improve support for enum_exists

[orklah]

This introduces:

• enum-string as an assertion
• the possibility to use enum-string as a type in phpdoc
• autoloading of enum-string used in enum_exists
• some documentation
• some fixes in callmaps and stubs

This is built upon the work of @DannyvdSluijs started here: #6431 (comment)

This should fix #6431 but I'm pretty sure there are still some support missing, it will have to be reported in the future so we can know there are issues

[DannyvdSluijs]

Given a ReflectionClass in constructed anyway why not check (in an php <= 8.1 safe way) if it is an actual enum using:

array_search ('UnitEnum', $c->getInterfaceNames(), true);

As per https://www.php.net/manual/en/class.unitenum.php all Enums implement the UnitEnum interface

[orklah]

Well, it will only work if PHP was able to autoload the file and parse it and detect it is indeed an Enum. Which mean it will only work on PHP >8.1. At this point, we might as well use enum_exists as long as we checked we're in 8.1.

Thinking about it however, I don't see a point preventing scanning of a possible class that would have been pushed in an enum_exists. Either it exists and it's useful and it will end up scanned at one point or it's useless and it's possible Psalm will actually report it unused

Anyway, the real issue is for older versions of PHP, I have no idea what will happen if we run Psalm on 8.0 and try to analyze an enum. It will probably crash? But I don't think I can prevent it

[orklah]

I'll put this in draft. I'll probably start this again from scratch on master to avoid conflicts with #7410

[DannyvdSluijs]

Hi @orklah anything I can to to assist either with this PR (#7404) or with #7410 ?
I can actually run your branch against some 8.1 code using enum on a PHP 8.0 binary to see if this would cause any issues? If there is anything else please let me know as I'm keen on getting the enum_exists feature in.

[orklah]

#7410 is a pretty complex refactoring of a pretty complex module of Psalm. That's why I don't want to get in the way because I can't wait to see it happen :)

This PR in comparison is simple and I'm not worried I'll be able to do it again quickly once #4710 is merged. You should be able to test Psalm with this PR if you want, it should work OK and if you detect bugs, I can fix them.

This will be added to Psalm 5 that should came out in a few weeks

[orklah]

This is not blocked anymore, I'll work on it tomorrow :)

[orklah]

@DannyvdSluijs it should be ok on master now

[DannyvdSluijs]

I've checked it and it seems to be working very nicely, thanks for your efforts.

To summarise the results:
Running ./vendor/bin/psalm --php-version=8.1 --no-cache with PHP 7.4 results in a No errors found!
Leaving off the --php-version argument will target PHP 7.4 and returns the following errors (as part of the regular output.)

Target PHP version: 7.4 (inferred from current PHP version)
Scanning files...
Analyzing files...

EE

ERROR: ParseError - src/SomeEnum.php:8:6 - Syntax error, unexpected T_STRING on line 8 (see https://psalm.dev/173)
enum SomeEnum


ERROR: UndefinedFunction - src/Test.php:13:13 - Function enum_exists does not exist (see https://psalm.dev/021)
        if (\enum_exists(SomeEnum::class)) {


ERROR: UndefinedClass - src/Test.php:13:26 - Class, interface or enum named Dannyvandersluijs\Test\SomeEnum does not exist (see https://psalm.dev/019)
        if (\enum_exists(SomeEnum::class)) {


ERROR: UndefinedClass - src/Test.php:14:13 - Class, interface or enum named Dannyvandersluijs\Test\SomeEnum does not exist (see https://psalm.dev/019)
            SomeEnum::cases();


------------------------------
4 errors found
------------------------------

Checks took 2.35 seconds and used 42.146MB of memory
Psalm was unable to infer types in the codebase

[orklah]

the ParserError comes from our dependency (PHP-Parser) when it encounters a syntax it doesn't recognize for a given php version.

The rest of the errors is the effect of the first because Psalm couldn't see there is an enum here.

Those errors are indeed expected to happen on 7.4 :)

Great to know it works for you!