Fix false positive about unused class elements when the class uses a trait

Author: ondrejmirtes

src/Type/ThisType.php

@@ -30,7 +30,21 @@ public function changeBaseClass(ClassReflection $classReflection): StaticType
 
 	public function describe(VerbosityLevel $level): string
 	{
-		return sprintf('$this(%s)', $this->getStaticObjectType()->describe($level));
+		$callback = fn () => sprintf('$this(%s)', $this->getStaticObjectType()->describe($level));
+		return $level->handle(
+			$callback,
+			$callback,
+			$callback,
+			function () use ($callback): string {
+				$base = $callback();
+				$trait = $this->getTraitReflection();
+				if ($trait === null) {
+					return $base;
+				}
+
+				return sprintf('%s-trait-%s', $base, $trait->getDisplayName());
+			},
+		);
 	}
 
 	public function isSuperTypeOf(Type $type): TrinaryLogic

tests/PHPStan/Rules/DeadCode/UnusedPrivateMethodRuleTest.php

@@ -90,4 +90,13 @@ public function testBug7389(): void
 		]);
 	}
 
+	public function testFalsePositiveWithTraitUse(): void
+	{
+		if (PHP_VERSION_ID < 80100) {
+			$this->markTestSkipped('This test needs PHP 8.1');
+		}
+
+		$this->analyse([__DIR__ . '/data/unused-method-false-positive-with-trait.php'], []);
+	}
+
 }

tests/PHPStan/Rules/DeadCode/data/unused-method-false-positive-with-trait.php

@@ -0,0 +1,72 @@
+<?php // lint >= 8.1
+
+namespace UnusedMethodFalsePositiveWithTrait;
+
+use ReflectionEnum;
+
+enum LocalOnlineReservationTime: string
+{
+
+	use LabeledEnumTrait;
+
+	case MORNING = 'morning';
+	case AFTERNOON = 'afternoon';
+	case EVENING = 'evening';
+
+	public static function getPeriodForHour(string $hour): self
+	{
+		$hour = self::hourToNumber($hour);
+
+		throw new \Exception('Internal error');
+	}
+
+	private static function hourToNumber(string $hour): int
+	{
+		return (int) str_replace(':', '', $hour);
+	}
+
+}
+
+trait LabeledEnumTrait
+{
+
+	use EnumTrait;
+
+}
+
+trait EnumTrait
+{
+
+	/**
+	 * @return list<static>
+	 */
+	public static function getDeprecatedEnums(): array
+	{
+		static $cache = [];
+		if ($cache === []) {
+			$reflection = new ReflectionEnum(self::class);
+			$cases = $reflection->getCases();
+
+			foreach ($cases as $case) {
+				$docComment = $case->getDocComment();
+				if ($docComment === false || !str_contains($docComment, '@deprecated')) {
+					continue;
+				}
+				$cache[] = self::from($case->getBackingValue());
+			}
+		}
+
+		return $cache;
+	}
+
+	public function isDeprecated(): bool
+	{
+		return $this->equalsAny(self::getDeprecatedEnums());
+	}
+
+	public function equalsAny(...$that): bool
+	{
+		return in_array($this, $that, true);
+	}
+
+}

tests/PHPStan/Type/ObjectTypeTest.php

@@ -34,6 +34,7 @@
 use Throwable;
 use ThrowPoints\TryCatch\MyInvalidArgumentException;
 use Traversable;
+use UnusedMethodFalsePositiveWithTrait\LocalOnlineReservationTime;
 use function count;
 use function sprintf;
 use const PHP_VERSION_ID;
@@ -432,6 +433,11 @@ public function dataIsSuperTypeOf(): array
 				new ObjectType(DateTime::class),
 				TrinaryLogic::createNo(),
 			],
+			61 => [
+				new ObjectType(LocalOnlineReservationTime::class),
+				new ThisType($reflectionProvider->getClass(LocalOnlineReservationTime::class)),
+				TrinaryLogic::createYes(),
+			],
 		];
 	}