Make ArrayKeyExistsFunctionTypeSpecifyingExtension understand an empty array

Author: ondrejmirtes

src/Type/ObjectType.php

@@ -540,6 +540,8 @@ public function toArray(): Type
 		$arrayKeys = [];
 		$arrayValues = [];
 
+		$isFinal = $classReflection->isFinal();
+
 		do {
 			foreach ($classReflection->getNativeReflection()->getProperties() as $nativeProperty) {
 				if ($nativeProperty->isStatic()) {
@@ -570,6 +572,10 @@ public function toArray(): Type
 			$classReflection = $classReflection->getParentClass();
 		} while ($classReflection !== null);
 
+		if (!$isFinal && count($arrayKeys) === 0) {
+			return new ArrayType(new MixedType(), new MixedType());
+		}
+
 		return new ConstantArrayType($arrayKeys, $arrayValues);
 	}
 

src/Type/Php/ArrayKeyExistsFunctionTypeSpecifyingExtension.php

@@ -55,13 +55,14 @@ public function specifyTypes(
 		$key = $node->getArgs()[0]->value;
 		$array = $node->getArgs()[1]->value;
 		$keyType = $scope->getType($key);
-		if (!$keyType instanceof ConstantIntegerType && !$keyType instanceof ConstantStringType) {
+		$arrayType = $scope->getType($array);
+		if (!$keyType instanceof ConstantIntegerType && !$keyType instanceof ConstantStringType && !$arrayType->isIterableAtLeastOnce()->no()) {
 			if ($context->truthy()) {
 				$arrayDimFetch = new ArrayDimFetch(
 					$array,
 					$key,
 				);
-				return $this->typeSpecifier->create($arrayDimFetch, $scope->getType($array)->getIterableValueType(), $context, false, $scope, new Identical($arrayDimFetch, new ConstFetch(new Name('__PHPSTAN_FAUX_CONSTANT'))));
+				return $this->typeSpecifier->create($arrayDimFetch, $arrayType->getIterableValueType(), $context, false, $scope, new Identical($arrayDimFetch, new ConstFetch(new Name('__PHPSTAN_FAUX_CONSTANT'))));
 			}
 
 			return new SpecifiedTypes();

tests/PHPStan/Analyser/NodeScopeResolverTest.php

@@ -1006,6 +1006,7 @@ public function dataFileAsserts(): iterable
 		yield from $this->gatherAssertTypes(__DIR__ . '/../Rules/Arrays/data/slevomat-foreach-unset-bug.php');
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/bug-6170.php');
 		yield from $this->gatherAssertTypes(__DIR__ . '/../Rules/Arrays/data/slevomat-foreach-array-key-exists-bug.php');
+		yield from $this->gatherAssertTypes(__DIR__ . '/data/array-key-exists.php');
 	}
 
 	/**

tests/PHPStan/Analyser/data/array-key-exists.php

@@ -0,0 +1,31 @@
+<?php
+
+namespace ArrayKeyExistsExtension;
+
+use function array_key_exists;
+use function PHPStan\Testing\assertType;
+
+class Foo
+{
+
+	/**
+	 * @param array<string, string> $a
+	 * @return void
+	 */
+	public function doFoo(array $a, string $key): void
+	{
+		assertType('false', array_key_exists(2, $a));
+		assertType('bool', array_key_exists('foo', $a));
+		assertType('false', array_key_exists('2', $a));
+
+		$a = ['foo' => 2, 3 => 'bar'];
+		assertType('true', array_key_exists('foo', $a));
+		assertType('true', array_key_exists('3', $a));
+		assertType('false', array_key_exists(4, $a));
+
+		$empty = [];
+		assertType('false', array_key_exists('foo', $empty));
+		assertType('false', array_key_exists($key, $empty));
+	}
+
+}

tests/PHPStan/Rules/Arrays/data/slevomat-foreach-array-key-exists-bug.php

@@ -15,27 +15,26 @@ public function doFoo(array $percentageIntervals, array $changes): void
 				if ($percentageInterval->isInInterval((float) $changeInPercents)) {
 					$key = $percentageInterval->getFormatted();
 					if (array_key_exists($key, $intervalResults)) {
-						assertType('aaa', $intervalResults);
-						assertType('aaa', $intervalResults[$key]);
+						assertType('array<int|string, array{itemsCount: mixed, interval: mixed}>', $intervalResults);
+						assertType('array{itemsCount: mixed, interval: mixed}', $intervalResults[$key]);
 						$intervalResults[$key]['itemsCount'] += $itemsCount;
-						assertType('aaa', $intervalResults);
-						assertType('aaa', $intervalResults[$key]);
+						assertType('non-empty-array<int|string, array{itemsCount: (array|float|int), interval: mixed}>', $intervalResults);
+						assertType('array{itemsCount: (array|float|int), interval: mixed}', $intervalResults[$key]);
 					} else {
-						assertType('aaa', $intervalResults);
-						assertType('aaa', $intervalResults[$key]);
+						assertType('array<int|string, array{itemsCount: mixed, interval: mixed}>', $intervalResults);
+						assertType('array{itemsCount: mixed, interval: mixed}', $intervalResults[$key]);
 						$intervalResults[$key] = [
 							'itemsCount' => $itemsCount,
 							'interval' => $percentageInterval,
 						];
-						assertType('aaa', $intervalResults);
-						assertType('aaa', $intervalResults[$key]);
+						assertType('non-empty-array<int|string, array{itemsCount: mixed, interval: mixed}>', $intervalResults);
+						assertType('array{itemsCount: mixed, interval: mixed}', $intervalResults[$key]);
 					}
 				}
 			}
 		}
 
-		assertType('aaa', $intervalResults);
-		assertType('aaa', $intervalResults);
+		assertType('array<int|string, array{itemsCount: mixed, interval: mixed}>', $intervalResults);
 		foreach ($intervalResults as $data) {
 			echo $data['interval'];
 		}