Why does Yii render "<?php" into every backend controller output? - php

Question

Reproduceable problem
In 2.0.3 "advanced" (Yii offers basic and advanced setup of a project) create an empty controller in the backend, like
public function actionTest()
{
}
and call it in the browser. You'll see an empty page. When looking at the source code, you'll see a lonely php tag.
<?php
This looks like a bug to me, as it does not happen in the frontend folder, just in backend folder. This is critical when you render out CSV files or so, it will break the file.
I'm unsure if this is a bug on my side or a real bug inside the framework.

Answer 1

This is a bug in Yii 2.0.3!
... caused by a lower-level and not-so-obvious whitespace problem in naked PHP files.
Tickets & more information:
https://github.com/githubjeka/yii2-rest/issues/3
https://github.com/yiisoft/yii2-app-advanced/issues/24
http://php.net/manual/en/language.basic-syntax.phptags.php#116883
How to fix this:
The problem in a nutshell: A PHP tag is <?php[whitespace character], not just <?php. Holy! Totally makes sense, but let's be honest, who would have known this instantly ?
Yii 2.x uses (in the advanced demo application) the "empty" file config/bootstrap.php, just containing a php tag <?php WITHOUT a whitespace directly after. When bootstrap.php is now loaded via index.php it is loaded as a text file containing <?php, not parsed as a PHP file.
You can fix this by simply added a whitespace directly after the tag.