Fix rendering of return types that are unions

Author: sunkan

src/Renderer/Php7Renderer.php

@@ -628,12 +628,14 @@ public function renderFunctionSignature(PhpFunction $function): array
 			$ret[] = ')';
 		}
 
-		if ($function->getReturnType()->getTypeHint()) {
+		$returnTypeHint = $this->renderFunctionReturnType($function);
+
+		if ($returnTypeHint) {
 			$lastKey = (int)array_key_last($ret);
 			if (!is_string($ret[$lastKey])) {
 				throw InvalidCode::invalidType();
 			}
-			$ret[$lastKey] .= ': ' . $function->getReturnType()->getTypeHint();
+			$ret[$lastKey] .= ': ' . $returnTypeHint;
 		}
 
 		$lastKey = (int)array_key_last($ret);
@@ -789,4 +791,9 @@ public function renderAttribute(PhpAttribute $attr): array
 		// not-supported
 		return [];
 	}
+
+	protected function renderFunctionReturnType(PhpFunction $function): string
+	{
+		return $function->getReturnType()->getTypeHint() ?? '';
+	}
 }

src/Renderer/Php8Renderer.php

@@ -223,6 +223,11 @@ public function renderMethod(PhpMethod $method): array
 		return $ret;
 	}
 
+	protected function renderFunctionReturnType(PhpFunction $function): string
+	{
+		return $function->getReturnType()->getTypeHint(true) ?? '';
+	}
+
 	public function renderComment(?PhpDocComment $comment): array
 	{
 		if (!$comment) {

tests/Renderer/PhpMethodTest.php

@@ -401,4 +401,14 @@ public function testVariadicParamInCtorAndPropertyPromotion(): void
 		$renderer = new Php8Renderer();
 		$this->assertSourceResult($renderer->renderClass($c), 'PhpMethodTest.testVariadicParamInCtorAndPropertyPromotion');
 	}
+
+	public function testRenderUnionResponseTypeForPhp8(): void
+	{
+		$type = Type::empty();
+		$type->addUnion(\DateTimeImmutable::class);
+		$type->addUnion(\PDO::class);
+		$method = PhpMethod::public('test', [], [], $type);
+		$renderer = new Php8Renderer();
+		$this->assertSourceResult($renderer->renderMethod($method), 'PhpMethodTest.testRenderUnionResponseTypeForPhp8');
+	}
 }

tests/Renderer/resources/PhpMethodTest.testRenderUnionResponseTypeForPhp8.result

@@ -0,0 +1,6 @@
+/**
+ * @return DateTimeImmutable|PDO
+ */
+public function test(): DateTimeImmutable|PDO
+{
+}