Fix type inference for reportUnsafeArrayStringKeyCasting: detect

Author: ondrejmirtes

src/Type/ArrayType.php

@@ -2,7 +2,6 @@
 
 namespace PHPStan\Type;
 
-use PHPStan\DependencyInjection\ReportUnsafeArrayStringKeyCastingToggle;
 use PHPStan\Php\PhpVersion;
 use PHPStan\PhpDocParser\Ast\Type\GenericTypeNode;
 use PHPStan\PhpDocParser\Ast\Type\IdentifierTypeNode;
@@ -13,7 +12,6 @@
 use PHPStan\ShouldNotHappenException;
 use PHPStan\TrinaryLogic;
 use PHPStan\Type\Accessory\AccessoryArrayListType;
-use PHPStan\Type\Accessory\AccessoryDecimalIntegerStringType;
 use PHPStan\Type\Accessory\AccessoryLowercaseStringType;
 use PHPStan\Type\Accessory\AccessoryNonEmptyStringType;
 use PHPStan\Type\Accessory\AccessoryNonFalsyStringType;
@@ -37,6 +35,7 @@
 use PHPStan\Type\Traits\NonObjectTypeTrait;
 use PHPStan\Type\Traits\UndecidedBooleanTypeTrait;
 use PHPStan\Type\Traits\UndecidedComparisonTypeTrait;
+use PHPStan\Type\Traverser\UnsafeArrayStringKeyCastingTraverser;
 use function array_map;
 use function array_merge;
 use function count;
@@ -239,33 +238,7 @@ public function getIterableKeyType(): Type
 			$keyType = (new BenevolentUnionType([new IntegerType(), new StringType()]))->toArrayKey();
 		}
 
-		$level = ReportUnsafeArrayStringKeyCastingToggle::getLevel();
-		if ($level === null) {
-			return $this->cachedIterableKeyType = $keyType;
-		}
-
-		if ($level === ReportUnsafeArrayStringKeyCastingToggle::PREVENT) {
-			return $this->cachedIterableKeyType = $keyType;
-		}
-
-		if ($level !== ReportUnsafeArrayStringKeyCastingToggle::DETECT) { // @phpstan-ignore notIdentical.alwaysFalse
-			throw new ShouldNotHappenException();
-		}
-
-		return $this->cachedIterableKeyType = TypeTraverser::map($keyType, static function (Type $type, callable $traverse): Type {
-			if ($type instanceof UnionType) {
-				return $traverse($type);
-			}
-
-			if ($type->isString()->yes() && !$type->isDecimalIntegerString()->no()) {
-				return TypeCombinator::union(
-					new IntegerType(),
-					TypeCombinator::intersect($type, new AccessoryDecimalIntegerStringType(inverse: true)),
-				);
-			}
-
-			return $type;
-		});
+		return $this->cachedIterableKeyType = UnsafeArrayStringKeyCastingTraverser::castKeyType($keyType);
 	}
 
 	public function getFirstIterableKeyType(): Type

src/Type/Constant/ConstantArrayType.php

@@ -61,6 +61,7 @@
 use PHPStan\Type\Traits\ArrayTypeTrait;
 use PHPStan\Type\Traits\NonObjectTypeTrait;
 use PHPStan\Type\Traits\UndecidedComparisonTypeTrait;
+use PHPStan\Type\Traverser\UnsafeArrayStringKeyCastingTraverser;
 use PHPStan\Type\Type;
 use PHPStan\Type\TypeCombinator;
 use PHPStan\Type\UnionType;
@@ -301,7 +302,7 @@ public function getIterableKeyType(): Type
 			$keyType = TypeCombinator::union($keyType, $unsealedKeyType);
 		}
 
-		return $this->iterableKeyType = $keyType;
+		return $this->iterableKeyType = UnsafeArrayStringKeyCastingTraverser::castKeyType($keyType);
 	}
 
 	public function getIterableValueType(): Type

src/Type/Traverser/UnsafeArrayStringKeyCastingTraverser.php

@@ -0,0 +1,53 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Type\Traverser;
+
+use PHPStan\DependencyInjection\ReportUnsafeArrayStringKeyCastingToggle;
+use PHPStan\Type\Accessory\AccessoryDecimalIntegerStringType;
+use PHPStan\Type\IntegerType;
+use PHPStan\Type\Type;
+use PHPStan\Type\TypeCombinator;
+use PHPStan\Type\TypeTraverser;
+use PHPStan\Type\TypeTraverserCallable;
+use PHPStan\Type\UnionType;
+
+/**
+ * Under `reportUnsafeArrayStringKeyCasting: detect`, PHP casts a decimal-integer
+ * string array key ("123") to int when iterating, so the iterable key type widens
+ * from `string` to `int | non-decimal-int-string`. Shared by ArrayType and
+ * ConstantArrayType so both representations agree — otherwise comparing a general
+ * array (cast key) against a constant-array shape (raw key) yields a spurious
+ * `Maybe`.
+ */
+final class UnsafeArrayStringKeyCastingTraverser implements TypeTraverserCallable
+{
+
+	public static function castKeyType(Type $keyType): Type
+	{
+		if (ReportUnsafeArrayStringKeyCastingToggle::getLevel() !== ReportUnsafeArrayStringKeyCastingToggle::DETECT) {
+			return $keyType;
+		}
+
+		return TypeTraverser::map($keyType, new self());
+	}
+
+	/**
+	 * @param callable(Type): Type $traverse
+	 */
+	public function traverse(Type $type, callable $traverse): Type
+	{
+		if ($type instanceof UnionType) {
+			return $traverse($type);
+		}
+
+		if ($type->isString()->yes() && !$type->isDecimalIntegerString()->no()) {
+			return TypeCombinator::union(
+				new IntegerType(),
+				TypeCombinator::intersect($type, new AccessoryDecimalIntegerStringType(inverse: true)),
+			);
+		}
+
+		return $type;
+	}
+
+}

tests/PHPStan/Analyser/data/report-unsafe-array-string-key-casting-detect.php

@@ -89,3 +89,41 @@ public function doArrayCreationAndAssign(string $s): void
 	}
 
 }
+
+class Unsealed
+{
+
+	/**
+	 * @param array{a: self, ...<string, self>} $a
+	 */
+	public function doFoo(array $a): void
+	{
+		assertType('array{a: ReportUnsafeArrayStringKeyCastingDetect\Unsealed, ...<string, ReportUnsafeArrayStringKeyCastingDetect\Unsealed>}', $a);
+		foreach ($a as $k => $v) {
+			assertType('int|non-decimal-int-string', $k);
+		}
+	}
+
+	/**
+	 * @param array{a: self, ...<self>} $a
+	 */
+	public function doBar(array $a): void
+	{
+		assertType('array{a: ReportUnsafeArrayStringKeyCastingDetect\Unsealed, ...<ReportUnsafeArrayStringKeyCastingDetect\Unsealed>}', $a);
+		foreach ($a as $k => $v) {
+			assertType('(int|non-decimal-int-string)', $k);
+		}
+	}
+
+	/**
+	 * @param array{a: self, ...<int|string, self>} $a
+	 */
+	public function doBaz(array $a): void
+	{
+		assertType('array{a: ReportUnsafeArrayStringKeyCastingDetect\Unsealed, ...<int|string, ReportUnsafeArrayStringKeyCastingDetect\Unsealed>}', $a);
+		foreach ($a as $k => $v) {
+			assertType('int|non-decimal-int-string', $k);
+		}
+	}
+
+}