From: jenkins-bot <jenkins-bot@gerrit.wikimedia.org>
Date: Sun, 3 Apr 2016 10:01:14 +0000 (+0000)
Subject: Merge "Remove used of deprecated MemCachedClientforWiki"
X-Git-Tag: 1.31.0-rc.0~7390
X-Git-Url: http://git.heureux-cyclage.org/?a=commitdiff_plain;h=c99397d8145d20fc36e44fdfbc79a4882eea7c8b;hp=77adf7534b9251e8973a18ff6c848fd0d8318df1;p=lhc%2Fweb%2Fwiklou.git

Merge "Remove used of deprecated MemCachedClientforWiki"
---

diff --git a/autoload.php b/autoload.php
index fd4f873d41..df87d98d9f 100644
--- a/autoload.php
+++ b/autoload.php
@@ -240,9 +240,9 @@ $wgAutoloadLocalClasses = [
 	'CliInstaller' => __DIR__ . '/includes/installer/CliInstaller.php',
 	'CloneDatabase' => __DIR__ . '/includes/db/CloneDatabase.php',
 	'CodeContentHandler' => __DIR__ . '/includes/content/CodeContentHandler.php',
-	'Collation' => __DIR__ . '/includes/Collation.php',
-	'CollationCkb' => __DIR__ . '/includes/Collation.php',
-	'CollationEt' => __DIR__ . '/includes/Collation.php',
+	'Collation' => __DIR__ . '/includes/collation/Collation.php',
+	'CollationCkb' => __DIR__ . '/includes/collation/CollationCkb.php',
+	'CollationEt' => __DIR__ . '/includes/collation/CollationEt.php',
 	'CommandLineInc' => __DIR__ . '/maintenance/commandLine.inc',
 	'CommandLineInstaller' => __DIR__ . '/maintenance/install.php',
 	'CompareParserCache' => __DIR__ . '/maintenance/compareParserCache.php',
@@ -398,7 +398,7 @@ $wgAutoloadLocalClasses = [
 	'EventRelayer' => __DIR__ . '/includes/libs/eventrelayer/EventRelayer.php',
 	'EventRelayerGroup' => __DIR__ . '/includes/EventRelayerGroup.php',
 	'EventRelayerMCRD' => __DIR__ . '/includes/libs/eventrelayer/EventRelayerMCRD.php',
-	'EventRelayerNull' => __DIR__ . '/includes/libs/eventrelayer/EventRelayer.php',
+	'EventRelayerNull' => __DIR__ . '/includes/libs/eventrelayer/EventRelayerNull.php',
 	'Exif' => __DIR__ . '/includes/media/Exif.php',
 	'ExifBitmapHandler' => __DIR__ . '/includes/media/ExifBitmap.php',
 	'ExplodeIterator' => __DIR__ . '/includes/libs/ExplodeIterator.php',
@@ -564,8 +564,8 @@ $wgAutoloadLocalClasses = [
 	'IPSet' => __DIR__ . '/includes/compat/IPSetCompat.php',
 	'IPTC' => __DIR__ . '/includes/media/IPTC.php',
 	'IRCColourfulRCFeedFormatter' => __DIR__ . '/includes/rcfeed/IRCColourfulRCFeedFormatter.php',
-	'IcuCollation' => __DIR__ . '/includes/Collation.php',
-	'IdentityCollation' => __DIR__ . '/includes/Collation.php',
+	'IcuCollation' => __DIR__ . '/includes/collation/IcuCollation.php',
+	'IdentityCollation' => __DIR__ . '/includes/collation/IdentityCollation.php',
 	'ImageBuilder' => __DIR__ . '/maintenance/rebuildImages.php',
 	'ImageCleanup' => __DIR__ . '/maintenance/cleanupImages.php',
 	'ImageGallery' => __DIR__ . '/includes/gallery/TraditionalImageGallery.php',
@@ -1375,7 +1375,7 @@ $wgAutoloadLocalClasses = [
 	'UploadStashNotLoggedInException' => __DIR__ . '/includes/upload/UploadStash.php',
 	'UploadStashWrongOwnerException' => __DIR__ . '/includes/upload/UploadStash.php',
 	'UploadStashZeroLengthFileException' => __DIR__ . '/includes/upload/UploadStash.php',
-	'UppercaseCollation' => __DIR__ . '/includes/Collation.php',
+	'UppercaseCollation' => __DIR__ . '/includes/collation/UppercaseCollation.php',
 	'UsageException' => __DIR__ . '/includes/api/ApiMain.php',
 	'User' => __DIR__ . '/includes/user/User.php',
 	'UserArray' => __DIR__ . '/includes/user/UserArray.php',
diff --git a/includes/Collation.php b/includes/Collation.php
deleted file mode 100644
index 7a3623d7d7..0000000000
--- a/includes/Collation.php
+++ /dev/null
@@ -1,648 +0,0 @@
-<?php
-/**
- * Database row sorting.
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License along
- * with this program; if not, write to the Free Software Foundation, Inc.,
- * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
- * http://www.gnu.org/copyleft/gpl.html
- *
- * @file
- */
-
-abstract class Collation {
-	private static $instance;
-
-	/**
-	 * @return Collation
-	 */
-	static function singleton() {
-		if ( !self::$instance ) {
-			global $wgCategoryCollation;
-			self::$instance = self::factory( $wgCategoryCollation );
-		}
-		return self::$instance;
-	}
-
-	/**
-	 * @throws MWException
-	 * @param string $collationName
-	 * @return Collation
-	 */
-	static function factory( $collationName ) {
-		switch ( $collationName ) {
-			case 'uppercase':
-				return new UppercaseCollation;
-			case 'identity':
-				return new IdentityCollation;
-			case 'uca-default':
-				return new IcuCollation( 'root' );
-			case 'xx-uca-ckb':
-				return new CollationCkb;
-			case 'xx-uca-et':
-				return new CollationEt;
-			default:
-				$match = [];
-				if ( preg_match( '/^uca-([a-z@=-]+)$/', $collationName, $match ) ) {
-					return new IcuCollation( $match[1] );
-				}
-
-				# Provide a mechanism for extensions to hook in.
-				$collationObject = null;
-				Hooks::run( 'Collation::factory', [ $collationName, &$collationObject ] );
-
-				if ( $collationObject instanceof Collation ) {
-					return $collationObject;
-				}
-
-				// If all else fails...
-				throw new MWException( __METHOD__ . ": unknown collation type \"$collationName\"" );
-		}
-	}
-
-	/**
-	 * Given a string, convert it to a (hopefully short) key that can be used
-	 * for efficient sorting.  A binary sort according to the sortkeys
-	 * corresponds to a logical sort of the corresponding strings.  Current
-	 * code expects that a line feed character should sort before all others, but
-	 * has no other particular expectations (and that one can be changed if
-	 * necessary).
-	 *
-	 * @param string $string UTF-8 string
-	 * @return string Binary sortkey
-	 */
-	abstract function getSortKey( $string );
-
-	/**
-	 * Given a string, return the logical "first letter" to be used for
-	 * grouping on category pages and so on.  This has to be coordinated
-	 * carefully with convertToSortkey(), or else the sorted list might jump
-	 * back and forth between the same "initial letters" or other pathological
-	 * behavior.  For instance, if you just return the first character, but "a"
-	 * sorts the same as "A" based on getSortKey(), then you might get a
-	 * list like
-	 *
-	 * == A ==
-	 * * [[Aardvark]]
-	 *
-	 * == a ==
-	 * * [[antelope]]
-	 *
-	 * == A ==
-	 * * [[Ape]]
-	 *
-	 * etc., assuming for the sake of argument that $wgCapitalLinks is false.
-	 *
-	 * @param string $string UTF-8 string
-	 * @return string UTF-8 string corresponding to the first letter of input
-	 */
-	abstract function getFirstLetter( $string );
-}
-
-class UppercaseCollation extends Collation {
-	private $lang;
-
-	function __construct() {
-		// Get a language object so that we can use the generic UTF-8 uppercase
-		// function there
-		$this->lang = Language::factory( 'en' );
-	}
-
-	function getSortKey( $string ) {
-		return $this->lang->uc( $string );
-	}
-
-	function getFirstLetter( $string ) {
-		if ( $string[0] == "\0" ) {
-			$string = substr( $string, 1 );
-		}
-		return $this->lang->ucfirst( $this->lang->firstChar( $string ) );
-	}
-}
-
-/**
- * Collation class that's essentially a no-op.
- *
- * Does sorting based on binary value of the string.
- * Like how things were pre 1.17.
- */
-class IdentityCollation extends Collation {
-
-	function getSortKey( $string ) {
-		return $string;
-	}
-
-	function getFirstLetter( $string ) {
-		global $wgContLang;
-		// Copied from UppercaseCollation.
-		// I'm kind of unclear on when this could happen...
-		if ( $string[0] == "\0" ) {
-			$string = substr( $string, 1 );
-		}
-		return $wgContLang->firstChar( $string );
-	}
-}
-
-class IcuCollation extends Collation {
-	const FIRST_LETTER_VERSION = 2;
-
-	/** @var Collator */
-	private $primaryCollator;
-
-	/** @var Collator */
-	private $mainCollator;
-
-	/** @var string */
-	private $locale;
-
-	/** @var Language */
-	protected $digitTransformLanguage;
-
-	/** @var array */
-	private $firstLetterData;
-
-	/**
-	 * Unified CJK blocks.
-	 *
-	 * The same definition of a CJK block must be used for both Collation and
-	 * generateCollationData.php. These blocks are omitted from the first
-	 * letter data, as an optimisation measure and because the default UCA table
-	 * is pretty useless for sorting Chinese text anyway. Japanese and Korean
-	 * blocks are not included here, because they are smaller and more useful.
-	 */
-	private static $cjkBlocks = [
-		[ 0x2E80, 0x2EFF ], // CJK Radicals Supplement
-		[ 0x2F00, 0x2FDF ], // Kangxi Radicals
-		[ 0x2FF0, 0x2FFF ], // Ideographic Description Characters
-		[ 0x3000, 0x303F ], // CJK Symbols and Punctuation
-		[ 0x31C0, 0x31EF ], // CJK Strokes
-		[ 0x3200, 0x32FF ], // Enclosed CJK Letters and Months
-		[ 0x3300, 0x33FF ], // CJK Compatibility
-		[ 0x3400, 0x4DBF ], // CJK Unified Ideographs Extension A
-		[ 0x4E00, 0x9FFF ], // CJK Unified Ideographs
-		[ 0xF900, 0xFAFF ], // CJK Compatibility Ideographs
-		[ 0xFE30, 0xFE4F ], // CJK Compatibility Forms
-		[ 0x20000, 0x2A6DF ], // CJK Unified Ideographs Extension B
-		[ 0x2A700, 0x2B73F ], // CJK Unified Ideographs Extension C
-		[ 0x2B740, 0x2B81F ], // CJK Unified Ideographs Extension D
-		[ 0x2F800, 0x2FA1F ], // CJK Compatibility Ideographs Supplement
-	];
-
-	/**
-	 * Additional characters (or character groups) to be considered separate
-	 * letters for given languages, or to be removed from the list of such
-	 * letters (denoted by keys starting with '-').
-	 *
-	 * These are additions to (or subtractions from) the data stored in the
-	 * first-letters-root.ser file (which among others includes full basic latin,
-	 * cyrillic and greek alphabets).
-	 *
-	 * "Separate letter" is a letter that would have a separate heading/section
-	 * for it in a dictionary or a phone book in this language. This data isn't
-	 * used for sorting (the ICU library handles that), only for deciding which
-	 * characters (or character groups) to use as headings.
-	 *
-	 * Initially generated based on the primary level of Unicode collation
-	 * tailorings available at http://developer.mimer.com/charts/tailorings.htm ,
-	 * later modified.
-	 *
-	 * Empty arrays are intended; this signifies that the data for the language is
-	 * available and that there are, in fact, no additional letters to consider.
-	 */
-	private static $tailoringFirstLetters = [
-		// Verified by native speakers
-		'be' => [ "Ё" ],
-		'be-tarask' => [ "Ё" ],
-		'cy' => [ "Ch", "Dd", "Ff", "Ng", "Ll", "Ph", "Rh", "Th" ],
-		'en' => [],
-		'fa' => [ "آ", "ء", "ه" ],
-		'fi' => [ "Å", "Ä", "Ö" ],
-		'fr' => [],
-		'hu' => [ "Cs", "Dz", "Dzs", "Gy", "Ly", "Ny", "Ö", "Sz", "Ty", "Ü", "Zs" ],
-		'is' => [ "Á", "Ð", "É", "Í", "Ó", "Ú", "Ý", "Þ", "Æ", "Ö", "Å" ],
-		'it' => [],
-		'lv' => [ "Č", "Ģ", "Ķ", "Ļ", "Ņ", "Š", "Ž" ],
-		'pl' => [ "Ą", "Ć", "Ę", "Ł", "Ń", "Ó", "Ś", "Ź", "Ż" ],
-		'pt' => [],
-		'ru' => [],
-		'sv' => [ "Å", "Ä", "Ö" ],
-		'sv@collation=standard' => [ "Å", "Ä", "Ö" ],
-		'uk' => [ "Ґ", "Ь" ],
-		'vi' => [ "Ă", "Â", "Đ", "Ê", "Ô", "Ơ", "Ư" ],
-		// Not verified, but likely correct
-		'af' => [],
-		'ast' => [ "Ch", "Ll", "Ñ" ],
-		'az' => [ "Ç", "Ə", "Ğ", "İ", "Ö", "Ş", "Ü" ],
-		'bg' => [],
-		'br' => [ "Ch", "C'h" ],
-		'bs' => [ "Č", "Ć", "Dž", "Đ", "Lj", "Nj", "Š", "Ž" ],
-		'ca' => [],
-		'co' => [],
-		'cs' => [ "Č", "Ch", "Ř", "Š", "Ž" ],
-		'da' => [ "Æ", "Ø", "Å" ],
-		'de' => [],
-		'dsb' => [ "Č", "Ć", "Dź", "Ě", "Ch", "Ł", "Ń", "Ŕ", "Š", "Ś", "Ž", "Ź" ],
-		'el' => [],
-		'eo' => [ "Ĉ", "Ĝ", "Ĥ", "Ĵ", "Ŝ", "Ŭ" ],
-		'es' => [ "Ñ" ],
-		'et' => [ "Š", "Ž", "Õ", "Ä", "Ö", "Ü", "W" ], // added W for CollationEt (xx-uca-et)
-		'eu' => [ "Ñ" ],
-		'fo' => [ "Á", "Ð", "Í", "Ó", "Ú", "Ý", "Æ", "Ø", "Å" ],
-		'fur' => [ "À", "Á", "Â", "È", "Ì", "Ò", "Ù" ],
-		'fy' => [],
-		'ga' => [],
-		'gd' => [],
-		'gl' => [ "Ch", "Ll", "Ñ" ],
-		'hr' => [ "Č", "Ć", "Dž", "Đ", "Lj", "Nj", "Š", "Ž" ],
-		'hsb' => [ "Č", "Dź", "Ě", "Ch", "Ł", "Ń", "Ř", "Š", "Ć", "Ž" ],
-		'kk' => [ "Ү", "І" ],
-		'kl' => [ "Æ", "Ø", "Å" ],
-		'ku' => [ "Ç", "Ê", "Î", "Ş", "Û" ],
-		'ky' => [ "Ё" ],
-		'la' => [],
-		'lb' => [],
-		'lt' => [ "Č", "Š", "Ž" ],
-		'mk' => [],
-		'mo' => [ "Ă", "Â", "Î", "Ş", "Ţ" ],
-		'mt' => [ "Ċ", "Ġ", "Għ", "Ħ", "Ż" ],
-		'nl' => [],
-		'no' => [ "Æ", "Ø", "Å" ],
-		'oc' => [],
-		'rm' => [],
-		'ro' => [ "Ă", "Â", "Î", "Ş", "Ţ" ],
-		'rup' => [ "Ă", "Â", "Î", "Ľ", "Ń", "Ş", "Ţ" ],
-		'sco' => [],
-		'sk' => [ "Ä", "Č", "Ch", "Ô", "Š", "Ž" ],
-		'sl' => [ "Č", "Š", "Ž" ],
-		'smn' => [ "Á", "Č", "Đ", "Ŋ", "Š", "Ŧ", "Ž", "Æ", "Ø", "Å", "Ä", "Ö" ],
-		'sq' => [ "Ç", "Dh", "Ë", "Gj", "Ll", "Nj", "Rr", "Sh", "Th", "Xh", "Zh" ],
-		'sr' => [],
-		'tk' => [ "Ç", "Ä", "Ž", "Ň", "Ö", "Ş", "Ü", "Ý" ],
-		'tl' => [ "Ñ", "Ng" ],
-		'tr' => [ "Ç", "Ğ", "İ", "Ö", "Ş", "Ü" ],
-		'tt' => [ "Ә", "Ө", "Ү", "Җ", "Ң", "Һ" ],
-		'uz' => [ "Ch", "G'", "Ng", "O'", "Sh" ],
-	];
-
-	const RECORD_LENGTH = 14;
-
-	function __construct( $locale ) {
-		if ( !extension_loaded( 'intl' ) ) {
-			throw new MWException( 'An ICU collation was requested, ' .
-				'but the intl extension is not available.' );
-		}
-
-		$this->locale = $locale;
-		// Drop everything after the '@' in locale's name
-		$localeParts = explode( '@', $locale );
-		$this->digitTransformLanguage = Language::factory( $locale === 'root' ? 'en' : $localeParts[0] );
-
-		$this->mainCollator = Collator::create( $locale );
-		if ( !$this->mainCollator ) {
-			throw new MWException( "Invalid ICU locale specified for collation: $locale" );
-		}
-
-		$this->primaryCollator = Collator::create( $locale );
-		$this->primaryCollator->setStrength( Collator::PRIMARY );
-	}
-
-	function getSortKey( $string ) {
-		// intl extension produces non null-terminated
-		// strings. Appending '' fixes it so that it doesn't generate
-		// a warning on each access in debug php.
-		MediaWiki\suppressWarnings();
-		$key = $this->mainCollator->getSortKey( $string ) . '';
-		MediaWiki\restoreWarnings();
-		return $key;
-	}
-
-	function getPrimarySortKey( $string ) {
-		MediaWiki\suppressWarnings();
-		$key = $this->primaryCollator->getSortKey( $string ) . '';
-		MediaWiki\restoreWarnings();
-		return $key;
-	}
-
-	function getFirstLetter( $string ) {
-		$string = strval( $string );
-		if ( $string === '' ) {
-			return '';
-		}
-
-		// Check for CJK
-		$firstChar = mb_substr( $string, 0, 1, 'UTF-8' );
-		if ( ord( $firstChar ) > 0x7f && self::isCjk( UtfNormal\Utils::utf8ToCodepoint( $firstChar ) ) ) {
-			return $firstChar;
-		}
-
-		$sortKey = $this->getPrimarySortKey( $string );
-
-		// Do a binary search to find the correct letter to sort under
-		$min = ArrayUtils::findLowerBound(
-			[ $this, 'getSortKeyByLetterIndex' ],
-			$this->getFirstLetterCount(),
-			'strcmp',
-			$sortKey );
-
-		if ( $min === false ) {
-			// Before the first letter
-			return '';
-		}
-		return $this->getLetterByIndex( $min );
-	}
-
-	function getFirstLetterData() {
-		if ( $this->firstLetterData !== null ) {
-			return $this->firstLetterData;
-		}
-
-		$cache = wfGetCache( CACHE_ANYTHING );
-		$cacheKey = wfMemcKey(
-			'first-letters',
-			$this->locale,
-			$this->digitTransformLanguage->getCode(),
-			self::getICUVersion()
-		);
-		$cacheEntry = $cache->get( $cacheKey );
-
-		if ( $cacheEntry && isset( $cacheEntry['version'] )
-			&& $cacheEntry['version'] == self::FIRST_LETTER_VERSION
-		) {
-			$this->firstLetterData = $cacheEntry;
-			return $this->firstLetterData;
-		}
-
-		// Generate data from serialized data file
-
-		if ( isset( self::$tailoringFirstLetters[$this->locale] ) ) {
-			$letters = wfGetPrecompiledData( "first-letters-root.ser" );
-			// Append additional characters
-			$letters = array_merge( $letters, self::$tailoringFirstLetters[$this->locale] );
-			// Remove unnecessary ones, if any
-			if ( isset( self::$tailoringFirstLetters['-' . $this->locale] ) ) {
-				$letters = array_diff( $letters, self::$tailoringFirstLetters['-' . $this->locale] );
-			}
-			// Apply digit transforms
-			$digits = [ '0', '1', '2', '3', '4', '5', '6', '7', '8', '9' ];
-			$letters = array_diff( $letters, $digits );
-			foreach ( $digits as $digit ) {
-				$letters[] = $this->digitTransformLanguage->formatNum( $digit, true );
-			}
-		} else {
-			$letters = wfGetPrecompiledData( "first-letters-{$this->locale}.ser" );
-			if ( $letters === false ) {
-				throw new MWException( "MediaWiki does not support ICU locale " .
-					"\"{$this->locale}\"" );
-			}
-		}
-
-		/* Sort the letters.
-		 *
-		 * It's impossible to have the precompiled data file properly sorted,
-		 * because the sort order changes depending on ICU version. If the
-		 * array is not properly sorted, the binary search will return random
-		 * results.
-		 *
-		 * We also take this opportunity to remove primary collisions.
-		 */
-		$letterMap = [];
-		foreach ( $letters as $letter ) {
-			$key = $this->getPrimarySortKey( $letter );
-			if ( isset( $letterMap[$key] ) ) {
-				// Primary collision
-				// Keep whichever one sorts first in the main collator
-				if ( $this->mainCollator->compare( $letter, $letterMap[$key] ) < 0 ) {
-					$letterMap[$key] = $letter;
-				}
-			} else {
-				$letterMap[$key] = $letter;
-			}
-		}
-		ksort( $letterMap, SORT_STRING );
-
-		/* Remove duplicate prefixes. Basically if something has a sortkey
-		 * which is a prefix of some other sortkey, then it is an
-		 * expansion and probably should not be considered a section
-		 * header.
-		 *
-		 * For example 'þ' is sometimes sorted as if it is the letters
-		 * 'th'. Other times it is its own primary element. Another
-		 * example is '₨'. Sometimes its a currency symbol. Sometimes it
-		 * is an 'R' followed by an 's'.
-		 *
-		 * Additionally an expanded element should always sort directly
-		 * after its first element due to they way sortkeys work.
-		 *
-		 * UCA sortkey elements are of variable length but no collation
-		 * element should be a prefix of some other element, so I think
-		 * this is safe. See:
-		 * - https://ssl.icu-project.org/repos/icu/icuhtml/trunk/design/collation/ICU_collation_design.htm
-		 * - http://site.icu-project.org/design/collation/uca-weight-allocation
-		 *
-		 * Additionally, there is something called primary compression to
-		 * worry about. Basically, if you have two primary elements that
-		 * are more than one byte and both start with the same byte then
-		 * the first byte is dropped on the second primary. Additionally
-		 * either \x03 or \xFF may be added to mean that the next primary
-		 * does not start with the first byte of the first primary.
-		 *
-		 * This shouldn't matter much, as the first primary is not
-		 * changed, and that is what we are comparing against.
-		 *
-		 * tl;dr: This makes some assumptions about how icu implements
-		 * collations. It seems incredibly unlikely these assumptions
-		 * will change, but nonetheless they are assumptions.
-		 */
-
-		$prev = false;
-		$duplicatePrefixes = [];
-		foreach ( $letterMap as $key => $value ) {
-			// Remove terminator byte. Otherwise the prefix
-			// comparison will get hung up on that.
-			$trimmedKey = rtrim( $key, "\0" );
-			if ( $prev === false || $prev === '' ) {
-				$prev = $trimmedKey;
-				// We don't yet have a collation element
-				// to compare against, so continue.
-				continue;
-			}
-
-			// Due to the fact the array is sorted, we only have
-			// to compare with the element directly previous
-			// to the current element (skipping expansions).
-			// An element "X" will always sort directly
-			// before "XZ" (Unless we have "XY", but we
-			// do not update $prev in that case).
-			if ( substr( $trimmedKey, 0, strlen( $prev ) ) === $prev ) {
-				$duplicatePrefixes[] = $key;
-				// If this is an expansion, we don't want to
-				// compare the next element to this element,
-				// but to what is currently $prev
-				continue;
-			}
-			$prev = $trimmedKey;
-		}
-		foreach ( $duplicatePrefixes as $badKey ) {
-			wfDebug( "Removing '{$letterMap[$badKey]}' from first letters.\n" );
-			unset( $letterMap[$badKey] );
-			// This code assumes that unsetting does not change sort order.
-		}
-		$data = [
-			'chars' => array_values( $letterMap ),
-			'keys' => array_keys( $letterMap ),
-			'version' => self::FIRST_LETTER_VERSION,
-		];
-
-		// Reduce memory usage before caching
-		unset( $letterMap );
-
-		// Save to cache
-		$this->firstLetterData = $data;
-		$cache->set( $cacheKey, $data, $cache::TTL_WEEK );
-		return $data;
-	}
-
-	function getLetterByIndex( $index ) {
-		if ( $this->firstLetterData === null ) {
-			$this->getFirstLetterData();
-		}
-		return $this->firstLetterData['chars'][$index];
-	}
-
-	function getSortKeyByLetterIndex( $index ) {
-		if ( $this->firstLetterData === null ) {
-			$this->getFirstLetterData();
-		}
-		return $this->firstLetterData['keys'][$index];
-	}
-
-	function getFirstLetterCount() {
-		if ( $this->firstLetterData === null ) {
-			$this->getFirstLetterData();
-		}
-		return count( $this->firstLetterData['chars'] );
-	}
-
-	static function isCjk( $codepoint ) {
-		foreach ( self::$cjkBlocks as $block ) {
-			if ( $codepoint >= $block[0] && $codepoint <= $block[1] ) {
-				return true;
-			}
-		}
-		return false;
-	}
-
-	/**
-	 * Return the version of ICU library used by PHP's intl extension,
-	 * or false when the extension is not installed of the version
-	 * can't be determined.
-	 *
-	 * The constant INTL_ICU_VERSION this function refers to isn't really
-	 * documented. It is available since PHP 5.3.7 (see PHP bug 54561).
-	 * This function will return false on older PHPs.
-	 *
-	 * @since 1.21
-	 * @return string|bool
-	 */
-	static function getICUVersion() {
-		return defined( 'INTL_ICU_VERSION' ) ? INTL_ICU_VERSION : false;
-	}
-
-	/**
-	 * Return the version of Unicode appropriate for the version of ICU library
-	 * currently in use, or false when it can't be determined.
-	 *
-	 * @since 1.21
-	 * @return string|bool
-	 */
-	static function getUnicodeVersionForICU() {
-		$icuVersion = IcuCollation::getICUVersion();
-		if ( !$icuVersion ) {
-			return false;
-		}
-
-		$versionPrefix = substr( $icuVersion, 0, 3 );
-		// Source: http://site.icu-project.org/download
-		$map = [
-			'50.' => '6.2',
-			'49.' => '6.1',
-			'4.8' => '6.0',
-			'4.6' => '6.0',
-			'4.4' => '5.2',
-			'4.2' => '5.1',
-			'4.0' => '5.1',
-			'3.8' => '5.0',
-			'3.6' => '5.0',
-			'3.4' => '4.1',
-		];
-
-		if ( isset( $map[$versionPrefix] ) ) {
-			return $map[$versionPrefix];
-		} else {
-			return false;
-		}
-	}
-}
-
-/**
- * Workaround for the lack of support of Sorani Kurdish / Central Kurdish language ('ckb') in ICU.
- *
- * Uses the same collation rules as Persian / Farsi ('fa'), but different characters for digits.
- */
-class CollationCkb extends IcuCollation {
-	function __construct() {
-		// This will set $locale and collators, which affect the actual sorting order
-		parent::__construct( 'fa' );
-		// Override the 'fa' language set by parent constructor, which affects #getFirstLetterData()
-		$this->digitTransformLanguage = Language::factory( 'ckb' );
-	}
-}
-
-/**
- * Workaround for incorrect collation of Estonian language ('et') in ICU (bug 54168).
- *
- * 'W' and 'V' should not be considered the same letter for the purposes of collation in modern
- * Estonian. We work around this by replacing 'W' and 'w' with 'á´¡' U+1D21 'LATIN LETTER SMALL
- * CAPITAL W' for sortkey generation, which is collated like 'W' and is not tailored to have the
- * same primary weight as 'V' in Estonian.
- */
-class CollationEt extends IcuCollation {
-	function __construct() {
-		parent::__construct( 'et' );
-	}
-
-	private static function mangle( $string ) {
-		return str_replace(
-			[ 'w', 'W' ],
-			'á´¡', // U+1D21 'LATIN LETTER SMALL CAPITAL W'
-			$string
-		);
-	}
-
-	private static function unmangle( $string ) {
-		// Casing data is lost…
-		return str_replace(
-			'á´¡', // U+1D21 'LATIN LETTER SMALL CAPITAL W'
-			'W',
-			$string
-		);
-	}
-
-	function getSortKey( $string ) {
-		return parent::getSortKey( self::mangle( $string ) );
-	}
-
-	function getFirstLetter( $string ) {
-		return self::unmangle( parent::getFirstLetter( self::mangle( $string ) ) );
-	}
-}
diff --git a/includes/SiteStats.php b/includes/SiteStats.php
index 74c2997525..acd5262b0e 100644
--- a/includes/SiteStats.php
+++ b/includes/SiteStats.php
@@ -36,9 +36,6 @@ class SiteStats {
 	/** @var int[] */
 	private static $pageCount = [];
 
-	/** @var int[] */
-	private static $groupMemberCounts = [];
-
 	static function recache() {
 		self::load( true );
 	}
diff --git a/includes/StubObject.php b/includes/StubObject.php
index 211afda671..0b4d048e74 100644
--- a/includes/StubObject.php
+++ b/includes/StubObject.php
@@ -149,7 +149,6 @@ class StubObject {
 		}
 
 		if ( get_class( $GLOBALS[$this->global] ) != $this->class ) {
-			$fname = __METHOD__ . '-' . $this->global;
 			$caller = wfGetCaller( $level );
 			if ( ++$recursionLevel > 2 ) {
 				throw new MWException( "Unstub loop detected on call of "
diff --git a/includes/collation/Collation.php b/includes/collation/Collation.php
new file mode 100644
index 0000000000..9fb06604f8
--- /dev/null
+++ b/includes/collation/Collation.php
@@ -0,0 +1,121 @@
+<?php
+/**
+ * Database row sorting.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ */
+
+/**
+ * @since 1.16.3
+ * @author Tim Starling
+ */
+abstract class Collation {
+	private static $instance;
+
+	/**
+	 * @since 1.16.3
+	 * @return Collation
+	 */
+	public static function singleton() {
+		if ( !self::$instance ) {
+			global $wgCategoryCollation;
+			self::$instance = self::factory( $wgCategoryCollation );
+		}
+		return self::$instance;
+	}
+
+	/**
+	 * @since 1.16.3
+	 * @throws MWException
+	 * @param string $collationName
+	 * @return Collation
+	 */
+	public static function factory( $collationName ) {
+		switch ( $collationName ) {
+			case 'uppercase':
+				return new UppercaseCollation;
+			case 'identity':
+				return new IdentityCollation;
+			case 'uca-default':
+				return new IcuCollation( 'root' );
+			case 'xx-uca-ckb':
+				return new CollationCkb;
+			case 'xx-uca-et':
+				return new CollationEt;
+			default:
+				$match = [];
+				if ( preg_match( '/^uca-([a-z@=-]+)$/', $collationName, $match ) ) {
+					return new IcuCollation( $match[1] );
+				}
+
+				# Provide a mechanism for extensions to hook in.
+				$collationObject = null;
+				Hooks::run( 'Collation::factory', [ $collationName, &$collationObject ] );
+
+				if ( $collationObject instanceof Collation ) {
+					return $collationObject;
+				}
+
+				// If all else fails...
+				throw new MWException( __METHOD__ . ": unknown collation type \"$collationName\"" );
+		}
+	}
+
+	/**
+	 * Given a string, convert it to a (hopefully short) key that can be used
+	 * for efficient sorting.  A binary sort according to the sortkeys
+	 * corresponds to a logical sort of the corresponding strings.  Current
+	 * code expects that a line feed character should sort before all others, but
+	 * has no other particular expectations (and that one can be changed if
+	 * necessary).
+	 *
+	 * @since 1.16.3
+	 *
+	 * @param string $string UTF-8 string
+	 * @return string Binary sortkey
+	 */
+	abstract function getSortKey( $string );
+
+	/**
+	 * Given a string, return the logical "first letter" to be used for
+	 * grouping on category pages and so on.  This has to be coordinated
+	 * carefully with convertToSortkey(), or else the sorted list might jump
+	 * back and forth between the same "initial letters" or other pathological
+	 * behavior.  For instance, if you just return the first character, but "a"
+	 * sorts the same as "A" based on getSortKey(), then you might get a
+	 * list like
+	 *
+	 * == A ==
+	 * * [[Aardvark]]
+	 *
+	 * == a ==
+	 * * [[antelope]]
+	 *
+	 * == A ==
+	 * * [[Ape]]
+	 *
+	 * etc., assuming for the sake of argument that $wgCapitalLinks is false.
+	 *
+	 * @since 1.16.3
+	 *
+	 * @param string $string UTF-8 string
+	 * @return string UTF-8 string corresponding to the first letter of input
+	 */
+	abstract function getFirstLetter( $string );
+
+}
diff --git a/includes/collation/CollationCkb.php b/includes/collation/CollationCkb.php
new file mode 100644
index 0000000000..01a4f7f52a
--- /dev/null
+++ b/includes/collation/CollationCkb.php
@@ -0,0 +1,35 @@
+<?php
+/**
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ */
+
+/**
+ * Workaround for the lack of support of Sorani Kurdish / Central Kurdish language ('ckb') in ICU.
+ *
+ * Uses the same collation rules as Persian / Farsi ('fa'), but different characters for digits.
+ *
+ * @since 1.23
+ */
+class CollationCkb extends IcuCollation {
+	public function __construct() {
+		// This will set $locale and collators, which affect the actual sorting order
+		parent::__construct( 'fa' );
+		// Override the 'fa' language set by parent constructor, which affects #getFirstLetterData()
+		$this->digitTransformLanguage = Language::factory( 'ckb' );
+	}
+}
diff --git a/includes/collation/CollationEt.php b/includes/collation/CollationEt.php
new file mode 100644
index 0000000000..5dc9fa29ec
--- /dev/null
+++ b/includes/collation/CollationEt.php
@@ -0,0 +1,60 @@
+<?php
+/**
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ */
+
+/**
+ * Workaround for incorrect collation of Estonian language ('et') in ICU (bug 54168).
+ *
+ * 'W' and 'V' should not be considered the same letter for the purposes of collation in modern
+ * Estonian. We work around this by replacing 'W' and 'w' with 'á´¡' U+1D21 'LATIN LETTER SMALL
+ * CAPITAL W' for sortkey generation, which is collated like 'W' and is not tailored to have the
+ * same primary weight as 'V' in Estonian.
+ *
+ * @since 1.24
+ */
+class CollationEt extends IcuCollation {
+	public function __construct() {
+		parent::__construct( 'et' );
+	}
+
+	private static function mangle( $string ) {
+		return str_replace(
+			[ 'w', 'W' ],
+			'á´¡', // U+1D21 'LATIN LETTER SMALL CAPITAL W'
+			$string
+		);
+	}
+
+	private static function unmangle( $string ) {
+		// Casing data is lost…
+		return str_replace(
+			'á´¡', // U+1D21 'LATIN LETTER SMALL CAPITAL W'
+			'W',
+			$string
+		);
+	}
+
+	public function getSortKey( $string ) {
+		return parent::getSortKey( self::mangle( $string ) );
+	}
+
+	public function getFirstLetter( $string ) {
+		return self::unmangle( parent::getFirstLetter( self::mangle( $string ) ) );
+	}
+}
diff --git a/includes/collation/IcuCollation.php b/includes/collation/IcuCollation.php
new file mode 100644
index 0000000000..0aa14065aa
--- /dev/null
+++ b/includes/collation/IcuCollation.php
@@ -0,0 +1,481 @@
+<?php
+/**
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ */
+
+/**
+ * @since 1.16.3
+ */
+class IcuCollation extends Collation {
+	const FIRST_LETTER_VERSION = 2;
+
+	/** @var Collator */
+	private $primaryCollator;
+
+	/** @var Collator */
+	private $mainCollator;
+
+	/** @var string */
+	private $locale;
+
+	/** @var Language */
+	protected $digitTransformLanguage;
+
+	/** @var array */
+	private $firstLetterData;
+
+	/**
+	 * Unified CJK blocks.
+	 *
+	 * The same definition of a CJK block must be used for both Collation and
+	 * generateCollationData.php. These blocks are omitted from the first
+	 * letter data, as an optimisation measure and because the default UCA table
+	 * is pretty useless for sorting Chinese text anyway. Japanese and Korean
+	 * blocks are not included here, because they are smaller and more useful.
+	 */
+	private static $cjkBlocks = [
+		[ 0x2E80, 0x2EFF ], // CJK Radicals Supplement
+		[ 0x2F00, 0x2FDF ], // Kangxi Radicals
+		[ 0x2FF0, 0x2FFF ], // Ideographic Description Characters
+		[ 0x3000, 0x303F ], // CJK Symbols and Punctuation
+		[ 0x31C0, 0x31EF ], // CJK Strokes
+		[ 0x3200, 0x32FF ], // Enclosed CJK Letters and Months
+		[ 0x3300, 0x33FF ], // CJK Compatibility
+		[ 0x3400, 0x4DBF ], // CJK Unified Ideographs Extension A
+		[ 0x4E00, 0x9FFF ], // CJK Unified Ideographs
+		[ 0xF900, 0xFAFF ], // CJK Compatibility Ideographs
+		[ 0xFE30, 0xFE4F ], // CJK Compatibility Forms
+		[ 0x20000, 0x2A6DF ], // CJK Unified Ideographs Extension B
+		[ 0x2A700, 0x2B73F ], // CJK Unified Ideographs Extension C
+		[ 0x2B740, 0x2B81F ], // CJK Unified Ideographs Extension D
+		[ 0x2F800, 0x2FA1F ], // CJK Compatibility Ideographs Supplement
+	];
+
+	/**
+	 * Additional characters (or character groups) to be considered separate
+	 * letters for given languages, or to be removed from the list of such
+	 * letters (denoted by keys starting with '-').
+	 *
+	 * These are additions to (or subtractions from) the data stored in the
+	 * first-letters-root.ser file (which among others includes full basic latin,
+	 * cyrillic and greek alphabets).
+	 *
+	 * "Separate letter" is a letter that would have a separate heading/section
+	 * for it in a dictionary or a phone book in this language. This data isn't
+	 * used for sorting (the ICU library handles that), only for deciding which
+	 * characters (or character groups) to use as headings.
+	 *
+	 * Initially generated based on the primary level of Unicode collation
+	 * tailorings available at http://developer.mimer.com/charts/tailorings.htm ,
+	 * later modified.
+	 *
+	 * Empty arrays are intended; this signifies that the data for the language is
+	 * available and that there are, in fact, no additional letters to consider.
+	 */
+	private static $tailoringFirstLetters = [
+		// Verified by native speakers
+		'be' => [ "Ё" ],
+		'be-tarask' => [ "Ё" ],
+		'cy' => [ "Ch", "Dd", "Ff", "Ng", "Ll", "Ph", "Rh", "Th" ],
+		'en' => [],
+		'fa' => [ "آ", "ء", "ه" ],
+		'fi' => [ "Å", "Ä", "Ö" ],
+		'fr' => [],
+		'hu' => [ "Cs", "Dz", "Dzs", "Gy", "Ly", "Ny", "Ö", "Sz", "Ty", "Ü", "Zs" ],
+		'is' => [ "Á", "Ð", "É", "Í", "Ó", "Ú", "Ý", "Þ", "Æ", "Ö", "Å" ],
+		'it' => [],
+		'lv' => [ "Č", "Ģ", "Ķ", "Ļ", "Ņ", "Š", "Ž" ],
+		'pl' => [ "Ą", "Ć", "Ę", "Ł", "Ń", "Ó", "Ś", "Ź", "Ż" ],
+		'pt' => [],
+		'ru' => [],
+		'sv' => [ "Å", "Ä", "Ö" ],
+		'sv@collation=standard' => [ "Å", "Ä", "Ö" ],
+		'uk' => [ "Ґ", "Ь" ],
+		'vi' => [ "Ă", "Â", "Đ", "Ê", "Ô", "Ơ", "Ư" ],
+		// Not verified, but likely correct
+		'af' => [],
+		'ast' => [ "Ch", "Ll", "Ñ" ],
+		'az' => [ "Ç", "Ə", "Ğ", "İ", "Ö", "Ş", "Ü" ],
+		'bg' => [],
+		'br' => [ "Ch", "C'h" ],
+		'bs' => [ "Č", "Ć", "Dž", "Đ", "Lj", "Nj", "Š", "Ž" ],
+		'ca' => [],
+		'co' => [],
+		'cs' => [ "Č", "Ch", "Ř", "Š", "Ž" ],
+		'da' => [ "Æ", "Ø", "Å" ],
+		'de' => [],
+		'dsb' => [ "Č", "Ć", "Dź", "Ě", "Ch", "Ł", "Ń", "Ŕ", "Š", "Ś", "Ž", "Ź" ],
+		'el' => [],
+		'eo' => [ "Ĉ", "Ĝ", "Ĥ", "Ĵ", "Ŝ", "Ŭ" ],
+		'es' => [ "Ñ" ],
+		'et' => [ "Š", "Ž", "Õ", "Ä", "Ö", "Ü", "W" ], // added W for CollationEt (xx-uca-et)
+		'eu' => [ "Ñ" ],
+		'fo' => [ "Á", "Ð", "Í", "Ó", "Ú", "Ý", "Æ", "Ø", "Å" ],
+		'fur' => [ "À", "Á", "Â", "È", "Ì", "Ò", "Ù" ],
+		'fy' => [],
+		'ga' => [],
+		'gd' => [],
+		'gl' => [ "Ch", "Ll", "Ñ" ],
+		'hr' => [ "Č", "Ć", "Dž", "Đ", "Lj", "Nj", "Š", "Ž" ],
+		'hsb' => [ "Č", "Dź", "Ě", "Ch", "Ł", "Ń", "Ř", "Š", "Ć", "Ž" ],
+		'kk' => [ "Ү", "І" ],
+		'kl' => [ "Æ", "Ø", "Å" ],
+		'ku' => [ "Ç", "Ê", "Î", "Ş", "Û" ],
+		'ky' => [ "Ё" ],
+		'la' => [],
+		'lb' => [],
+		'lt' => [ "Č", "Š", "Ž" ],
+		'mk' => [],
+		'mo' => [ "Ă", "Â", "Î", "Ş", "Ţ" ],
+		'mt' => [ "Ċ", "Ġ", "Għ", "Ħ", "Ż" ],
+		'nl' => [],
+		'no' => [ "Æ", "Ø", "Å" ],
+		'oc' => [],
+		'rm' => [],
+		'ro' => [ "Ă", "Â", "Î", "Ş", "Ţ" ],
+		'rup' => [ "Ă", "Â", "Î", "Ľ", "Ń", "Ş", "Ţ" ],
+		'sco' => [],
+		'sk' => [ "Ä", "Č", "Ch", "Ô", "Š", "Ž" ],
+		'sl' => [ "Č", "Š", "Ž" ],
+		'smn' => [ "Á", "Č", "Đ", "Ŋ", "Š", "Ŧ", "Ž", "Æ", "Ø", "Å", "Ä", "Ö" ],
+		'sq' => [ "Ç", "Dh", "Ë", "Gj", "Ll", "Nj", "Rr", "Sh", "Th", "Xh", "Zh" ],
+		'sr' => [],
+		'tk' => [ "Ç", "Ä", "Ž", "Ň", "Ö", "Ş", "Ü", "Ý" ],
+		'tl' => [ "Ñ", "Ng" ],
+		'tr' => [ "Ç", "Ğ", "İ", "Ö", "Ş", "Ü" ],
+		'tt' => [ "Ә", "Ө", "Ү", "Җ", "Ң", "Һ" ],
+		'uz' => [ "Ch", "G'", "Ng", "O'", "Sh" ],
+	];
+
+	/**
+	 * @since 1.16.3
+	 */
+	const RECORD_LENGTH = 14;
+
+	public function __construct( $locale ) {
+		if ( !extension_loaded( 'intl' ) ) {
+			throw new MWException( 'An ICU collation was requested, ' .
+				'but the intl extension is not available.' );
+		}
+
+		$this->locale = $locale;
+		// Drop everything after the '@' in locale's name
+		$localeParts = explode( '@', $locale );
+		$this->digitTransformLanguage = Language::factory( $locale === 'root' ? 'en' : $localeParts[0] );
+
+		$this->mainCollator = Collator::create( $locale );
+		if ( !$this->mainCollator ) {
+			throw new MWException( "Invalid ICU locale specified for collation: $locale" );
+		}
+
+		$this->primaryCollator = Collator::create( $locale );
+		$this->primaryCollator->setStrength( Collator::PRIMARY );
+	}
+
+	public function getSortKey( $string ) {
+		// intl extension produces non null-terminated
+		// strings. Appending '' fixes it so that it doesn't generate
+		// a warning on each access in debug php.
+		MediaWiki\suppressWarnings();
+		$key = $this->mainCollator->getSortKey( $string ) . '';
+		MediaWiki\restoreWarnings();
+		return $key;
+	}
+
+	public function getPrimarySortKey( $string ) {
+		MediaWiki\suppressWarnings();
+		$key = $this->primaryCollator->getSortKey( $string ) . '';
+		MediaWiki\restoreWarnings();
+		return $key;
+	}
+
+	public function getFirstLetter( $string ) {
+		$string = strval( $string );
+		if ( $string === '' ) {
+			return '';
+		}
+
+		// Check for CJK
+		$firstChar = mb_substr( $string, 0, 1, 'UTF-8' );
+		if ( ord( $firstChar ) > 0x7f && self::isCjk( UtfNormal\Utils::utf8ToCodepoint( $firstChar ) ) ) {
+			return $firstChar;
+		}
+
+		$sortKey = $this->getPrimarySortKey( $string );
+
+		// Do a binary search to find the correct letter to sort under
+		$min = ArrayUtils::findLowerBound(
+			[ $this, 'getSortKeyByLetterIndex' ],
+			$this->getFirstLetterCount(),
+			'strcmp',
+			$sortKey );
+
+		if ( $min === false ) {
+			// Before the first letter
+			return '';
+		}
+		return $this->getLetterByIndex( $min );
+	}
+
+	/**
+	 * @since 1.16.3
+	 */
+	public function getFirstLetterData() {
+		if ( $this->firstLetterData !== null ) {
+			return $this->firstLetterData;
+		}
+
+		$cache = wfGetCache( CACHE_ANYTHING );
+		$cacheKey = wfMemcKey(
+			'first-letters',
+			$this->locale,
+			$this->digitTransformLanguage->getCode(),
+			self::getICUVersion()
+		);
+		$cacheEntry = $cache->get( $cacheKey );
+
+		if ( $cacheEntry && isset( $cacheEntry['version'] )
+			&& $cacheEntry['version'] == self::FIRST_LETTER_VERSION
+		) {
+			$this->firstLetterData = $cacheEntry;
+			return $this->firstLetterData;
+		}
+
+		// Generate data from serialized data file
+
+		if ( isset( self::$tailoringFirstLetters[$this->locale] ) ) {
+			$letters = wfGetPrecompiledData( "first-letters-root.ser" );
+			// Append additional characters
+			$letters = array_merge( $letters, self::$tailoringFirstLetters[$this->locale] );
+			// Remove unnecessary ones, if any
+			if ( isset( self::$tailoringFirstLetters['-' . $this->locale] ) ) {
+				$letters = array_diff( $letters, self::$tailoringFirstLetters['-' . $this->locale] );
+			}
+			// Apply digit transforms
+			$digits = [ '0', '1', '2', '3', '4', '5', '6', '7', '8', '9' ];
+			$letters = array_diff( $letters, $digits );
+			foreach ( $digits as $digit ) {
+				$letters[] = $this->digitTransformLanguage->formatNum( $digit, true );
+			}
+		} else {
+			$letters = wfGetPrecompiledData( "first-letters-{$this->locale}.ser" );
+			if ( $letters === false ) {
+				throw new MWException( "MediaWiki does not support ICU locale " .
+					"\"{$this->locale}\"" );
+			}
+		}
+
+		/* Sort the letters.
+		 *
+		 * It's impossible to have the precompiled data file properly sorted,
+		 * because the sort order changes depending on ICU version. If the
+		 * array is not properly sorted, the binary search will return random
+		 * results.
+		 *
+		 * We also take this opportunity to remove primary collisions.
+		 */
+		$letterMap = [];
+		foreach ( $letters as $letter ) {
+			$key = $this->getPrimarySortKey( $letter );
+			if ( isset( $letterMap[$key] ) ) {
+				// Primary collision
+				// Keep whichever one sorts first in the main collator
+				if ( $this->mainCollator->compare( $letter, $letterMap[$key] ) < 0 ) {
+					$letterMap[$key] = $letter;
+				}
+			} else {
+				$letterMap[$key] = $letter;
+			}
+		}
+		ksort( $letterMap, SORT_STRING );
+
+		/* Remove duplicate prefixes. Basically if something has a sortkey
+		 * which is a prefix of some other sortkey, then it is an
+		 * expansion and probably should not be considered a section
+		 * header.
+		 *
+		 * For example 'þ' is sometimes sorted as if it is the letters
+		 * 'th'. Other times it is its own primary element. Another
+		 * example is '₨'. Sometimes its a currency symbol. Sometimes it
+		 * is an 'R' followed by an 's'.
+		 *
+		 * Additionally an expanded element should always sort directly
+		 * after its first element due to they way sortkeys work.
+		 *
+		 * UCA sortkey elements are of variable length but no collation
+		 * element should be a prefix of some other element, so I think
+		 * this is safe. See:
+		 * - https://ssl.icu-project.org/repos/icu/icuhtml/trunk/design/collation/ICU_collation_design.htm
+		 * - http://site.icu-project.org/design/collation/uca-weight-allocation
+		 *
+		 * Additionally, there is something called primary compression to
+		 * worry about. Basically, if you have two primary elements that
+		 * are more than one byte and both start with the same byte then
+		 * the first byte is dropped on the second primary. Additionally
+		 * either \x03 or \xFF may be added to mean that the next primary
+		 * does not start with the first byte of the first primary.
+		 *
+		 * This shouldn't matter much, as the first primary is not
+		 * changed, and that is what we are comparing against.
+		 *
+		 * tl;dr: This makes some assumptions about how icu implements
+		 * collations. It seems incredibly unlikely these assumptions
+		 * will change, but nonetheless they are assumptions.
+		 */
+
+		$prev = false;
+		$duplicatePrefixes = [];
+		foreach ( $letterMap as $key => $value ) {
+			// Remove terminator byte. Otherwise the prefix
+			// comparison will get hung up on that.
+			$trimmedKey = rtrim( $key, "\0" );
+			if ( $prev === false || $prev === '' ) {
+				$prev = $trimmedKey;
+				// We don't yet have a collation element
+				// to compare against, so continue.
+				continue;
+			}
+
+			// Due to the fact the array is sorted, we only have
+			// to compare with the element directly previous
+			// to the current element (skipping expansions).
+			// An element "X" will always sort directly
+			// before "XZ" (Unless we have "XY", but we
+			// do not update $prev in that case).
+			if ( substr( $trimmedKey, 0, strlen( $prev ) ) === $prev ) {
+				$duplicatePrefixes[] = $key;
+				// If this is an expansion, we don't want to
+				// compare the next element to this element,
+				// but to what is currently $prev
+				continue;
+			}
+			$prev = $trimmedKey;
+		}
+		foreach ( $duplicatePrefixes as $badKey ) {
+			wfDebug( "Removing '{$letterMap[$badKey]}' from first letters.\n" );
+			unset( $letterMap[$badKey] );
+			// This code assumes that unsetting does not change sort order.
+		}
+		$data = [
+			'chars' => array_values( $letterMap ),
+			'keys' => array_keys( $letterMap ),
+			'version' => self::FIRST_LETTER_VERSION,
+		];
+
+		// Reduce memory usage before caching
+		unset( $letterMap );
+
+		// Save to cache
+		$this->firstLetterData = $data;
+		$cache->set( $cacheKey, $data, $cache::TTL_WEEK );
+		return $data;
+	}
+
+	/**
+	 * @since 1.16.3
+	 */
+	public function getLetterByIndex( $index ) {
+		if ( $this->firstLetterData === null ) {
+			$this->getFirstLetterData();
+		}
+		return $this->firstLetterData['chars'][$index];
+	}
+
+	/**
+	 * @since 1.16.3
+	 */
+	public function getSortKeyByLetterIndex( $index ) {
+		if ( $this->firstLetterData === null ) {
+			$this->getFirstLetterData();
+		}
+		return $this->firstLetterData['keys'][$index];
+	}
+
+	/**
+	 * @since 1.16.3
+	 */
+	public function getFirstLetterCount() {
+		if ( $this->firstLetterData === null ) {
+			$this->getFirstLetterData();
+		}
+		return count( $this->firstLetterData['chars'] );
+	}
+
+	/**
+	 * @since 1.16.3
+	 */
+	public static function isCjk( $codepoint ) {
+		foreach ( self::$cjkBlocks as $block ) {
+			if ( $codepoint >= $block[0] && $codepoint <= $block[1] ) {
+				return true;
+			}
+		}
+		return false;
+	}
+
+	/**
+	 * Return the version of ICU library used by PHP's intl extension,
+	 * or false when the extension is not installed of the version
+	 * can't be determined.
+	 *
+	 * The constant INTL_ICU_VERSION this function refers to isn't really
+	 * documented. It is available since PHP 5.3.7 (see PHP bug 54561).
+	 * This function will return false on older PHPs.
+	 *
+	 * @since 1.21
+	 * @return string|bool
+	 */
+	static function getICUVersion() {
+		return defined( 'INTL_ICU_VERSION' ) ? INTL_ICU_VERSION : false;
+	}
+
+	/**
+	 * Return the version of Unicode appropriate for the version of ICU library
+	 * currently in use, or false when it can't be determined.
+	 *
+	 * @since 1.21
+	 * @return string|bool
+	 */
+	static function getUnicodeVersionForICU() {
+		$icuVersion = IcuCollation::getICUVersion();
+		if ( !$icuVersion ) {
+			return false;
+		}
+
+		$versionPrefix = substr( $icuVersion, 0, 3 );
+		// Source: http://site.icu-project.org/download
+		$map = [
+			'50.' => '6.2',
+			'49.' => '6.1',
+			'4.8' => '6.0',
+			'4.6' => '6.0',
+			'4.4' => '5.2',
+			'4.2' => '5.1',
+			'4.0' => '5.1',
+			'3.8' => '5.0',
+			'3.6' => '5.0',
+			'3.4' => '4.1',
+		];
+
+		if ( isset( $map[$versionPrefix] ) ) {
+			return $map[$versionPrefix];
+		} else {
+			return false;
+		}
+	}
+}
diff --git a/includes/collation/IdentityCollation.php b/includes/collation/IdentityCollation.php
new file mode 100644
index 0000000000..46e7f38f5b
--- /dev/null
+++ b/includes/collation/IdentityCollation.php
@@ -0,0 +1,44 @@
+<?php
+/**
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ */
+
+/**
+ * Collation class that's essentially a no-op.
+ *
+ * Does sorting based on binary value of the string.
+ * Like how things were pre 1.17.
+ *
+ * @since 1.18
+ */
+class IdentityCollation extends Collation {
+
+	public function getSortKey( $string ) {
+		return $string;
+	}
+
+	public function getFirstLetter( $string ) {
+		global $wgContLang;
+		// Copied from UppercaseCollation.
+		// I'm kind of unclear on when this could happen...
+		if ( $string[0] == "\0" ) {
+			$string = substr( $string, 1 );
+		}
+		return $wgContLang->firstChar( $string );
+	}
+}
diff --git a/includes/collation/UppercaseCollation.php b/includes/collation/UppercaseCollation.php
new file mode 100644
index 0000000000..92a4c3b47a
--- /dev/null
+++ b/includes/collation/UppercaseCollation.php
@@ -0,0 +1,44 @@
+<?php
+/**
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @since 1.16.3
+ *
+ * @file
+ */
+
+class UppercaseCollation extends Collation {
+
+	private $lang;
+
+	public function __construct() {
+		// Get a language object so that we can use the generic UTF-8 uppercase
+		// function there
+		$this->lang = Language::factory( 'en' );
+	}
+
+	public function getSortKey( $string ) {
+		return $this->lang->uc( $string );
+	}
+
+	public function getFirstLetter( $string ) {
+		if ( $string[0] == "\0" ) {
+			$string = substr( $string, 1 );
+		}
+		return $this->lang->ucfirst( $this->lang->firstChar( $string ) );
+	}
+
+}
diff --git a/includes/libs/eventrelayer/EventRelayer.php b/includes/libs/eventrelayer/EventRelayer.php
index c385c38dfb..b61cae77b7 100644
--- a/includes/libs/eventrelayer/EventRelayer.php
+++ b/includes/libs/eventrelayer/EventRelayer.php
@@ -55,11 +55,3 @@ abstract class EventRelayer {
 	abstract protected function doNotify( $channel, array $events );
 }
 
-/**
- * No-op class for publishing messages into a PubSub system
- */
-class EventRelayerNull extends EventRelayer {
-	public function doNotify( $channel, array $events ) {
-		return true;
-	}
-}
diff --git a/includes/libs/eventrelayer/EventRelayerNull.php b/includes/libs/eventrelayer/EventRelayerNull.php
new file mode 100644
index 0000000000..b8ec55fc5d
--- /dev/null
+++ b/includes/libs/eventrelayer/EventRelayerNull.php
@@ -0,0 +1,29 @@
+<?php
+/**
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ * @author Aaron Schulz
+ */
+
+/**
+ * No-op class for publishing messages into a PubSub system
+ */
+class EventRelayerNull extends EventRelayer {
+	public function doNotify( $channel, array $events ) {
+		return true;
+	}
+}
diff --git a/includes/media/Bitmap.php b/includes/media/Bitmap.php
index b055d16fc0..4da41c8de4 100644
--- a/includes/media/Bitmap.php
+++ b/includes/media/Bitmap.php
@@ -115,7 +115,7 @@ class BitmapHandler extends TransformationalImageHandler {
 	protected function transformImageMagick( $image, $params ) {
 		# use ImageMagick
 		global $wgSharpenReductionThreshold, $wgSharpenParameter, $wgMaxAnimatedGifArea,
-			$wgImageMagickTempDir, $wgImageMagickConvertCommand, $wgMaxInterlacingAreas;
+			$wgImageMagickTempDir, $wgImageMagickConvertCommand;
 
 		$quality = [];
 		$sharpen = [];
diff --git a/includes/specialpage/SpecialPage.php b/includes/specialpage/SpecialPage.php
index 90ace7b2dc..fb153fcee2 100644
--- a/includes/specialpage/SpecialPage.php
+++ b/includes/specialpage/SpecialPage.php
@@ -342,10 +342,10 @@ class SpecialPage {
 			return [];
 		}
 
-		$search = SearchEngine::create();
-		$search->setLimitOffset( $limit, $offset );
-		$search->setNamespaces( [] );
-		$result = $search->defaultPrefixSearch( $search );
+		$searchEngine = SearchEngine::create();
+		$searchEngine->setLimitOffset( $limit, $offset );
+		$searchEngine->setNamespaces( [] );
+		$result = $searchEngine->defaultPrefixSearch( $search );
 		return array_map( function( Title $t ) {
 			return $t->getPrefixedText();
 		}, $result );
diff --git a/includes/specials/SpecialBotPasswords.php b/includes/specials/SpecialBotPasswords.php
index bcba190570..1027f1f6e8 100644
--- a/includes/specials/SpecialBotPasswords.php
+++ b/includes/specials/SpecialBotPasswords.php
@@ -84,9 +84,6 @@ class SpecialBotPasswords extends FormSpecialPage {
 	}
 
 	protected function getFormFields() {
-		$user = $this->getUser();
-		$request = $this->getRequest();
-
 		$fields = [];
 
 		if ( $this->par !== null ) {
diff --git a/includes/specials/SpecialStatistics.php b/includes/specials/SpecialStatistics.php
index c352927fd6..86f1e2080c 100644
--- a/includes/specials/SpecialStatistics.php
+++ b/includes/specials/SpecialStatistics.php
@@ -36,8 +36,6 @@ class SpecialStatistics extends SpecialPage {
 	}
 
 	public function execute( $par ) {
-		$miserMode = $this->getConfig()->get( 'MiserMode' );
-
 		$this->setHeaders();
 		$this->getOutput()->addModuleStyles( 'mediawiki.special' );