Re: [VOTE] noreturn type

On 01.04.21 10:56, Benjamin Eberlei wrote:

This RFC is using the declaration of the return type, to specify that it never returns. As such noreturn or never is a keyword a long the lines of public or final, but it is not a return type. I don't think the argument for potential optimizations in Opcache to eliminate dead code or allow IDEs to hint at dead code are valuable enough to justify this change.

I already use @return no-return (supported by Psalm/PHPStan) in my code now, to clarify the code flow, and for me it fits perfectly for return types, as not returning is also a result of the function/method. Having a return type of "int" or "string" (or even "void") seems misleading when the method will never return anyway. noreturn/never might not be useful in all code, but for some parts like in a controller of a web application it makes handling redirects, authorization or 404 errors much easier, clearer and less error-prone, for example:

if (!isset($user)) {
  $this->notFound(); // this is a noreturn/never method
}

if (!$this->isGranted('adminPrivileges')) {
  $this->notAuthorized(); // this is a noreturn/never method
}

Adding noreturn/never on a language level would make sure calling "$this->notAuthorized();" never continues code flow. This is often also a security issue, as seen by an alternative way of handling the above use cases:

if (!isset($user)) {
  $this->notFound();
  return;
}

if (!$this->isGranted('adminPrivileges')) {
  $this->notAuthorized();
  return;
}

If you forget a return, suddenly you have issues. So even though noreturn/never is a niche language feature not everyone will use, it does address a very real use case. Using attributes has the disadvantage of not making the intent clear:

#[\NoReturn]
function notAuthorized(): string
{
  // Some code
}

Now you have a return type of string, but also the information that the function will never return anyway. That is confusing, but will be inevitable in some cases when implementing interfaces or an abstract class. In my opinion, the string return type is wrong in this case and can only mislead a developer.