Enforce restriction: no HPy call for legacy type with inherited struct

Author: fangerer

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/objects/cext/hpy/GraalHPyNodes.java

@@ -1299,6 +1299,9 @@ static Object doIt(GraalHPyContext context, PythonClass enclosingType, Object sl
                 if (enclosingType.getItemSize() > 0) {
                     throw raiseNode.raise(TypeError, ErrorMessages.HPY_CANNOT_USE_CALL_WITH_VAR_OBJECTS);
                 }
+                if (enclosingType.getBuiltinShape() == GraalHPyDef.HPyType_BUILTIN_SHAPE_LEGACY && enclosingType.getBasicSize() == 0) {
+                    throw raiseNode.raise(TypeError, ErrorMessages.HPY_CANNOT_USE_CALL_WITH_LEGACY);
+                }
                 enclosingType.setHPyDefaultCallFunc(slotData.impl());
             }
             return property;

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/nodes/ErrorMessages.java

@@ -1483,6 +1483,8 @@ public abstract class ErrorMessages {
     public static final TruffleString HPY_CANNOT_USE_CALL_WITH_VAR_OBJECTS = tsLiteral("Cannot use HPy call protocol with var objects");
     public static final TruffleString HPY_CANNOT_HAVE_CALL_AND_VECTORCALLOFFSET = tsLiteral("Cannot have HPy_tp_call and explicit member '__vectorcalloffset__'. Specify just one of them.");
     public static final TruffleString HPY_CANNOT_SPECIFY_LEG_SLOTS_WO_SETTING_LEG = tsLiteral("cannot specify .legacy_slots without setting .builtin_shape=HPyType_BuiltinShape_Legacy");
+    public static final TruffleString HPY_CANNOT_USE_CALL_WITH_LEGACY = tsLiteral("Cannot use HPy call protocol with legacy types that inherit the struct. " +
+                    "Either set the basicsize to a non-zero value or use legacy slot 'Py_tp_call'.");
 
     // AST Validator
     public static final TruffleString ANN_ASSIGN_WITH_SIMPLE_NON_NAME_TARGET = tsLiteral("AnnAssign with simple non-Name target");