Avoid warning about non-nullable class-property in traits.

src/Rules/IssetCheck.php

@@ -4,10 +4,13 @@
 
 use PhpParser\Node;
 use PhpParser\Node\Expr;
+use PHPStan\Analyser\CollectedDataEmitter;
+use PHPStan\Analyser\NodeCallbackInvoker;
 use PHPStan\Analyser\Scope;
 use PHPStan\DependencyInjection\AutowiredParameter;
 use PHPStan\DependencyInjection\AutowiredService;
 use PHPStan\Node\Expr\PropertyInitializationExpr;
+use PHPStan\Rules\Comparison\ConstantConditionInTraitHelper;
 use PHPStan\Rules\Properties\PropertyDescriptor;
 use PHPStan\Rules\Properties\PropertyReflectionFinder;
 use PHPStan\Type\NeverType;
@@ -27,6 +30,7 @@ final class IssetCheck
 	public function __construct(
 		private PropertyDescriptor $propertyDescriptor,
 		private PropertyReflectionFinder $propertyReflectionFinder,
+		private ConstantConditionInTraitHelper $constantConditionInTraitHelper,
 		#[AutowiredParameter]
 		private bool $checkAdvancedIsset,
 		#[AutowiredParameter]
@@ -36,10 +40,32 @@ public function __construct(
 	}
 
 	/**
+	 * @param class-string<Rule<covariant Node>>|null $ruleName
 	 * @param ErrorIdentifier $identifier
 	 * @param callable(Type): ?string $typeMessageCallback
 	 */
-	public function check(Expr $expr, Scope $scope, string $operatorDescription, string $identifier, callable $typeMessageCallback, ?IdentifierRuleError $error = null): ?IdentifierRuleError
+	public function check(Expr $expr, Scope&NodeCallbackInvoker&CollectedDataEmitter $scope, string $operatorDescription, string $identifier, callable $typeMessageCallback, ?string $ruleName = null, ?IdentifierRuleError $error = null): ?IdentifierRuleError
+	{
+		$result = $this->checkInternal($expr, $scope, $operatorDescription, $identifier, $typeMessageCallback, $ruleName, $expr, $error);
+
+		if ($ruleName !== null && $scope->isInTrait()) {
+			if ($result !== null) {
+				$this->constantConditionInTraitHelper->emitError($ruleName, $scope, $expr, true, $result);
+				return null;
+			}
+			$this->constantConditionInTraitHelper->emitNoError($ruleName, $scope, $expr);
+			return null;
+		}
+
+		return $result;
+	}
+
+	/**
+	 * @param class-string<Rule<covariant Node>>|null $ruleName
+	 * @param ErrorIdentifier $identifier
+	 * @param callable(Type): ?string $typeMessageCallback
+	 */
+	private function checkInternal(Expr $expr, Scope&NodeCallbackInvoker&CollectedDataEmitter $scope, string $operatorDescription, string $identifier, callable $typeMessageCallback, ?string $ruleName, Expr $originalExpr, ?IdentifierRuleError $error = null): ?IdentifierRuleError
 	{
 		// mirrored in PHPStan\Analyser\MutatingScope::issetCheck()
 		if ($expr instanceof Node\Expr\Variable && is_string($expr->name)) {
@@ -114,7 +140,7 @@ public function check(Expr $expr, Scope $scope, string $operatorDescription, str
 				), $typeMessageCallback, $identifier, 'offset');
 
 				if ($error !== null) {
-					return $this->check($expr->var, $scope, $operatorDescription, $identifier, $typeMessageCallback, $error);
+					return $this->checkInternal($expr->var, $scope, $operatorDescription, $identifier, $typeMessageCallback, $ruleName, $originalExpr, $error);
 				}
 			}
 
@@ -220,11 +246,11 @@ static function (Type $type) use ($typeMessageCallback): ?string {
 
 			if ($error !== null) {
 				if ($expr instanceof Node\Expr\PropertyFetch) {
-					return $this->check($expr->var, $scope, $operatorDescription, $identifier, $typeMessageCallback, $error);
+					return $this->checkInternal($expr->var, $scope, $operatorDescription, $identifier, $typeMessageCallback, $ruleName, $originalExpr, $error);
 				}
 
 				if ($expr->class instanceof Expr) {
-					return $this->check($expr->class, $scope, $operatorDescription, $identifier, $typeMessageCallback, $error);
+					return $this->checkInternal($expr->class, $scope, $operatorDescription, $identifier, $typeMessageCallback, $ruleName, $originalExpr, $error);
 				}
 			}
 

src/Rules/Variables/EmptyRule.php

@@ -3,6 +3,8 @@
 namespace PHPStan\Rules\Variables;
 
 use PhpParser\Node;
+use PHPStan\Analyser\CollectedDataEmitter;
+use PHPStan\Analyser\NodeCallbackInvoker;
 use PHPStan\Analyser\Scope;
 use PHPStan\DependencyInjection\RegisteredRule;
 use PHPStan\Rules\IssetCheck;
@@ -25,7 +27,7 @@ public function getNodeType(): string
 		return Node\Expr\Empty_::class;
 	}
 
-	public function processNode(Node $node, Scope $scope): array
+	public function processNode(Node $node, Scope&NodeCallbackInvoker&CollectedDataEmitter $scope): array
 	{
 		$error = $this->issetCheck->check($node->expr, $scope, 'in empty()', 'empty', static function (Type $type): ?string {
 			$isNull = $type->isNull();
@@ -57,7 +59,7 @@ public function processNode(Node $node, Scope $scope): array
 			}
 
 			return 'is not nullable';
-		});
+		}, self::class);
 
 		if ($error === null) {
 			return [];

src/Rules/Variables/IssetRule.php

@@ -3,6 +3,8 @@
 namespace PHPStan\Rules\Variables;
 
 use PhpParser\Node;
+use PHPStan\Analyser\CollectedDataEmitter;
+use PHPStan\Analyser\NodeCallbackInvoker;
 use PHPStan\Analyser\Scope;
 use PHPStan\DependencyInjection\RegisteredRule;
 use PHPStan\Rules\IssetCheck;
@@ -25,7 +27,7 @@ public function getNodeType(): string
 		return Node\Expr\Isset_::class;
 	}
 
-	public function processNode(Node $node, Scope $scope): array
+	public function processNode(Node $node, Scope&NodeCallbackInvoker&CollectedDataEmitter $scope): array
 	{
 		$messages = [];
 		foreach ($node->vars as $var) {
@@ -40,7 +42,7 @@ public function processNode(Node $node, Scope $scope): array
 				}
 
 				return 'is not nullable';
-			});
+			}, self::class);
 			if ($error === null) {
 				continue;
 			}

src/Rules/Variables/NullCoalesceRule.php

@@ -3,6 +3,8 @@
 namespace PHPStan\Rules\Variables;
 
 use PhpParser\Node;
+use PHPStan\Analyser\CollectedDataEmitter;
+use PHPStan\Analyser\NodeCallbackInvoker;
 use PHPStan\Analyser\Scope;
 use PHPStan\DependencyInjection\RegisteredRule;
 use PHPStan\Rules\IssetCheck;
@@ -25,7 +27,7 @@ public function getNodeType(): string
 		return Node\Expr::class;
 	}
 
-	public function processNode(Node $node, Scope $scope): array
+	public function processNode(Node $node, Scope&NodeCallbackInvoker&CollectedDataEmitter $scope): array
 	{
 		$typeMessageCallback = static function (Type $type): ?string {
 			$isNull = $type->isNull();
@@ -41,9 +43,9 @@ public function processNode(Node $node, Scope $scope): array
 		};
 
 		if ($node instanceof Node\Expr\BinaryOp\Coalesce) {
-			$error = $this->issetCheck->check($node->left, $scope, 'on left side of ??', 'nullCoalesce', $typeMessageCallback);
+			$error = $this->issetCheck->check($node->left, $scope, 'on left side of ??', 'nullCoalesce', $typeMessageCallback, self::class);
 		} elseif ($node instanceof Node\Expr\AssignOp\Coalesce) {
-			$error = $this->issetCheck->check($node->var, $scope, 'on left side of ??=', 'nullCoalesce', $typeMessageCallback);
+			$error = $this->issetCheck->check($node->var, $scope, 'on left side of ??=', 'nullCoalesce', $typeMessageCallback, self::class);
 		} else {
 			return [];
 		}

tests/PHPStan/Rules/Variables/EmptyRuleTest.php

@@ -2,16 +2,19 @@
 
 namespace PHPStan\Rules\Variables;
 
+use PHPStan\Rules\Comparison\ConstantConditionInTraitHelper;
+use PHPStan\Rules\Comparison\ConstantConditionInTraitRule;
 use PHPStan\Rules\IssetCheck;
 use PHPStan\Rules\Properties\PropertyDescriptor;
 use PHPStan\Rules\Properties\PropertyReflectionFinder;
 use PHPStan\Rules\Rule;
+use PHPStan\Testing\CompositeRule;
 use PHPStan\Testing\RuleTestCase;
 use PHPUnit\Framework\Attributes\DataProvider;
 use PHPUnit\Framework\Attributes\RequiresPhp;
 
 /**
- * @extends RuleTestCase<EmptyRule>
+ * @extends RuleTestCase<CompositeRule>
  */
 class EmptyRuleTest extends RuleTestCase
 {
@@ -20,12 +23,17 @@ class EmptyRuleTest extends RuleTestCase
 
 	protected function getRule(): Rule
 	{
-		return new EmptyRule(new IssetCheck(
-			new PropertyDescriptor(),
-			new PropertyReflectionFinder(),
-			true,
-			$this->treatPhpDocTypesAsCertain,
-		));
+		// @phpstan-ignore argument.type
+		return new CompositeRule([
+			new EmptyRule(new IssetCheck(
+				new PropertyDescriptor(),
+				new PropertyReflectionFinder(),
+				self::getContainer()->getByType(ConstantConditionInTraitHelper::class),
+				true,
+				$this->treatPhpDocTypesAsCertain,
+			)),
+			new ConstantConditionInTraitRule(),
+		]);
 	}
 
 	protected function shouldTreatPhpDocTypesAsCertain(): bool
@@ -252,4 +260,10 @@ public function testIssetAfterRememberedConstructor(): void
 		]);
 	}
 
+	public function testInTrait(): void
+	{
+		$this->treatPhpDocTypesAsCertain = true;
+		$this->analyse([__DIR__ . '/data/isset-in-trait.php'], []);
+	}
+
 }

tests/PHPStan/Rules/Variables/IssetRuleTest.php

@@ -2,15 +2,18 @@
 
 namespace PHPStan\Rules\Variables;
 
+use PHPStan\Rules\Comparison\ConstantConditionInTraitHelper;
+use PHPStan\Rules\Comparison\ConstantConditionInTraitRule;
 use PHPStan\Rules\IssetCheck;
 use PHPStan\Rules\Properties\PropertyDescriptor;
 use PHPStan\Rules\Properties\PropertyReflectionFinder;
 use PHPStan\Rules\Rule;
+use PHPStan\Testing\CompositeRule;
 use PHPStan\Testing\RuleTestCase;
 use PHPUnit\Framework\Attributes\RequiresPhp;
 
 /**
- * @extends RuleTestCase<IssetRule>
+ * @extends RuleTestCase<CompositeRule>
  */
 class IssetRuleTest extends RuleTestCase
 {
@@ -19,12 +22,17 @@ class IssetRuleTest extends RuleTestCase
 
 	protected function getRule(): Rule
 	{
-		return new IssetRule(new IssetCheck(
-			new PropertyDescriptor(),
-			new PropertyReflectionFinder(),
-			true,
-			$this->treatPhpDocTypesAsCertain,
-		));
+		// @phpstan-ignore argument.type
+		return new CompositeRule([
+			new IssetRule(new IssetCheck(
+				new PropertyDescriptor(),
+				new PropertyReflectionFinder(),
+				self::getContainer()->getByType(ConstantConditionInTraitHelper::class),
+				true,
+				$this->treatPhpDocTypesAsCertain,
+			)),
+			new ConstantConditionInTraitRule(),
+		]);
 	}
 
 	protected function shouldTreatPhpDocTypesAsCertain(): bool
@@ -562,4 +570,19 @@ public function testBug14393(): void
 		]);
 	}
 
+	public function testInTrait(): void
+	{
+		$this->treatPhpDocTypesAsCertain = true;
+		$this->analyse([__DIR__ . '/data/isset-in-trait.php'], [
+			[
+				'Property IssetInTrait\ClassA::$j (int) in isset() is not nullable.',
+				36,
+			],
+			[
+				'Property IssetInTrait\ClassB::$j (int) in isset() is not nullable.',
+				36,
+			],
+		]);
+	}
+
 }

tests/PHPStan/Rules/Variables/NullCoalesceRuleTest.php

@@ -2,28 +2,36 @@
 
 namespace PHPStan\Rules\Variables;
 
+use PHPStan\Rules\Comparison\ConstantConditionInTraitHelper;
+use PHPStan\Rules\Comparison\ConstantConditionInTraitRule;
 use PHPStan\Rules\IssetCheck;
 use PHPStan\Rules\Properties\PropertyDescriptor;
 use PHPStan\Rules\Properties\PropertyReflectionFinder;
 use PHPStan\Rules\Rule;
+use PHPStan\Testing\CompositeRule;
 use PHPStan\Testing\RuleTestCase;
 use PHPUnit\Framework\Attributes\RequiresPhp;
 use const PHP_VERSION_ID;
 
 /**
- * @extends RuleTestCase<NullCoalesceRule>
+ * @extends RuleTestCase<CompositeRule>
  */
 class NullCoalesceRuleTest extends RuleTestCase
 {
 
 	protected function getRule(): Rule
 	{
-		return new NullCoalesceRule(new IssetCheck(
-			new PropertyDescriptor(),
-			new PropertyReflectionFinder(),
-			true,
-			$this->shouldTreatPhpDocTypesAsCertain(),
-		));
+		// @phpstan-ignore argument.type
+		return new CompositeRule([
+			new NullCoalesceRule(new IssetCheck(
+				new PropertyDescriptor(),
+				new PropertyReflectionFinder(),
+				self::getContainer()->getByType(ConstantConditionInTraitHelper::class),
+				true,
+				$this->shouldTreatPhpDocTypesAsCertain(),
+			)),
+			new ConstantConditionInTraitRule(),
+		]);
 	}
 
 	public function testCoalesceRule(): void
@@ -448,4 +456,18 @@ public function testBug14393(): void
 		]);
 	}
 
+	public function testInTrait(): void
+	{
+		$this->analyse([__DIR__ . '/data/isset-in-trait.php'], [
+			[
+				'Property IssetInTrait\ClassA::$j (int) on left side of ?? is not nullable.',
+				35,
+			],
+			[
+				'Property IssetInTrait\ClassB::$j (int) on left side of ?? is not nullable.',
+				35,
+			],
+		]);
+	}
+
 }

tests/PHPStan/Rules/Variables/data/isset-in-trait.php

@@ -0,0 +1,53 @@
+<?php
+
+namespace IssetInTrait;
+
+// Trait where property type differs across classes (should suppress errors)
+trait IssetTrait
+{
+	public function doFoo(): void
+	{
+		var_dump($this->i ?? -1);
+		var_dump(isset($this->i));
+		var_dump(empty($this->i));
+	}
+}
+
+class MyClass
+{
+	use IssetTrait;
+
+	public int $i = 10;
+}
+
+class MyClassNullable
+{
+	use IssetTrait;
+
+	public ?int $i = null;
+}
+
+// Trait where property type is the same in all classes (should still report errors)
+trait AlwaysNonNullableTrait
+{
+	public function doFoo(): void
+	{
+		var_dump($this->j ?? -1);
+		var_dump(isset($this->j));
+		var_dump(empty($this->j));
+	}
+}
+
+class ClassA
+{
+	use AlwaysNonNullableTrait;
+
+	public int $j = 10;
+}
+
+class ClassB
+{
+	use AlwaysNonNullableTrait;
+
+	public int $j = 20;
+}