From a0ed2d304e0344df34b49e010d5f491f0d321d3a Mon Sep 17 00:00:00 2001
From: Ondrej Mirtes <ondrej@mirtes.cz>
Date: Sat, 15 Jan 2022 14:20:33 +0100
Subject: [PATCH] ClassReflection - getBackedEnumType() method

---
 src/Reflection/ClassReflection.php            | 19 +++++++++++++++++++
 .../Reflection/ClassReflectionTest.php        | 12 ++++++++++++
 2 files changed, 31 insertions(+)

diff --git a/src/Reflection/ClassReflection.php b/src/Reflection/ClassReflection.php
index 90f9dba904..10e4c9aa7a 100644
--- a/src/Reflection/ClassReflection.php
+++ b/src/Reflection/ClassReflection.php
@@ -29,6 +29,7 @@
 use PHPStan\Type\Generic\TemplateTypeScope;
 use PHPStan\Type\Type;
 use PHPStan\Type\TypeAlias;
+use PHPStan\Type\TypehintHelper;
 use PHPStan\Type\VerbosityLevel;
 use ReflectionClass;
 use ReflectionEnum;
@@ -512,6 +513,24 @@ public function isBackedEnum(): bool
 		return $this->reflection->isBacked();
 	}
 
+	public function getBackedEnumType(): ?Type
+	{
+		if (!$this->reflection instanceof ReflectionEnum) {
+			return null;
+		}
+
+		if (!$this->reflection->isBacked()) {
+			return null;
+		}
+
+		$reflectionType = $this->reflection->getBackingType();
+		if ($reflectionType === null) {
+			return null;
+		}
+
+		return TypehintHelper::decideTypeFromReflection($reflectionType);
+	}
+
 	public function hasEnumCase(string $name): bool
 	{
 		if (!$this->isEnum()) {
diff --git a/tests/PHPStan/Reflection/ClassReflectionTest.php b/tests/PHPStan/Reflection/ClassReflectionTest.php
index 7e116809f9..2b7eaf367b 100644
--- a/tests/PHPStan/Reflection/ClassReflectionTest.php
+++ b/tests/PHPStan/Reflection/ClassReflectionTest.php
@@ -33,6 +33,7 @@
 use PHPStan\PhpDoc\StubPhpDocProvider;
 use PHPStan\Testing\PHPStanTestCase;
 use PHPStan\Type\FileTypeMapper;
+use PHPStan\Type\IntegerType;
 use ReflectionClass;
 use ReflectionEnum;
 use WrongClassConstantFile\SecuredRouter;
@@ -339,4 +340,15 @@ public function testEnumIsFinal(): void
 		$this->assertTrue($enum->isFinalByKeyword());
 	}
 
+	public function testBackedEnumType(): void
+	{
+		if (PHP_VERSION_ID < 80100) {
+			$this->markTestSkipped('Test requires PHP 8.1.');
+		}
+
+		$reflectionProvider = $this->createReflectionProvider();
+		$enum = $reflectionProvider->getClass('PHPStan\Fixture\TestEnum');
+		$this->assertInstanceOf(IntegerType::class, $enum->getBackedEnumType());
+	}
+
 }