From da460d9d00c283bf2e34680603521bb7e5e715ff Mon Sep 17 00:00:00 2001
From: Tim Otten <totten@civicrm.org>
Date: Thu, 21 May 2020 00:22:46 -0700
Subject: [PATCH] CRM_Core_I18n::setLocale() - Fix bug with repeated usage

Overview
--------

Suppose you use `setLocale()` to change back and forth between languages, e.g.

```php
/*1*/ $i18n->setLocale('en_US'); echo ts('Yes');
/*2*/ $i18n->setLocale('fr_FR'); echo ts('Yes');
/*3*/ $i18n->setLocale('de_DE'); echo ts('Yes');
/*4*/ $i18n->setLocale('en_US'); echo ts('Yes');
/*5*/ $i18n->setLocale('fr_FR'); echo ts('Yes');
/*6*/ $i18n->setLocale('de_DE'); echo ts('Yes');
```

This fixes a bug with that use-case.

For more detailed example/reproduction, see https://gist.github.com/totten/de0dc9add8dee3956ecad29ec0906cc3 -
specifically variant 2.

Before
------

There is a leak which causes mistranslations.

After
-----

You can freely switch between instances of `CRM_Core_I18n`.

Technical Details
-----------------

(1) I'm using a default configuration, wherein `CIVICRM_GETTEXT_NATIVE` is not
set...  so it uses phpgettext.

(2) As you use multiple locales, `CRM_Core_I18n::singleton()` constructs
multiple instances of `CRM_Core_I18n` (one for each locale; this despite the
misnomer of `singleton`). `singleton()` always returns the instance indicated
by the active locale (as directed by `global $tsLocale`).

The problem: if you call `$enUS->setPhpGettextLocale('fr_FR')`, then future
requests for American English will actually return French.  Similarly, if
you call `$frFR->setPhpGettextLocale('de_DE')`, then future requests for
French will actually return German.
---
 CRM/Core/I18n.php                          |  7 ++++---
 tests/phpunit/CRM/Core/I18n/LocaleTest.php | 13 +++++++++++++
 2 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/CRM/Core/I18n.php b/CRM/Core/I18n.php
index 357dc2f936..a033519dbe 100644
--- a/CRM/Core/I18n.php
+++ b/CRM/Core/I18n.php
@@ -623,13 +623,14 @@ class CRM_Core_I18n {
     // Change the language of the CMS as well, for URLs.
     CRM_Utils_System::setUFLocale($locale);
 
-    // change the gettext ressources
     if ($this->_nativegettext) {
+      // Native gettext has its own global flag indicating the active locale.
       $this->setNativeGettextLocale($locale);
     }
     else {
-      // phpgettext
-      $this->setPhpGettextLocale($locale);
+      // With phpgettext, each locale is retained as a separate instance of CRM_Core_I18n.
+      // It is sufficient to update `$tsLocale` and switch to the designated instance.
+      // Changing the locale for a live instance will actually cause problems when alternating locales.
     }
 
     // For sql queries, if running in DB multi-lingual mode.
diff --git a/tests/phpunit/CRM/Core/I18n/LocaleTest.php b/tests/phpunit/CRM/Core/I18n/LocaleTest.php
index ab66bd4dff..95f8d5e0c8 100644
--- a/tests/phpunit/CRM/Core/I18n/LocaleTest.php
+++ b/tests/phpunit/CRM/Core/I18n/LocaleTest.php
@@ -45,6 +45,11 @@ class CRM_Core_I18n_LocaleTest extends CiviUnitTestCase {
       'fr_CA' => 'French (Canada)',
       'de_DE' => 'German',
     ];
+    $examples = [
+      'en_US' => 'Yes',
+      'fr_CA' => 'Oui',
+      'de_DE' => 'Ja',
+    ];
     $codes = array_keys($languages);
     Civi::settings()->set('uiLanguages', $codes);
 
@@ -77,6 +82,14 @@ class CRM_Core_I18n_LocaleTest extends CiviUnitTestCase {
       'fr_CA' => 'French (Canada)',
     ], $result);
 
+    // If you switch back and forth among these languages, `ts()` should follow suit.
+    for ($trial = 0; $trial < 3; $trial++) {
+      foreach ($examples as $exLocale => $exString) {
+        CRM_Core_I18n::singleton()->setLocale($exLocale);
+        $this->assertEquals($exString, ts('Yes'), "Translate");
+      }
+    }
+
     CRM_Core_I18n::singleton()->setLocale('en_US');
     CRM_Core_I18n_Schema::makeSinglelingual('en_US');
     Civi::$statics['CRM_Core_I18n']['singleton'] = [];
-- 
2.25.1