[Console] StringInput removes backslashes from a normal string

[seriquynh]

Symfony version(s) affected: 2.8+

Description
StringInput removes backslashes from a normal string.

For example:

1. I pass the php string "search SomeNamesapce\SomeClass" to the StringInput constructor.
2. In StringInput::tokenize() method, "SomeNamesapce\SomeClass" matches StringInput::REGEX_STRING, so it is passed into stripcslashes function.
3. Finally, I got "SomeNamespaceSomeClass".

symfony/src/Symfony/Component/Console/Input/StringInput.php

Line 60 in 5aa0967

} elseif (preg_match('/'.self::REGEX_STRING.'/A', $input, $match, null, $cursor)) {

How to reproduce
Create an index.php file with the code below.

<?php

use Symfony\Component\Console\Input\StringInput;

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

$input = new StringInput('search SomeNamesapce\SomeClass');
echo $input->__toString(), PHP_EOL;
// Expected: "search SomeNamespace\SomeClass"
// Actual: "search SomeNamespaceSomeClass"

$input = new StringInput('search SomeNamesapce\\SomeClass');
echo $input->__toString(), PHP_EOL;
// Expected: "search SomeNamespace\SomeClass"
// Actual: "search SomeNamespaceSomeClass"

$input = new StringInput('search SomeNamesapce\\\SomeClass');
echo $input->__toString(), PHP_EOL;
// Expected: "search SomeNamespace\\SomeClass"
// Actual: "search SomeNamespace\SomeClass"

$input = new StringInput('search SomeNamesapce\\\\SomeClass');
echo $input->__toString(), PHP_EOL; // "search SomeNamespace\SomeClass"
// Expected: "search SomeNamespace\\SomeClass"
// Actual: "search SomeNamespace\SomeClass"

$input = new StringInput('search SomeNamesapce\\\\\SomeClass');
echo $input->__toString(), PHP_EOL;
// Expected: "search SomeNamespace\\\SomeClass"
// Actual: "search SomeNamespace\SomeClass"

Possible Solution
I am not sure that it is a bug because I couldn't find any relevant issues.
Is it an expected behavior?

Additional context
This is the result when running "php index.php"

$ php index.php
search SomeNamesapceSomeClass
search SomeNamesapceSomeClass
search 'SomeNamesapce\SomeClass'
search 'SomeNamesapce\SomeClass'
search 'SomeNamesapce\SomeClass'

[seriquynh]

There is seem no issue with this behavior.