Correctly fallback to english, if the plural case is not translated

lib/private/l10n.php

@@ -238,7 +238,7 @@ class OC_L10N implements \OCP\IL10N {
 		$this->init();
 		$identifier = "_${text_singular}_::_${text_plural}_";
 		if( array_key_exists($identifier, $this->translations)) {
-			return new OC_L10N_String( $this, $identifier, $parameters, $count );
+			return new OC_L10N_String($this, $identifier, $parameters, $count, array($text_singular, $text_plural));
 		}else{
 			if($count === 1) {
 				return new OC_L10N_String($this, $text_singular, $parameters, $count);

lib/private/l10n/string.php

@@ -22,6 +22,11 @@ class OC_L10N_String{
 	 */
 	protected $parameters;
 
+	/**
+	 * @var array
+	 */
+	protected $plurals;
+
 	/**
 	 * @var integer
 	 */
@@ -30,11 +35,12 @@ class OC_L10N_String{
 	/**
 	 * @param OC_L10N $l10n
 	 */
-	public function __construct($l10n, $text, $parameters, $count = 1) {
+	public function __construct($l10n, $text, $parameters, $count = 1, $plurals = array()) {
 		$this->l10n = $l10n;
 		$this->text = $text;
 		$this->parameters = $parameters;
 		$this->count = $count;
+		$this->plurals = $plurals;
 	}
 
 	public function __toString() {
@@ -45,7 +51,19 @@ class OC_L10N_String{
 			if(is_array($translations[$this->text])) {
 				$fn = $this->l10n->getPluralFormFunction();
 				$id = $fn($this->count);
-				$text = $translations[$this->text][$id];
+
+				if ($translations[$this->text][$id] !== '') {
+					// The translation of this plural case is not empty, so use it
+					$text = $translations[$this->text][$id];
+				} else {
+					// We didn't find the plural in the language,
+					// so we fall back to english.
+					$id = ($id != 0) ? 1 : 0;
+					if (isset($this->plurals[$id])) {
+						// Fallback to the english plural
+						$text = $this->plurals[$id];
+					}
+				}
 			}
 			else{
 				$text = $translations[$this->text];

tests/data/l10n/ru.json

@@ -1,6 +1,7 @@
 {
 	"translations" : {
-		"_%n file_::_%n files_" : ["%n файл", "%n файла", "%n файлов"]
+		"_%n file_::_%n files_" : ["%n файл", "%n файла", "%n файлов"],
+		"_%n missing plural_::_%n missing plurals_" : ["", "", ""]
 	},
 	"pluralForm" :	"nplurals=3; plural=(n%10==1 && n%100!=11 ? 0 : n%10>=2 && n%10<=4 && (n%100<10 || n%100>=20) ? 1 : 2);"
 }

tests/lib/l10n.php

@@ -42,6 +42,24 @@ class Test_L10n extends \Test\TestCase {
 		*/
 	}
 
+	public function russianMissingPluralTranslationsData() {
+		return array(
+			array(1, '1 missing plural'),
+			array(2, '2 missing plurals'),
+			array(6, '6 missing plurals'),
+		);
+	}
+
+	/**
+	 * @dataProvider russianMissingPluralTranslationsData
+	 */
+	public function testRussianMissingPluralTranslations($count, $expected) {
+		$l = new OC_L10N('test');
+		$l->load(OC::$SERVERROOT.'/tests/data/l10n/ru.json');
+
+		$this->assertEquals($expected, (string)$l->n('%n missing plural', '%n missing plurals', $count));
+	}
+
 	public function testCzechPluralTranslations() {
 		$l = new OC_L10N('test');
 		$transFile = OC::$SERVERROOT.'/tests/data/l10n/cs.json';