Add getLastModified() to extensions

[GromNaN]

Give to extensions the ability to set a last modification date for cache invalidation.

Runtime

Currently, the cache is not invalidated when the signature of a runtime method is modified. This is an issue for templates that use named arguments, as argument names have an impact on the generated class.

With this change, extensions using runtime classes can compute a modification date by including the files on which they depend.

By default, the AbstractExtension checks if there is a file for the runtime class with the same name of the extension suffixed by Runtime instead of Extension.
This is the convention applied in Symfony and Twig Extra: MarkdownExtension has MarkdownRuntime.

Attribute

Contributing to #3916.

The extension class that will get the configuration from attributes will be able to track the classes having attributes to find the last modification date of all this classes.

BC break

In Twig 4.0, the method getLastModified will be added to ExtensionInterface. It is extremely rare to implement this interface without extending AbstractExtension. So adding this method to the interface shouldn't be a problem as the base class has an implementation.

[smnandre]

Do we need to add it to the interface ? Could we not simply ignore extensions not implementing this interface ?

[GromNaN]

Is it a thing to implement the interface without extending the abstract class? Adding this method should not be an issue for the large majority of projects, but it helps keeping the code simple.

[smnandre]

Well this may break external extensions in prod ... but you're right:

• there is some time before 4.0
• no one is forced to upgrade day one
• and .... yes in the vast majority i guess AbstractExtension is behind :)

[fabpot]

Is it a thing to implement the interface without extending the abstract class? Adding this method should not be an issue for the large majority of projects, but it helps keeping the code simple.

"large majority" is not enough when talking about BC breaks :)

Let's add a proper interface as this is a new capability (we've done it in the past with ExistsLoaderInterface for instance).

[GromNaN]

Let's add a proper interface as this is a new capability

Ok, interface added.

I'll also add automatic detection of Runtime classes to make it automatically work with Symfony TwigBridge extensions.

[fabpot]

@GromNaN LGMT, can you add a note in the CHANGELOG (you will need to rebase as I've just bump the version to 3.19.0)?

[GromNaN]

Rebased, squashed, changelog updated.

[fabpot]

Thank you @GromNaN.