Are you sure that the Type constraint does not add a violation?

@xabbuh it matters in what order they invoked: if Type is checked first - it would be added (I haven't checked it but I see no reason why it wouldn't).

In that case I don't think that this is a bug. If you cannot ensure that the value you check using composite constraints is a collection, I suggest to add the Type constraint as you did, but additionally make use of validation groups and a group sequence which checks types first and only executes the other checks when the type requirements are fulfilled.

@xabbuh added Type validation changes nothing - since the exception is still thrown. At the moment All validator does more job than it should have - it simply MUST NOT check for the type, it's not its responsibility.

At the moment it's impossible to validate collections with symfony validator.

I honestly cannot see what benefits that type check brings.

If you cannot ensure that the value you check using composite constraints is a collection

I surely cannot ensure (the request comes from the client and contains arbitrary data) - that's why I want to validate it, but I cannot due to a bug in the implementation.

To clarify why it's a bug:

1. If you pass an array - then validation works as expected
2. If you pass not an array (eg a number) - then the validator throws an exception (while it should return a validation violation)

The All type does not check for emptiness - it's a NotBlank validator responsibility. The same way it must not check for the type - it's a Type validator responsibility.

Right, I checked other constraints and it looks like almost every other constraint check for type. Which makes symfony/validator impossible to validate an arbitrary input. That's correct: validator must be able to validate anything, but it cannot. Correct me somebody if I wrong.

<?php

use Symfony\Component\Validator\Constraints\Email;
use Symfony\Component\Validator\Constraints\Type;
use Symfony\Component\Validator\Validation;

require __DIR__ . '/vendor/autoload.php';

$validator = Validation::createValidator();

$constraints = [
    new Type('string'),
    new Email(),
];

$violations = $validator->validate([], $constraints);

var_dump($violations);

This cannot validate an email. Expected: a violation. Actual: an exception.

What is the point to throw exceptions from a validator, while the validation result should be returned as a collection of violations instead?

Thank you all for the discussion. I am going to close here in favour of #12312.