Report new on an expression whose type is not string|object via new.nonObject

conf/bleedingEdge.neon

@@ -20,3 +20,4 @@ parameters:
 		reportMethodPurityOverride: true
 		checkDynamicConstantNameValues: true
 		unusedLabel: true
+		newOnNonObject: true

conf/config.neon

@@ -47,6 +47,7 @@ parameters:
 		reportMethodPurityOverride: false
 		checkDynamicConstantNameValues: false
 		unusedLabel: false
+		newOnNonObject: false
 	fileExtensions:
 		- php
 	checkAdvancedIsset: false

conf/parametersSchema.neon

@@ -49,6 +49,7 @@ parametersSchema:
 		reportMethodPurityOverride: bool()
 		checkDynamicConstantNameValues: bool()
 		unusedLabel: bool()
+		newOnNonObject: bool()
 	])
 	fileExtensions: listOf(string())
 	checkAdvancedIsset: bool()

src/Rules/Classes/InstantiationRule.php

@@ -24,8 +24,15 @@
 use PHPStan\Rules\RestrictedUsage\RewrittenDeclaringClassMethodReflection;
 use PHPStan\Rules\Rule;
 use PHPStan\Rules\RuleErrorBuilder;
+use PHPStan\Rules\RuleLevelHelper;
 use PHPStan\ShouldNotHappenException;
 use PHPStan\Type\Constant\ConstantStringType;
+use PHPStan\Type\ErrorType;
+use PHPStan\Type\ObjectWithoutClassType;
+use PHPStan\Type\StringType;
+use PHPStan\Type\Type;
+use PHPStan\Type\UnionType;
+use PHPStan\Type\VerbosityLevel;
 use function array_filter;
 use function array_map;
 use function array_merge;
@@ -48,7 +55,10 @@
 		private ReflectionProvider $reflectionProvider,
 		private FunctionCallParametersCheck $check,
 		private ClassNameCheck $classCheck,
+		private RuleLevelHelper $ruleLevelHelper,
 		private ConsistentConstructorHelper $consistentConstructorHelper,
+		#[AutowiredParameter(ref: '%featureToggles.newOnNonObject%')]
+		private bool $newOnNonObject,
 		#[AutowiredParameter(ref: '%tips.discoveringSymbols%')]
 		private bool $discoveringSymbolsTip,
 	)
@@ -62,13 +72,51 @@
 
 	public function processNode(Node $node, Scope&NodeCallbackInvoker&CollectedDataEmitter $scope): array
 	{
+		if ($this->newOnNonObject && $node->class instanceof Node\Expr) {
+			$errors = $this->checkClassNameExprType($node->class, $scope);
+			if ($errors !== []) {
+				return $errors;
+			}
+		}
+
 		$errors = [];
 		foreach ($this->getClassNames($node, $scope) as [$class, $isName]) {
 			$errors = array_merge($errors, $this->checkClassName($class, $isName, $node, $scope));
 		}
 		return $errors;
 	}
 
+	/**
+	 * @return list<IdentifierRuleError>
+	 */
+	private function checkClassNameExprType(Node\Expr $class, Scope $scope): array
+	{
+		$acceptedType = new UnionType([new StringType(), new ObjectWithoutClassType()]);
+		$typeResult = $this->ruleLevelHelper->findTypeToCheck(
+			$scope,
+			$class,
+			'',
+			static fn (Type $type): bool => $acceptedType->isSuperTypeOf($type)->yes(),
+		);
+
+		$foundType = $typeResult->getType();
+		if ($foundType instanceof ErrorType) {
+			// Unknown classes and mixed are reported elsewhere (e.g. "Instantiated class X not found.").
+			return [];
+		}
+
+		if ($acceptedType->isSuperTypeOf($foundType)->yes()) {
+			return [];
+		}
+
+		return [
+			RuleErrorBuilder::message(sprintf(
+				'Cannot instantiate class using %s.',
+				$foundType->describe(VerbosityLevel::typeOnly()),
+			))->identifier('new.nonObject')->build(),
+		];
+	}
+
 	/**
 	 * @param Node\Expr\New_ $node
 	 * @return list<IdentifierRuleError>

tests/PHPStan/Rules/Classes/ForbiddenNameCheckExtensionRuleTest.php

@@ -24,20 +24,21 @@ protected function getRule(): Rule
 	{
 		$reflectionProvider = self::createReflectionProvider();
 		$container = self::getContainer();
+		$ruleLevelHelper = new RuleLevelHelper(
+			$reflectionProvider,
+			checkNullables: true,
+			checkThisOnly: false,
+			checkUnionTypes: true,
+			checkExplicitMixed: false,
+			checkImplicitMixed: false,
+			checkBenevolentUnionTypes: false,
+			discoveringSymbolsTip: true,
+		);
 		return new InstantiationRule(
 			$container,
 			$reflectionProvider,
 			new FunctionCallParametersCheck(
-				new RuleLevelHelper(
-					$reflectionProvider,
-					checkNullables: true,
-					checkThisOnly: false,
-					checkUnionTypes: true,
-					checkExplicitMixed: false,
-					checkImplicitMixed: false,
-					checkBenevolentUnionTypes: false,
-					discoveringSymbolsTip: true,
-				),
+				$ruleLevelHelper,
 				new NullsafeCheck(),
 				new UnresolvableTypeHelper(),
 				new PropertyReflectionFinder(),
@@ -53,7 +54,9 @@ protected function getRule(): Rule
 				$reflectionProvider,
 				$container,
 			),
+			$ruleLevelHelper,
 			new ConsistentConstructorHelper(),
+			newOnNonObject: true,
 			discoveringSymbolsTip: true,
 		);
 	}

tests/PHPStan/Rules/Classes/InstantiationRuleTest.php

@@ -26,20 +26,21 @@ protected function getRule(): Rule
 	{
 		$reflectionProvider = self::createReflectionProvider();
 		$container = self::getContainer();
+		$ruleLevelHelper = new RuleLevelHelper(
+			$reflectionProvider,
+			checkNullables: true,
+			checkThisOnly: false,
+			checkUnionTypes: true,
+			checkExplicitMixed: $this->checkExplicitMixed,
+			checkImplicitMixed: false,
+			checkBenevolentUnionTypes: false,
+			discoveringSymbolsTip: true,
+		);
 		return new InstantiationRule(
 			$container,
 			$reflectionProvider,
 			new FunctionCallParametersCheck(
-				new RuleLevelHelper(
-					$reflectionProvider,
-					checkNullables: true,
-					checkThisOnly: false,
-					checkUnionTypes: true,
-					checkExplicitMixed: $this->checkExplicitMixed,
-					checkImplicitMixed: false,
-					checkBenevolentUnionTypes: false,
-					discoveringSymbolsTip: true,
-				),
+				$ruleLevelHelper,
 				new NullsafeCheck(),
 				new UnresolvableTypeHelper(),
 				new PropertyReflectionFinder(),
@@ -55,7 +56,9 @@ protected function getRule(): Rule
 				$reflectionProvider,
 				$container,
 			),
+			$ruleLevelHelper,
 			new ConsistentConstructorHelper(),
+			newOnNonObject: true,
 			discoveringSymbolsTip: true,
 		);
 	}
@@ -682,4 +685,42 @@ public function testBug14499(): void
 		$this->analyse([__DIR__ . '/data/bug-14499.php'], []);
 	}
 
+	public function testInstantiationWithNonObjectType(): void
+	{
+		$this->analyse([__DIR__ . '/data/instantiation-non-object.php'], [
+			[
+				'Cannot instantiate class using int.',
+				35,
+			],
+			[
+				'Cannot instantiate class using int.',
+				39,
+			],
+			[
+				'Cannot instantiate class using float.',
+				40,
+			],
+			[
+				'Cannot instantiate class using bool.',
+				41,
+			],
+			[
+				'Cannot instantiate class using int|string.',
+				42,
+			],
+			[
+				'Cannot instantiate class using float|int.',
+				43,
+			],
+			[
+				'Cannot instantiate class using string|null.',
+				44,
+			],
+			[
+				'Cannot instantiate class using array<int, string>.',
+				50,
+			],
+		]);
+	}
+
 }

tests/PHPStan/Rules/Classes/data/instantiation-non-object.php

@@ -0,0 +1,51 @@
+<?php declare(strict_types = 1);
+
+namespace InstantiationNonObject;
+
+function get_class_name(): int
+{
+	return 123;
+}
+
+class Foo
+{
+}
+
+/**
+ * @param int|string $intOrString
+ * @param int|float $intOrFloat
+ * @param class-string $classString
+ * @param class-string<Foo> $classStringOfFoo
+ */
+function doFoo(
+	string $string,
+	object $object,
+	int $int,
+	float $float,
+	bool $bool,
+	$intOrString,
+	$intOrFloat,
+	?string $nullableString,
+	string $classString,
+	string $classStringOfFoo,
+	Foo $foo
+): void
+{
+	$class = get_class_name();
+	new $class;
+
+	new $string;
+	new $object;
+	new $int;
+	new $float;
+	new $bool;
+	new $intOrString;
+	new $intOrFloat;
+	new $nullableString;
+	new $classString;
+	new $classStringOfFoo;
+	new $foo;
+
+	$array = ['a'];
+	new $array;
+}