Fix phpstan/phpstan#14390: Unconsistant behavior for offsetAccess.notFound

src/Rules/Arrays/NonexistentOffsetInArrayDimFetchRule.php

@@ -3,13 +3,15 @@
 namespace PHPStan\Rules\Arrays;
 
 use PhpParser\Node;
+use PhpParser\Node\Expr;
 use PhpParser\Node\Expr\ArrayDimFetch;
 use PhpParser\Node\Expr\Variable;
 use PHPStan\Analyser\NullsafeOperatorHelper;
 use PHPStan\Analyser\Scope;
 use PHPStan\DependencyInjection\AutowiredParameter;
 use PHPStan\DependencyInjection\RegisteredRule;
 use PHPStan\Internal\SprintfHelper;
+use PHPStan\Node\Printer\ExprPrinter;
 use PHPStan\Rules\Rule;
 use PHPStan\Rules\RuleErrorBuilder;
 use PHPStan\Rules\RuleLevelHelper;
@@ -33,6 +35,7 @@
 	public function __construct(
 		private RuleLevelHelper $ruleLevelHelper,
 		private NonexistentOffsetInArrayDimFetchCheck $nonexistentOffsetInArrayDimFetchCheck,
+		private ExprPrinter $exprPrinter,
 		#[AutowiredParameter]
 		private bool $reportMaybes,
 	)
@@ -120,10 +123,8 @@
 			$arrayArg = $node->dim->getArgs()[0]->value;
 			$arrayType = $scope->getType($arrayArg);
 			if (
-				$arrayArg instanceof Node\Expr\Variable
-				&& $node->var instanceof Node\Expr\Variable
-				&& is_string($arrayArg->name)
-				&& $arrayArg->name === $node->var->name
+				$this->isDeterministicExpr($node->var, $scope)
+				&& $this->exprPrinter->printExpr($arrayArg) === $this->exprPrinter->printExpr($node->var)
 				&& $arrayType->isArray()->yes()
 				&& $arrayType->isIterableAtLeastOnce()->yes()
 			) {
@@ -146,10 +147,8 @@
 			$arrayType = $scope->getType($arrayArg);
 
 			if (
-				$arrayArg instanceof Node\Expr\Variable
-				&& $node->var instanceof Node\Expr\Variable
-				&& is_string($arrayArg->name)
-				&& $arrayArg->name === $node->var->name
+				$this->isDeterministicExpr($node->var, $scope)
+				&& $this->exprPrinter->printExpr($arrayArg) === $this->exprPrinter->printExpr($node->var)
 				&& $arrayType->isArray()->yes()
 				&& $arrayType->isIterableAtLeastOnce()->yes()
 				&& ($numArg === null || $one->isSuperTypeOf($scope->getType($numArg))->yes())
@@ -170,10 +169,8 @@
 			$arrayArg = $node->dim->left->getArgs()[0]->value;
 			$arrayType = $scope->getType($arrayArg);
 			if (
-				$arrayArg instanceof Node\Expr\Variable
-				&& $node->var instanceof Node\Expr\Variable
-				&& is_string($arrayArg->name)
-				&& $arrayArg->name === $node->var->name
+				$this->isDeterministicExpr($node->var, $scope)
+				&& $this->exprPrinter->printExpr($arrayArg) === $this->exprPrinter->printExpr($node->var)
 				&& $arrayType->isList()->yes()
 				&& $arrayType->isIterableAtLeastOnce()->yes()
 			) {
@@ -189,6 +186,67 @@
 		);
 	}
 
+	private function isDeterministicExpr(Expr $expr, Scope $scope): bool
+	{
+		if ($expr instanceof Variable) {
+			return true;
+		}
+
+		if ($expr instanceof Expr\PropertyFetch) {
+			return $this->isDeterministicExpr($expr->var, $scope);
+		}
+
+		if ($expr instanceof Expr\StaticPropertyFetch) {
+			return true;
+		}
+
+		if ($expr instanceof Expr\ArrayDimFetch) {
+			if ($expr->dim === null) {
+				return false;
+			}
+
+			return $this->isDeterministicExpr($expr->var, $scope)
+				&& $this->isDeterministicExpr($expr->dim, $scope);
+		}
+
+		if ($expr instanceof Expr\MethodCall && $expr->name instanceof Node\Identifier) {
+			$callerType = $scope->getType($expr->var);
+			$methodReflection = $scope->getMethodReflection($callerType, $expr->name->name);
+			if ($methodReflection !== null && $methodReflection->hasSideEffects()->no()) {
+				return $this->isDeterministicExpr($expr->var, $scope)
+					&& $this->areDeterministicArgs($expr->getArgs(), $scope);
+			}
+
+			return false;
+		}
+
+		if ($expr instanceof Expr\StaticCall && $expr->name instanceof Node\Identifier && $expr->class instanceof Node\Name) {
+			$classType = $scope->resolveTypeByName($expr->class);
+			$methodReflection = $scope->getMethodReflection($classType, $expr->name->name);
+			if ($methodReflection !== null && $methodReflection->hasSideEffects()->no()) {
+				return $this->areDeterministicArgs($expr->getArgs(), $scope);
+			}
+
+			return false;
+		}
+
+		return false;
+	}
+
+	/**
+	 * @param Node\Arg[] $args
+	 */
+	private function areDeterministicArgs(array $args, Scope $scope): bool
+	{
+		foreach ($args as $arg) {
+			if (!$this->isDeterministicExpr($arg->value, $scope)) {
+				return false;
+			}
+		}
+
+		return true;
+	}
+
 	private function isImplicitArrayCreation(Node\Expr\ArrayDimFetch $node, Scope $scope): TrinaryLogic
 	{
 		$varNode = $node->var;

tests/PHPStan/Rules/Arrays/NonexistentOffsetInArrayDimFetchRuleTest.php

@@ -2,6 +2,8 @@
 
 namespace PHPStan\Rules\Arrays;
 
+use PHPStan\Node\Printer\ExprPrinter;
+use PHPStan\Node\Printer\Printer;
 use PHPStan\Rules\Rule;
 use PHPStan\Rules\RuleLevelHelper;
 use PHPStan\Testing\RuleTestCase;
@@ -44,6 +46,7 @@ protected function getRule(): Rule
 				reportPossiblyNonexistentGeneralArrayOffset: $this->reportPossiblyNonexistentGeneralArrayOffset,
 				reportPossiblyNonexistentConstantArrayOffset: $this->reportPossiblyNonexistentConstantArrayOffset,
 			),
+			new ExprPrinter(new Printer()),
 			true,
 		);
 	}
@@ -1277,4 +1280,25 @@ public function testBug14308(): void
 		$this->analyse([__DIR__ . '/data/bug-14308.php'], []);
 	}
 
+	#[RequiresPhp('>= 8.2')]
+	public function testBug14390(): void
+	{
+		$this->reportPossiblyNonexistentGeneralArrayOffset = true;
+
+		$this->analyse([__DIR__ . '/data/bug-14390.php'], [
+			[
+				'Offset (int|string) might not exist on non-empty-array.',
+				135,
+			],
+			[
+				'Offset (int|string) might not exist on non-empty-array.',
+				136,
+			],
+			[
+				'Offset string might not exist on non-empty-array<string, string>.',
+				169,
+			],
+		]);
+	}
+
 }

tests/PHPStan/Rules/Arrays/data/bug-14390.php

@@ -0,0 +1,171 @@
+<?php // lint >= 8.2
+
+declare(strict_types = 1);
+
+namespace Bug14390;
+
+readonly class Sample
+{
+	/**
+	 * @param array<string, string> $fields
+	 */
+	public function __construct(
+		public array $fields = [],
+	) {
+	}
+}
+
+class Foo
+{
+	public function bar(
+		Sample $sample,
+	): void {
+		if ($sample->fields !== []) {
+			echo $sample->fields[array_key_first($sample->fields)];
+		}
+	}
+
+	/**
+	 * @param array<string, string> $fields
+	 */
+	public function zoo(
+		array $fields,
+	): void {
+		if ($fields !== []) {
+			echo $fields[array_key_first($fields)];
+		}
+	}
+
+	public function withKey(
+		Sample $sample,
+	): void {
+		if ($sample->fields !== []) {
+			$key = array_key_first($sample->fields);
+			echo $sample->fields[$key];
+		}
+	}
+
+	public function arrayKeyLast(
+		Sample $sample,
+	): void {
+		if ($sample->fields !== []) {
+			echo $sample->fields[array_key_last($sample->fields)];
+		}
+	}
+
+	public function arrayRand(
+		Sample $sample,
+	): void {
+		if ($sample->fields !== []) {
+			echo $sample->fields[array_rand($sample->fields)];
+		}
+	}
+
+	/**
+	 * @param non-empty-list<string> $list
+	 */
+	public function countMinus1(
+		array $list,
+	): void {
+		echo $list[count($list) - 1];
+	}
+}
+
+readonly class SampleList
+{
+	/**
+	 * @param list<string> $items
+	 */
+	public function __construct(
+		public array $items = [],
+	) {
+	}
+}
+
+class Bar
+{
+	public function countMinus1Property(
+		SampleList $sample,
+	): void {
+		if ($sample->items !== []) {
+			echo $sample->items[count($sample->items) - 1];
+		}
+	}
+}
+
+class StaticProps
+{
+	/** @var array<string, string> */
+	public static array $fields = [];
+
+	/** @var list<string> */
+	public static array $items = [];
+
+	public function arrayKeyFirstStatic(): void
+	{
+		if (self::$fields !== []) {
+			echo self::$fields[array_key_first(self::$fields)];
+		}
+	}
+
+	public function arrayKeyLastStatic(): void
+	{
+		if (self::$fields !== []) {
+			echo self::$fields[array_key_last(self::$fields)];
+		}
+	}
+
+	public function arrayRandStatic(): void
+	{
+		if (self::$fields !== []) {
+			echo self::$fields[array_rand(self::$fields)];
+		}
+	}
+
+	public function countMinus1Static(): void
+	{
+		if (self::$items !== []) {
+			echo self::$items[count(self::$items) - 1];
+		}
+	}
+}
+
+function doWithMethods(WithMethods $withMethods) {
+	echo $withMethods->pureMethod()[array_key_first($withMethods->pureMethod())];
+	echo $withMethods->impureMethod()[array_key_first($withMethods->impureMethod())];
+	echo $withMethods->pureMethod($withMethods->impureMethod())[array_key_first($withMethods->pureMethod($withMethods->impureMethod()))];
+}
+
+class WithMethods {
+	/**
+	 * @phpstan-pure
+	 * @return non-empty-array
+	 */
+	public function pureMethod(mixed ...$args):array {}
+	/**
+	 * @phpstan-impure
+	 * @return non-empty-array
+	 */
+	public function impureMethod():array {}
+}
+
+class NestedArray
+{
+	/**
+	 * @param array<string, non-empty-array<string, string>> $nested
+	 */
+	public function dimFetchDeterministic(array $nested, string $key): void
+	{
+		if (isset($nested[$key])) {
+			echo $nested[$key][array_key_first($nested[$key])];
+		}
+	}
+
+	/**
+	 * @param non-empty-array<string, non-empty-array<string, string>> $nested
+	 */
+	public function dimFetchWithMethodKey(WithMethods $w, array $nested): void
+	{
+		echo $nested[$w->impureMethod()][array_key_first($nested[$w->impureMethod()])];
+	}
+}