Do not generalize class-string during template type inference

src/Type/Accessory/AccessoryLiteralStringType.php

@@ -9,6 +9,7 @@
 use PHPStan\Type\Constant\ConstantIntegerType;
 use PHPStan\Type\ErrorType;
 use PHPStan\Type\FloatType;
+use PHPStan\Type\GeneralizePrecision;
 use PHPStan\Type\IntegerType;
 use PHPStan\Type\IntersectionType;
 use PHPStan\Type\MixedType;
@@ -186,6 +187,11 @@ public function traverse(callable $cb): Type
 		return $this;
 	}
 
+	public function generalize(GeneralizePrecision $precision): Type
+	{
+		return new StringType();
+	}
+
 	public static function __set_state(array $properties): Type
 	{
 		return new self();

src/Type/Accessory/AccessoryNonEmptyStringType.php

@@ -8,6 +8,7 @@
 use PHPStan\Type\Constant\ConstantIntegerType;
 use PHPStan\Type\ErrorType;
 use PHPStan\Type\FloatType;
+use PHPStan\Type\GeneralizePrecision;
 use PHPStan\Type\IntegerType;
 use PHPStan\Type\IntersectionType;
 use PHPStan\Type\StringType;
@@ -182,6 +183,11 @@ public function traverse(callable $cb): Type
 		return $this;
 	}
 
+	public function generalize(GeneralizePrecision $precision): Type
+	{
+		return new StringType();
+	}
+
 	public static function __set_state(array $properties): Type
 	{
 		return new self();

src/Type/Accessory/AccessoryNumericStringType.php

@@ -8,6 +8,7 @@
 use PHPStan\Type\Constant\ConstantIntegerType;
 use PHPStan\Type\ErrorType;
 use PHPStan\Type\FloatType;
+use PHPStan\Type\GeneralizePrecision;
 use PHPStan\Type\IntegerType;
 use PHPStan\Type\IntersectionType;
 use PHPStan\Type\StringType;
@@ -181,6 +182,11 @@ public function traverse(callable $cb): Type
 		return $this;
 	}
 
+	public function generalize(GeneralizePrecision $precision): Type
+	{
+		return new StringType();
+	}
+
 	public static function __set_state(array $properties): Type
 	{
 		return new self();

src/Type/Accessory/HasMethodType.php

@@ -11,6 +11,7 @@
 use PHPStan\TrinaryLogic;
 use PHPStan\Type\CompoundType;
 use PHPStan\Type\IntersectionType;
+use PHPStan\Type\Traits\NonGeneralizableTypeTrait;
 use PHPStan\Type\Traits\NonGenericTypeTrait;
 use PHPStan\Type\Traits\NonRemoveableTypeTrait;
 use PHPStan\Type\Traits\ObjectTypeTrait;
@@ -28,6 +29,7 @@ class HasMethodType implements AccessoryType, CompoundType
 	use NonGenericTypeTrait;
 	use UndecidedComparisonCompoundTypeTrait;
 	use NonRemoveableTypeTrait;
+	use NonGeneralizableTypeTrait;
 
 	/** @api */
 	public function __construct(private string $methodName)

src/Type/Accessory/HasOffsetType.php

@@ -11,6 +11,7 @@
 use PHPStan\Type\Traits\MaybeCallableTypeTrait;
 use PHPStan\Type\Traits\MaybeIterableTypeTrait;
 use PHPStan\Type\Traits\MaybeObjectTypeTrait;
+use PHPStan\Type\Traits\NonGeneralizableTypeTrait;
 use PHPStan\Type\Traits\NonGenericTypeTrait;
 use PHPStan\Type\Traits\NonRemoveableTypeTrait;
 use PHPStan\Type\Traits\TruthyBooleanTypeTrait;
@@ -30,6 +31,7 @@ class HasOffsetType implements CompoundType, AccessoryType
 	use NonGenericTypeTrait;
 	use UndecidedComparisonCompoundTypeTrait;
 	use NonRemoveableTypeTrait;
+	use NonGeneralizableTypeTrait;
 
 	/** @api */
 	public function __construct(private Type $offsetType)

src/Type/Accessory/HasPropertyType.php

@@ -7,6 +7,7 @@
 use PHPStan\TrinaryLogic;
 use PHPStan\Type\CompoundType;
 use PHPStan\Type\IntersectionType;
+use PHPStan\Type\Traits\NonGeneralizableTypeTrait;
 use PHPStan\Type\Traits\NonGenericTypeTrait;
 use PHPStan\Type\Traits\NonRemoveableTypeTrait;
 use PHPStan\Type\Traits\ObjectTypeTrait;
@@ -23,6 +24,7 @@ class HasPropertyType implements AccessoryType, CompoundType
 	use NonGenericTypeTrait;
 	use UndecidedComparisonCompoundTypeTrait;
 	use NonRemoveableTypeTrait;
+	use NonGeneralizableTypeTrait;
 
 	/** @api */
 	public function __construct(private string $propertyName)

src/Type/Accessory/NonEmptyArrayType.php

@@ -10,6 +10,7 @@
 use PHPStan\Type\IntersectionType;
 use PHPStan\Type\MixedType;
 use PHPStan\Type\Traits\MaybeCallableTypeTrait;
+use PHPStan\Type\Traits\NonGeneralizableTypeTrait;
 use PHPStan\Type\Traits\NonGenericTypeTrait;
 use PHPStan\Type\Traits\NonObjectTypeTrait;
 use PHPStan\Type\Traits\NonRemoveableTypeTrait;
@@ -28,6 +29,7 @@ class NonEmptyArrayType implements CompoundType, AccessoryType
 	use NonGenericTypeTrait;
 	use UndecidedComparisonCompoundTypeTrait;
 	use NonRemoveableTypeTrait;
+	use NonGeneralizableTypeTrait;
 
 	/** @api */
 	public function __construct()

src/Type/ArrayType.php

@@ -18,6 +18,7 @@
 use PHPStan\Type\Generic\TemplateTypeMap;
 use PHPStan\Type\Generic\TemplateTypeVariance;
 use PHPStan\Type\Traits\MaybeCallableTypeTrait;
+use PHPStan\Type\Traits\NonGeneralizableTypeTrait;
 use PHPStan\Type\Traits\NonObjectTypeTrait;
 use PHPStan\Type\Traits\UndecidedBooleanTypeTrait;
 use PHPStan\Type\Traits\UndecidedComparisonTypeTrait;
@@ -36,6 +37,7 @@ class ArrayType implements Type
 	use NonObjectTypeTrait;
 	use UndecidedBooleanTypeTrait;
 	use UndecidedComparisonTypeTrait;
+	use NonGeneralizableTypeTrait;
 
 	private Type $keyType;
 

src/Type/BooleanType.php

@@ -8,6 +8,7 @@
 use PHPStan\Type\Constant\ConstantIntegerType;
 use PHPStan\Type\Constant\ConstantStringType;
 use PHPStan\Type\Traits\NonCallableTypeTrait;
+use PHPStan\Type\Traits\NonGeneralizableTypeTrait;
 use PHPStan\Type\Traits\NonGenericTypeTrait;
 use PHPStan\Type\Traits\NonIterableTypeTrait;
 use PHPStan\Type\Traits\NonObjectTypeTrait;
@@ -27,6 +28,7 @@ class BooleanType implements Type
 	use UndecidedComparisonTypeTrait;
 	use NonGenericTypeTrait;
 	use NonOffsetAccessibleTypeTrait;
+	use NonGeneralizableTypeTrait;
 
 	/** @api */
 	public function __construct()

src/Type/CallableType.php

@@ -16,6 +16,7 @@
 use PHPStan\Type\Traits\MaybeIterableTypeTrait;
 use PHPStan\Type\Traits\MaybeObjectTypeTrait;
 use PHPStan\Type\Traits\MaybeOffsetAccessibleTypeTrait;
+use PHPStan\Type\Traits\NonGeneralizableTypeTrait;
 use PHPStan\Type\Traits\NonRemoveableTypeTrait;
 use PHPStan\Type\Traits\TruthyBooleanTypeTrait;
 use PHPStan\Type\Traits\UndecidedComparisonCompoundTypeTrait;
@@ -34,6 +35,7 @@ class CallableType implements CompoundType, ParametersAcceptor
 	use TruthyBooleanTypeTrait;
 	use UndecidedComparisonCompoundTypeTrait;
 	use NonRemoveableTypeTrait;
+	use NonGeneralizableTypeTrait;
 
 	/** @var array<int, ParameterReflection> */
 	private array $parameters;

src/Type/ClosureType.php

@@ -22,6 +22,7 @@
 use PHPStan\Type\Generic\TemplateType;
 use PHPStan\Type\Generic\TemplateTypeHelper;
 use PHPStan\Type\Generic\TemplateTypeMap;
+use PHPStan\Type\Traits\NonGeneralizableTypeTrait;
 use PHPStan\Type\Traits\NonGenericTypeTrait;
 use PHPStan\Type\Traits\NonOffsetAccessibleTypeTrait;
 use PHPStan\Type\Traits\NonRemoveableTypeTrait;
@@ -39,6 +40,7 @@ class ClosureType implements TypeWithClassName, ParametersAcceptor
 	use UndecidedComparisonTypeTrait;
 	use NonOffsetAccessibleTypeTrait;
 	use NonRemoveableTypeTrait;
+	use NonGeneralizableTypeTrait;
 
 	private ObjectType $objectType;
 

src/Type/Constant/ConstantArrayType.php

@@ -625,6 +625,10 @@ public function generalize(GeneralizePrecision $precision): Type
 			return $this;
 		}
 
+		if ($precision->isTemplateArgument()) {
+			return $this->traverse(static fn (Type $type) => $type->generalize($precision));
+		}
+
 		$arrayType = new ArrayType(
 			TypeUtils::generalizeType($this->getKeyType(), $precision),
 			TypeUtils::generalizeType($this->getItemType(), $precision),

src/Type/FloatType.php

@@ -7,6 +7,7 @@
 use PHPStan\Type\Constant\ConstantArrayType;
 use PHPStan\Type\Constant\ConstantIntegerType;
 use PHPStan\Type\Traits\NonCallableTypeTrait;
+use PHPStan\Type\Traits\NonGeneralizableTypeTrait;
 use PHPStan\Type\Traits\NonGenericTypeTrait;
 use PHPStan\Type\Traits\NonIterableTypeTrait;
 use PHPStan\Type\Traits\NonObjectTypeTrait;
@@ -28,6 +29,7 @@ class FloatType implements Type
 	use NonGenericTypeTrait;
 	use NonOffsetAccessibleTypeTrait;
 	use NonRemoveableTypeTrait;
+	use NonGeneralizableTypeTrait;
 
 	/** @api */
 	public function __construct()

src/Type/GeneralizePrecision.php

@@ -7,6 +7,7 @@ class GeneralizePrecision
 
 	private const LESS_SPECIFIC = 1;
 	private const MORE_SPECIFIC = 2;
+	private const TEMPLATE_ARGUMENT = 3;
 
 	/** @var self[] */
 	private static array $registry;
@@ -33,9 +34,25 @@ public static function moreSpecific(): self
 		return self::create(self::MORE_SPECIFIC);
 	}
 
+	/** @api */
+	public static function templateArgument(): self
+	{
+		return self::create(self::TEMPLATE_ARGUMENT);
+	}
+
+	public function isLessSpecific(): bool
+	{
+		return $this->value === self::LESS_SPECIFIC;
+	}
+
 	public function isMoreSpecific(): bool
 	{
 		return $this->value === self::MORE_SPECIFIC;
 	}
 
+	public function isTemplateArgument(): bool
+	{
+		return $this->value === self::TEMPLATE_ARGUMENT;
+	}
+
 }

src/Type/Generic/TemplateTypeHelper.php

@@ -2,11 +2,7 @@
 
 namespace PHPStan\Type\Generic;
 
-use PHPStan\Type\Constant\ConstantArrayType;
-use PHPStan\Type\ConstantType;
 use PHPStan\Type\ErrorType;
-use PHPStan\Type\GeneralizePrecision;
-use PHPStan\Type\StringType;
 use PHPStan\Type\Type;
 use PHPStan\Type\TypeTraverser;
 
@@ -64,23 +60,4 @@ public static function toArgument(Type $type): Type
 		});
 	}
 
-	public static function generalizeType(Type $type): Type
-	{
-		return TypeTraverser::map($type, static function (Type $type, callable $traverse): Type {
-			if ($type instanceof ConstantType && !$type instanceof ConstantArrayType) {
-				return $type->generalize(GeneralizePrecision::lessSpecific());
-			}
-
-			if ($type->isNonEmptyString()->yes()) {
-				return new StringType();
-			}
-
-			if ($type->isLiteralString()->yes()) {
-				return new StringType();
-			}
-
-			return $traverse($type);
-		});
-	}
-
 }

src/Type/Generic/TemplateTypeTrait.php

@@ -3,6 +3,7 @@
 namespace PHPStan\Type\Generic;
 
 use PHPStan\TrinaryLogic;
+use PHPStan\Type\GeneralizePrecision;
 use PHPStan\Type\IntersectionType;
 use PHPStan\Type\MixedType;
 use PHPStan\Type\Type;
@@ -194,7 +195,7 @@ public function inferTemplateTypes(Type $receivedType): TemplateTypeMap
 		$resolvedBound = TemplateTypeHelper::resolveTemplateTypes($this->getBound(), $map);
 		if ($resolvedBound->isSuperTypeOf($receivedType)->yes()) {
 			return (new TemplateTypeMap([
-				$this->name => $this->shouldGeneralizeInferredType() ? TemplateTypeHelper::generalizeType($receivedType) : $receivedType,
+				$this->name => $this->shouldGeneralizeInferredType() ? $receivedType->generalize(GeneralizePrecision::templateArgument()) : $receivedType,
 			]))->union($map);
 		}
 

src/Type/IntegerType.php

@@ -6,6 +6,7 @@
 use PHPStan\Type\Constant\ConstantArrayType;
 use PHPStan\Type\Constant\ConstantIntegerType;
 use PHPStan\Type\Traits\NonCallableTypeTrait;
+use PHPStan\Type\Traits\NonGeneralizableTypeTrait;
 use PHPStan\Type\Traits\NonGenericTypeTrait;
 use PHPStan\Type\Traits\NonIterableTypeTrait;
 use PHPStan\Type\Traits\NonObjectTypeTrait;
@@ -25,6 +26,7 @@ class IntegerType implements Type
 	use UndecidedComparisonTypeTrait;
 	use NonGenericTypeTrait;
 	use NonOffsetAccessibleTypeTrait;
+	use NonGeneralizableTypeTrait;
 
 	/** @api */
 	public function __construct()

src/Type/IntersectionType.php

@@ -22,6 +22,8 @@
 use PHPStan\Type\Generic\TemplateType;
 use PHPStan\Type\Generic\TemplateTypeMap;
 use PHPStan\Type\Generic\TemplateTypeVariance;
+use PHPStan\Type\Traits\NonGeneralizableTypeTrait;
+use PHPStan\Type\Traits\NonRemoveableTypeTrait;
 use function array_map;
 use function count;
 use function implode;
@@ -34,6 +36,9 @@
 class IntersectionType implements CompoundType
 {
 
+	use NonRemoveableTypeTrait;
+	use NonGeneralizableTypeTrait;
+
 	/** @var Type[] */
 	private array $types;
 

src/Type/IterableType.php

@@ -12,6 +12,7 @@
 use PHPStan\Type\Traits\MaybeCallableTypeTrait;
 use PHPStan\Type\Traits\MaybeObjectTypeTrait;
 use PHPStan\Type\Traits\MaybeOffsetAccessibleTypeTrait;
+use PHPStan\Type\Traits\NonGeneralizableTypeTrait;
 use PHPStan\Type\Traits\UndecidedBooleanTypeTrait;
 use PHPStan\Type\Traits\UndecidedComparisonCompoundTypeTrait;
 use Traversable;
@@ -27,6 +28,7 @@ class IterableType implements CompoundType
 	use MaybeOffsetAccessibleTypeTrait;
 	use UndecidedBooleanTypeTrait;
 	use UndecidedComparisonCompoundTypeTrait;
+	use NonGeneralizableTypeTrait;
 
 	/** @api */
 	public function __construct(

src/Type/MixedType.php

@@ -19,6 +19,7 @@
 use PHPStan\Type\Constant\ConstantBooleanType;
 use PHPStan\Type\Generic\TemplateMixedType;
 use PHPStan\Type\Generic\TemplateType;
+use PHPStan\Type\Traits\NonGeneralizableTypeTrait;
 use PHPStan\Type\Traits\NonGenericTypeTrait;
 use PHPStan\Type\Traits\UndecidedComparisonCompoundTypeTrait;
 use function sprintf;
@@ -29,6 +30,7 @@ class MixedType implements CompoundType, SubtractableType
 
 	use NonGenericTypeTrait;
 	use UndecidedComparisonCompoundTypeTrait;
+	use NonGeneralizableTypeTrait;
 
 	private ?Type $subtractedType;
 

src/Type/NeverType.php

@@ -12,6 +12,7 @@
 use PHPStan\Reflection\Type\UnresolvedPropertyPrototypeReflection;
 use PHPStan\ShouldNotHappenException;
 use PHPStan\TrinaryLogic;
+use PHPStan\Type\Traits\NonGeneralizableTypeTrait;
 use PHPStan\Type\Traits\NonGenericTypeTrait;
 use PHPStan\Type\Traits\NonRemoveableTypeTrait;
 use PHPStan\Type\Traits\UndecidedBooleanTypeTrait;
@@ -25,6 +26,7 @@ class NeverType implements CompoundType
 	use NonGenericTypeTrait;
 	use UndecidedComparisonCompoundTypeTrait;
 	use NonRemoveableTypeTrait;
+	use NonGeneralizableTypeTrait;
 
 	/** @api */
 	public function __construct(private bool $isExplicit = false)