Correctly retrieve hasSideEffects metadata for inherited methods

Author: zonuexe

src/Reflection/Php/PhpClassReflectionExtension.php

@@ -839,7 +839,17 @@ public function createUserlandMethodReflection(ClassReflection $fileDeclaringCla
 }
 $isInternal = $resolvedPhpDoc->isInternal();
 $isFinal = $resolvedPhpDoc->isFinal();
-$isPure = $resolvedPhpDoc->isPure();
+$isPure = null;
+foreach ($actualDeclaringClass->getAncestors() as $className => $ancestor) {
+if ($this->signatureMapProvider->hasMethodMetadata($className, $methodReflection->getName())) {
+$hasSideEffects = $this->signatureMapProvider->getMethodMetadata($className, $methodReflection->getName())['hasSideEffects'];
+$isPure = !$hasSideEffects;
+
+break;
+}
+}
+
+$isPure ??= $resolvedPhpDoc->isPure();
 $asserts = Assertions::createFromResolvedPhpDocBlock($resolvedPhpDoc);
 $acceptsNamedArguments = $resolvedPhpDoc->acceptsNamedArguments();
 $selfOutType = $resolvedPhpDoc->getSelfOutTag() !== null ? $resolvedPhpDoc->getSelfOutTag()->getType() : null;

src/Reflection/SignatureMap/Php8SignatureMapProvider.php

@@ -64,9 +64,6 @@ public function __construct(
 public function hasMethodSignature(string $className, string $methodName): bool
 {
 $lowerClassName = strtolower($className);
-if ($lowerClassName === 'backedenum') {
-return false;
-}
 if (!array_key_exists($lowerClassName, $this->map->classes)) {
 return $this->functionSignatureMapProvider->hasMethodSignature($className, $methodName);
 }

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;
+}