Narrow type of Collection::last() when using Collection::isEmpty()

Author: ruudk

extension.neon

@@ -313,6 +313,6 @@ services:
 
 	# Doctrine Collection
 	-
-		class: PHPStan\Type\Doctrine\Collection\FirstTypeSpecifyingExtension
+		class: PHPStan\Type\Doctrine\Collection\IsEmptyTypeSpecifyingExtension
 		tags:
 			- phpstan.typeSpecifier.methodTypeSpecifyingExtension

src/Type/Doctrine/Collection/FirstTypeSpecifyingExtension.php renamed to src/Type/Doctrine/Collection/IsEmptyTypeSpecifyingExtension.php

@@ -12,12 +12,13 @@
 use PHPStan\Type\Constant\ConstantBooleanType;
 use PHPStan\Type\MethodTypeSpecifyingExtension;
 
-final class FirstTypeSpecifyingExtension implements MethodTypeSpecifyingExtension, TypeSpecifierAwareExtension
+final class IsEmptyTypeSpecifyingExtension implements MethodTypeSpecifyingExtension, TypeSpecifierAwareExtension
 {
 
 	private const COLLECTION_CLASS = 'Doctrine\Common\Collections\Collection';
 	private const IS_EMPTY_METHOD_NAME = 'isEmpty';
 	private const FIRST_METHOD_NAME = 'first';
+	private const LAST_METHOD_NAME = 'last';
 
 	/** @var TypeSpecifier */
 	private $typeSpecifier;
@@ -47,11 +48,19 @@ public function specifyTypes(
 		TypeSpecifierContext $context
 	): SpecifiedTypes
 	{
-		return $this->typeSpecifier->create(
+		$first = $this->typeSpecifier->create(
 			new MethodCall($node->var, self::FIRST_METHOD_NAME),
 			new ConstantBooleanType(false),
 			$context
 		);
+
+		$last = $this->typeSpecifier->create(
+			new MethodCall($node->var, self::LAST_METHOD_NAME),
+			new ConstantBooleanType(false),
+			$context
+		);
+
+		return $first->unionWith($last);
 	}
 
 	public function setTypeSpecifier(TypeSpecifier $typeSpecifier): void

tests/Type/Doctrine/Collection/FirstTypeSpecifyingExtensionTest.php renamed to tests/Type/Doctrine/Collection/IsEmptyTypeSpecifyingExtensionTest.php

@@ -7,7 +7,7 @@
 /**
  * @extends \PHPStan\Testing\RuleTestCase<VariableTypeReportingRule>
  */
-class FirstTypeSpecifyingExtensionTest extends \PHPStan\Testing\RuleTestCase
+class IsEmptyTypeSpecifyingExtensionTest extends \PHPStan\Testing\RuleTestCase
 {
 
 	protected function getRule(): Rule
@@ -21,24 +21,36 @@ protected function getRule(): Rule
 	protected function getMethodTypeSpecifyingExtensions(): array
 	{
 		return [
-			new FirstTypeSpecifyingExtension(),
+			new IsEmptyTypeSpecifyingExtension(),
 		];
 	}
 
 	public function testExtension(): void
 	{
 		$this->analyse([__DIR__ . '/data/collection.php'], [
 			[
-				'Variable $entityOrFalse is: MyEntity|false',
+				'Variable $entityOrFalse1 is: MyEntity|false',
 				18,
 			],
 			[
-				'Variable $false is: false',
-				22,
+				'Variable $entityOrFalse2 is: MyEntity|false',
+				21,
 			],
 			[
-				'Variable $entity is: MyEntity',
-				27,
+				'Variable $false1 is: false',
+				25,
+			],
+			[
+				'Variable $false2 is: false',
+				28,
+			],
+			[
+				'Variable $entity1 is: MyEntity',
+				33,
+			],
+			[
+				'Variable $entity2 is: MyEntity',
+				36,
 			],
 		]);
 	}

tests/Type/Doctrine/Collection/data/collection.php

@@ -14,15 +14,24 @@ class MyEntity
  */
 $collection = new ArrayCollection();
 
-$entityOrFalse = $collection->first();
-$entityOrFalse;
+$entityOrFalse1 = $collection->first();
+$entityOrFalse1;
+
+$entityOrFalse2 = $collection->last();
+$entityOrFalse2;
 
 if ($collection->isEmpty()) {
-	$false = $collection->first();
-	$false;
+	$false1 = $collection->first();
+	$false1;
+
+	$false2 = $collection->last();
+	$false2;
 }
 
 if (!$collection->isEmpty()) {
-	$entity = $collection->first();
-	$entity;
+	$entity1 = $collection->first();
+	$entity1;
+
+	$entity2 = $collection->last();
+	$entity2;
 }