Add ResultInterface template

[bram123]

Q	A
Documentation	no
Bugfix	no
BC Break	maybe
New Feature	no
RFC	yes
QA	no

Add ResultInterface template for the data field, for strict typing in the Check classes.

Started with DiskFree and DiskUsage checks.

• Changed the data value/structure so it's visible what kind of data is returned as well

If acceptable I will continue with the other checks.

Signed-off-by: Bram Leeda bram@123inkt.nl

[bram123]

Had to add @template to all Result implementation classes (success/warning/skip/failure) and all interfaces.
For some reason psalm did not let me set the @return docblock to ResultInterface, I had to set it to Success|Warning|Failure

[Ocramius]

I think CheckInterface should specify the psalm template here: not each concrete implementation.

Declaring an @template TResult of Failure|Success|Warning on the interface should highlight the missing @template-implements in each implementation of CheckInterface, and then we can remove all manual @return declarations on each of the check() methods.

WDYT?

[bram123]

@Ocramius
That means that other code repositories with custom implementations of the interface, would also have failing psalm/phpstan checks after updating right?
It would be the better solution yes, and mean that all new checks would also set this up.
If the static-analysis issue is okay (don't know if it falls under a bc break, as the code api doesnt change) I will change this :)

[Ocramius]

Yes, they would get a failure during analysis, but we don't really consider those BC breaks: the code works as it did before, and the types are just more precise.

[bram123]

@Ocramius
Did a small test, and the current psalm version (4.30) does not error when I add a template to CheckInterface. Updating locally to psalm 5.6 does trigger MissingTemplateParam errors, but I see that update is being worked on in #62

[Ocramius]

I would leave #62 alone for now :)

As for the patch: please rebase, instead of merging upstream.