inform user if inheritance cannot be resolved (#1956)

* inform user if inheritance cannot be resolved

* lint

* update explanation

slither/solc_parsing/slither_compilation_unit_solc.py

@@ -33,6 +33,10 @@
 logger.setLevel(logging.INFO)
 
 
+class InheritanceResolutionError(SlitherException):
+    pass
+
+
 def _handle_import_aliases(
     symbol_aliases: Dict, import_directive: Import, scope: FileScope
 ) -> None:
@@ -432,7 +436,12 @@ def parse_contracts(self) -> None:  # pylint: disable=too-many-statements,too-ma
                     target = contract_parser.underlying_contract.file_scope.get_contract_from_name(
                         contract_name
                     )
-                    assert target
+                    if target == contract_parser.underlying_contract:
+                        raise InheritanceResolutionError(
+                            "Could not resolve contract inheritance. This is likely caused by an import renaming that collides with existing names (see https://github.com/crytic/slither/issues/1758)."
+                            f"\n Try changing `contract {target}` ({target.source_mapping}) to a unique name."
+                        )
+                    assert target, f"Contract {contract_name} not found"
                     ancestors.append(target)
                 elif i in self._contracts_by_id:
                     ancestors.append(self._contracts_by_id[i])

tests/unit/core/test_data/inheritance_resolution_error/contract_with_duplicate_names.sol

@@ -0,0 +1,2 @@
+import {ERC20 as ERC20_1} from "./import.sol"; 
+contract ERC20 is ERC20_1 {}

tests/unit/core/test_data/inheritance_resolution_error/import.sol

@@ -0,0 +1 @@
+contract ERC20 {}

tests/unit/core/test_error_messages.py

@@ -0,0 +1,18 @@
+from pathlib import Path
+import pytest
+
+
+from slither import Slither
+from slither.solc_parsing.slither_compilation_unit_solc import InheritanceResolutionError
+
+TEST_DATA_DIR = Path(__file__).resolve().parent / "test_data"
+INHERITANCE_ERROR_ROOT = Path(TEST_DATA_DIR, "inheritance_resolution_error")
+
+
+def test_inheritance_resolution_error(solc_binary_path) -> None:
+    with pytest.raises(InheritanceResolutionError):
+        solc_path = solc_binary_path("0.8.0")
+        Slither(
+            Path(INHERITANCE_ERROR_ROOT, "contract_with_duplicate_names.sol").as_posix(),
+            solc=solc_path,
+        )