[wp-trac] [WordPress Trac] #64552: wp_trim_words fails with certain charsets in the Excerpt

[WordPress Trac]

#64552: wp_trim_words fails with certain charsets in the Excerpt
--------------------------+---------------------------------------
 Reporter:  SirLouen      |      Owner:  (none)
     Type:  defect (bug)  |     Status:  new
 Priority:  normal        |  Milestone:  7.0
Component:  Formatting    |    Version:  3.0
 Severity:  normal        |   Keywords:  needs-patch has-test-info
  Focuses:                |
--------------------------+---------------------------------------
 == Bug Report

 Following the [https://github.com/WordPress/gutenberg/pull/74925 GB74925]
 we have noticed that the excerpts were not being adapted accordingly in
 the Editor. It was also noticed that the current regex trim was not
 applying for certain more edge character types of cases like

 === Environment
 - WordPress: 7.0-alpha-61215-src
 - PHP: 8.2.29
 - Server: nginx/1.29.4
 - Database: mysqli (Server: 8.4.7 / Client: mysqlnd 8.2.29)
 - Browser: Chrome 144.0.0.0
 - OS: Windows 10/11
 - Theme: Twenty Twenty-Three 1.6
 - MU Plugins: None activated
 - Plugins:
   * Gutenberg 22.4.1

 === Testing Instructions
 1. Ideally use the 2023 theme
 2. Create a new post and add the following excerpt:

 {{{
 Fabio　vel　iudice　vincam,　sunt   in      culpa   qui　officia.
 Inmensae　subtilitatis,　obscuris　et　malesuada　fames.
 Ambitioni　dedisse　scripsisse　iudicaretur.
 Nec　dubitamus　multa　iter　quae　et　nos　invenerat.
 Petierunt　uti　sibi　concilium　totius　Galliae　in　diem　certam
 indicere.
 }}}

 3. Go to Appearance > Editor
 4. Click on the canvas
 5. Select the excerpt of the newly created Post
 6. Adjust the Excerpt Max Number of Words (you need Gutenberg trunk to
 test this; if you don't use trunk, it will not work either in the Editor).
 7. Set, for example, 30 words, and Save
 8. Go to the front end.
 9. 🐞 The number of words is not the same as in the editor.

 === Expected Behaviour
 - The number of words of the excerpt should be the same in the Editor and
 in the front end.

 === Additional Information
 Apparently, it appears that the `wp_trim_words` is not trimming all types
 of spacing characters accordingly; hence, the word count is inconsistent.
 @t-hamano proposed that the `/[\n\r\t ]+/` must be fixed for this purpose.

 It appears that this was first introduced in [13942]/#10376

-- 
Ticket URL: <https://core.trac.wordpress.org/ticket/64552>
WordPress Trac <https://core.trac.wordpress.org/>
WordPress publishing platform