Looks good now, thanks. Some more edge cases (e.g. regular whitespaces) could be added for tests, but not sure how strict are they here yet

Thanks for the review @Destroy666x.

Would it make sense to update other constraint validators too?

Hey guys, how do you like this PR right now?

@renan-taranto For consistency, I would add this option to the other string constraints too.

Hello,

for me as a developer using symfony the normalizer option is a little bit confusing. I am referring to the naming of it. Maybe it's because in the syfmony world when I hear normalizer my mind goes to the Serializer component. So in the end when I saw the title of this PR I was expecting to see about an option that will be able to convert objects into strings and remove this code:

       if (!is_scalar($value) && !(\is_object($value) && method_exists($value, '__toString'))) {

I am not sure if the same confusion will be caused later for whatever reason. Therefore my suggestion would be formatter. Or simple trim and allowing this option to be either true or callable and if it is true just use plain trim. It's just a suggestion your call :)

You can pass even callable which makes input pass the above check, it's your choice. Hence formatter is not good name.

PR updated. AppVeyor broke due to the unrelated Symfony\Component\Process\Tests\ProcessTest.

Hi @nicolas-grekas, is there anything else I can do for this PR?

Thank you @renan-taranto.