yes would be a shorter and more elegant solution

    nl2br($str, false, true);

nice and clean..

In my eyes this is an unnecessary change. nl2br handles the common case, where you want to have linebreaks displayed and have the code nicely formatted at the same time. This is what nl2br does and I don't think it need to do any more.

I don't see why we should add support for incorrect usages of the function inside <pre>. And in any case, if you should have need for this (for whatever odd reason), then it is trivial to write yourself. Quite honestly I think that preg_replace('#([\r?\n]+)#', '<br>', $string) is a good bit clearer than nl2br($string, false, true). That's just too many unclear boolean parameters.

Nikic, 2 booleans parameters for you are "too many unclear boolean parameters"
LOL...

As additional note..
If I can have linebreaks and nicely formated text in just one function, why don't do'it ?
I don't think is such a big deal, or should change the name to something like "addbr2nl", it will be more "correct"..

The bigger issue here is how you'd reverse the process. Without knowing that the function just adds instead of replacing, one would try the following:

function br2nl($string, $is_xhtml = TRUE)
{
    return str_replace(
        $is_xhtml ? '<br />' : '<br>',
        PHP_EOL
    );
}

The problem is that this would result in doubling the newline characters.

Like Nikita, I don't see the point here. Within a <pre> you don't need to use nl2br(). Outside of a <pre>, you need to use nl2br(). Either way, the new-lines will be kept and your source code will be readable.

The only argument for this would be efficiency. But it's not a massive saving, it's 20% off... but only for line endings.

For the reason stated before, I'm closing this. There's little worth in adding this, nor is it likely to ever happen.