Make sure $label_markup is always defined.

[SergeyBiryukov]

Fixes #16188.

Description

Since $label_markup in render_block_core_search() is defined conditionally, it causes a PHP notice if there's no label provided.

Making sure that the variable is always defined fixes the issue.

Screenshots

Types of changes

Bug fix (non-breaking change which fixes an issue)

Checklist:

• My code is tested.
• My code follows the WordPress code style.
• My code follows the accessibility standards.
• My code has proper inline documentation.
• I've included developer documentation if appropriate.

[gziolo]

Thanks for fixing 👍

[afercia]

It's important to note that the search input field should always be labelled.

WordPress aims to produce semantic, web standards compliant, and accessible markup in the front end. This block should make sure there's a label. If developers want to visually hide the label (which is not recommended), then there should be an option or a fallback to a visually hidden label (with screen-reader-text).

Input fields can be labelled in a few ways:

• recommended: with a visible <label> element associated with for/id attributes, according to the WordPress accessibility coding standards
• with an aria-label attribute set on the input field
• with an aria-labelledby attribute referencing some existing, visible, text in the page

Seems to me the simpler, and more standard, option is the first one. A simple fallback could be:

• when the label is empty, fallback to a default label Search
• add the screen-reader-text CSS class to the label element
• document somewhere that a label is required and, if desired, developers can visually hide the label but that's not recommended 🙂