Provide return type of ReflectionParameter::getType()

[dbrekelmans]

Fixes #5258

Thanks to @orklah for giving me some hints 👍

[weirdan]

@dbrekelmans mind fixing CS (https://circleci.com/gh/vimeo/psalm/22383)?

Tests failures are unrelated, fixed in #5335

[muglug]

First, thanks for this!

I think I prefer the option you presented in the original issue, following this recent dictum.

Given that ReflectionParameter is an immutable class the assertion would be entirely safe — though it requires a bugfix for Psalm to allow this specific syntax, which I'm working on now.

<?php

/**
 * @immutable
 */
class ReflectionParameter {
  /**
   * @psalm-assert-if-true $this->getType() ReflectionType
   * @psalm-assert-if-false $this->getType() null
   */
  public function hasType() : bool {
      return true;
  }
    
  public function getType() : ?ReflectionType {
   	return null;   
  }
}

The PR is not for nought, as I'll re-use your tests.

[orklah]

@muglug I'm kinda lost
The else part seems to correctly infer that the type is null: https://psalm.dev/r/82732b730e

However, there is no assert-if-false in the stub like in your example above:
https://github.com/vimeo/psalm/blob/master/stubs/Reflection.phpstub#L108

How does that works then?

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/82732b730e

<?php
    $method = new ReflectionMethod(stdClass::class);
    $parameters = $method->getParameters();
    foreach ($parameters as $parameter) {
        if ($parameter->hasType()) {
            $parameter->getType()->__toString();
        }
        else{
            $parameter->getType()->__toString();
        }
    }

Psalm output (using commit 65f0fb0):

ERROR: NullReference - 9:36 - Cannot call method __toString on null value

[weirdan]

How does that works then?

I mentioned it here: #5248 (comment)
Looks like a bug to me.