framework: Queueing email fails with PHP 7.3: Class setQueue does not exist

• Laravel Version: 5.7.17
• PHP Version: 7.3
• Database Driver & Version: MySQL 5.7

Description:

When using Laravel with PHP 7.3, you get an error when queueing emails. I’m using a Redis queue for this. With PHP 7.2 everything works fine.

Steps To Reproduce:

I get an error on the line:

Mail::to($user->email)->send(new FooMail($user));

where Mail is Illuminate\Support\Facades\Mail

the class FooMail:

use Illuminate\Bus\Queueable;
use Illuminate\Mail\Mailable;
use Illuminate\Queue\SerializesModels;
use Illuminate\Contracts\Queue\ShouldQueue;

class FooMail extends Mailable implements ShouldQueue
{
    use Queueable, SerializesModels;
    public function build() {
      return $this->view('emails.foo')->subject(...)->replyTo(...)->with([...]);
    }
}

My config:

MAIL_DRIVER=smtp
MAIL_HOST=email_host
MAIL_PORT=25
MAIL_USERNAME=username
MAIL_PASSWORD=secret
MAIL_ENCRYPTION=tls
MAIL_FROM_NAME='Foo Bar'

CACHE_DRIVER=redis
QUEUE_CONNECTION=redis
SESSION_DRIVER=redis

REDIS_HOST=redis-master
REDIS_PASSWORD=null
REDIS_PORT=6379
REDIS_QUEUE=default

Furthermore I’m using phpredis as the client, not predis.

When I send an email I get the following error:

[2018-12-12 19:05:17] local.ERROR: Class setQueue does not exist {"exception":"[object] (ReflectionException(code: -1): Class setQueue does not exist at /Users/thom/Sites/fooProject/vendor/laravel/framework/src/Illuminate/Container/Container.php:779)
[stacktrace]
#0 /Users/thom/Sites/fooProject/vendor/laravel/framework/src/Illuminate/Container/Container.php(779): ReflectionClass->__construct('setQueue')
#1 /Users/thom/Sites/fooProject/vendor/laravel/framework/src/Illuminate/Container/Container.php(658): Illuminate\\Container\\Container->build('setQueue')
#2 /Users/thom/Sites/fooProject/vendor/laravel/framework/src/Illuminate/Container/Container.php(609): Illuminate\\Container\\Container->resolve('setQueue', Array)
#3 /Users/thom/Sites/fooProject/vendor/laravel/framework/src/Illuminate/Foundation/Application.php(733): Illuminate\\Container\\Container->make('setQueue', Array)
#4 /Users/thom/Sites/fooProject/vendor/laravel/framework/src/Illuminate/Container/Container.php(1222): Illuminate\\Foundation\\Application->make('setQueue')
#5 /Users/thom/Sites/fooProject/vendor/laravel/framework/src/Illuminate/Mail/MailServiceProvider.php(52): Illuminate\\Container\\Container->offsetGet('setQueue')
#6 /Users/thom/Sites/fooProject/vendor/laravel/framework/src/Illuminate/Container/Container.php(776): Illuminate\\Mail\\MailServiceProvider->Illuminate\\Mail\\{closure}(Object(Illuminate\\Foundation\\Application), Array)
#7 /Users/thom/Sites/fooProject/vendor/laravel/framework/src/Illuminate/Container/Container.php(658): Illuminate\\Container\\Container->build(Object(Closure))
#8 /Users/thom/Sites/fooProject/vendor/laravel/framework/src/Illuminate/Container/Container.php(609): Illuminate\\Container\\Container->resolve('mailer', Array)
#9 /Users/thom/Sites/fooProject/vendor/laravel/framework/src/Illuminate/Foundation/Application.php(733): Illuminate\\Container\\Container->make('mailer', Array)
#10 /Users/thom/Sites/fooProject/vendor/laravel/framework/src/Illuminate/Container/Container.php(1222): Illuminate\\Foundation\\Application->make('mailer')
#11 /Users/thom/Sites/fooProject/vendor/laravel/framework/src/Illuminate/Support/Facades/Facade.php(161): Illuminate\\Container\\Container->offsetGet('mailer')
#12 /Users/thom/Sites/fooProject/vendor/laravel/framework/src/Illuminate/Support/Facades/Facade.php(130): Illuminate\\Support\\Facades\\Facade::resolveFacadeInstance('mailer')
#13 /Users/thom/Sites/fooProject/vendor/laravel/framework/src/Illuminate/Support/Facades/Facade.php(217): Illuminate\\Support\\Facades\\Facade::getFacadeRoot()
#14 /Users/thom/Sites/fooProject/app/Observers/FooObserver.php(189): Illuminate\\Support\\Facades\\Facade::__callStatic('to', Array)
#15 /Users/thom/Sites/fooProject/app/Observers/FooObserver.php(132): App\\Observers\\CommentObserver->sendFooEmails(Object(App\\Foo), Object(Illuminate\\Database\\Eloquent\\Collection))

When I use PHP 7.2 instead of PHP 7.3 then, without changing anything else, it works fine and it sends the email without errors.