Fix value-of for multiple enums

src/PhpDoc/TypeNodeResolver.php

@@ -628,32 +628,22 @@ private function resolveGenericTypeNode(GenericTypeNode $typeNode, NameScope $na
 			return new ErrorType();
 		} elseif ($mainTypeName === 'value-of') {
 			if (count($genericTypes) === 1) { // value-of<ValueType>
-				$genericTypeObjectClassNames = $genericTypes[0]->getObjectClassNames();
-				if (count($genericTypeObjectClassNames) > 1) {
-					throw new ShouldNotHappenException();
-				}
-
-				if ($genericTypeObjectClassNames !== []) {
-					if ($this->getReflectionProvider()->hasClass($genericTypeObjectClassNames[0])) {
-						$classReflection = $this->getReflectionProvider()->getClass($genericTypeObjectClassNames[0]);
-
-						if ($classReflection->isBackedEnum()) {
-							$cases = [];
-							foreach ($classReflection->getEnumCases() as $enumCaseReflection) {
-								$backingType = $enumCaseReflection->getBackingValueType();
-								if ($backingType === null) {
-									continue;
-								}
-
-								$cases[] = $backingType;
-							}
-
-							return TypeCombinator::union(...$cases);
+				$genericType = $genericTypes[0];
+				if ($genericType->isEnum()->yes()) {
+					$valueTypes = [];
+					foreach ($genericType->getEnumCases() as $enumCase) {
+						$valueType = $enumCase->getBackingValueType();
+						if ($valueType === null) {
+							continue;
 						}
+
+						$valueTypes[] = $valueType;
 					}
+
+					return TypeCombinator::union(...$valueTypes);
 				}
 
-				$type = new ValueOfType($genericTypes[0]);
+				$type = new ValueOfType($genericType);
 				return $type->isResolvable() ? $type->resolve() : $type;
 			}
 

src/Type/Enum/EnumCaseObjectType.php

@@ -136,6 +136,26 @@ public function getProperty(string $propertyName, ClassMemberAccessAnswerer $sco
 		return parent::getProperty($propertyName, $scope);
 	}
 
+	public function getBackingValueType(): ?Type
+	{
+		$classReflection = $this->getClassReflection();
+		if ($classReflection === null) {
+			return null;
+		}
+
+		if (!$classReflection->isBackedEnum()) {
+			return null;
+		}
+
+		if ($classReflection->hasEnumCase($this->enumCaseName)) {
+			$enumCase = $classReflection->getEnumCase($this->enumCaseName);
+
+			return $enumCase->getBackingValueType();
+		}
+
+		return null;
+	}
+
 	public function generalize(GeneralizePrecision $precision): Type
 	{
 		return new parent($this->getClassName(), null, $this->getClassReflection());

tests/PHPStan/Analyser/AnalyserIntegrationTest.php

@@ -1154,6 +1154,12 @@ public function testSkipCheckNoGenericClasses(): void
 		$this->assertSame('Method SkipCheckNoGenericClasses\Foo::doFoo() has parameter $i with generic class LimitIterator but does not specify its types: TKey, TValue, TIterator', $errors[0]->getMessage());
 	}
 
+	public function testBug8983(): void
+	{
+		$errors = $this->runAnalyse(__DIR__ . '/data/bug-8983.php');
+		$this->assertNoErrors($errors);
+	}
+
 	/**
 	 * @param string[]|null $allAnalysedFiles
 	 * @return Error[]

tests/PHPStan/Analyser/data/bug-8983.php

@@ -0,0 +1,30 @@
+<?php
+
+namespace Bug8983;
+
+use function PHPStan\Testing\assertType;
+
+enum Enum1: string
+{
+
+	case FOO = 'foo';
+
+}
+
+enum Enum2: string
+{
+
+	case BAR = 'bar';
+
+}
+
+class Foo
+{
+
+	/** @param value-of<Enum1|Enum2> $bar */
+	public function doFoo($bar): void
+	{
+		assertType("'bar'|'foo'", $bar);
+	}
+
+}