Added Enum stubs to make method purity precise

src/PhpDoc/ReflectionEnumStubFilesExtension.php

@@ -19,11 +19,16 @@ public function getFiles(): array
 			return [];
 		}
 
+		$files = [
+			__DIR__ . '/../../stubs/UnitEnum.stub',
+			__DIR__ . '/../../stubs/BackedEnum.stub',
+		];
+
 		if (!$this->phpVersion->supportsLazyObjects()) {
-			return [__DIR__ . '/../../stubs/ReflectionEnum.stub'];
+			return [__DIR__ . '/../../stubs/ReflectionEnum.stub', ...$files];
 		}
 
-		return [__DIR__ . '/../../stubs/ReflectionEnumWithLazyObjects.stub'];
+		return [__DIR__ . '/../../stubs/ReflectionEnumWithLazyObjects.stub', ...$files];
 	}
 
 }

stubs/BackedEnum.stub

@@ -0,0 +1,14 @@
+<?php
+
+interface BackedEnum extends UnitEnum
+{
+	/**
+	 * @pure
+	 */
+	public static function from(int|string $value): static;
+
+	/**
+	 * @pure
+	 */
+	public static function tryFrom(int|string $value): ?static;
+}

stubs/UnitEnum.stub

@@ -0,0 +1,10 @@
+<?php
+
+interface UnitEnum
+{
+	/**
+	 * @return list<static>
+	 * @pure
+	 */
+	public static function cases(): array;
+}

tests/PHPStan/Rules/Pure/PureFunctionRuleTest.php

@@ -174,4 +174,10 @@ public function testBug12224(): void
 		]);
 	}
 
+	#[RequiresPhp('>= 8.1')]
+	public function testBug13201(): void
+	{
+		$this->analyse([__DIR__ . '/data/bug-13201.php'], []);
+	}
+
 }

tests/PHPStan/Rules/Pure/data/bug-13201.php

@@ -0,0 +1,19 @@
+<?php // lint >= 8.1
+
+namespace PHPStan\Rules\Pure\data\Bug13201;
+
+enum Foo: string
+{
+
+	case Bar     = 'bar';
+	case Unknown = 'unknown';
+
+}
+
+/**
+ * @pure
+ */
+function createWithFallback(string $type): Foo
+{
+	return Foo::tryFrom($type) ?? Foo::Unknown;
+}