ClassReflection: make getTraits recursive

src/Reflection/ClassReflection.php

@@ -672,11 +672,24 @@ public function getInterfaces(): array
 	/**
 	 * @return \PHPStan\Reflection\ClassReflection[]
 	 */
-	public function getTraits(): array
+	public function getTraits(bool $recursive = false): array
 	{
-		return array_map(function (\ReflectionClass $trait): ClassReflection {
+		$traits = array_map(function (\ReflectionClass $trait): ClassReflection {
 			return $this->reflectionProvider->getClass($trait->getName());
-		}, $this->getNativeReflection()->getTraits());
+		}, $this->collectTraits($this->getNativeReflection()));
+
+		if ($recursive) {
+			$parentClass = $this->getNativeReflection()->getParentClass();
+
+			if ($parentClass !== false) {
+				return array_merge(
+					$traits,
+					$this->reflectionProvider->getClass($parentClass->getName())->getTraits(true)
+				);
+			}
+		}
+
+		return $traits;
 	}
 
 	/**

tests/PHPStan/Reflection/ClassReflectionTest.php

@@ -220,4 +220,96 @@ public function testDeprecatedConstantFromAnotherFile(): void
 		$this->assertTrue($constant->isDeprecated()->yes());
 	}
 
+	/**
+	 * @dataProvider dataNestedRecursiveTraits
+	 * @param class-string $className
+	 * @param class-string[] $expected
+	 * @param bool $recursive
+	 */
+	public function testGetTraits(string $className, array $expected, bool $recursive = false): void
+	{
+		$reflectionProvider = $this->createBroker();
+
+		$this->assertSame(
+			array_map(
+				static fn(ClassReflection $classReflection) => $classReflection->getNativeReflection()->getName(),
+				$reflectionProvider->getClass($className)->getTraits($recursive)
+			),
+			$expected
+		);
+	}
+
+	public function dataNestedRecursiveTraits(): array
+	{
+		return [
+			[
+				\NestedTraits\NoTrait::class,
+				[],
+			],
+			[
+				\NestedTraits\NoTrait::class,
+				[],
+				true,
+			],
+			[
+				\NestedTraits\Foo::class,
+				[
+					\NestedTraits\FooTrait::class,
+				],
+			],
+			[
+				\NestedTraits\Foo::class,
+				[
+					\NestedTraits\FooTrait::class,
+				],
+				true,
+			],
+			[
+				\NestedTraits\Bar::class,
+				[
+					\NestedTraits\BarTrait::class,
+					\NestedTraits\FooTrait::class,
+				],
+			],
+			[
+				\NestedTraits\Bar::class,
+				[
+					\NestedTraits\BarTrait::class,
+					\NestedTraits\FooTrait::class,
+				],
+				true,
+			],
+			[
+				\NestedTraits\Baz::class,
+				[
+					\NestedTraits\BazTrait::class,
+					\NestedTraits\BarTrait::class,
+					\NestedTraits\FooTrait::class,
+				],
+			],
+			[
+				\NestedTraits\Baz::class,
+				[
+					\NestedTraits\BazTrait::class,
+					\NestedTraits\BarTrait::class,
+					\NestedTraits\FooTrait::class,
+				],
+				true,
+			],
+			[
+				\NestedTraits\BazChild::class,
+				[],
+			],
+			[
+				\NestedTraits\BazChild::class,
+				[
+					\NestedTraits\BazTrait::class,
+					\NestedTraits\BarTrait::class,
+					\NestedTraits\FooTrait::class,
+				],
+				true,
+			],
+		];
+	}
+
 }

tests/PHPStan/Reflection/data/NestedTraits.php

@@ -0,0 +1,40 @@
+<?php
+
+namespace NestedTraits;
+
+trait FooTrait
+{
+}
+
+trait BarTrait
+{
+    use FooTrait;
+}
+
+trait BazTrait
+{
+    use BarTrait;
+}
+
+class NoTrait
+{
+}
+
+class Foo
+{
+    use FooTrait;
+}
+
+class Bar
+{
+    use BarTrait;
+}
+
+class Baz
+{
+    use BazTrait;
+}
+
+class BazChild extends Baz
+{
+}