Added regression test

phpstan-baseline.neon

@@ -1602,11 +1602,6 @@ parameters:
 			count: 4
 			path: src/Type/TypeCombinator.php
 
-		-
-			message: "#^Doing instanceof PHPStan\\\\Type\\\\Enum\\\\EnumCaseObjectType is error\\-prone and deprecated\\. Use Type\\:\\:getEnumCases\\(\\) instead\\.$#"
-			count: 1
-			path: src/Type/TypeCombinator.php
-
 		-
 			message: "#^Doing instanceof PHPStan\\\\Type\\\\FloatType is error\\-prone and deprecated\\. Use Type\\:\\:isFloat\\(\\) instead\\.$#"
 			count: 1

src/Type/ObjectType.php

@@ -94,6 +94,9 @@ class ObjectType implements TypeWithClassName, SubtractableType
 
 	private ?string $cachedDescription = null;
 
+	/** @var array<string, list<EnumCaseObjectType>> */
+	private static array $enumCases = [];
+
 	/** @api */
 	public function __construct(
 		private string $className,
@@ -114,6 +117,7 @@ public static function resetCaches(): void
 		self::$methods = [];
 		self::$properties = [];
 		self::$ancestors = [];
+		self::$enumCases = [];
 	}
 
 	private static function createFromReflection(ClassReflection $reflection): self
@@ -1215,23 +1219,31 @@ public function getEnumCases(): array
 			return [];
 		}
 
-		$subtracted = [];
-		if ($this->subtractedType !== null) {
-			foreach ($this->subtractedType->getEnumCases() as $enumCase) {
-				$subtracted[$enumCase->getEnumCaseName()] = true;
-			}
+		$cacheKey = $this->describeCache();
+		if (array_key_exists($cacheKey, self::$enumCases)) {
+			return self::$enumCases[$cacheKey];
 		}
 
-		$cases = [];
 		$className = $classReflection->getName();
+
+		$cases = [];
 		foreach ($classReflection->getEnumCases() as $enumCase) {
-			if (array_key_exists($enumCase->getName(), $subtracted)) {
-				continue;
-			}
 			$cases[] = new EnumCaseObjectType($className, $enumCase->getName(), $classReflection);
 		}
 
-		return $cases;
+		if ($this->subtractedType !== null) {
+			foreach ($cases as $i => $case) {
+				$caseName = $case->getEnumCaseName();
+				foreach ($this->subtractedType->getEnumCases() as $subtracedCase) {
+					if ($caseName === $subtracedCase->getEnumCaseName()) {
+						unset($cases[$i]);
+						continue 2;
+					}
+				}
+			}
+		}
+
+		return self::$enumCases[$cacheKey] = array_values($cases);
 	}
 
 	public function isCallable(): TrinaryLogic

src/Type/TypeCombinator.php

@@ -16,7 +16,6 @@
 use PHPStan\Type\Constant\ConstantFloatType;
 use PHPStan\Type\Constant\ConstantIntegerType;
 use PHPStan\Type\Constant\ConstantStringType;
-use PHPStan\Type\Enum\EnumCaseObjectType;
 use PHPStan\Type\Generic\GenericClassStringType;
 use PHPStan\Type\Generic\TemplateArrayType;
 use PHPStan\Type\Generic\TemplateBenevolentUnionType;
@@ -201,7 +200,8 @@ public static function union(Type ...$types): Type
 			if ($types[$i] instanceof StringType && !$types[$i] instanceof ClassStringType) {
 				$hasGenericScalarTypes[ConstantStringType::class] = true;
 			}
-			if ($types[$i] instanceof EnumCaseObjectType) {
+			$enumCases = $types[$i]->getEnumCases();
+			if (count($enumCases) === 1) {
 				$enumCaseTypes[$types[$i]->describe(VerbosityLevel::cache())] = $types[$i];
 
 				unset($types[$i]);

tests/PHPStan/Analyser/AnalyserIntegrationTest.php

@@ -1338,6 +1338,16 @@ public function testBug10772(): void
 		$this->assertNoErrors($errors);
 	}
 
+	public function testBug10979(): void
+	{
+		if (PHP_VERSION_ID < 80100) {
+			$this->markTestSkipped('Test requires PHP 8.1.');
+		}
+
+		$errors = $this->runAnalyse(__DIR__ . '/data/bug-10979.php');
+		$this->assertNoErrors($errors);
+	}
+
 	/**
 	 * @param string[]|null $allAnalysedFiles
 	 * @return Error[]