PHP 8.1: Passing null to non-nullable parameters of built-in functions is deprecated

[selfsimilar]

• Laravel Version: 9.3..1
• PHP Version: 8.1.x
• Database Driver & Version:

Description:

See Migrating from PHP 8.0.x to PHP 8.1.x - Deprecated Features

A PHP warning is emitted when trim() is passed a null. trim() is used extensively throughout the framework,
but specifically in src/Illuminate/View/Compilers/Concerns/CompilesStacks.php the framework sets $id to null
as part of default behavior when processing a standard Blade pushOnce directive. There may be other instances
in the framework where this happens, but I have only triggered this particular instance.

Steps To Reproduce:

This was discovered by running tlint in a repository where the pushOnce directive was used.

Recommendation

Replace null with the empty string '' when setting a default 'empty' value that will be passed on to trim().

[selfsimilar]

Apparently a lot of the string functions, not just trim() have more strongly-typed parameters now. It's probably a decision better made by the maintainers whether to fix everything in on big PR (probably just casting with (string) before parameter # 1 is sufficient where appropriate), or to spread the fixes over many PRs in more easily reasoned-about chunks.

[selfsimilar]

@tristanh00 PHP has done type juggling for decades, and according to the PHP string docs on casting:

null is always converted to an empty string

[selfsimilar]

As a follow-up thought, this deprecation seems like an indication that PHP is becoming more strongly typed, and it's likely worth having a long think about whether or not casting null values will be enough in the long-term. There's probably a good case to be made that adding type declarations wherever possible (function arguments, return values, class properties) should be a part of the fix, in order to better align with the direction that PHP is headed. There's probably a lot of other things I'm not considering here in terms of knock-on effects of a stronger type system or a move away from ad hoc type juggling.

[driesvints]

A PR was sent in for this, thanks.