Metadata field type validation against Entity property type does not detect nullability

[AlexMinaev19]

Bug Report

In feature request there was added an ability to validate field type against Entity property type.

Schema validation tool does not detect mapping problems when a typed property of the entity defined as nullable, but there is no nullable: true in the column metadata definition.

Q	A
BC Break	no
Version	2.19.7

Summary

For example, we have the following entity:

class User
{
    // ...

    #[ORM\Column(type: Types::STRING, length: 64)]
    private ?string $name;

    // ...
}

Schema validation tool should report, that mapping is invalid due to property is type string|null, but metadata mapping expecting string due to nullable named property of ORM\Column is false by default. The error should gone when manually will be specified nullable: true of ORM\Column.

Current behavior

There are no errors for provided example class, but should be.

How to reproduce

Create entity:

namespace App\Entity;

use Doctrine\DBAL\Types\Types;
use Doctrine\ORM\Mapping as ORM;

#[ORM\Entity]
#[ORM\Table('user')]
class User
{
    #[ORM\Column(type: Types::STRING, length: 64)]
    private ?string $name;

    public function __construct(?string $name)
    {
         $this->name = $name;
    }

    public function getName(): ?string
    {
         return $this->name;
    }
}

Create migration based on this entity. The table definition in migration will have a non-nullable column name. After that, please go ahead and execute this migration. And then run orm:validate-schema.

Expected behavior

The command should report mapping error:

Mapping
-------

 [FAIL] The entity-class App\Entity\User mapping is invalid:
 * The field 'App\Entity\User#name' has the property type 'string|null' that differs from the metadata field type 'string' returned by the 'string' DBAL type.