'.��.' === wp_scrub_utf8( ".\xC1\xBF." );         // Overlong sequence.
	 *     '.���.' === wp_scrub_utf8( ".\xED\xA0\x80." );    // Surrogate half.
	 *
	 * Note! The Unicode Replacement Character is itself a Unicode character (U+FFFD).
	 * Once a span of invalid bytes has been replaced by one, it will not be possible
	 * to know whether the replacement character was originally intended to be there
	 * or if it is the result of scrubbing bytes. It is ideal to leave replacement for
	 * display only, but some contexts (e.g. generating XML or passing data into a
	 * large language model) require valid input strings.
	 *
	 * @since 6.9.0
	 *
	 * @see https://www.unicode.org/versions/Unicode16.0.0/core-spec/chapter-5/#G40630
	 *
	 * @param string $text String which is assumed to be UTF-8 but may contain invalid sequences of bytes.
	 * @return string Input text with invalid sequences of bytes replaced with the Unicode replacement character.
	 */
	function wp_scrub_utf8( $text ) {
		/*
		 * While it looks like setting the substitute character could fail,
		 * the internal PHP code will never fail when provided a valid
		 * code point as a number. In this case, there’s no need to check
		 * its return value to see if it succeeded.
		 */
		$prev_replacement_character = mb_substitute_character();
		mb_substitute_character( 0xFFFD );
		$scrubbed = mb_scrub( $text, 'UTF-8' );
		mb_substitute_character( $prev_replacement_character );

		return $scrubbed;
	}
else :
	/**
	 * Fallback function for scrubbing UTF-8.
	 *
	 * @ignore
	 * @private
	 *
	 * @since 6.9.0
	 */
	function wp_scrub_utf8( $text ) {
		return _wp_scrub_utf8_fallback( $text );
	}
endif;

if ( _wp_can_use_pcre_u() ) :
	/**
	 * Returns whether the given string contains Unicode noncharacters.
	 *
	 * XML recommends against using noncharacters and HTML forbids their
	 * use in attribute names. Unicode recommends that they not be used
	 * in open exchange of data.
	 *
	 * Noncharacters are code points within the following ranges:
	 *  - U+FDD0–U+FDEF
	 *  - U+FFFE–U+FFFF
	 *  - U+1FFFE, U+1FFFF, U+2FFFE, U+2FFFF, …, U+10FFFE, U+10FFFF
	 *
	 * @see https://www.unicode.org/versions/Unicode17.0.0/core-spec/chapter-23/#G12612
	 * @see https://www.w3.org/TR/xml/#charsets
	 * @see https://html.spec.whatwg.org/#attributes-2
	 *
	 * @since 6.9.0
	 *
	 * @param string $text Are there noncharacters in this string?
	 * @return bool Whether noncharacters were found in the string.
	 */
	function wp_has_noncharacters( string $text ): bool {
		return 1 === preg_match(
			'/[\x{FDD0}-\x{FDEF}\x{FFFE}\x{FFFF}\x{1FFFE}\x{1FFFF}\x{2FFFE}\x{2FFFF}\x{3FFFE}\x{3FFFF}\x{4FFFE}\x{4FFFF}\x{5FFFE}\x{5FFFF}\x{6FFFE}\x{6FFFF}\x{7FFFE}\x{7FFFF}\x{8FFFE}\x{8FFFF}\x{9FFFE}\x{9FFFF}\x{AFFFE}\x{AFFFF}\x{BFFFE}\x{BFFFF}\x{CFFFE}\x{CFFFF}\x{DFFFE}\x{DFFFF}\x{EFFFE}\x{EFFFF}\x{FFFFE}\x{FFFFF}\x{10FFFE}\x{10FFFF}]/u',
			$text
		);
	}
else :
	/**
	 * Fallback function for detecting noncharacters in a text.
	 *
	 * @ignore
	 * @private
	 *
	 * @since 6.9.0
	 */
	function wp_has_noncharacters( string $text ): bool {
		return _wp_has_noncharacters_fallback( $text );
	}
endif;