How can PHP developers ensure that their code continues to work as intended with the changes in PHP 8 regarding warnings and deprecated features?

PHP developers can ensure that their code continues to work as intended with the changes in PHP 8 regarding warnings and deprecated features by updating their code to remove any deprecated functions or features, handling warnings appropriately, and using strict typing where necessary. They can also make use of tools like PHP_CodeSniffer to identify and fix any issues in their code.

// Example code snippet with strict typing and handling of warnings
declare(strict_types=1);

// Handle warnings as exceptions
set_error_handler(function ($errno, $errstr, $errfile, $errline) {
    throw new ErrorException($errstr, 0, $errno, $errfile, $errline);
});

// Deprecated function call
$deprecatedVar = $_GET['deprecated_var'] ?? '';

// Use strict typing for function parameters
function sum(int $a, int $b): int {
    return $a + $b;
}

// Call the function with strict typing
$result = sum(5, 10);
echo $result;