#15893·OpenTTD

[Bug]: AI: Function::acall() does not work on some functions

Author: yangflCreated Jul 22, 2026Updated Sep 9, 2026

Version of OpenTTD

15.3

Expected result

fn.acall([this, ...]) == fn(...)

Actual result

You are not allowed to execute any DoCommand (even indirect) in your constructor, Save(), Load(), and any valuator.

Steps to reproduce

{
  local test_mode = AITestMode();
  local accounting = AIAccounting();
  AIVehicle.BuildVehicle(depot, engine);
  AILog.Info(accounting.GetCosts());  // ok
}

function GetCosts(fn, args) {
  local test_mode = AITestMode();
  local accounting = AIAccounting();
  fn.acall(args);
  return accounting.GetCosts();
}
AILog.Info(GetCosts(AIVehicle.BuildVehicle, [this, depot, engine]));  // error

Source: OpenTTD/OpenTTD

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