PHP 8.0 Changes

PHP 8.0 is a major compatibility boundary. Union types, attributes, named arguments, match, constructor property promotion, and the nullsafe operator are valuable, while stricter error behaviour can expose legacy assumptions.

Changes Worth Recognising

• Use union types when multiple types are genuinely part of the API.
• match uses strict comparison and does not fall through like switch.
• Named arguments couple callers to parameter names, so library maintainers must treat names carefully.
• The nullsafe operator short-circuits a read chain; it is not a replacement for validation.

Representative Code

<?php

function badge(string $status): string
{
    return match ($status) {
        'draft' => 'Needs review',
        'published' => 'Live',
        default => 'Unknown',
    };
}

echo badge('published') . PHP_EOL;

// Prints:
// Live

Upgrade Review

• Run tests for loose string-number comparisons and internal function calls.
• Review switch conversions carefully because match is strict.
• Do not adopt named arguments for unstable third-party parameter names without considering compatibility.

Treat an 8.0 migration as a tested application change, not a runtime package update.