MDL-72347 filter: Remove censor filter

Word censorship filter is not widely used these days so it has been
removed from Moodle core.

filter/upgrade.txt

@@ -1,6 +1,11 @@
 This file describes API changes in core filter API and plugins,
 information provided here is intended especially for developers.
 
+=== 4.0 ===
+
+* The Word censorship (filter_censor) filter has been completely removed from core. It has been moved to the plugins database
+repository, so it can still be installed as a third-party plugin.
+
 === 3.9 ===
 
 * The following functions, previously used (exclusively) by upgrade steps are not available anymore because of the upgrade cleanup performed for this version. See MDL-65809 for more info:

lib/classes/plugin_manager.php

@@ -1725,8 +1725,9 @@ public static function is_deleted_standard_plugin($type, $name) {
             'block' => array('course_overview', 'messages', 'community', 'participants'),
             'cachestore' => array('memcache'),
             'enrol' => array('authorize'),
-            'portfolio' => array('picasa'),
+            'filter' => array('censor'),
             'media' => array('swf'),
+            'portfolio' => array('picasa'),
             'qformat' => array('webct'),
             'message' => array('jabber'),
             'quizaccess' => array('safebrowser'),
@@ -1861,7 +1862,7 @@ public static function standard_plugins_list($type) {
             ),
 
             'filter' => array(
-                'activitynames', 'algebra', 'censor', 'emailprotect',
+                'activitynames', 'algebra', 'emailprotect',
                 'emoticon', 'displayh5p', 'mathjaxloader', 'mediaplugin', 'multilang', 'tex', 'tidy',
                 'urltolink', 'data', 'glossary'
             ),

lib/db/upgrade.php

@@ -2862,5 +2862,15 @@ function xmldb_main_upgrade($oldversion) {
         upgrade_main_savepoint(true, 2021092400.03);
     }
 
+    if ($oldversion < 2021100300.01) {
+        // Remove filter_censor (unless it has manually been added back).
+        if (!file_exists($CFG->dirroot . '/filter/censor/filter.php')) {
+            unset_all_config_for_plugin('filter_censor');
+        }
+
+        // Main savepoint reached.
+        upgrade_main_savepoint(true, 2021100300.01);
+    }
+
     return true;
 }

lib/tests/weblib_test.php

@@ -76,9 +76,9 @@ public function test_format_string_static_caching_with_filters() {
         $generator = $this->getDataGenerator();
         $course = $generator->create_course();
         $user = $generator->create_user();
-        $rawstring = 'Shortname <a href="#">link</a> curseword';
-        $expectednofilter = strip_links($rawstring);
-        $expectedfilter = 'Shortname link \*\**';
+        $rawstring = '<span lang="en" class="multilang">English</span><span lang="ca" class="multilang">Catalan</span>';
+        $expectednofilter = strip_tags($rawstring);
+        $expectedfilter = 'English';
         $striplinks = true;
         $context = context_course::instance($course->id);
         $options = [
@@ -94,22 +94,21 @@ public function test_format_string_static_caching_with_filters() {
         $nofilterresult = format_string($rawstring, $striplinks, $options);
         $this->assertEquals($expectednofilter, $nofilterresult);
 
-        // Add the censor filter. Make sure it's enabled globally.
+        // Add the multilang filter. Make sure it's enabled globally.
         $CFG->filterall = true;
-        $CFG->stringfilters = 'censor';
-        $CFG->filter_censor_badwords = 'curseword';
-        filter_set_global_state('censor', TEXTFILTER_ON);
-        filter_set_local_state('censor', $context->id, TEXTFILTER_ON);
+        $CFG->stringfilters = 'multilang';
+        filter_set_global_state('multilang', TEXTFILTER_ON);
+        filter_set_local_state('multilang', $context->id, TEXTFILTER_ON);
         // This time we want to apply the filters.
         $options['filter'] = true;
         $filterresult = format_string($rawstring, $striplinks, $options);
         $this->assertMatchesRegularExpression("/$expectedfilter/", $filterresult);
 
-        filter_set_local_state('censor', $context->id, TEXTFILTER_OFF);
+        filter_set_local_state('multilang', $context->id, TEXTFILTER_OFF);
 
         // Confirm that we get back the cached string. The result should be
         // the same as the filtered text above even though we've disabled the
-        // censor filter in between.
+        // multilang filter in between.
         $cachedresult = format_string($rawstring, $striplinks, $options);
         $this->assertMatchesRegularExpression("/$expectedfilter/", $cachedresult);
     }

version.php

@@ -29,7 +29,7 @@
 
 defined('MOODLE_INTERNAL') || die();
 
-$version  = 2021100300.00;              // YYYYMMDD      = weekly release date of this DEV branch.
+$version  = 2021100300.01;              // YYYYMMDD      = weekly release date of this DEV branch.
                                         //         RR    = release increments - 00 in DEV branches.
                                         //           .XX = incremental changes.
 $release  = '4.0dev (Build: 20211003)'; // Human-friendly version name