PHP8 specific removed create_function error

[mglaman]

Part of phpstan/phpstan#5368

This handles an improved error message when running on PHP8 to explain why the function no longer exists.

[ondrejmirtes]

We already have that: https://github.com/JetBrains/phpstorm-stubs/blob/5cae90f74aa33a4cdbeb4da654525fe665e735c9/Core/Core.php#L755-L768

PHPStan should currently read the @removed annotation That's done here: https://github.com/ondrejmirtes/BetterReflection/blob/348a8777d11b9dd88f13e0d99a84d1671a8cf8a7/src/SourceLocator/SourceStubber/PhpStormStubsSourceStubber.php#L410-L417

But it's probably skipped or unused for functions. It works for classes+methods because RuntimeReflectionProvider is skipped in here:

phpstan-src/src/Reflection/ReflectionProvider/ClassBlacklistReflectionProvider.php

Lines 78 to 82 in cacc8bb

	if ($this->phpStormStubsSourceStubber->hasClass($className)) {
	// check that userland class isn't aliased to the same name as a class from stubs
	if (!class_exists($className, false)) {
	return true;
	}

But RuntimeReflectionProvider isn't skipped for functions:

phpstan-src/src/Reflection/ReflectionProvider/ClassBlacklistReflectionProvider.php

Lines 129 to 146 in cacc8bb

	public function hasFunction(\PhpParser\Node\Name $nameNode, ?Scope $scope): bool
	{
	$has = $this->reflectionProvider->hasFunction($nameNode, $scope);
	if (!$has) {
	return false;
	}
	if ($this->singleReflectionInsteadOfFile === null) {
	return true;
	}
	$functionReflection = $this->reflectionProvider->getFunction($nameNode, $scope);
	if (!$functionReflection instanceof ReflectionWithFilename) {
	return true;
	}
	return $functionReflection->getFileName() !== $this->singleReflectionInsteadOfFile;
	}

Try to prototype some code in the last location to see if you get anywhere and the function is detected as removed.

You could try to check PhpStormStubsSourceStubber::isPresentFunction() === false which should say that the function no longer exists on PHP 8 and skip in that case.

[ondrejmirtes]

Oh, I haven't noticed this is actually already reported on PHP 8: https://phpstan.org/r/7b7db20f-8b1d-411d-9d9e-41dbec9bae4d

So all of my advice here is actually outdated, it already works. So I don't think it's worth doing a special message about this in PHPStan - the fact that the function does not exist is correct and it's up to the user to educate themselves about it. I understand why you'd want a special message here, but I don't think that widening the scope of this tool is worth it - it would take too much effort to explain everything like this when PHP manual does already a good job at this.

[ondrejmirtes]

And the reason why this works is this line in RuntimeReflectionProvider:

phpstan-src/src/Reflection/Runtime/RuntimeReflectionProvider.php

Lines 314 to 316 in 1501229

	if ($this->phpStormStubsSourceStubber->isPresentFunction($name) === false) {
	return false;
	}

[mglaman]

+1 to closing this. Fixing phpstan/phpstan#5373 and getting core functions to report deprecation is a better step.