Beispiel #1
0
def parse_expression(expression, caller_context):
    """

    Returns:
        str: expression
    """
    #  Expression
    #    = Expression ('++' | '--')
    #    | NewExpression
    #    | IndexAccess
    #    | MemberAccess
    #    | FunctionCall
    #    | '(' Expression ')'
    #    | ('!' | '~' | 'delete' | '++' | '--' | '+' | '-') Expression
    #    | Expression '**' Expression
    #    | Expression ('*' | '/' | '%') Expression
    #    | Expression ('+' | '-') Expression
    #    | Expression ('<<' | '>>') Expression
    #    | Expression '&' Expression
    #    | Expression '^' Expression
    #    | Expression '|' Expression
    #    | Expression ('<' | '>' | '<=' | '>=') Expression
    #    | Expression ('==' | '!=') Expression
    #    | Expression '&&' Expression
    #    | Expression '||' Expression
    #    | Expression '?' Expression ':' Expression
    #    | Expression ('=' | '|=' | '^=' | '&=' | '<<=' | '>>=' | '+=' | '-=' | '*=' | '/=' | '%=') Expression
    #    | PrimaryExpression

    # The AST naming does not follow the spec
    name = expression[caller_context.get_key()]
    is_compact_ast = caller_context.is_compact_ast
    src = expression['src']

    if name == 'UnaryOperation':
        if is_compact_ast:
            attributes = expression
        else:
            attributes = expression['attributes']
        assert 'prefix' in attributes
        operation_type = UnaryOperationType.get_type(attributes['operator'],
                                                     attributes['prefix'])

        if is_compact_ast:
            expression = parse_expression(expression['subExpression'],
                                          caller_context)
        else:
            assert len(expression['children']) == 1
            expression = parse_expression(expression['children'][0],
                                          caller_context)
        unary_op = UnaryOperation(expression, operation_type)
        unary_op.set_offset(src, caller_context.slither)
        return unary_op

    elif name == 'BinaryOperation':
        if is_compact_ast:
            attributes = expression
        else:
            attributes = expression['attributes']
        operation_type = BinaryOperationType.get_type(attributes['operator'])

        if is_compact_ast:
            left_expression = parse_expression(expression['leftExpression'],
                                               caller_context)
            right_expression = parse_expression(expression['rightExpression'],
                                                caller_context)
        else:
            assert len(expression['children']) == 2
            left_expression = parse_expression(expression['children'][0],
                                               caller_context)
            right_expression = parse_expression(expression['children'][1],
                                                caller_context)
        binary_op = BinaryOperation(left_expression, right_expression,
                                    operation_type)
        binary_op.set_offset(src, caller_context.slither)
        return binary_op

    elif name in 'FunctionCall':
        return parse_call(expression, caller_context)

    elif name == 'FunctionCallOptions':
        # call/gas info are handled in parse_call
        called = parse_expression(expression['expression'], caller_context)
        assert isinstance(called, (MemberAccess, NewContract))
        return called

    elif name == 'TupleExpression':
        """
            For expression like
            (a,,c) = (1,2,3)
            the AST provides only two children in the left side
            We check the type provided (tuple(uint256,,uint256))
            To determine that there is an empty variable
            Otherwhise we would not be able to determine that
            a = 1, c = 3, and 2 is lost

            Note: this is only possible with Solidity >= 0.4.12
        """
        if is_compact_ast:
            expressions = [
                parse_expression(e, caller_context) if e else None
                for e in expression['components']
            ]
        else:
            if 'children' not in expression:
                attributes = expression['attributes']
                components = attributes['components']
                expressions = [
                    parse_expression(c, caller_context) if c else None
                    for c in components
                ]
            else:
                expressions = [
                    parse_expression(e, caller_context)
                    for e in expression['children']
                ]
        # Add none for empty tuple items
        if "attributes" in expression:
            if "type" in expression['attributes']:
                t = expression['attributes']['type']
                if ',,' in t or '(,' in t or ',)' in t:
                    t = t[len('tuple('):-1]
                    elems = t.split(',')
                    for idx in range(len(elems)):
                        if elems[idx] == '':
                            expressions.insert(idx, None)
        t = TupleExpression(expressions)
        t.set_offset(src, caller_context.slither)
        return t

    elif name == 'Conditional':
        if is_compact_ast:
            if_expression = parse_expression(expression['condition'],
                                             caller_context)
            then_expression = parse_expression(expression['trueExpression'],
                                               caller_context)
            else_expression = parse_expression(expression['falseExpression'],
                                               caller_context)
        else:
            children = expression['children']
            assert len(children) == 3
            if_expression = parse_expression(children[0], caller_context)
            then_expression = parse_expression(children[1], caller_context)
            else_expression = parse_expression(children[2], caller_context)
        conditional = ConditionalExpression(if_expression, then_expression,
                                            else_expression)
        conditional.set_offset(src, caller_context.slither)
        return conditional

    elif name == 'Assignment':
        if is_compact_ast:
            left_expression = parse_expression(expression['leftHandSide'],
                                               caller_context)
            right_expression = parse_expression(expression['rightHandSide'],
                                                caller_context)

            operation_type = AssignmentOperationType.get_type(
                expression['operator'])

            operation_return_type = expression['typeDescriptions'][
                'typeString']
        else:
            attributes = expression['attributes']
            children = expression['children']
            assert len(expression['children']) == 2
            left_expression = parse_expression(children[0], caller_context)
            right_expression = parse_expression(children[1], caller_context)

            operation_type = AssignmentOperationType.get_type(
                attributes['operator'])
            operation_return_type = attributes['type']

        assignement = AssignmentOperation(left_expression, right_expression,
                                          operation_type,
                                          operation_return_type)
        assignement.set_offset(src, caller_context.slither)
        return assignement

    elif name == 'Literal':

        subdenomination = None

        assert 'children' not in expression

        if is_compact_ast:
            value = expression['value']
            if value:
                if 'subdenomination' in expression and expression[
                        'subdenomination']:
                    subdenomination = expression['subdenomination']
            elif not value and value != "":
                value = '0x' + expression['hexValue']
            type = expression['typeDescriptions']['typeString']

            # Length declaration for array was None until solc 0.5.5
            if type is None:
                if expression['kind'] == 'number':
                    type = 'int_const'
        else:
            value = expression['attributes']['value']
            if value:
                if 'subdenomination' in expression['attributes'] and expression[
                        'attributes']['subdenomination']:
                    subdenomination = expression['attributes'][
                        'subdenomination']
            elif value is None:
                # for literal declared as hex
                # see https://solidity.readthedocs.io/en/v0.4.25/types.html?highlight=hex#hexadecimal-literals
                assert 'hexvalue' in expression['attributes']
                value = '0x' + expression['attributes']['hexvalue']
            type = expression['attributes']['type']

        if type is None:
            if value.isdecimal():
                type = ElementaryType('uint256')
            else:
                type = ElementaryType('string')
        elif type.startswith('int_const '):
            type = ElementaryType('uint256')
        elif type.startswith('bool'):
            type = ElementaryType('bool')
        elif type.startswith('address'):
            type = ElementaryType('address')
        else:
            type = ElementaryType('string')
        literal = Literal(value, type, subdenomination)
        literal.set_offset(src, caller_context.slither)
        return literal

    elif name == 'Identifier':
        assert 'children' not in expression

        t = None

        if caller_context.is_compact_ast:
            value = expression['name']
            t = expression['typeDescriptions']['typeString']
        else:
            value = expression['attributes']['value']
            if 'type' in expression['attributes']:
                t = expression['attributes']['type']

        if t:
            found = re.findall(
                '[struct|enum|function|modifier] \(([\[\] ()a-zA-Z0-9\.,_]*)\)',
                t)
            assert len(found) <= 1
            if found:
                value = value + '(' + found[0] + ')'
                value = filter_name(value)

        if 'referencedDeclaration' in expression:
            referenced_declaration = expression['referencedDeclaration']
        else:
            referenced_declaration = None

        var = find_variable(value, caller_context, referenced_declaration)

        identifier = Identifier(var)
        identifier.set_offset(src, caller_context.slither)
        return identifier

    elif name == 'IndexAccess':
        if is_compact_ast:
            index_type = expression['typeDescriptions']['typeString']
            left = expression['baseExpression']
            right = expression['indexExpression']
        else:
            index_type = expression['attributes']['type']
            children = expression['children']
            assert len(children) == 2
            left = children[0]
            right = children[1]
        # IndexAccess is used to describe ElementaryTypeNameExpression
        # if abi.decode is used
        # For example, abi.decode(data, ...(uint[]) )
        if right is None:
            return parse_expression(left, caller_context)

        left_expression = parse_expression(left, caller_context)
        right_expression = parse_expression(right, caller_context)
        index = IndexAccess(left_expression, right_expression, index_type)
        index.set_offset(src, caller_context.slither)
        return index

    elif name == 'MemberAccess':
        if caller_context.is_compact_ast:
            member_name = expression['memberName']
            member_type = expression['typeDescriptions']['typeString']
            member_expression = parse_expression(expression['expression'],
                                                 caller_context)
        else:
            member_name = expression['attributes']['member_name']
            member_type = expression['attributes']['type']
            children = expression['children']
            assert len(children) == 1
            member_expression = parse_expression(children[0], caller_context)
        if str(member_expression) == 'super':
            super_name = parse_super_name(expression, is_compact_ast)
            var = find_variable(super_name, caller_context, is_super=True)
            if var is None:
                raise VariableNotFound(
                    'Variable not found: {}'.format(super_name))
            sup = SuperIdentifier(var)
            sup.set_offset(src, caller_context.slither)
            return sup
        member_access = MemberAccess(member_name, member_type,
                                     member_expression)
        member_access.set_offset(src, caller_context.slither)
        if str(member_access) in SOLIDITY_VARIABLES_COMPOSED:
            idx = Identifier(SolidityVariableComposed(str(member_access)))
            idx.set_offset(src, caller_context.slither)
            return idx
        return member_access

    elif name == 'ElementaryTypeNameExpression':
        return _parse_elementary_type_name_expression(expression,
                                                      is_compact_ast,
                                                      caller_context)

    # NewExpression is not a root expression, it's always the child of another expression
    elif name == 'NewExpression':

        if is_compact_ast:
            type_name = expression['typeName']
        else:
            children = expression['children']
            assert len(children) == 1
            type_name = children[0]

        if type_name[caller_context.get_key()] == 'ArrayTypeName':
            depth = 0
            while type_name[caller_context.get_key()] == 'ArrayTypeName':
                # Note: dont conserve the size of the array if provided
                # We compute it directly
                if is_compact_ast:
                    type_name = type_name['baseType']
                else:
                    type_name = type_name['children'][0]
                depth += 1
            if type_name[caller_context.get_key()] == 'ElementaryTypeName':
                if is_compact_ast:
                    array_type = ElementaryType(type_name['name'])
                else:
                    array_type = ElementaryType(
                        type_name['attributes']['name'])
            elif type_name[caller_context.get_key()] == 'UserDefinedTypeName':
                if is_compact_ast:
                    array_type = parse_type(UnknownType(type_name['name']),
                                            caller_context)
                else:
                    array_type = parse_type(
                        UnknownType(type_name['attributes']['name']),
                        caller_context)
            elif type_name[caller_context.get_key()] == 'FunctionTypeName':
                array_type = parse_type(type_name, caller_context)
            else:
                raise ParsingError('Incorrect type array {}'.format(type_name))
            array = NewArray(depth, array_type)
            array.set_offset(src, caller_context.slither)
            return array

        if type_name[caller_context.get_key()] == 'ElementaryTypeName':
            if is_compact_ast:
                elem_type = ElementaryType(type_name['name'])
            else:
                elem_type = ElementaryType(type_name['attributes']['name'])
            new_elem = NewElementaryType(elem_type)
            new_elem.set_offset(src, caller_context.slither)
            return new_elem

        assert type_name[caller_context.get_key()] == 'UserDefinedTypeName'

        if is_compact_ast:
            contract_name = type_name['name']
        else:
            contract_name = type_name['attributes']['name']
        new = NewContract(contract_name)
        new.set_offset(src, caller_context.slither)
        return new

    elif name == 'ModifierInvocation':

        if is_compact_ast:
            called = parse_expression(expression['modifierName'],
                                      caller_context)
            arguments = []
            if expression['arguments']:
                arguments = [
                    parse_expression(a, caller_context)
                    for a in expression['arguments']
                ]
        else:
            children = expression['children']
            called = parse_expression(children[0], caller_context)
            arguments = [
                parse_expression(a, caller_context) for a in children[1::]
            ]

        call = CallExpression(called, arguments, 'Modifier')
        call.set_offset(src, caller_context.slither)
        return call

    raise ParsingError('Expression not parsed %s' % name)
def parse_expression(expression: Dict, caller_context: CallerContext) -> "Expression":
    # pylint: disable=too-many-nested-blocks,too-many-statements
    """

    Returns:
        str: expression
    """
    #  Expression
    #    = Expression ('++' | '--')
    #    | NewExpression
    #    | IndexAccess
    #    | MemberAccess
    #    | FunctionCall
    #    | '(' Expression ')'
    #    | ('!' | '~' | 'delete' | '++' | '--' | '+' | '-') Expression
    #    | Expression '**' Expression
    #    | Expression ('*' | '/' | '%') Expression
    #    | Expression ('+' | '-') Expression
    #    | Expression ('<<' | '>>') Expression
    #    | Expression '&' Expression
    #    | Expression '^' Expression
    #    | Expression '|' Expression
    #    | Expression ('<' | '>' | '<=' | '>=') Expression
    #    | Expression ('==' | '!=') Expression
    #    | Expression '&&' Expression
    #    | Expression '||' Expression
    #    | Expression '?' Expression ':' Expression
    #    | Expression ('=' | '|=' | '^=' | '&=' | '<<=' | '>>=' | '+=' | '-=' | '*=' | '/=' | '%=') Expression
    #    | PrimaryExpression
    # The AST naming does not follow the spec
    name = expression[caller_context.get_key()]
    is_compact_ast = caller_context.is_compact_ast
    src = expression["src"]

    if name == "UnaryOperation":
        if is_compact_ast:
            attributes = expression
        else:
            attributes = expression["attributes"]
        assert "prefix" in attributes
        operation_type = UnaryOperationType.get_type(attributes["operator"], attributes["prefix"])

        if is_compact_ast:
            expression = parse_expression(expression["subExpression"], caller_context)
        else:
            assert len(expression["children"]) == 1
            expression = parse_expression(expression["children"][0], caller_context)
        unary_op = UnaryOperation(expression, operation_type)
        unary_op.set_offset(src, caller_context.slither)
        return unary_op

    if name == "BinaryOperation":
        if is_compact_ast:
            attributes = expression
        else:
            attributes = expression["attributes"]
        operation_type = BinaryOperationType.get_type(attributes["operator"])

        if is_compact_ast:
            left_expression = parse_expression(expression["leftExpression"], caller_context)
            right_expression = parse_expression(expression["rightExpression"], caller_context)
        else:
            assert len(expression["children"]) == 2
            left_expression = parse_expression(expression["children"][0], caller_context)
            right_expression = parse_expression(expression["children"][1], caller_context)
        binary_op = BinaryOperation(left_expression, right_expression, operation_type)
        binary_op.set_offset(src, caller_context.slither)
        return binary_op

    if name in "FunctionCall":
        return parse_call(expression, caller_context)

    if name == "FunctionCallOptions":
        # call/gas info are handled in parse_call
        if is_compact_ast:
            called = parse_expression(expression["expression"], caller_context)
        else:
            called = parse_expression(expression["children"][0], caller_context)
        assert isinstance(called, (MemberAccess, NewContract, Identifier, TupleExpression))
        return called

    if name == "TupleExpression":
        #     For expression like
        #     (a,,c) = (1,2,3)
        #     the AST provides only two children in the left side
        #     We check the type provided (tuple(uint256,,uint256))
        #     To determine that there is an empty variable
        #     Otherwhise we would not be able to determine that
        #     a = 1, c = 3, and 2 is lost
        #
        #     Note: this is only possible with Solidity >= 0.4.12
        if is_compact_ast:
            expressions = [
                parse_expression(e, caller_context) if e else None for e in expression["components"]
            ]
        else:
            if "children" not in expression:
                attributes = expression["attributes"]
                components = attributes["components"]
                expressions = [
                    parse_expression(c, caller_context) if c else None for c in components
                ]
            else:
                expressions = [parse_expression(e, caller_context) for e in expression["children"]]
        # Add none for empty tuple items
        if "attributes" in expression:
            if "type" in expression["attributes"]:
                t = expression["attributes"]["type"]
                if ",," in t or "(," in t or ",)" in t:
                    t = t[len("tuple(") : -1]
                    elems = t.split(",")
                    for idx, _ in enumerate(elems):
                        if elems[idx] == "":
                            expressions.insert(idx, None)
        t = TupleExpression(expressions)
        t.set_offset(src, caller_context.slither)
        return t

    if name == "Conditional":
        if is_compact_ast:
            if_expression = parse_expression(expression["condition"], caller_context)
            then_expression = parse_expression(expression["trueExpression"], caller_context)
            else_expression = parse_expression(expression["falseExpression"], caller_context)
        else:
            children = expression["children"]
            assert len(children) == 3
            if_expression = parse_expression(children[0], caller_context)
            then_expression = parse_expression(children[1], caller_context)
            else_expression = parse_expression(children[2], caller_context)
        conditional = ConditionalExpression(if_expression, then_expression, else_expression)
        conditional.set_offset(src, caller_context.slither)
        return conditional

    if name == "Assignment":
        if is_compact_ast:
            left_expression = parse_expression(expression["leftHandSide"], caller_context)
            right_expression = parse_expression(expression["rightHandSide"], caller_context)

            operation_type = AssignmentOperationType.get_type(expression["operator"])

            operation_return_type = expression["typeDescriptions"]["typeString"]
        else:
            attributes = expression["attributes"]
            children = expression["children"]
            assert len(expression["children"]) == 2
            left_expression = parse_expression(children[0], caller_context)
            right_expression = parse_expression(children[1], caller_context)

            operation_type = AssignmentOperationType.get_type(attributes["operator"])
            operation_return_type = attributes["type"]

        assignement = AssignmentOperation(
            left_expression, right_expression, operation_type, operation_return_type
        )
        assignement.set_offset(src, caller_context.slither)
        return assignement

    if name == "Literal":

        subdenomination = None

        assert "children" not in expression

        if is_compact_ast:
            value = expression["value"]
            if value:
                if "subdenomination" in expression and expression["subdenomination"]:
                    subdenomination = expression["subdenomination"]
            elif not value and value != "":
                value = "0x" + expression["hexValue"]
            type_candidate = expression["typeDescriptions"]["typeString"]

            # Length declaration for array was None until solc 0.5.5
            if type_candidate is None:
                if expression["kind"] == "number":
                    type_candidate = "int_const"
        else:
            value = expression["attributes"]["value"]
            if value:
                if (
                    "subdenomination" in expression["attributes"]
                    and expression["attributes"]["subdenomination"]
                ):
                    subdenomination = expression["attributes"]["subdenomination"]
            elif value is None:
                # for literal declared as hex
                # see https://solidity.readthedocs.io/en/v0.4.25/types.html?highlight=hex#hexadecimal-literals
                assert "hexvalue" in expression["attributes"]
                value = "0x" + expression["attributes"]["hexvalue"]
            type_candidate = expression["attributes"]["type"]

        if type_candidate is None:
            if value.isdecimal():
                type_candidate = ElementaryType("uint256")
            else:
                type_candidate = ElementaryType("string")
        elif type_candidate.startswith("int_const "):
            type_candidate = ElementaryType("uint256")
        elif type_candidate.startswith("bool"):
            type_candidate = ElementaryType("bool")
        elif type_candidate.startswith("address"):
            type_candidate = ElementaryType("address")
        else:
            type_candidate = ElementaryType("string")
        literal = Literal(value, type_candidate, subdenomination)
        literal.set_offset(src, caller_context.slither)
        return literal

    if name == "Identifier":
        assert "children" not in expression

        t = None

        if caller_context.is_compact_ast:
            value = expression["name"]
            t = expression["typeDescriptions"]["typeString"]
        else:
            value = expression["attributes"]["value"]
            if "type" in expression["attributes"]:
                t = expression["attributes"]["type"]

        if t:
            found = re.findall("[struct|enum|function|modifier] \(([\[\] ()a-zA-Z0-9\.,_]*)\)", t)
            assert len(found) <= 1
            if found:
                value = value + "(" + found[0] + ")"
                value = filter_name(value)

        if "referencedDeclaration" in expression:
            referenced_declaration = expression["referencedDeclaration"]
        else:
            referenced_declaration = None

        var = find_variable(value, caller_context, referenced_declaration)

        identifier = Identifier(var)
        identifier.set_offset(src, caller_context.slither)
        return identifier

    if name == "IndexAccess":
        if is_compact_ast:
            index_type = expression["typeDescriptions"]["typeString"]
            left = expression["baseExpression"]
            right = expression.get("indexExpression", None)
        else:
            index_type = expression["attributes"]["type"]
            children = expression["children"]
            left = children[0]
            right = children[1] if len(children) > 1 else None
        # IndexAccess is used to describe ElementaryTypeNameExpression
        # if abi.decode is used
        # For example, abi.decode(data, ...(uint[]) )
        if right is None:
            ret = parse_expression(left, caller_context)
            # Nested array are not yet available in abi.decode
            if isinstance(ret, ElementaryTypeNameExpression):
                old_type = ret.type
                ret.type = ArrayType(old_type, None)
            return ret

        left_expression = parse_expression(left, caller_context)
        right_expression = parse_expression(right, caller_context)
        index = IndexAccess(left_expression, right_expression, index_type)
        index.set_offset(src, caller_context.slither)
        return index

    if name == "MemberAccess":
        if caller_context.is_compact_ast:
            member_name = expression["memberName"]
            member_type = expression["typeDescriptions"]["typeString"]
            # member_type = parse_type(
            #     UnknownType(expression["typeDescriptions"]["typeString"]), caller_context
            # )
            member_expression = parse_expression(expression["expression"], caller_context)
        else:
            member_name = expression["attributes"]["member_name"]
            member_type = expression["attributes"]["type"]
            # member_type = parse_type(UnknownType(expression["attributes"]["type"]), caller_context)
            children = expression["children"]
            assert len(children) == 1
            member_expression = parse_expression(children[0], caller_context)
        if str(member_expression) == "super":
            super_name = parse_super_name(expression, is_compact_ast)
            var = find_variable(super_name, caller_context, is_super=True)
            if var is None:
                raise VariableNotFound("Variable not found: {}".format(super_name))
            sup = SuperIdentifier(var)
            sup.set_offset(src, caller_context.slither)
            return sup
        member_access = MemberAccess(member_name, member_type, member_expression)
        member_access.set_offset(src, caller_context.slither)
        if str(member_access) in SOLIDITY_VARIABLES_COMPOSED:
            id_idx = Identifier(SolidityVariableComposed(str(member_access)))
            id_idx.set_offset(src, caller_context.slither)
            return id_idx
        return member_access

    if name == "ElementaryTypeNameExpression":
        return _parse_elementary_type_name_expression(expression, is_compact_ast, caller_context)

    # NewExpression is not a root expression, it's always the child of another expression
    if name == "NewExpression":

        if is_compact_ast:
            type_name = expression["typeName"]
        else:
            children = expression["children"]
            assert len(children) == 1
            type_name = children[0]

        if type_name[caller_context.get_key()] == "ArrayTypeName":
            depth = 0
            while type_name[caller_context.get_key()] == "ArrayTypeName":
                # Note: dont conserve the size of the array if provided
                # We compute it directly
                if is_compact_ast:
                    type_name = type_name["baseType"]
                else:
                    type_name = type_name["children"][0]
                depth += 1
            if type_name[caller_context.get_key()] == "ElementaryTypeName":
                if is_compact_ast:
                    array_type = ElementaryType(type_name["name"])
                else:
                    array_type = ElementaryType(type_name["attributes"]["name"])
            elif type_name[caller_context.get_key()] == "UserDefinedTypeName":
                if is_compact_ast:
                    array_type = parse_type(UnknownType(type_name["name"]), caller_context)
                else:
                    array_type = parse_type(
                        UnknownType(type_name["attributes"]["name"]), caller_context
                    )
            elif type_name[caller_context.get_key()] == "FunctionTypeName":
                array_type = parse_type(type_name, caller_context)
            else:
                raise ParsingError("Incorrect type array {}".format(type_name))
            array = NewArray(depth, array_type)
            array.set_offset(src, caller_context.slither)
            return array

        if type_name[caller_context.get_key()] == "ElementaryTypeName":
            if is_compact_ast:
                elem_type = ElementaryType(type_name["name"])
            else:
                elem_type = ElementaryType(type_name["attributes"]["name"])
            new_elem = NewElementaryType(elem_type)
            new_elem.set_offset(src, caller_context.slither)
            return new_elem

        assert type_name[caller_context.get_key()] == "UserDefinedTypeName"

        if is_compact_ast:

            # Changed introduced in Solidity 0.8
            # see https://github.com/crytic/slither/issues/794

            # TODO explore more the changes introduced in 0.8 and the usage of pathNode/IdentifierPath
            if "name" not in type_name:
                assert "pathNode" in type_name and "name" in type_name["pathNode"]
                contract_name = type_name["pathNode"]["name"]
            else:
                contract_name = type_name["name"]
        else:
            contract_name = type_name["attributes"]["name"]
        new = NewContract(contract_name)
        new.set_offset(src, caller_context.slither)
        return new

    if name == "ModifierInvocation":

        if is_compact_ast:
            called = parse_expression(expression["modifierName"], caller_context)
            arguments = []
            if expression.get("arguments", None):
                arguments = [parse_expression(a, caller_context) for a in expression["arguments"]]
        else:
            children = expression["children"]
            called = parse_expression(children[0], caller_context)
            arguments = [parse_expression(a, caller_context) for a in children[1::]]

        call = CallExpression(called, arguments, "Modifier")
        call.set_offset(src, caller_context.slither)
        return call

    if name == "IndexRangeAccess":
        # For now, we convert array slices to a direct array access
        # As a result the generated IR will lose the slices information
        # As far as I understand, array slice are only used in abi.decode
        # https://solidity.readthedocs.io/en/v0.6.12/types.html
        # TODO: Investigate array slices usage and implication for the IR
        base = parse_expression(expression["baseExpression"], caller_context)
        return base

    # Introduced with solc 0.8
    if name == "IdentifierPath":

        if caller_context.is_compact_ast:
            value = expression["name"]

            if "referencedDeclaration" in expression:
                referenced_declaration = expression["referencedDeclaration"]
            else:
                referenced_declaration = None

            var = find_variable(value, caller_context, referenced_declaration)

            identifier = Identifier(var)
            identifier.set_offset(src, caller_context.slither)
            return identifier

        raise ParsingError("IdentifierPath not currently supported for the legacy ast")

    raise ParsingError("Expression not parsed %s" % name)