[Firehed]

I've never once had the impression that nl2br did anything more than make whitespace significant in an HTML document. Even during my first days of using PHP... I don't think there's anything in the documentation or even trivially basic experimentation that could reasonably lead someone to believe that.

Plus the actual HTML-escaping tools (htmlspecialchars, htmlentities) do not make whitespace significant.

Though these days, you might arguably be better off with "white-space: pre-line" in CSS instead.

[pornel]

It does less than making HTML whitespace-significant. It's unsuitable for use on HTML markup, because newlines in <script>, inside tags, attributes, comments, etc. should not be changed.

It's only safe and reliable as a part of nl2br(htmlspecialchars()) combo, so a function that does both could have been a better idea.