Use null coalescing operator instead of isset() in if/else statements

[westonruter]

Search: \bif\s*\(\s*isset\(\s*(\$.+?)\s*\)\s*\)\s*\{\s*(\$.+?)\s*=\s*\1;\s*\}\s*else\s*\{\s*\2\s*=\s*(\S*?);\s*}

Replace: $2 = $1 ?? $3;

Trac ticket: https://core.trac.wordpress.org/ticket/58874

---

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.

[github-actions]

The following accounts have interacted with this PR and/or linked issues. I will continue to update these lists as activity occurs. You can also manually ask me to refresh this list by adding the props-bot label.

Core Committers: Use this line as a base for the props when committing in SVN:

Props westonruter.

To understand the WordPress project's expectations around crediting contributors, please review the Contributor Attribution page in the Core Handbook.

[github-actions]

Test using WordPress Playground

The changes in this pull request can previewed and tested using a WordPress Playground instance.

WordPress Playground is an experimental project that creates a full WordPress instance entirely within the browser.

Some things to be aware of

• The Plugin and Theme Directories cannot be accessed within Playground.
• All changes will be lost when closing a tab with a Playground instance.
• All changes will be lost when refreshing the page.
• A fresh instance is created each time the link below is clicked.
• Every time this pull request is updated, a new ZIP file containing all changes is created. If changes are not reflected in the Playground instance,
  it's possible that the most recent build failed, or has not completed. Check the list of workflow runs to be sure.

For more details about these limitations and more, check out the Limitations page in the WordPress Playground documentation.

Test this pull request with WordPress Playground.

[Copilot]

Pull request overview

This pull request modernizes WordPress code by replacing traditional isset() checks with the null coalescing operator (??), making the code more concise and readable while maintaining identical behavior.

Changes:

• Replaced if (isset($var)) { $result = $var; } else { $result = $default; } patterns with $result = $var ?? $default;
• Applied this refactoring consistently across 15 files in both wp-includes and wp-admin directories
• Maintained existing code alignment and formatting conventions

Reviewed changes

Copilot reviewed 15 out of 15 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
src/wp-includes/theme.php	Simplified array key check for attachment_parent in header images
src/wp-includes/rest-api/class-wp-rest-server.php	Simplified $_SERVER['PATH_INFO'] check in request handling
src/wp-includes/meta.php	Simplified array key check for meta cache retrieval
src/wp-includes/media.php	Simplified decoding attribute check for image optimization
src/wp-includes/general-template.php	Simplified object property check for post type description
src/wp-includes/class-wp-xmlrpc-server.php	Simplified array key check for comment status in XML-RPC
src/wp-includes/class-wp-styles.php	Simplified object property check for media type
src/wp-includes/class-wp-post-type.php	Simplified array key check for permalink endpoint mask
src/wp-includes/class-wp-http-streams.php	Simplified Host header check in HTTP streams
src/wp-includes/class-wp-date-query.php	Simplified array key check for date query parameters
src/wp-admin/upgrade.php	Simplified $_GET['step'] check in upgrade process
src/wp-admin/includes/theme.php	Simplified nested array key check for theme features
src/wp-admin/includes/template.php	Simplified $_REQUEST['post_status'] check for post states
src/wp-admin/includes/post.php	Simplified array key check for post ID
src/wp-admin/includes/class-wp-importer.php	Simplified array key check for CLI argument parsing

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[westonruter]

Committed in r61463.