How to Use PHP's Never Return Type

Table Of Contents

• The Solution
• Why This Works

The Solution

Here's how to use the never return type for functions that never return to the caller:

<?php

function terminateApplication(string $message): never {
    echo "Critical error: " . $message;
    exit(1);
}

function redirectAndExit(string $url): never {
    header("Location: " . $url);
    exit();
}

function throwException(string $error): never {
    throw new RuntimeException($error);
}

// Usage examples
if ($criticalError) {
    terminateApplication("Database connection failed");
    // This line is never reached
}

if (!$user->isAuthorized()) {
    redirectAndExit("/login");
    // Code after this is unreachable
}

try {
    validateInput($data);
} catch (Exception $e) {
    throwException("Validation failed: " . $e->getMessage());
}

Why This Works

The never return type serves as a contract that tells PHP and other developers:

1. Function Never Returns: The function will always terminate execution through exit(), die(), or throwing an exception
2. Static Analysis: Tools can detect unreachable code after these function calls
3. Type Safety: PHP enforces that functions declared with never must actually never return

Common Use Cases:

• Functions that call exit() or die()
• Functions that always throw exceptions
• Functions that redirect and terminate
• Error handlers that stop execution

The never type makes your code's intent crystal clear and helps prevent bugs from unreachable code assumptions.