When callable returns callable the return type needs to be put in parentheses

Author: ondrejmirtes

src/Ast/Type/CallableTypeNode.php

@@ -29,8 +29,12 @@ public function __construct(IdentifierTypeNode $identifier, array $parameters, T
 
 	public function __toString(): string
 	{
+		$returnType = $this->returnType;
+		if ($returnType instanceof self) {
+			$returnType = "({$returnType})";
+		}
 		$parameters = implode(', ', $this->parameters);
-		return "{$this->identifier}({$parameters}): {$this->returnType}";
+		return "{$this->identifier}({$parameters}): {$returnType}";
 	}
 
 }

tests/PHPStan/Parser/TypeParserTest.php

@@ -1885,6 +1885,22 @@ public function provideParseData(): array
 					),
 				]),
 			],
+			[
+				'Closure(Foo): (Closure(Foo): Bar)',
+				new CallableTypeNode(
+					new IdentifierTypeNode('Closure'),
+					[
+						new CallableTypeParameterNode(new IdentifierTypeNode('Foo'), false, false, '', false),
+					],
+					new CallableTypeNode(
+						new IdentifierTypeNode('Closure'),
+						[
+							new CallableTypeParameterNode(new IdentifierTypeNode('Foo'), false, false, '', false),
+						],
+						new IdentifierTypeNode('Bar')
+					)
+				),
+			],
 		];
 	}