The never return type in PHP 8.1 indicates that a function will not return any value, such as when it throws an exception, exits the script, or runs indefinitely. 1. Use never for functions that always throw exceptions. 2. Apply it to functions that terminate execution like exit() or die(). 3. Utilize it for infinite loops such as event loops. Unlike void, which implies intentional no return value, never means the function cannot return at all. Attempting to return a value—even null—results in a compile-time error. Benefits include improved static analysis, better code clarity, and safer logic handling, especially in validation functions that halt execution on failure.

The never return type in PHP 8.1 is used to indicate that a function will never return a value — not even null. This could be because the function throws an exception, exits the script, or enters an infinite loop. It’s a way to communicate intent clearly in your code and help static analyzers catch potential bugs.

When Should You Use never?

You should use the never return type in situations where execution after the function call won't continue normally. Common cases include:

• Functions that always throw exceptions
• Functions that terminate the script (like exit() or die())
• Functions that run indefinitely (e.g., event loops or daemons)

Using never makes it clear to other developers — and tools like IDEs and static analysis — that this function doesn’t return control to the caller.

Examples:

• A utility function that throws a custom exception
• A function that validates input and throws if something's wrong
• A script bootstrapper that exits early under certain conditions

How Is It Different From void?

At first glance, never might look similar to void, but they're quite different:

• void means a function returns nothing intentionally — it just does something.
• never means the function cannot return at all because something interrupts normal flow.

For example:

function logMessage(string $message): void {
    echo $message;
}

function fail(): never {
    throw new Exception('Failure!');
}

In this case, logMessage() just does its job and returns, while fail() never gives the program a chance to continue.

One important thing: you can't return anything from a never function — not even null. If you try, PHP will throw a compile-time error.

Practical Benefits of Using never

Using never helps with better code clarity and improves tooling support:

• Static analysis: Tools like Psalm or PHPStan can catch unreachable code or invalid assumptions.
• Code readability: Other developers can immediately see that this function changes the normal flow.
• Safer logic: Helps avoid incorrect handling of return values that will never exist.

A real-world example might be validation functions that throw early:

function validateEmail(string $email): never {
    if (!filter_var($email, FILTER_VALIDATE_EMAIL)) {
        throw new InvalidArgumentException("Invalid email address.");
    }
}

This makes it clear that if the function completes, execution stops — which helps when chaining validations or building APIs with strict input checks.

That’s the basic idea behind never in PHP 8.1. It's not something you'll use every day, but when appropriate, it makes your intentions clearer and helps prevent logic errors.

The above is the detailed content of What is the never return type in PHP 8.1?. For more information, please follow other related articles on the PHP Chinese website!