better error handling of malformed symbol alias AST node for solc <0.6.0

slither/solc_parsing/slither_compilation_unit_solc.py

@@ -45,17 +45,23 @@ def _handle_import_aliases(
 
     """
     for symbol_alias in symbol_aliases:
-        if (
+        if "foreign" in symbol_alias and "local" in symbol_alias:
-            "foreign" in symbol_alias
+            if isinstance(symbol_alias["foreign"], dict) and "name" in symbol_alias["foreign"]:
-            and "name" in symbol_alias["foreign"]
+
-            and "local" in symbol_alias
-        ):
                 original_name = symbol_alias["foreign"]["name"]
                 local_name = symbol_alias["local"]
                 import_directive.renaming[local_name] = original_name
                 # Assuming that two imports cannot collide in renaming
                 scope.renaming[local_name] = original_name
 
+            # This path should only be hit for the malformed AST of solc 0.5.12 where
+            # the foreign identifier cannot be found but is required to resolve the alias.
+            # see https://github.com/crytic/slither/issues/1319
+            if symbol_alias["local"]:
+                raise SlitherException(
+                    "Cannot resolve local alias for import directive due to malformed AST. Please upgrade to solc 0.6.0 or higher."
+                )
+
 
 class SlitherCompilationUnitSolc:
     # pylint: disable=no-self-use,too-many-instance-attributes
@@ -389,7 +395,6 @@ Please rename it, this name is reserved for Slither's internals"""
                 )
             self._contracts_by_id[contract.id] = contract
             self._compilation_unit.contracts.append(contract)
-
         # Update of the inheritance
         for contract_parser in self._underlying_contract_to_parser.values():
             # remove the first elem in linearizedBaseContracts as it is the contract itself

tests/ast-parsing/complex_imports/import_aliases_issue_1319/import.sol

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

tests/ast-parsing/complex_imports/import_aliases_issue_1319/test.sol

@@ -0,0 +1,9 @@
+pragma solidity 0.5.12;
+
+import {A} from "./import.sol";
+
+contract Z is A {
+    function test() public pure returns (uint) {
+        return 1;
+    }
+}

tests/ast-parsing/complex_imports/import_aliases_issue_1319/test_fail.sol

@@ -0,0 +1,9 @@
+pragma solidity 0.5.12;
+
+import {A as X, A as Y} from "./import.sol";
+
+contract Z is X {
+    function test() public pure returns (uint) {
+        return 1;
+    }
+}