script-loader 'colors' src true invalid argument

[kkmuffme]

​https://github.com/WordPress/wordpress-develop/blob/trunk/src/wp-includes/script-loader.php#L1587

<?php
$styles->add( 'colors', true, array( 'wp-admin', 'buttons' ) );

true is not a valid 2nd argument for add, string|false expected.

Trac ticket: https://core.trac.wordpress.org/ticket/63043

[abcd95]

Thank you for reporting this issue.

After testing, I found that changing true to false or an empty string breaks the admin color scheme functionality.

Upon closer inspection of wp_style_loader_src(), it appears the current implementation expects $src to be a truthy value for the 'colors' handle to properly process it through parse_url(). ​See this

While technically true doesn't match the expected string|false type, it's a historical implementation detail that's working in practice. I think it's best to document this behavior rather than change it for backward compatibility.

Follow-up:

After further testing, I found that we can use any non-falsy string instead of true while maintaining the admin color scheme functionality. The wp_style_loader_src() function only needs a truthy value to process.

This opens up an opportunity to use a more descriptive string that both satisfies type requirements and documents the intent. Options could include 'placeholder', 'dynamic-color-scheme', or even just '#'.

This is open for discussion and I'd appreciate any appropriate placeholder suggestion for this.