Issue #3128190 by phthlaap, Keshav Patel, msuthars, sja112, rlmumford, Prashant.c, smustgrave, quietone: FieldItemDataDefinition::getLabel() should show the label of the field type

(cherry picked from commit 94b03bcdec)

core/lib/Drupal/Core/Field/TypedData/FieldItemDataDefinition.php

@@ -87,4 +87,19 @@ class FieldItemDataDefinition extends DataDefinition implements FieldItemDataDef
     return $this;
   }
 
+  /**
+   * Gets the label of the field type.
+   *
+   * If the label hasn't been set, then fall back to the label of the
+   * typed data definition.
+   *
+   * @return string
+   *   The label of the field type.
+   *
+   * @throws \Drupal\Component\Plugin\Exception\PluginNotFoundException
+   */
+  public function getLabel() {
+    return parent::getLabel() ?: $this->getTypedDataManager()->getDefinition($this->getDataType())['label'];
+  }
+
 }

core/tests/Drupal/KernelTests/Core/Field/FieldItemTest.php

@@ -99,4 +99,16 @@ class FieldItemTest extends EntityKernelTestBase {
     $this->assertEquals($expected_value, $entity->{$this->fieldName}->value);
   }
 
+  /**
+   * Tests \Drupal\Core\Field\TypedData\FieldItemDataDefinition::getLabel().
+   */
+  public function testGetLabel(): void {
+    $data_definition = \Drupal::service('typed_data_manager')->createDataDefinition('field_item:string');
+    $this->assertEquals('Text (plain)', $data_definition->getLabel());
+
+    $label = 'Foo bar';
+    $data_definition->setLabel($label);
+    $this->assertEquals($label, $data_definition->getLabel());
+  }
+
 }