Issue #2449069 by Berdir: Remove default block_plugin cache tags, because they're useless

core/lib/Drupal/Core/Block/BlockBase.php

@@ -370,10 +370,7 @@ public function getCacheContexts() {
    * {@inheritdoc}
    */
   public function getCacheTags() {
-    // If a block plugin's output changes, then it must be able to invalidate a
-    // cache tag that affects all instances of this block: across themes and
-    // across regions.
-    return array('block_plugin:' . str_replace(':', '__', $this->getPluginID()));
+    return [];
   }
 
   /**

core/modules/aggregator/src/Tests/AggregatorRenderingTest.php

@@ -58,7 +58,6 @@ public function testBlockLinks() {
     $this->assert(isset($links[0]), format_string('Link to href %href found.', array('%href' => $href)));
     $cache_tags_header = $this->drupalGetHeader('X-Drupal-Cache-Tags');
     $cache_tags = explode(' ', $cache_tags_header);
-    $this->assertTrue(in_array('block_plugin:aggregator_feed_block', $cache_tags));
     $this->assertTrue(in_array('aggregator_feed:' . $feed->id(), $cache_tags));
 
     // Visit that page.

core/modules/block/src/Tests/BlockTest.php

@@ -330,7 +330,6 @@ public function testBlockCacheTags() {
       'config:block_list',
       'block_view',
       'config:block.block.powered',
-      'block_plugin:system_powered_by_block',
       'rendered',
     );
     sort($expected_cache_tags);
@@ -339,7 +338,6 @@ public function testBlockCacheTags() {
     $expected_cache_tags = array(
       'block_view',
       'config:block.block.powered',
-      'block_plugin:system_powered_by_block',
       'rendered',
     );
     sort($expected_cache_tags);
@@ -371,7 +369,6 @@ public function testBlockCacheTags() {
       'block_view',
       'config:block.block.powered',
       'config:block.block.powered-2',
-      'block_plugin:system_powered_by_block',
       'rendered',
     );
     sort($expected_cache_tags);
@@ -379,7 +376,6 @@ public function testBlockCacheTags() {
     $expected_cache_tags = array(
       'block_view',
       'config:block.block.powered',
-      'block_plugin:system_powered_by_block',
       'rendered',
     );
     sort($expected_cache_tags);
@@ -388,19 +384,12 @@ public function testBlockCacheTags() {
     $expected_cache_tags = array(
       'block_view',
       'config:block.block.powered-2',
-      'block_plugin:system_powered_by_block',
       'rendered',
     );
     sort($expected_cache_tags);
     $cache_entry = \Drupal::cache('render')->get('entity_view:block:powered-2:en:classy');
     $this->assertIdentical($cache_entry->tags, $expected_cache_tags);
 
-    // The plugin providing the "Powered by Drupal" block is modified; verify a
-    // cache miss.
-    Cache::invalidateTags(array('block_plugin:system_powered_by_block'));
-    $this->drupalGet('<front>');
-    $this->assertEqual($this->drupalGetHeader('X-Drupal-Cache'), 'MISS');
-
     // Now we should have a cache hit again.
     $this->drupalGet('<front>');
     $this->assertEqual($this->drupalGetHeader('X-Drupal-Cache'), 'HIT');

core/modules/block/src/Tests/BlockViewBuilderTest.php

@@ -215,7 +215,7 @@ public function testBlockViewBuilderAlter() {
     $request->setMethod('GET');
 
     $default_keys = array('entity_view', 'block', 'test_block');
-    $default_tags = array('block_view', 'config:block.block.test_block', 'block_plugin:test_cache');
+    $default_tags = array('block_view', 'config:block.block.test_block');
 
     // Advanced: cached block, but an alter hook adds an additional cache key.
     $this->setBlockCacheConfig(array(

core/modules/menu_ui/src/Tests/MenuCacheTagsTest.php

@@ -53,7 +53,6 @@ public function testMenuBlock() {
       'block_view',
       'config:block_list',
       'config:block.block.' . $block->id(),
-      'block_plugin:system_menu_block__llama',
       'config:system.menu.llama',
     );
     $this->verifyPageCache($url, 'HIT', $expected_tags);

core/modules/system/src/Tests/Cache/PageCacheTagsIntegrationTest.php

@@ -94,14 +94,6 @@ function testPageCacheTags() {
       'config:block.block.bartik_powered',
       'config:block.block.bartik_main_menu',
       'config:block.block.bartik_account_menu',
-      'block_plugin:system_breadcrumb_block',
-      'block_plugin:system_main_block',
-      'block_plugin:system_menu_block__account',
-      'block_plugin:system_menu_block__main',
-      'block_plugin:system_menu_block__tools',
-      'block_plugin:user_login_block',
-      'block_plugin:system_menu_block__footer',
-      'block_plugin:system_powered_by_block',
       'node_view',
       'node:' . $node_1->id(),
       'user:' . $author_1->id(),
@@ -127,15 +119,6 @@ function testPageCacheTags() {
       'config:block.block.bartik_powered',
       'config:block.block.bartik_main_menu',
       'config:block.block.bartik_account_menu',
-      'block_plugin:system_breadcrumb_block',
-      'block_plugin:system_main_block',
-      'block_plugin:system_menu_block__account',
-      'block_plugin:system_menu_block__main',
-      'block_plugin:system_menu_block__tools',
-      'block_plugin:user_login_block',
-      'block_plugin:views_block__comments_recent-block_1',
-      'block_plugin:system_menu_block__footer',
-      'block_plugin:system_powered_by_block',
       'node_view',
       'node:' . $node_2->id(),
       'user:' . $author_2->id(),