Add descriptor for AsciiStringType

extension.neon

@@ -278,6 +278,9 @@ services:
 	-
 		class: PHPStan\Type\Doctrine\Descriptors\ArrayType
 		tags: [phpstan.doctrine.typeDescriptor]
+	-
+		class: PHPStan\Type\Doctrine\Descriptors\AsciiStringType
+		tags: [phpstan.doctrine.typeDescriptor]
 	-
 		class: PHPStan\Type\Doctrine\Descriptors\BigIntType
 		tags: [phpstan.doctrine.typeDescriptor]

src/Type/Doctrine/Descriptors/AsciiStringType.php

@@ -0,0 +1,31 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Type\Doctrine\Descriptors;
+
+use PHPStan\Type\StringType;
+use PHPStan\Type\Type;
+
+class AsciiStringType implements DoctrineTypeDescriptor
+{
+
+	public function getType(): string
+	{
+		return \Doctrine\DBAL\Types\AsciiStringType::class;
+	}
+
+	public function getWritableToPropertyType(): Type
+	{
+		return new StringType();
+	}
+
+	public function getWritableToDatabaseType(): Type
+	{
+		return new StringType();
+	}
+
+	public function getDatabaseInternalType(): Type
+	{
+		return new StringType();
+	}
+
+}