[Bug]: slither-flat can't flatten contracts containing structs with nested-arrays

[asmitadhungana]

Describe the issue:

The slither-flattener can flatten a library/contract that contain structs with single arrays as their elements but can't flatten contracts that contain structs with double arrays as elements.

Code example to reproduce the issue:

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.4;

struct DoubleArray {
  uint256[2][2] doubleArray;
}

library Lib_Throws_Error {
    function add(DoubleArray memory ss) internal view returns (bool) {
        return true;
    }
}

Command:

slither-flat contracts/crytic/e2e-fuzz/Lib.sol --strategy OneFile --pragma-solidity 0.8.7

Version:

0.9.1

Relevant log output:

Traceback (most recent call last):
  File "/opt/homebrew/bin/slither-flat", line 8, in <module>
    sys.exit(main())
  File "/opt/homebrew/lib/python3.10/site-packages/slither/tools/flattening/__main__.py", line 112, in main
    slither = Slither(args.filename, **vars(args))
  File "/opt/homebrew/lib/python3.10/site-packages/slither/slither.py", line 125, in __init__
    parser.parse_contracts()
  File "/opt/homebrew/lib/python3.10/site-packages/slither/solc_parsing/slither_compilation_unit_solc.py", line 489, in parse_contracts
    self._analyze_second_part(contracts_to_be_analyzed, libraries)
  File "/opt/homebrew/lib/python3.10/site-packages/slither/solc_parsing/slither_compilation_unit_solc.py", line 557, in _analyze_second_part
    self._analyze_top_level_structures()
  File "/opt/homebrew/lib/python3.10/site-packages/slither/solc_parsing/slither_compilation_unit_solc.py", line 635, in _analyze_top_level_structures
    struct.analyze()
  File "/opt/homebrew/lib/python3.10/site-packages/slither/solc_parsing/declarations/structure_top_level.py", line 57, in analyze
    elem_parser.analyze(self)
  File "/opt/homebrew/lib/python3.10/site-packages/slither/solc_parsing/variables/variable_declaration.py", line 210, in analyze
    self._variable.type = parse_type(self._elem_to_parse, caller_context)
  File "/opt/homebrew/lib/python3.10/site-packages/slither/solc_parsing/solidity_types/type_parsing.py", line 419, in parse_type
    array_type = parse_type(t["baseType"], next_context)
  File "/opt/homebrew/lib/python3.10/site-packages/slither/solc_parsing/solidity_types/type_parsing.py", line 418, in parse_type
    length = parse_expression(t["length"], caller_context)
  File "/opt/homebrew/lib/python3.10/site-packages/slither/solc_parsing/expressions/expression_parsing.py", line 258, in parse_expression
    assert isinstance(caller_context, CallerContextExpression)
AssertionError

[asmitadhungana]

Hi, what's the status on this bug-fix process?
Also, would this bug prevent echidna from testing a similar contract containing multidimensional arrays?
For my testing process, even on similar contracts flattened using other flattening tools, running echidna-test won't get past the static-analysis part, due to Slither issues.

[smonicas]

This issue was fixed in slither 0.9.2 with #1545. Update slither and it should work.