Wouldn't a dynamic return type extension be better for this?

Thank you, but yes, dynamic return type extension would be better so that the user doesn't have to check against values that cannot occur in their situation :)

@spaze I'm sure you won't have any problems writing one as you've already written some custom PHPStan rules :) Here are some pointers:

* Basic info: https://phpstan.org/developing-extensions/dynamic-return-type-extensions

• This is a similar extension that also reads various constants (although it's probably much more complicated than one needed for preg_split: https://github.com/phpstan/phpstan-src/blob/master/src/Type/Php/FilterVarDynamicReturnTypeExtension.php
• This is a useful method:

  phpstan-src/src/Type/Php/FilterVarDynamicReturnTypeExtension.php

  Lines 75 to 84 in 4f152b2

  	private function getConstant(string $constantName): int
  	{
  	$constant = $this->reflectionProvider->getConstant(new Node\Name($constantName), null);
  	$valueType = $constant->getValueType();
  	if (!$valueType instanceof ConstantIntegerType) {
  	throw new \PHPStan\ShouldNotHappenException(sprintf('Constant %s does not have integer type.', $constantName));
  	}
  	return $valueType->getValue();
  	}

  (feel free to copy it to your extension as well)
• I'm not sure if preg_split flags can be combined using bitwise operators, if yes then the extension has to account for it.
• Test the implementation by adding a new data provider to NodeScopeResolverTest::testFileAsserts, call assertType in the test file and test various inputs :)

Thanks, I've vaguely remembered there was a better way of doing things like this but...

I've now changed this PR to use a dynamic type extension for that.

And thanks @ondrejmirtes for those hints, helped a lot!

Perfect, thank you :)

Thanks for the release @ondrejmirtes! :-)