Fix GetDebugTypeFunctionReturnTypeExtension - should use TypeCombinator instead of new UnionType

Author: ondrejmirtes

src/Type/Php/GetDebugTypeFunctionReturnTypeExtension.php

@@ -2,14 +2,14 @@
 
 namespace PHPStan\Type\Php;
 
-use Closure;
 use PhpParser\Node\Expr\FuncCall;
 use PHPStan\Analyser\Scope;
 use PHPStan\Reflection\FunctionReflection;
 use PHPStan\Type\Constant\ConstantStringType;
 use PHPStan\Type\DynamicFunctionReturnTypeExtension;
 use PHPStan\Type\StringType;
 use PHPStan\Type\Type;
+use PHPStan\Type\TypeCombinator;
 use PHPStan\Type\UnionType;
 use function array_key_first;
 use function array_map;
@@ -31,7 +31,7 @@ public function getTypeFromFunctionCall(FunctionReflection $functionReflection,
 
 		$argType = $scope->getType($functionCall->getArgs()[0]->value);
 		if ($argType instanceof UnionType) {
-			return new UnionType(array_map(Closure::fromCallable([self::class, 'resolveOneType']), $argType->getTypes()));
+			return TypeCombinator::union(...array_map(static fn (Type $type) => self::resolveOneType($type), $argType->getTypes()));
 		}
 		return self::resolveOneType($argType);
 	}
@@ -92,7 +92,7 @@ private static function resolveOneType(Type $type): Type
 				case 1:
 					return $types[0];
 				default:
-					return new UnionType($types);
+					return TypeCombinator::union(...$types);
 			}
 		}
 

tests/PHPStan/Analyser/AnalyserIntegrationTest.php

@@ -448,6 +448,16 @@ public function testBug5231Two(): void
 		$this->assertNotEmpty($errors);
 	}
 
+	public function testBug12512(): void
+	{
+		if (PHP_VERSION_ID < 80100) {
+			$this->markTestSkipped('Test requires PHP 8.1.');
+		}
+
+		$errors = $this->runAnalyse(__DIR__ . '/data/bug-12512.php');
+		$this->assertNoErrors($errors);
+	}
+
 	public function testBug5529(): void
 	{
 		$errors = $this->runAnalyse(__DIR__ . '/nsrt/bug-5529.php');

tests/PHPStan/Analyser/data/bug-12512.php

@@ -0,0 +1,22 @@
+<?php // lint >= 8.1
+
+namespace Bug12512;
+
+enum FooBarEnum: string
+{
+	case CASE_ONE = 'case_one';
+	case CASE_TWO = 'case_two';
+	case CASE_THREE = 'case_three';
+	case CASE_FOUR = 'case_four';
+
+	public function matchFunction(): string
+	{
+		return match ($this) {
+			self::CASE_ONE => 'one',
+			self::CASE_TWO => 'two',
+			default => throw new \Exception(
+				sprintf('"%s" is not implemented yet', get_debug_type($this))
+			)
+		};
+	}
+}