In fact, there is no problem in even terminating the last element in an array with a comma (and it's the code style used in Symfony). Are you sure that the syntax error was caused by this code?

@xabbuh While you are correct that there is no problem in terminating the last element in an array with a comma, this is not the case here.

The comma is in the wrong place for it to be in the array. See that it is following a curly brace} and not a bracket)

@PhilETaylor the problem is that this example is a bit complex and the comma looks wrong and out of place ... but I think it's technically correct. If we remove the entire function contents, it looks like this:

publicfunctionconfigureOptions(OptionsResolver$resolver){$resolver->setDefaults(array('validation_groups' =>function (FormInterface$form) {... },    ));}

In any case, maybe here we shouldn't add the trailing comma. We generally do that, but we don't always do that. For example, some examples in this page:https://github.com/symfony/symfony-docs/blob/master/service_container.rst contain arrays but they don't include the trailing comma.

In short: even if the current example is technically correct, maybe removing the trailing comma makes it easier to understand it.

indeed you are right, now that I put the code in my ide it's a lot clearer and the PHP syntax is correct, still, best to remove it by merging this anyway like you said :)

I would rather update the other examples to include the trailing comma. We decided that we follow the Symfony Coding Guidelines a couple years ago. Adding the trailing comma for array items is one of the rules in there.

So a 👎 from me. (but this of course doesn't mean I hate your PR, thanks for taking the time to improve the docs!)

Closing as we all agree here that should not be changed. Thanks@rouenollivier for trying to improve the docs :).