Fix a bug in class virtual method dispatch.

We don't produce LLVM arguments for 'Void' function arguments. Kind of an
annoying feature of LLVM that its not allowed to pass 'void'. In any case,
we have to be careful to filter these arguments out in all the right places.

Author: braxtonmckee

typed_python/compiler/expression_conversion_context.py

@@ -773,7 +773,9 @@ def finalize(self, expr, exceptionsTakeFrom=None):
 
     def call_function_pointer(self, funcPtr, args, returnType):
         # force arguments to a type appropriate for argpassing
-        native_args = [a.as_native_call_arg() for a in args if not a.expr_type.is_empty]
+        args = [a for a in args if not a.expr_type.is_empty]
+
+        native_args = [a.as_native_call_arg() for a in args]
 
         if returnType.is_pass_by_ref:
             nativeFunType = native_ast.Type.Function(

typed_python/compiler/tests/class_compilation_test.py

@@ -3001,3 +3001,18 @@ def loopWithHasattr(c):
         elapsedWithout = time.time() - t0
 
         assert .6 < elapsedWithout / elapsedWith < 1.4
+
+    def test_virtual_dispatch_with_none(self):
+        class C(Class):
+            def f(self, x, y):
+                return (x, y, C)
+
+        class B(C):
+            def f(self, x, y):
+                return (x, y, B)
+
+        @Entrypoint
+        def callf(c: C):
+            return c.f(1, None)
+
+        callf(B())