Fonts API: Replace _doing_it_wrong() with wp_trigger_error() in WP_Font_Face

[NoumaanAhamed]

Summary

Replaces four instances of _doing_it_wrong() with wp_trigger_error() in WP_Font_Face::validate_font_face_declarations().

Root Cause / Context

In src/wp-includes/fonts/class-wp-font-face.php, _doing_it_wrong() is currently used to trigger notices when invalid font face properties are encountered (e.g., missing or invalid font-family, src, or font-weight).

Above each of these occurrences is an inline comment:
// @todo replace with wp_trigger_error().

wp_trigger_error() was introduced in WordPress 6.4.0 (the same version WP_Font_Face was introduced). The new function is the modernized, preferred API for triggering developer notices in core. However, the initial @todo comments remained unresolved.

Solution

• Replaced the four _doing_it_wrong() calls with wp_trigger_error() inside the WP_Font_Face::validate_font_face_declarations() method.
• Removed the inline // @todo replace with wp_trigger_error(). comments.
• Omitted the 3rd argument since wp_trigger_error() defaults to E_USER_NOTICE, which accurately mirrors the exact error level behavior previously provided by _doing_it_wrong().

Testing

1. Set up a local WordPress dev environment (e.g. using wp-env, Local, or Docker).
2. Enable WP_DEBUG in your wp-config.php:

   define( 'WP_DEBUG', true );

3. Trigger an invalid font face declaration by adding this code snippet to a mu-plugins file or your theme's functions.php:

   add_action( 'init', function() {
       $font_face = new WP_Font_Face();
       
       // Pass an array of arrays to trigger the validation
       $font_face->generate_and_print( array(
           array(
               array(
                   'font-family' => '', 
                   'src'         => ''
               )
           )
       ) );
   } );

4. Verify the PHP Notice:
   Load any page on the frontend or backend. You should see a standard PHP notice generated by wp_trigger_error() in your debug.log:
   Notice: WP_Font_Face::validate_font_face_declarations(): Font font-family must be a non-empty string.
   The behavior should match exactly how it functioned prior to the patch, just utilizing the modern Core API.
5. Run the PHPUnit tests for the class:

   npm run test:php -- --filter WP_Font_Face

---

Trac Ticket: https://core.trac.wordpress.org/ticket/65475

---

Test Case	Expected / Result	Status
validate_font_face_declarations with invalid properties	Triggers standard notice via wp_trigger_error() rather than _doing_it_wrong()	✅ Passed
PHPUnit tests for WP_Font_Face	All tests pass successfully	✅ Passed
PHPCS Linting (composer lint src/wp-includes/fonts/class-wp-font-face.php)	No syntax or coding standards errors	✅ Passed

Use of AI Tools:

None Used

[github-actions]

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[github-actions]

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[westonruter]

Thank you for the PR. Please update the description to include the missing AI disclosure.