Add support for CustomError (#947)

* Add support for CustomError
- Create a new CustomError/CustomErrorTopLevel/CustomErrorContract core objects, and associated parsing classes
- Create a specific solidity function to handle the revert CustomError call
- Fix #919, Fix #893

slither/core/compilation_unit.py

@@ -13,6 +13,7 @@ from slither.core.declarations import (
     Function,
     Modifier,
 )
+from slither.core.declarations.custom_error import CustomError
 from slither.core.declarations.enum_top_level import EnumTopLevel
 from slither.core.declarations.function_top_level import FunctionTopLevel
 from slither.core.declarations.structure_top_level import StructureTopLevel
@@ -40,6 +41,7 @@ class SlitherCompilationUnit(Context):
         self._functions_top_level: List[FunctionTopLevel] = []
         self._pragma_directives: List[Pragma] = []
         self._import_directives: List[Import] = []
+        self._custom_errors: List[CustomError] = []
 
         self._all_functions: Set[Function] = set()
         self._all_modifiers: Set[Modifier] = set()
@@ -210,6 +212,10 @@ class SlitherCompilationUnit(Context):
     def functions_top_level(self) -> List[FunctionTopLevel]:
         return self._functions_top_level
 
+    @property
+    def custom_errors(self) -> List[CustomError]:
+        return self._custom_errors
+
     # endregion
     ###################################################################################
     ###################################################################################

slither/core/declarations/contract.py

@@ -38,6 +38,7 @@ if TYPE_CHECKING:
     from slither.core.variables.variable import Variable
     from slither.core.variables.state_variable import StateVariable
     from slither.core.compilation_unit import SlitherCompilationUnit
+    from slither.core.declarations.custom_error_contract import CustomErrorContract
 
 
 LOGGER = logging.getLogger("Contract")
@@ -68,6 +69,7 @@ class Contract(SourceMapping):  # pylint: disable=too-many-public-methods
         self._modifiers: Dict[str, "Modifier"] = {}
         self._functions: Dict[str, "FunctionContract"] = {}
         self._linearizedBaseContracts: List[int] = []
+        self._custom_errors: Dict[str:"CustomErrorContract"] = {}
 
         # The only str is "*"
         self._using_for: Dict[Union[str, Type], List[str]] = {}
@@ -242,6 +244,38 @@ class Contract(SourceMapping):  # pylint: disable=too-many-public-methods
     def using_for(self) -> Dict[Union[str, Type], List[str]]:
         return self._using_for
 
+    # endregion
+    ###################################################################################
+    ###################################################################################
+    # region Custom Errors
+    ###################################################################################
+    ###################################################################################
+
+    @property
+    def custom_errors(self) -> List["CustomErrorContract"]:
+        """
+        list(CustomErrorContract): List of the contract's custom errors
+        """
+        return list(self._custom_errors.values())
+
+    @property
+    def custom_errors_inherited(self) -> List["CustomErrorContract"]:
+        """
+        list(CustomErrorContract): List of the inherited custom errors
+        """
+        return [s for s in self.custom_errors if s.contract != self]
+
+    @property
+    def custom_errors_declared(self) -> List["CustomErrorContract"]:
+        """
+        list(CustomErrorContract): List of the custom errors declared within the contract (not inherited)
+        """
+        return [s for s in self.custom_errors if s.contract == self]
+
+    @property
+    def custom_errors_as_dict(self) -> Dict[str, "CustomErrorContract"]:
+        return self._custom_errors
+
     # endregion
     ###################################################################################
     ###################################################################################

slither/core/declarations/custom_error.py

@@ -0,0 +1,71 @@
+from typing import List, TYPE_CHECKING, Optional, Type, Union
+
+from slither.core.solidity_types import UserDefinedType
+from slither.core.source_mapping.source_mapping import SourceMapping
+from slither.core.variables.local_variable import LocalVariable
+
+if TYPE_CHECKING:
+    from slither.core.compilation_unit import SlitherCompilationUnit
+
+
+class CustomError(SourceMapping):
+    def __init__(self, compilation_unit: "SlitherCompilationUnit"):
+        super().__init__()
+        self._name: str = ""
+        self._parameters: List[LocalVariable] = []
+        self._compilation_unit = compilation_unit
+
+        self._solidity_signature: Optional[str] = None
+
+    @property
+    def name(self) -> str:
+        return self._name
+
+    @name.setter
+    def name(self, new_name: str) -> None:
+        self._name = new_name
+
+    @property
+    def parameters(self) -> List[LocalVariable]:
+        return self._parameters
+
+    def add_parameters(self, p: "LocalVariable"):
+        self._parameters.append(p)
+
+    @property
+    def compilation_unit(self) -> "SlitherCompilationUnit":
+        return self._compilation_unit
+
+    # region Signature
+    ###################################################################################
+    ###################################################################################
+
+    @staticmethod
+    def _convert_type_for_solidity_signature(t: Optional[Union[Type, List[Type]]]):
+        # pylint: disable=import-outside-toplevel
+        from slither.core.declarations import Contract
+
+        if isinstance(t, UserDefinedType) and isinstance(t.type, Contract):
+            return "address"
+        return str(t)
+
+    @property
+    def solidity_signature(self) -> str:
+        """
+        Return a signature following the Solidity Standard
+        Contract and converted into address
+        :return: the solidity signature
+        """
+        if self._solidity_signature is None:
+            parameters = [
+                self._convert_type_for_solidity_signature(x.type) for x in self.parameters
+            ]
+            self._solidity_signature = self.name + "(" + ",".join(parameters) + ")"
+        return self._solidity_signature
+
+    # endregion
+    ###################################################################################
+    ###################################################################################
+
+    def __str__(self):
+        return "revert " + self.solidity_signature

slither/core/declarations/custom_error_contract.py

@@ -0,0 +1,12 @@
+from slither.core.children.child_contract import ChildContract
+from slither.core.declarations.custom_error import CustomError
+
+
+class CustomErrorContract(CustomError, ChildContract):
+    def is_declared_by(self, contract):
+        """
+        Check if the element is declared by the contract
+        :param contract:
+        :return:
+        """
+        return self.contract == contract

slither/core/declarations/custom_error_top_level.py

@@ -0,0 +1,6 @@
+from slither.core.declarations.custom_error import CustomError
+from slither.core.declarations.top_level import TopLevel
+
+
+class CustomErrorTopLevel(CustomError, TopLevel):
+    pass

slither/core/declarations/solidity_variables.py

@@ -2,6 +2,7 @@
 from typing import List, Dict, Union, TYPE_CHECKING
 
 from slither.core.context.context import Context
+from slither.core.declarations.custom_error import CustomError
 from slither.core.solidity_types import ElementaryType, TypeInformation
 from slither.exceptions import SlitherException
 
@@ -42,6 +43,7 @@ SOLIDITY_FUNCTIONS: Dict[str, List[str]] = {
     "require(bool,string)": [],
     "revert()": [],
     "revert(string)": [],
+    "revert ": [],
     "addmod(uint256,uint256,uint256)": ["uint256"],
     "mulmod(uint256,uint256,uint256)": ["uint256"],
     "keccak256()": ["bytes32"],
@@ -184,3 +186,20 @@ class SolidityFunction:
 
     def __hash__(self):
         return hash(self.name)
+
+
+class SolidityCustomRevert(SolidityFunction):
+    def __init__(self, custom_error: CustomError):  # pylint: disable=super-init-not-called
+        self._name = "revert " + custom_error.solidity_signature
+        self._custom_error = custom_error
+        self._return_type: List[Union[TypeInformation, ElementaryType]] = []
+
+    def __eq__(self, other):
+        return (
+            self.__class__ == other.__class__
+            and self.name == other.name
+            and self._custom_error == other._custom_error
+        )
+
+    def __hash__(self):
+        return hash(hash(self.name) + hash(self._custom_error))

slither/printers/inheritance/inheritance.py

@@ -30,9 +30,6 @@ class PrinterInheritance(AbstractPrinter):
         """
         info = "Inheritance\n"
 
-        if not self.contracts:
-            return []
-
         info += blue("Child_Contract -> ") + green("Immediate_Base_Contracts")
         info += green(" [Not_Immediate_Base_Contracts]")
 

slither/slithir/convert.py

@@ -13,8 +13,10 @@ from slither.core.declarations import (
     SolidityVariableComposed,
     Structure,
 )
+from slither.core.declarations.custom_error import CustomError
 from slither.core.declarations.function_contract import FunctionContract
 from slither.core.declarations.solidity_import_placeholder import SolidityImportPlaceHolder
+from slither.core.declarations.solidity_variables import SolidityCustomRevert
 from slither.core.expressions import Identifier, Literal
 from slither.core.solidity_types import (
     ArrayType,
@@ -941,6 +943,12 @@ def extract_tmp_call(ins: TmpCall, contract: Optional[Contract]):  # pylint: dis
         s.set_expression(ins.expression)
         return s
 
+    if isinstance(ins.called, CustomError):
+        sol_function = SolidityCustomRevert(ins.called)
+        s = SolidityCall(sol_function, ins.nbr_arguments, ins.lvalue, ins.type_call)
+        s.set_expression(ins.expression)
+        return s
+
     if isinstance(ins.ori, TmpNewElementaryType):
         n = NewElementaryType(ins.ori.type, ins.lvalue)
         n.set_expression(ins.expression)

slither/slithir/tmp_operations/tmp_call.py

@@ -5,6 +5,7 @@ from slither.core.declarations import (
     SolidityFunction,
     Structure,
 )
+from slither.core.declarations.custom_error import CustomError
 from slither.core.variables.variable import Variable
 from slither.slithir.operations.lvalue import OperationWithLValue
 
@@ -20,6 +21,7 @@ class TmpCall(OperationWithLValue):  # pylint: disable=too-many-instance-attribu
                 SolidityFunction,
                 Structure,
                 Event,
+                CustomError,
             ),
         )
         super().__init__()

slither/solc_parsing/declarations/contract.py

@@ -3,8 +3,10 @@ from typing import List, Dict, Callable, TYPE_CHECKING, Union, Set
 
 from slither.core.declarations import Modifier, Event, EnumContract, StructureContract, Function
 from slither.core.declarations.contract import Contract
+from slither.core.declarations.custom_error_contract import CustomErrorContract
 from slither.core.declarations.function_contract import FunctionContract
 from slither.core.variables.state_variable import StateVariable
+from slither.solc_parsing.declarations.custom_error import CustomErrorSolc
 from slither.solc_parsing.declarations.event import EventSolc
 from slither.solc_parsing.declarations.function import FunctionSolc
 from slither.solc_parsing.declarations.modifier import ModifierSolc
@@ -35,15 +37,17 @@ class ContractSolc:
         self._modifiersNotParsed: List[Dict] = []
         self._functions_no_params: List[FunctionSolc] = []
         self._modifiers_no_params: List[ModifierSolc] = []
-        self._eventsNotParsed: List[EventSolc] = []
+        self._eventsNotParsed: List[Dict] = []
         self._variablesNotParsed: List[Dict] = []
         self._enumsNotParsed: List[Dict] = []
         self._structuresNotParsed: List[Dict] = []
         self._usingForNotParsed: List[Dict] = []
+        self._customErrorParsed: List[Dict] = []
 
         self._functions_parser: List[FunctionSolc] = []
         self._modifiers_parser: List[ModifierSolc] = []
         self._structures_parser: List[StructureContractSolc] = []
+        self._custom_errors_parser: List[CustomErrorSolc] = []
 
         self._is_analyzed: bool = False
 
@@ -246,6 +250,8 @@ class ContractSolc:
                 self._structuresNotParsed.append(item)
             elif item[self.get_key()] == "UsingForDirective":
                 self._usingForNotParsed.append(item)
+            elif item[self.get_key()] == "ErrorDefinition":
+                self._customErrorParsed.append(item)
             else:
                 raise ParsingError("Unknown contract item: " + item[self.get_key()])
         return
@@ -268,6 +274,23 @@ class ContractSolc:
             self._parse_struct(struct)
         self._structuresNotParsed = None
 
+    def _parse_custom_error(self, custom_error: Dict):
+        ce = CustomErrorContract(self.compilation_unit)
+        ce.set_contract(self._contract)
+        ce.set_offset(custom_error["src"], self.compilation_unit)
+
+        ce_parser = CustomErrorSolc(ce, custom_error, self._slither_parser)
+        self._contract.custom_errors_as_dict[ce.name] = ce
+        self._custom_errors_parser.append(ce_parser)
+
+    def parse_custom_errors(self):
+        for father in self._contract.inheritance_reverse:
+            self._contract.custom_errors_as_dict.update(father.custom_errors_as_dict)
+
+        for custom_error in self._customErrorParsed:
+            self._parse_custom_error(custom_error)
+        self._customErrorParsed = None
+
     def parse_state_variables(self):
         for father in self._contract.inheritance_reverse:
             self._contract.variables_as_dict.update(father.variables_as_dict)
@@ -600,6 +623,10 @@ class ContractSolc:
         except (VariableNotFound, KeyError) as e:
             self.log_incorrect_parsing(f"Missing struct {e}")
 
+    def analyze_custom_errors(self):
+        for custom_error in self._custom_errors_parser:
+            custom_error.analyze_params()
+
     def analyze_events(self):
         try:
             for father in self._contract.inheritance_reverse:
@@ -640,6 +667,7 @@ class ContractSolc:
         self._enumsNotParsed = []
         self._structuresNotParsed = []
         self._usingForNotParsed = []
+        self._customErrorParsed = []
 
     # endregion
     ###################################################################################

slither/solc_parsing/declarations/custom_error.py

@@ -0,0 +1,101 @@
+from typing import TYPE_CHECKING, Dict
+
+from slither.core.declarations.custom_error import CustomError
+from slither.core.variables.local_variable import LocalVariable
+from slither.solc_parsing.variables.local_variable import LocalVariableSolc
+
+if TYPE_CHECKING:
+    from slither.solc_parsing.slither_compilation_unit_solc import SlitherCompilationUnitSolc
+
+
+# Part of the code was copied from the function parsing
+# In the long term we should refactor these two classes to merge the duplicated code
+
+
+class CustomErrorSolc:
+    def __init__(
+        self,
+        custom_error: CustomError,
+        custom_error_data: dict,
+        slither_parser: "SlitherCompilationUnitSolc",
+    ):
+        self._slither_parser: "SlitherCompilationUnitSolc" = slither_parser
+        self._custom_error = custom_error
+        custom_error.name = custom_error_data["name"]
+        self._params_was_analyzed = False
+
+        if not self._slither_parser.is_compact_ast:
+            custom_error_data = custom_error_data["attributes"]
+        self._custom_error_data = custom_error_data
+
+    def analyze_params(self):
+        # Can be re-analyzed due to inheritance
+        if self._params_was_analyzed:
+            return
+
+        self._params_was_analyzed = True
+
+        if self._slither_parser.is_compact_ast:
+            params = self._custom_error_data["parameters"]
+        else:
+            children = self._custom_error_data[self.get_children("children")]
+            # It uses to be
+            # params = children[0]
+            # returns = children[1]
+            # But from Solidity 0.6.3 to 0.6.10 (included)
+            # Comment above a function might be added in the children
+            child_iter = iter(
+                [child for child in children if child[self.get_key()] == "ParameterList"]
+            )
+            params = next(child_iter)
+
+        if params:
+            self._parse_params(params)
+
+    @property
+    def is_compact_ast(self) -> bool:
+        return self._slither_parser.is_compact_ast
+
+    def get_key(self) -> str:
+        return self._slither_parser.get_key()
+
+    def get_children(self, key: str) -> str:
+        if self._slither_parser.is_compact_ast:
+            return key
+        return "children"
+
+    def _parse_params(self, params: Dict):
+        assert params[self.get_key()] == "ParameterList"
+
+        if self._slither_parser.is_compact_ast:
+            params = params["parameters"]
+        else:
+            params = params[self.get_children("children")]
+
+        for param in params:
+            assert param[self.get_key()] == "VariableDeclaration"
+            local_var = self._add_param(param)
+            self._custom_error.add_parameters(local_var.underlying_variable)
+
+    def _add_param(self, param: Dict) -> LocalVariableSolc:
+
+        local_var = LocalVariable()
+        local_var.set_offset(param["src"], self._slither_parser.compilation_unit)
+
+        local_var_parser = LocalVariableSolc(local_var, param)
+
+        local_var_parser.analyze(self)
+
+        # see https://solidity.readthedocs.io/en/v0.4.24/types.html?highlight=storage%20location#data-location
+        if local_var.location == "default":
+            local_var.set_location("memory")
+
+        return local_var_parser
+
+    @property
+    def underlying_custom_error(self) -> CustomError:
+        return self._custom_error
+
+    @property
+    def slither_parser(self) -> "SlitherCompilationUnitSolc":
+        return self._slither_parser

slither/solc_parsing/declarations/function.py

@@ -10,12 +10,11 @@ from slither.core.declarations.function import (
     FunctionType,
 )
 from slither.core.declarations.function_contract import FunctionContract
-
 from slither.core.expressions import AssignmentOperation
 from slither.core.variables.local_variable import LocalVariable
 from slither.core.variables.local_variable_init_from_tuple import LocalVariableInitFromTuple
-
 from slither.solc_parsing.cfg.node import NodeSolc
+from slither.solc_parsing.exceptions import ParsingError
 from slither.solc_parsing.expressions.expression_parsing import parse_expression
 from slither.solc_parsing.variables.local_variable import LocalVariableSolc
 from slither.solc_parsing.variables.local_variable_init_from_tuple import (
@@ -26,13 +25,11 @@ from slither.solc_parsing.yul.parse_yul import YulBlock
 from slither.utils.expression_manipulations import SplitTernaryExpression
 from slither.visitors.expression.export_values import ExportValues
 from slither.visitors.expression.has_conditional import HasConditional
-from slither.solc_parsing.exceptions import ParsingError
 
 if TYPE_CHECKING:
     from slither.core.expressions.expression import Expression
     from slither.solc_parsing.declarations.contract import ContractSolc
     from slither.solc_parsing.slither_compilation_unit_solc import SlitherCompilationUnitSolc
-    from slither.core.slither_core import SlitherCore
     from slither.core.compilation_unit import SlitherCompilationUnit
 
 
@@ -1012,6 +1009,15 @@ class FunctionSolc:
             node = self._parse_try_catch(statement, node)
         # elif name == 'TryCatchClause':
         #     self._parse_catch(statement, node)
+        elif name == "RevertStatement":
+            if self.is_compact_ast:
+                expression = statement[self.get_children("errorCall")]
+            else:
+                expression = statement[self.get_children("errorCall")][0]
+            new_node = self._new_node(NodeType.EXPRESSION, statement["src"], scope)
+            new_node.add_unparsed_expression(expression)
+            link_underlying_nodes(node, new_node)
+            node = new_node
         else:
             raise ParsingError("Statement not parsed %s" % name)
 

slither/solc_parsing/expressions/find_variable.py

@@ -2,6 +2,7 @@ from typing import TYPE_CHECKING, Optional, Union, List, Tuple
 
 from slither.core.declarations import Event, Enum, Structure
 from slither.core.declarations.contract import Contract
+from slither.core.declarations.custom_error import CustomError
 from slither.core.declarations.function import Function
 from slither.core.declarations.function_contract import FunctionContract
 from slither.core.declarations.function_top_level import FunctionTopLevel
@@ -100,7 +101,7 @@ def _find_variable_in_function_parser(
 
 def _find_top_level(
     var_name: str, sl: "SlitherCompilationUnit"
-) -> Tuple[Optional[Union[Enum, Structure, SolidityImportPlaceHolder]], bool]:
+) -> Tuple[Optional[Union[Enum, Structure, SolidityImportPlaceHolder, CustomError]], bool]:
     """
     Return the top level variable use, and a boolean indicating if the variable returning was cretead
     If the variable was created, it has no source_mapping
@@ -127,6 +128,11 @@ def _find_top_level(
             new_val = SolidityImportPlaceHolder(import_directive)
             return new_val, True
 
+    # Note for now solidity prevent two custom error from having the same name
+    for custom_error in sl.custom_errors:
+        if custom_error.solidity_signature == var_name:
+            return custom_error, False
+
     return None, False
 
 
@@ -135,7 +141,7 @@ def _find_in_contract(
     contract: Optional[Contract],
     contract_declarer: Optional[Contract],
     is_super: bool,
-) -> Optional[Union[Variable, Function, Contract, Event, Enum, Structure,]]:
+) -> Optional[Union[Variable, Function, Contract, Event, Enum, Structure, CustomError]]:
 
     if contract is None or contract_declarer is None:
         return None
@@ -191,6 +197,14 @@ def _find_in_contract(
     if var_name in enums:
         return enums[var_name]
 
+    # Note: contract.custom_errors_as_dict uses the name (not the sol sig) as key
+    # This is because when the dic is populated the underlying object is not yet parsed
+    # As a result, we need to iterate over all the custom errors here instead of using the dict
+    custom_errors = contract.custom_errors
+    for custom_error in custom_errors:
+        if var_name == custom_error.solidity_signature:
+            return custom_error
+
     # If the enum is refered as its name rather than its canonicalName
     enums = {e.name: e for e in contract.enums}
     if var_name in enums:
@@ -260,6 +274,7 @@ def find_variable(
         Event,
         Enum,
         Structure,
+        CustomError,
     ],
     bool,
 ]:
@@ -384,4 +399,4 @@ def find_variable(
     if ret:
         return ret, False
 
-    raise VariableNotFound("Variable not found: {} (context {})".format(var_name, caller_context))
+    raise VariableNotFound("Variable not found: {} (context {})".format(var_name, contract))

slither/solc_parsing/slither_compilation_unit_solc.py

@@ -8,6 +8,7 @@ from typing import List, Dict
 from slither.analyses.data_dependency.data_dependency import compute_dependency
 from slither.core.compilation_unit import SlitherCompilationUnit
 from slither.core.declarations import Contract
+from slither.core.declarations.custom_error_top_level import CustomErrorTopLevel
 from slither.core.declarations.enum_top_level import EnumTopLevel
 from slither.core.declarations.function_top_level import FunctionTopLevel
 from slither.core.declarations.import_directive import Import
@@ -16,6 +17,7 @@ from slither.core.declarations.structure_top_level import StructureTopLevel
 from slither.core.variables.top_level_variable import TopLevelVariable
 from slither.exceptions import SlitherException
 from slither.solc_parsing.declarations.contract import ContractSolc
+from slither.solc_parsing.declarations.custom_error import CustomErrorSolc
 from slither.solc_parsing.declarations.function import FunctionSolc
 from slither.solc_parsing.declarations.structure_top_level import StructureTopLevelSolc
 from slither.solc_parsing.exceptions import VariableNotFound
@@ -37,6 +39,7 @@ class SlitherCompilationUnitSolc:
 
         self._underlying_contract_to_parser: Dict[Contract, ContractSolc] = dict()
         self._structures_top_level_parser: List[StructureTopLevelSolc] = []
+        self._custom_error_parser: List[CustomErrorSolc] = []
         self._variables_top_level_parser: List[TopLevelVariableSolc] = []
         self._functions_top_level_parser: List[FunctionSolc] = []
 
@@ -146,7 +149,7 @@ class SlitherCompilationUnitSolc:
 
     def parse_top_level_from_loaded_json(
         self, data_loaded: Dict, filename: str
-    ):  # pylint: disable=too-many-branches,too-many-statements
+    ):  # pylint: disable=too-many-branches,too-many-statements,too-many-locals
         if "nodeType" in data_loaded:
             self._is_compact_ast = True
 
@@ -164,6 +167,8 @@ class SlitherCompilationUnitSolc:
             logger.error("solc version is not supported")
             return
 
+        if self.get_children() not in data_loaded:
+            return
         for top_level_data in data_loaded[self.get_children()]:
             if top_level_data[self.get_key()] == "ContractDefinition":
                 contract = Contract(self._compilation_unit)
@@ -235,6 +240,14 @@ class SlitherCompilationUnitSolc:
                 self._functions_top_level_parser.append(func_parser)
                 self.add_function_or_modifier_parser(func_parser)
 
+            elif top_level_data[self.get_key()] == "ErrorDefinition":
+                custom_error = CustomErrorTopLevel(self._compilation_unit)
+                custom_error.set_offset(top_level_data["src"], self._compilation_unit)
+
+                custom_error_parser = CustomErrorSolc(custom_error, top_level_data, self)
+                self._compilation_unit.custom_errors.append(custom_error)
+                self._custom_error_parser.append(custom_error_parser)
+
             else:
                 raise SlitherException(f"Top level {top_level_data[self.get_key()]} not supported")
 
@@ -522,6 +535,7 @@ Please rename it, this name is reserved for Slither's internals"""
         contract.parse_state_variables()
         contract.parse_modifiers()
         contract.parse_functions()
+        contract.parse_custom_errors()
         contract.set_is_analyzed(True)
 
     def _analyze_struct_events(self, contract: ContractSolc):
@@ -534,6 +548,7 @@ Please rename it, this name is reserved for Slither's internals"""
         contract.analyze_events()
 
         contract.analyze_using_for()
+        contract.analyze_custom_errors()
 
         contract.set_is_analyzed(True)
 
@@ -556,6 +571,10 @@ Please rename it, this name is reserved for Slither's internals"""
             func_parser.analyze_params()
             self._compilation_unit.add_function(func_parser.underlying_function)
 
+    def _analyze_params_custom_error(self):
+        for custom_error_parser in self._custom_error_parser:
+            custom_error_parser.analyze_params()
+
     def _analyze_content_top_level_function(self):
         try:
             for func_parser in self._functions_top_level_parser:
@@ -569,6 +588,7 @@ Please rename it, this name is reserved for Slither's internals"""
         contract.analyze_params_modifiers()
         contract.analyze_params_functions()
         self._analyze_params_top_level_function()
+        self._analyze_params_custom_error()
 
         contract.analyze_state_variables()
 

slither/solc_parsing/solidity_types/type_parsing.py

@@ -190,7 +190,12 @@ def _find_from_type_name(  # pylint: disable=too-many-locals,too-many-branches,t
     return UserDefinedType(var_type)
 
 
-def parse_type(t: Union[Dict, UnknownType], caller_context):
+def parse_type(
+    t: Union[Dict, UnknownType],
+    caller_context: Union[
+        "SlitherCompilationUnitSolc", "FunctionSolc", "ContractSolc", "CustomSolc"
+    ],
+):
     # local import to avoid circular dependency
     # pylint: disable=too-many-locals,too-many-branches,too-many-statements
     # pylint: disable=import-outside-toplevel
@@ -198,17 +203,22 @@ def parse_type(t: Union[Dict, UnknownType], caller_context):
     from slither.solc_parsing.variables.function_type_variable import FunctionTypeVariableSolc
     from slither.solc_parsing.declarations.contract import ContractSolc
     from slither.solc_parsing.declarations.function import FunctionSolc
+    from slither.solc_parsing.declarations.custom_error import CustomErrorSolc
     from slither.solc_parsing.slither_compilation_unit_solc import SlitherCompilationUnitSolc
 
     sl: "SlitherCompilationUnit"
     # Note: for convenicence top level functions use the same parser than function in contract
     # but contract_parser is set to None
-    if isinstance(caller_context, SlitherCompilationUnitSolc) or (
+    if isinstance(caller_context, (SlitherCompilationUnitSolc, CustomErrorSolc)) or (
         isinstance(caller_context, FunctionSolc) and caller_context.contract_parser is None
     ):
+        structures_direct_access: List["Structure"]
         if isinstance(caller_context, SlitherCompilationUnitSolc):
             sl = caller_context.compilation_unit
             next_context = caller_context
+        elif isinstance(caller_context, CustomErrorSolc):
+            sl = caller_context.underlying_custom_error.compilation_unit
+            next_context = caller_context.slither_parser
         else:
             assert isinstance(caller_context, FunctionSolc)
             sl = caller_context.underlying_function.compilation_unit
@@ -235,13 +245,13 @@ def parse_type(t: Union[Dict, UnknownType], caller_context):
             contract = caller_context.underlying_contract
             next_context = caller_context
 
-        structures_direct_access = (
-            contract.structures + contract.compilation_unit.structures_top_level
-        )
+        structures_direct_access = contract.structures
+        structures_direct_access += contract.compilation_unit.structures_top_level
         all_structuress = [c.structures for c in contract.compilation_unit.contracts]
         all_structures = [item for sublist in all_structuress for item in sublist]
         all_structures += contract.compilation_unit.structures_top_level
-        enums_direct_access = contract.enums + contract.compilation_unit.enums_top_level
+        enums_direct_access: List["Enum"] = contract.enums
+        enums_direct_access += contract.compilation_unit.enums_top_level
         all_enumss = [c.enums for c in contract.compilation_unit.contracts]
         all_enums = [item for sublist in all_enumss for item in sublist]
         all_enums += contract.compilation_unit.enums_top_level