Enum support in query type inference

[arnaud-lb]

Fixes #344

Doctrine behavior

For reference:

Selecting an enum column directly returns an enum case (an instance of the enum class).

Using an enum column in an expression returns the raw value returned by the database driver. This is consistent with other column types (e.g. using a datetime column in an expression returns a string).

phpstan-doctrine behavior

In this PR I add support for enums as described above.

Since we know all the possible values of an enum, we can refine the database column type to a union of these values.

Examples

With the following classes:

#[Entity]
class X {
    #[Column]
    public Foo $f;
}

enum Foo: string {
    case A = 'a';
    case B = 'b';
}

--  Returns results of type array{f: Foo}
SELECT x.f FROM X

-- Returns results of type array{1: 'a'|'b'|''}
SELECT COALESCE(x.f, '') FROM X

Doctrine 2.11 issues

Enum support was introduced in Doctrine 2.11, but there was issues such as doctrine/orm#9622.

Here I add support for enums as implemented in Doctrine >= 2.12.

We have multiple options to handle Doctrine 2.11:

• Do nothing: Ignore Doctrine 2.11 issues. For users with Doctrine 2.11, type inference will be lying.
• Add special cases for 2.11
• Conflict with 2.11

I chose the third option here. I think that option two would be acceptable as well, but this adds complexity just for a minor version. WDYT ?

[ondrejmirtes]

About these options:

We have multiple options to handle Doctrine 2.11:

1. Do nothing: Ignore Doctrine 2.11 issues. For users with Doctrine 2.11, type inference will be lying.
2. Add special cases for 2.11
3. Conflict with 2.11

I think option 1) is the best. Conflict is too aggressive, if the user isn't using enums at all, the conflict wouldn't make sense for them 😊 So I think we can ignore the issue, it's not our bug to fix 😊

[arnaud-lb]

File copied from https://github.com/phpstan/phpstan-src/blob/07e341daedc018cf60bd7e8827bb59ae24566bee/stubs/runtime/Enum/BackedEnum.php

[arnaud-lb]

This makes supporting PHP versions bellow 8.1 much easier

Specifically, this allows code such as these to pass analysis:

is_subclass_of($className, BackedEnum::class)

/** @return class-string<BackedEnum> */

[ondrejmirtes]

Would be nice to ignore these runtime stubs in .gitattributes :)

[arnaud-lb]

Ok, done 👍

[arnaud-lb]

Changed this data provider to yield test cases so that I could return some cases conditionally.

Best reviewed with ?w=1 :D

[arnaud-lb]

The PHP 8.1 build with lowest dependencies happens to run Doctrine 2.11

[arnaud-lb]

We need this to skip some test when running Doctrine 2.11

[ondrejmirtes]

There's now a native Composer feature for this so we don't need a package I think? https://getcomposer.org/doc/07-runtime.md

[arnaud-lb]

Great, didn't know that. I've updated the PR to use this instead.

[ondrejmirtes]

We can remove this from composer.json now? :)

[arnaud-lb]

Ah, gone too fast and forgot this. I've removed it now

[ondrejmirtes]

Otherwise 👍 :)

[ondrejmirtes]

Would be nice to ignore these runtime stubs in .gitattributes :)

[ondrejmirtes]

There's now a native Composer feature for this so we don't need a package I think? https://getcomposer.org/doc/07-runtime.md

[ondrejmirtes]

Thank you!