…anagi)This PR was merged into the 3.3-dev branch.Discussion----------[DI] Allow to count on lazy collection arguments| Q             | A| ------------- | ---| Branch?       | master| Bug fix?      | no| New feature?  | yes| BC breaks?    | no| Deprecations? | no| Tests pass?   | yes| Fixed tickets |#21450 (comment)| License       | MIT| Doc PR        | todo (withsymfony/symfony-docs#7336)When using the new iterator feature of the DI component to lazy load collection, we always know the number of arguments in the collection (only the invalidBehavior set to `IGNORE_ON_INVALID_REFERENCE` may change this number). So we are able to generate and use a `RewindableGenerator` implementing `\Countable` by computing this value ahead.So, in a service accepting `array|iterable`, like in the `GuardAuthenticationListener` (see#21450):```phpclass GuardAuthenticationListener implements ListenerInterface{    private $guardAuthenticators;    /**       *@param iterable|GuardAuthenticatorInterface[]  $guardAuthenticators   The authenticators, with keys that match what's passed to GuardAuthenticationProvider       *@param LoggerInterface                         $logger                A LoggerInterface instance    */    public function __construct($guardAuthenticators, LoggerInterface $logger = null)    {          // ...    }    public function handle(GetResponseEvent $event)    {        if (null !== $this->logger) {            $context = array()            if (is_array($this->guardAuthenticators) || $this->guardAuthenticators instanceof \Countable) {                $context['authenticators'] = count($this->guardAuthenticators);            }            $this->logger->debug('Checking for guard authentication credentials.', $context);        }        // ...    }}```we still keep the ability to call count without loosing the lazy load benefits.Commits-------f23e460 [DI] Allow to count on lazy collection arguments

…anagi)This PR was merged into the 3.3-dev branch.Discussion----------[DI] Allow to count on lazy collection arguments| Q             | A| ------------- | ---| Branch?       | master| Bug fix?      | no| New feature?  | yes| BC breaks?    | no| Deprecations? | no| Tests pass?   | yes| Fixed tickets |symfony/symfony#21450 (comment)| License       | MIT| Doc PR        | todo (withsymfony/symfony-docs#7336)When using the new iterator feature of the DI component to lazy load collection, we always know the number of arguments in the collection (only the invalidBehavior set to `IGNORE_ON_INVALID_REFERENCE` may change this number). So we are able to generate and use a `RewindableGenerator` implementing `\Countable` by computing this value ahead.So, in a service accepting `array|iterable`, like in the `GuardAuthenticationListener` (see #21450):```phpclass GuardAuthenticationListener implements ListenerInterface{    private $guardAuthenticators;    /**       *@param iterable|GuardAuthenticatorInterface[]  $guardAuthenticators   The authenticators, with keys that match what's passed to GuardAuthenticationProvider       *@param LoggerInterface                         $logger                A LoggerInterface instance    */    public function __construct($guardAuthenticators, LoggerInterface $logger = null)    {          // ...    }    public function handle(GetResponseEvent $event)    {        if (null !== $this->logger) {            $context = array()            if (is_array($this->guardAuthenticators) || $this->guardAuthenticators instanceof \Countable) {                $context['authenticators'] = count($this->guardAuthenticators);            }            $this->logger->debug('Checking for guard authentication credentials.', $context);        }        // ...    }}```we still keep the ability to call count without loosing the lazy load benefits.Commits-------f23e460 [DI] Allow to count on lazy collection arguments

…cation providers (chalasr)This PR was squashed before being merged into the 3.3-dev branch (closes#21450).Discussion----------[Security] Lazy load guard authenticators and authentication providers| Q             | A| ------------- | ---| Branch?       | master| Bug fix?      | no| New feature?  | yes| BC breaks?    | no| Deprecations? | no| Tests pass?   | yes| Fixed tickets | n/a| License       | MIT| Doc PR        | n/aAuthentication stops on the first authenticator that fails or succeeds, let's instantiate them only if actually needed.Commits-------cd6422a [SecurityBundle] Lazy load authentication providersb8a23de [Security][Guard] Lazy load authenticators