Hi, has there been some work on this? I assume it means there would be a phpstan.xml file support?

I changed my mind, I no longer want to use XML for this. Currently the configuration format is really easy and can be written by hand. Behold: https://github.com/nunomaduro/skeleton-php/blob/master/phpstan.neon.dist

But from this PoV, XML is a nightmare. Proper XML configuration file would need begin with something like this:

<?xml version="1.0" encoding="UTF-8"?>
<phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:noNamespaceSchemaLocation="vendor/phpunit/phpunit/phpunit.xsd"
...

I understand NEON format is a bit exotic, but in practice there are rarely any problems with it. If I needed to change the format today, I'd switch to PHP, which would at least offer autocomplete in IDEs out of the box. But there's no pressure, and there's many more interesting priorities to work on.

It would be nice to have the configuration in PHP. 😉

I can appreciate this reasoning. Would it be difficult to at least support yaml which is both popular and well supported, especially with IDE integrations, and very close to neon syntactically?

Even phpunit.xml is starting to feel like an outlier at this point in time. When you integrate a dozen tools, the most popular formats are yaml, json, then become project specific, if its is a PHP project, some .php configuration, JS project, some JS files, python .py, so and so forth.

Would a PR be welcomed?

Personally, I'd prefer yaml over PHP, it really does feel like the language of project level configuration. My 2c.

YAML is very close to NEON indeed, but I don't think we need to support yet another very similar configuration format. I think it'd work very well if you persuaded your IDE to highlight NEON as YAML out of the box. For PhpStorm there's also NEON plugin.