add test

slither/core/declarations/function.py

@@ -450,17 +450,6 @@ class Function(SourceMapping, metaclass=ABCMeta):  # pylint: disable=too-many-pu
     ###################################################################################
     ###################################################################################
 
-    @property
-    def is_implemented(self) -> bool:
-        """
-        bool: True if the function is implemented
-        """
-        return self._is_implemented
-
-    @is_implemented.setter
-    def is_implemented(self, is_implemented: bool):
-        self._is_implemented = is_implemented
-
     @property
     def is_virtual(self) -> bool:
         """

slither/solc_parsing/declarations/function.py

@@ -262,7 +262,7 @@ class FunctionSolc(CallerContextExpression):
         if "overrides" in attributes and isinstance(attributes["overrides"], dict):
             for override in attributes["overrides"].get("overrides", []):
                 refId = override["referencedDeclaration"]
-                overridden_contract = self.slither_parser._contracts_by_id.get(refId, None)
+                overridden_contract = self.slither_parser.contracts_by_id.get(refId, None)
                 if overridden_contract:
                     overridden_contract.add_reference_from_raw_source(
                         override["src"], self.compilation_unit

tests/unit/core/test_data/virtual_overrides.sol

@@ -56,3 +56,10 @@ contract A2 is Test2 {
     }
 }
 
+abstract contract I {
+ function a() public virtual {}
+}
+contract J is I {}
+contract K is J {
+ function a() public override {}
+}

tests/unit/core/test_virtual_overrides.py

@@ -55,6 +55,18 @@ def test_overrides(solc_binary_path) -> None:
         ["Y.myVirtualFunction()", "X.myVirtualFunction()"]
     )
 
+    k = slither.get_contract_from_name("K")[0]
+    k_virtual_func = k.get_function_from_full_name("a()")
+    assert not k_virtual_func.is_virtual
+    assert k_virtual_func.is_override
+    assert len(k_virtual_func.overrides) == 1
+
+    i = slither.get_contract_from_name("I")[0]
+    i_virtual_func = i.get_function_from_full_name("a()")
+    assert i_virtual_func.is_virtual
+    assert not i_virtual_func.is_override
+    assert len(i_virtual_func.overrides) == 0
+    assert len(i_virtual_func.overridden_by) == 1
 
 def test_virtual_override_references_and_implementations(solc_binary_path) -> None:
     solc_path = solc_binary_path("0.8.15")