Resolve value of BackEnum

Author: VincentLanglet

src/Type/ValueOfType.php

@@ -5,6 +5,7 @@
 use PHPStan\PhpDocParser\Ast\Type\GenericTypeNode;
 use PHPStan\PhpDocParser\Ast\Type\IdentifierTypeNode;
 use PHPStan\PhpDocParser\Ast\Type\TypeNode;
+use PHPStan\Type\Generic\TemplateType;
 use PHPStan\Type\Generic\TemplateTypeVariance;
 use PHPStan\Type\Traits\LateResolvableTypeTrait;
 use PHPStan\Type\Traits\NonGeneralizableTypeTrait;
@@ -50,6 +51,13 @@ public function isResolvable(): bool
 	protected function getResult(): Type
 	{
 		if ($this->type->isEnum()->yes()) {
+			if ($this->type instanceof TemplateType) {
+				$bound = $this->type->getBound();
+				if ($bound->equals(new ObjectType('BackedEnum'))) {
+					return new UnionType([new IntegerType(), new StringType()]);
+				}
+			}
+
 			$valueTypes = [];
 			foreach ($this->type->getEnumCases() as $enumCase) {
 				$valueType = $enumCase->getBackingValueType();

tests/PHPStan/Rules/Methods/CallMethodsRuleTest.php

@@ -3666,6 +3666,16 @@ public function testBug3396(): void
 		$this->analyse([__DIR__ . '/data/bug-3396.php'], []);
 	}
 
+	#[RequiresPhp('>= 8.1')]
+	public function testBug12219(): void
+	{
+		$this->checkThisOnly = false;
+		$this->checkNullables = true;
+		$this->checkUnionTypes = true;
+		$this->checkExplicitMixed = true;
+		$this->analyse([__DIR__ . '/data/bug-12219.php'], []);
+	}
+
 	public function testBug13511(): void
 	{
 		$this->checkThisOnly = false;

tests/PHPStan/Rules/Methods/data/bug-12219.php

@@ -0,0 +1,26 @@
+<?php // lint >= 8.1
+
+namespace Bug12219;
+
+class Bug
+{
+	/**
+	 * @template T of \BackedEnum
+	 * @param class-string<T> $class
+	 * @param value-of<T> $value
+	 */
+	public function foo(string $class, mixed $value): void
+	{
+	}
+
+	/**
+	 * @template Q of \BackedEnum
+	 * @param class-string<Q> $class
+	 * @param value-of<Q> $value
+	 */
+	public function bar(string $class, mixed $value): void
+	{
+		// Parameter #2 $value of static method Bug::foo() contains unresolvable type.
+		$this->foo($class, $value);
+	}
+}