Handling arrays in PHP 8

Aside from improvements in performance, the two main changes in PHP 8 array handling pertain to the handling of negative offsets and curly brace ({}) usage. Since both of these changes could result in application code breaks following a PHP 8 migration, it's important to cover them here. Awareness of the issues presented here gives you a better chance to get broken code working again in short order.

Let's have a look at negative array offset handling first.

Dealing with negative offsets

When assigning a value to an array in PHP, if you do not specify an index, PHP will automatically assign one for you. The index chosen in this manner is an integer that represents a value one higher than the highest currently assigned integer key. If no integer index key has yet been assigned, the automatic index assignment algorithm starts at zero.

In PHP 7 and below, however, this algorithm is not applied consistently in the case of a negative integer...