wp_get_canonical_url always returns false for attachments

[othernoel]

The code for wp_get_canonical_url makes this check

if ( 'publish' !== $post->post_status ) {
  return false;
}

When $post is an attachment, post_status is likely 'inherit' and never 'publish', meaning this check always fails.

Consequently, if attachments have their own pages, those pages don't get a rel="canonical" printed in wp_head, and the 'get_canonical_url' filter is never called for attachment pages. Is this intended behavior?

I'd assume get_post_status() to be the correct function here, as it resolves 'inherit' in attachments returning the parent post's status?

I haven't seen this documented anywhere, so I'm not sure if this way for backwards compatibility or an actual bug.

#63041

## Description

This PR fixes an issue where wp_get_canonical_url() always returns false for attachments.

### Issue
Attachments have a post status of 'inherit' rather than 'publish'. The wp_get_canonical_url() function was directly checking $post->post_status === 'publish', causing it to always return false for attachments.

### Fix
This PR changes the condition to use get_post_status($post) instead of directly accessing $post->post_status. The get_post_status() function properly handles the 'inherit' status for attachments by checking their parent post's status.

## Combined Test Report and Unit Tests Patch
### Description
This report validates that the indicated patch works as expected.

Patch tested: ​https://github.com/WordPress/wordpress-develop/pull/8435.diff

### Environment

• WordPress: 6.8-beta3-60042-src
• PHP: 8.2.28
• Server: nginx/1.27.4
• Database: mysqli (Server: 8.4.4 / Client: mysqlnd 8.2.28)
• Browser: Chrome 134.0.0.0
• OS: Windows 10/11
• Theme: My Twenty Twenty Child Theme 1.0
• MU Plugins: None activated
• Plugins:
  • Test Reports 1.2.0

### Testing Instructions without the Patch

1. Enable wp_attachment_pages_enabledin the wp_options table (change 0 to 1)
2. Upload an image to Media > Add Media File
3. Click on Edit and then click on the Media Permalink
4. Check the source code for a canonical tag.

### Expected result
The canonical tag is in the code

### Results without the Patch

1. 🐞 Bug occurs.

### Results with the Patch

1. ✅ Issue resolved with patch.

### Additional Notes
I have also sorted all the PHPCS issues in the wpGetCanonicalUrl.php file (only missing comments)

Props to ​@Infinite-Null for the patch ​https://github.com/WordPress/wordpress-develop/pull/8435
Also Props to ​@othernoel who clearly hinted the patch solution in the report.

Trac ticket: https://core.trac.wordpress.org/ticket/63041

[SirLouen]

@SergeyBiryukov now this report is 100% complete and pretty simple and straightforward.
I think it can even make to 6.8.

[audrasjb]

It's too late for 6.8, we are at the RC step of the cycle.
Self assigning for final review and commit.

[audrasjb]

In 60108:

Canonical: Use get_post_status() to determine whether the post has a publish post status in wp_get_canonical_url().

This changeset fixes an issue where wp_get_canonical_url() always returned false for attachments. Attachments have a inherit post status rather than publish. The wp_get_canonical_url() function was directly checking $post->post_status === 'publish', causing it to always return false for attachments. Using get_post_status() fixes the issue as if the post is an attachment, then the parent post status will be given instead.

Follow-up to [37685].

Props othernoel, ankitkumarshah, SirLouen,
Fixes #63041.

[audrasjb]

In 60109:

Docs: Remove an unwanted trailing space found after [60108].

Follow-up to [60108].

See #63041, #63166.