Code around enum_exists() does not complain about nonexistent classes (#5751)

Author: staabm

src/Analyser/MutatingScope.php

@@ -309,6 +309,7 @@ private function rememberConstructorExpressions(array $currentExpressionTypes):
 			if ($expr instanceof FuncCall) {
 				if (
 					!$expr->name instanceof Name
+					// interface_exists() etc. imply class_exists() therefore not listed here
 					|| !in_array($expr->name->name, ['class_exists', 'function_exists'], true)
 				) {
 					continue;
@@ -1376,10 +1377,13 @@ public function isInClassExists(string $className): bool
 				'class_exists',
 				'interface_exists',
 				'trait_exists',
+				'enum_exists',
 			], true)) {
 				return true;
 			}
 		}
+
+		// interface_exists() etc. imply class_exists() therefore not listed here
 		$expr = new FuncCall(new FullyQualified('class_exists'), [
 			new Arg(new String_(ltrim($className, '\\'))),
 		]);

tests/PHPStan/Rules/Classes/ClassConstantRuleTest.php

@@ -206,6 +206,19 @@ public function testClassExists(): void
 		]);
 	}
 
+	#[RequiresPhp('>= 8.0.0')]
+	public function testEnumExists(): void
+	{
+		$this->phpVersion = PHP_VERSION_ID;
+		$this->analyse([__DIR__ . '/data/enum-exists.php'], [
+			[
+				'Class UnknownEnum\Foo not found.',
+				7,
+				'Learn more at https://phpstan.org/user-guide/discovering-symbols',
+			],
+		]);
+	}
+
 	public static function dataClassConstantOnExpression(): array
 	{
 		return [

tests/PHPStan/Rules/Classes/data/enum-exists.php

@@ -0,0 +1,8 @@
+<?php
+
+function () {
+	if (enum_exists(\UnknownEnum\Foo::class)) {
+		echo \UnknownEnum\Foo::class;
+	}
+	echo \UnknownEnum\Foo::class;
+};