[wp-trac] [WordPress Trac] #31328: Emoji in a slug fails to display

[WordPress Trac]

#31328: Emoji in a slug fails to display
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 Reporter:  kraftbj           |       Owner:  pento
     Type:  defect (bug)      |      Status:  reopened
 Priority:  normal            |   Milestone:  4.2
Component:  Formatting        |     Version:  trunk
 Severity:  normal            |  Resolution:
 Keywords:  has-patch commit  |     Focuses:  administration
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Comment (by pento):

 [attachment:31328.6.diff] doesn't re-break this ticket, so no complaints
 from me.

 For reference, the specific problem caused by #17689 was:

 * Start with no emoji terms
 * Create a term as a single emoji character, note that the slug correctly
 uses the character
 * Create a second term with a different emoji character, the slug
 incorrectly uses the character from the first term

 This is reproducible for any two terms containing the same number of emoji
 characters (as opposed to glyphs).

 This is because we were searching for duplicates by term name. All
 `utf8mb4_*` collations (prior to `utf8mb4_unicode_520_ci`) treat emoji as
 being equivalent characters, so would just match the first one found. Now
 that we're searching for duplicates by term term slug, this is no longer a
 problem. Term slugs store the URL-encoded version of the emoji character,
 which the `utf8mb4_` collations correctly interpret as a string of ASCII
 text.

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Ticket URL: <https://core.trac.wordpress.org/ticket/31328#comment:20>
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