Do not make it fail when args is empty. Rather return unresolvable in that case.

PiperOrigin-RevId: 763867054

Author: h-joo

pytype/overlays/fiddle_overlay.py

@@ -167,6 +167,9 @@ def new_slot(
       self, node, unused_cls, *args, **kwargs
   ) -> tuple[Node, "cfg.Variable"]:
     """Create a Config or Partial instance from args."""
+    # pass
+    if not args:
+      return node, self.ctx.new_unsolvable(node)
 
     underlying = args[0].data[0]
     self._check_init_args(node, underlying, args, kwargs)

pytype/tests/test_fiddle_overlay.py

@@ -665,6 +665,19 @@ def f() -> fiddle.Config[Simple]:
           return fiddle.Config(Simple, 1)
       """)
 
+  def test_no_crash_on_empty_args(self):
+    # pass
+    with self.DepTree([("fiddle.pyi", _FIDDLE_PYI)]):
+      self.Check("""
+        from typing import cast, Any
+        import fiddle
+
+        def foo(*args):
+          return
+
+        fiddle.Config(foo, *[1, 2], 3)
+      """)
+
 
 if __name__ == "__main__":
   test_base.main()