Avoid crashing on enum without value

src/Reflection/ClassReflection.php

@@ -964,7 +964,7 @@ public function getEnumCases(): array
 		$initializerExprContext = InitializerExprContext::fromClassReflection($this);
 		foreach ($this->reflection->getCases() as $case) {
 			$valueType = null;
-			if ($case instanceof ReflectionEnumBackedCase) {
+			if ($case instanceof ReflectionEnumBackedCase && $case->hasBackingValue()) {
 				$valueType = $this->initializerExprTypeResolver->getType($case->getValueExpression(), $initializerExprContext);
 			}
 			$caseName = $case->getName();
@@ -991,7 +991,7 @@ public function getEnumCase(string $name): EnumCaseReflection
 
 		$case = $this->reflection->getCase($name);
 		$valueType = null;
-		if ($case instanceof ReflectionEnumBackedCase) {
+		if ($case instanceof ReflectionEnumBackedCase && $case->hasBackingValue()) {
 			$valueType = $this->initializerExprTypeResolver->getType($case->getValueExpression(), InitializerExprContext::fromClassReflection($this));
 		}
 

tests/PHPStan/Analyser/AnalyserIntegrationTest.php

@@ -1163,6 +1163,15 @@ public function testBug8537(): void
 		$this->assertNoErrors($errors);
 	}
 
+	#[RequiresPhp('>= 8.1')]
+	public function testBug7927(): void
+	{
+		$errors = $this->runAnalyse(__DIR__ . '/data/bug-7927.php');
+		$this->assertCount(2, $errors);
+		$this->assertSame('Enum case Bug7927\Test::One does not have a value but the enum is backed with the "int" type.', $errors[0]->getMessage());
+		$this->assertSame('Enum case Bug7927\Test::Two does not have a value but the enum is backed with the "int" type.', $errors[1]->getMessage());
+	}
+
 	public function testBug8146(): void
 	{
 		$errors = $this->runAnalyse(__DIR__ . '/data/bug-8146b.php');

tests/PHPStan/Analyser/data/bug-7927.php

@@ -0,0 +1,26 @@
+<?php declare(strict_types = 1);
+
+namespace Bug7927;
+
+enum Test : int
+{
+	case One;
+	case Two;
+}
+
+$v = Test::One;
+
+function doIt(Test $v) : string
+{
+	switch($v)
+	{
+		case Test::One:
+			return "One";
+		case Test::Two:
+			return "Two";
+		default:
+			throw new \ErrorException("Unknown '{$v->name}'.");
+	}
+}
+
+echo doIt($v);