Tokenizer::$eolChar: change default value

[jrfnl]

Description

Recreation of upstream PR squizlabs/PHP_CodeSniffer#3870:

Tokenizer::$eolChar: change default value to be a more logical one. The property is supposed to be a string, so having an array as a default value is confusing.

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Additional context from the discussion on the ticket:

@fredden asked:

Should the default value be non-empty? What are your thoughts on using PHP_EOL here instead of an empty string. Or perhaps null or unset.

@jrfnl answered:

I did consider those options, but those were all rejected out of hand.

• The property is documented as a string, so the default should also be a string.
• Setting the default to null may lead to PHP 8.1 "passing null to non-nullable" deprecations in unexpected places.
• Setting the default to PHP_EOL is plain wrong as that depends on the OS on which PHPCS is run, while the property is about the EOL character of the file under scan.

Setting it to an empty string prevents any problems with a wrong value being used and still complies with the documented property type.

@jrfnl added:

In any case, the property is the first thing which will be set once the class is instantiated via the contructor, so the default value isn't even that interesting, though it should definitely not be one of an incorrect type.

Suggested changelog entry

N/A