widgets: check if $wp_registered_widgets[ $widget ]['id'] exists

[josephscott]

https://core.trac.wordpress.org/ticket/57518

This includes a test for this condition.

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This Pull Request is for code review only. Please keep all other discussion in the Trac ticket. Do not merge this Pull Request. See GitHub Pull Requests for Code Review in the Core Handbook for more details.

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Props josephscott, westonruter.

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[github-actions]

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[westonruter]

There's one error:

1) Tests_Widgets_WpBlockThemeRegisterClassicSidebars::test_should_reregister_previous_theme_sidebar
PHPUnit\Framework\InvalidArgumentException: Argument #1 of PHPUnit\Framework\Assert::assertArrayNotHasKey() must be an integer or string

/var/www/tests/phpunit/tests/widgets/wpBlockThemeRegisterClassicSidebar.php:54
phpvfscomposer:///var/www/vendor/phpunit/phpunit/phpunit:106
/var/www/vendor/bin/phpunit:118

[josephscott]

Thank you - I should have ran a broader set of the tests before pushing this. Updated.

[Copilot]

Pull request overview

This pull request fixes a PHP warning that occurs when is_active_widget() attempts to access the 'id' key of an unregistered widget in the $wp_registered_widgets array. The issue arises when a widget exists in sidebars_widgets but hasn't been registered yet (e.g., during early plugin/theme loading).

Changes:

• Added an isset() check before accessing $wp_registered_widgets[$widget]['id'] to prevent warnings
• Included a comprehensive test case to verify the fix handles unregistered widgets correctly
• Added defensive checks in existing sidebar tests to handle empty $wp_registered_sidebars arrays

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
src/wp-includes/widgets.php	Adds isset() check to prevent accessing array offset on null when checking widget ID
tests/phpunit/tests/widgets.php	Adds test case to verify is_active_widget() handles unregistered widgets without warnings
tests/phpunit/tests/widgets/wpBlockThemeRegisterClassicSidebar.php	Adds safety guards to register test sidebars when none exist

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[westonruter]

Confirmed that this causes a warning when the fix is not applied:

There was 1 error:

1) Tests_Widgets::test_is_active_widget_with_unregistered_widget_and_id_base_match
Undefined array key "search-2"

/var/www/src/wp-includes/widgets.php:928
/var/www/tests/phpunit/tests/widgets.php:1452

✅

[github-actions]

A commit was made that fixes the Trac ticket referenced in the description of this pull request.

SVN changeset: 61466
GitHub commit: 376539e

This PR will be closed, but please confirm the accuracy of this and reopen if there is more work to be done.