https://chrastecky.dev/programming/new-in-php-8-5-closures-as-constant-expressions
New in PHP 8.5: Closures as Constant Expressions | Blog by Dominik Chrástecký
Another exciting PHP 8.5 feature: Closures can now be used as constant expressions, allowing them to appear as default parameters or attribute values.
new inconstant expressionsphpclosuresblog
https://cppreference.com/w/cpp/language/constant_expression.html
Constant expressions - cppreference.com
constant expressions