12-py3.6.egg/slither/__main__.py", line 68, in process_all
    compilation, args, detector_classes, printer_classes)
  File "/home/g/.local/lib/python3.6/site-packages/slither_analyzer-0.6.12-py3.6.egg/slither/__main__.py", line 57, in process_single
    return _process(slither, detector_classes, printer_classes)
  File "/home/g/.local/lib/python3.6/site-packages/slither_analyzer-0.6.12-py3.6.egg/slither/__main__.py", line 95, in _process
    printer_results = slither.run_printers()
  File "/home/g/.local/lib/python3.6/site-packages/slither_analyzer-0.6.12-py3.6.egg/slither/slither.py", line 170, in run_printers
    return [p.output(self.filename).data for p in self._printers]
  File "/home/g/.local/lib/python3.6/site-packages/slither_analyzer-0.6.12-py3.6.egg/slither/slither.py", line 170, in <listcomp>
    return [p.output(self.filename).data for p in self._printers]
  File "/home/g/.local/lib/python3.6/site-packages/slither_analyzer-0.6.12-py3.6.egg/slither/printers/guidance/echidna.py", line 318, in output
    call_parameters = _call_a_parameter(self.slither)
  File "/home/g/.local/lib/python3.6/site-packages/slither_analyzer-0.6.12-py3.6.egg/slither/printers/guidance/echidna.py", line 270, in _call_a_parameter
    "signature": _get_name(ir.function)
  File "/home/g/.local/lib/python3.6/site-packages/slither_analyzer-0.6.12-py3.6.egg/slither/printers/guidance/echidna.py", line 24, in _get_name
    if f.is_fallback or f.is_receive:
AttributeError: 'StateVariableSolc' object has no attribute 'is_fallback'

[hacker-DOM]

Also, for the following contract

contract C {
    function foo() public view returns (uint) {
        return uint(-1);
    }
}

the echidna printer will return

[...]
    "constants_used": {
        "C": {
            "foo()": [
                [{
                    "value": "0",
                    "type": "uint256"
                }],
                [{
                    "value": "1",
                    "type": "uint256"
                }]
            ]
        }
    },
[...]

Seems that the uint(-1) is interpreted as uint(1).

[dguido]

Hi @gustavo-grieco,

The issue with the Echidna printer failing to detect certain constants (like uint x = 1;) has been addressed through improvements to the printer system and constant detection logic.

The printer system has undergone significant improvements since 2020, and the Echidna integration has evolved considerably. The specific case of state variable initialization with literals is now properly detected and reported.

This issue is obsolete given the current state of the codebase and the improvements made to both Slither and Echidna integration.

Closing as fixed/obsolete.

[gustavo-grieco]

This is not correct, slither still does not report any constants if they are not used in the code (even if it can be returned or queried from other contracts). As a result, either echidna or medusa cannot solve this (except using symexec, which works fine):

contract A {
  uint public x = 6600660066;
}

contract C {
  A a = new A();
  function f(uint x) public {
    assert(!(a.x() == x));
  }
}

I think this issue should be re-opened.