Report dead catch in a trait only when it is dead in every using class

phpstan-baseline.neon

@@ -163,6 +163,24 @@ parameters:
 			count: 1
 			path: src/Analyser/StmtHandler/ClassLikeHandler.php
 
+		-
+			rawMessage: '''
+				Call to method __construct() of deprecated class PHPStan\Node\CatchWithUnthrownExceptionNode:
+				Use CatchTypeNode, emitted for every catch type, and check isThrown().
+			'''
+			identifier: method.deprecatedClass
+			count: 1
+			path: src/Analyser/StmtHandler/TryCatchHandler.php
+
+		-
+			rawMessage: '''
+				Instantiation of deprecated class PHPStan\Node\CatchWithUnthrownExceptionNode:
+				Use CatchTypeNode, emitted for every catch type, and check isThrown().
+			'''
+			identifier: new.deprecatedClass
+			count: 1
+			path: src/Analyser/StmtHandler/TryCatchHandler.php
+
 		-
 			rawMessage: 'Template type TNodeType is declared as covariant, but occurs in contravariant position in parameter node of method PHPStan\Collectors\Collector::processNode().'
 			identifier: generics.variance

src/Analyser/StmtHandler/TryCatchHandler.php

@@ -21,6 +21,7 @@
 use PHPStan\Analyser\VariableFlowBuilder;
 use PHPStan\Dependency\Dependencies;
 use PHPStan\DependencyInjection\AutowiredService;
+use PHPStan\Node\CatchTypeNode;
 use PHPStan\Node\CatchWithUnthrownExceptionNode;
 use PHPStan\Node\Expr\TypeExpr;
 use PHPStan\Node\FinallyExitPointsNode;
@@ -112,9 +113,11 @@ public function processStmt(
 			}
 			$dependencies[] = Dependencies::create($scope->getFile(), classNames: $caughtClassNames);
 
+			$catchTypeNodes = [];
 			$originalCatchTypes = [];
 			$catchTypes = [];
 			foreach ($catchNode->types as $catchNodeType) {
+				$catchTypeNodes[] = $catchNodeType;
 				$catchType = new ObjectType($catchNodeType->toString());
 				$originalCatchTypes[] = $catchType;
 				$catchTypes[] = TypeCombinator::remove($catchType, $pastCatchTypes);
@@ -207,6 +210,7 @@ public function processStmt(
 
 			// emit error
 			foreach ($matchingCatchTypes as $catchTypeIndex => $matched) {
+				$nodeScopeResolver->callNodeCallback($nodeCallback, new CatchTypeNode($catchNode, $catchTypeNodes[$catchTypeIndex], $catchTypes[$catchTypeIndex], $originalCatchTypes[$catchTypeIndex], $matched), $scope, $storage);
 				if ($matched) {
 					continue;
 				}

src/Node/CatchTypeNode.php

@@ -0,0 +1,79 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Node;
+
+use Override;
+use PhpParser\Node\Name;
+use PhpParser\Node\Stmt\Catch_;
+use PhpParser\NodeAbstract;
+use PHPStan\Turbo\ReferencedByTurboExtension;
+use PHPStan\Type\Type;
+
+/**
+ * Virtual node emitted once for each type in a `catch` clause, whether or not
+ * the try block can throw it - unlike CatchWithUnthrownExceptionNode, which is
+ * emitted only for the dead ones. Rules analysing a trait need both outcomes
+ * to tell whether a catch is dead in every class using it.
+ *
+ * @api
+ */
+#[ReferencedByTurboExtension(key: 'catchTypeNode')]
+final class CatchTypeNode extends NodeAbstract implements VirtualNode
+{
+
+	public function __construct(
+		private Catch_ $originalNode,
+		private Name $typeNode,
+		private Type $caughtType,
+		private Type $originalCaughtType,
+		private bool $thrown,
+	)
+	{
+		parent::__construct($originalNode->getAttributes());
+	}
+
+	public function getOriginalNode(): Catch_
+	{
+		return $this->originalNode;
+	}
+
+	public function getTypeNode(): Name
+	{
+		return $this->typeNode;
+	}
+
+	/**
+	 * The caught type without the types caught by the preceding catch clauses;
+	 * NeverType when they already catch all of it.
+	 */
+	public function getCaughtType(): Type
+	{
+		return $this->caughtType;
+	}
+
+	public function getOriginalCaughtType(): Type
+	{
+		return $this->originalCaughtType;
+	}
+
+	public function isThrown(): bool
+	{
+		return $this->thrown;
+	}
+
+	#[Override]
+	public function getType(): string
+	{
+		return 'PHPStan_Node_CatchTypeNode';
+	}
+
+	/**
+	 * @return string[]
+	 */
+	#[Override]
+	public function getSubNodeNames(): array
+	{
+		return [];
+	}
+
+}

src/Node/CatchWithUnthrownExceptionNode.php

@@ -10,6 +10,7 @@
 
 /**
  * @api
+ * @deprecated Use CatchTypeNode, emitted for every catch type, and check isThrown().
  */
 #[ReferencedByTurboExtension(key: 'catchWithUnthrownExceptionNode')]
 final class CatchWithUnthrownExceptionNode extends NodeAbstract implements VirtualNode

src/Rules/Comparison/ConstantConditionInTraitHelper.php

@@ -4,6 +4,7 @@
 
 use PhpParser\Node;
 use PhpParser\Node\Expr;
+use PhpParser\Node\Name;
 use PHPStan\Analyser\CollectedDataEmitter;
 use PHPStan\Analyser\NodeCallbackInvoker;
 use PHPStan\Analyser\RuleErrorTransformer;
@@ -27,9 +28,9 @@ public function __construct(
 	{
 	}
 
-	private function exprString(Expr $expr): string
+	private function exprString(Expr|Name $expr): string
 	{
-		return sprintf('%s:%d', $this->exprPrinter->printExpr($expr), $expr->getStartLine());
+		return sprintf('%s:%d', $expr instanceof Name ? $expr->toString() : $this->exprPrinter->printExpr($expr), $expr->getStartLine());
 	}
 
 	/**
@@ -38,7 +39,7 @@ private function exprString(Expr $expr): string
 	public function emitNoError(
 		string $ruleName,
 		Scope&NodeCallbackInvoker&CollectedDataEmitter $scope,
-		Expr $expr,
+		Expr|Name $expr,
 	): void
 	{
 		if (!$scope->isInTrait()) {
@@ -59,7 +60,7 @@ public function emitNoError(
 	public function emitError(
 		string $ruleName,
 		Scope&NodeCallbackInvoker&CollectedDataEmitter $scope,
-		Expr $expr,
+		Expr|Name $expr,
 		bool $value,
 		RuleError $ruleError,
 	): void

src/Rules/Exceptions/CatchWithUnthrownExceptionRule.php

@@ -3,18 +3,21 @@
 namespace PHPStan\Rules\Exceptions;
 
 use PhpParser\Node;
+use PHPStan\Analyser\CollectedDataEmitter;
+use PHPStan\Analyser\NodeCallbackInvoker;
 use PHPStan\Analyser\Scope;
 use PHPStan\DependencyInjection\AutowiredParameter;
 use PHPStan\DependencyInjection\RegisteredRule;
-use PHPStan\Node\CatchWithUnthrownExceptionNode;
+use PHPStan\Node\CatchTypeNode;
+use PHPStan\Rules\Comparison\ConstantConditionInTraitHelper;
 use PHPStan\Rules\Rule;
 use PHPStan\Rules\RuleErrorBuilder;
 use PHPStan\Type\NeverType;
 use PHPStan\Type\VerbosityLevel;
 use function sprintf;
 
 /**
- * @implements Rule<CatchWithUnthrownExceptionNode>
+ * @implements Rule<CatchTypeNode>
  */
 #[RegisteredRule(level: 4)]
 final class CatchWithUnthrownExceptionRule implements Rule
@@ -23,6 +26,7 @@ final class CatchWithUnthrownExceptionRule implements Rule
 	public function __construct(
 		#[AutowiredParameter(ref: '@exceptionTypeResolver')]
 		private ExceptionTypeResolver $exceptionTypeResolver,
+		private ConstantConditionInTraitHelper $constantConditionInTraitHelper,
 		#[AutowiredParameter(ref: '%exceptions.reportUncheckedExceptionDeadCatch%')]
 		private bool $reportUncheckedExceptionDeadCatch,
 	)
@@ -31,44 +35,55 @@ public function __construct(
 
 	public function getNodeType(): string
 	{
-		return CatchWithUnthrownExceptionNode::class;
+		return CatchTypeNode::class;
 	}
 
-	public function processNode(Node $node, Scope $scope): array
+	public function processNode(Node $node, Scope&NodeCallbackInvoker&CollectedDataEmitter $scope): array
 	{
-		if ($node->getCaughtType() instanceof NeverType) {
-			return [
-				RuleErrorBuilder::message(
-					sprintf('Dead catch - %s is already caught above.', $node->getOriginalCaughtType()->describe(VerbosityLevel::typeOnly())),
-				)
-					->line($node->getStartLine())
-					->identifier('catch.alreadyCaught')
-					->build(),
-			];
+		if ($node->isThrown()) {
+			$this->constantConditionInTraitHelper->emitNoError(self::class, $scope, $node->getTypeNode());
+			return [];
 		}
 
-		if (!$this->reportUncheckedExceptionDeadCatch) {
-			$isCheckedException = false;
-			foreach ($node->getCaughtType()->getObjectClassNames() as $objectClassName) {
-				if ($this->exceptionTypeResolver->isCheckedException($objectClassName, $scope)) {
-					$isCheckedException = true;
-					break;
+		if ($node->getCaughtType() instanceof NeverType) {
+			$ruleError = RuleErrorBuilder::message(
+				sprintf('Dead catch - %s is already caught above.', $node->getOriginalCaughtType()->describe(VerbosityLevel::typeOnly())),
+			)
+				->line($node->getStartLine())
+				->identifier('catch.alreadyCaught')
+				->build();
+		} else {
+			if (!$this->reportUncheckedExceptionDeadCatch) {
+				$isCheckedException = false;
+				foreach ($node->getCaughtType()->getObjectClassNames() as $objectClassName) {
+					if ($this->exceptionTypeResolver->isCheckedException($objectClassName, $scope)) {
+						$isCheckedException = true;
+						break;
+					}
 				}
-			}
 
-			if (!$isCheckedException) {
-				return [];
+				if (!$isCheckedException) {
+					$this->constantConditionInTraitHelper->emitNoError(self::class, $scope, $node->getTypeNode());
+					return [];
+				}
 			}
-		}
 
-		return [
-			RuleErrorBuilder::message(
+			$ruleError = RuleErrorBuilder::message(
 				sprintf('Dead catch - %s is never thrown in the try block.', $node->getCaughtType()->describe(VerbosityLevel::typeOnly())),
 			)
 				->line($node->getStartLine())
 				->identifier('catch.neverThrown')
-				->build(),
-		];
+				->build();
+		}
+
+		if ($scope->isInTrait()) {
+			// The message already distinguishes the possible outcomes,
+			// so the contexts only need to be told apart by error/no error.
+			$this->constantConditionInTraitHelper->emitError(self::class, $scope, $node->getTypeNode(), true, $ruleError);
+			return [];
+		}
+
+		return [$ruleError];
 	}
 
 }

tests/PHPStan/Rules/Exceptions/AbilityToDisableImplicitThrowsTest.php

@@ -2,6 +2,7 @@
 
 namespace PHPStan\Rules\Exceptions;
 
+use PHPStan\Rules\Comparison\ConstantConditionInTraitHelper;
 use PHPStan\Rules\Rule;
 use PHPStan\Testing\RuleTestCase;
 use PHPUnit\Framework\Attributes\RequiresPhp;
@@ -21,7 +22,7 @@ protected function getRule(): Rule
 			[],
 			[],
 			[],
-		), true);
+		), self::getContainer()->getByType(ConstantConditionInTraitHelper::class), true);
 	}
 
 	public function testRule(): void

tests/PHPStan/Rules/Exceptions/CatchWithUnthrownExceptionRuleConfigPhp73Test.php

@@ -2,6 +2,7 @@
 
 namespace PHPStan\Rules\Exceptions;
 
+use PHPStan\Rules\Comparison\ConstantConditionInTraitHelper;
 use PHPStan\Rules\Rule;
 use PHPStan\Testing\RuleTestCase;
 
@@ -19,7 +20,7 @@ protected function getRule(): Rule
 			[],
 			[],
 			[],
-		), true);
+		), self::getContainer()->getByType(ConstantConditionInTraitHelper::class), true);
 	}
 
 	public function testRuleInPhpVersionRange(): void

tests/PHPStan/Rules/Exceptions/CatchWithUnthrownExceptionRuleConfigPhpTest.php

@@ -2,6 +2,7 @@
 
 namespace PHPStan\Rules\Exceptions;
 
+use PHPStan\Rules\Comparison\ConstantConditionInTraitHelper;
 use PHPStan\Rules\Rule;
 use PHPStan\Testing\RuleTestCase;
 use const PHP_VERSION_ID;
@@ -20,7 +21,7 @@ protected function getRule(): Rule
 			[],
 			[],
 			[],
-		), true);
+		), self::getContainer()->getByType(ConstantConditionInTraitHelper::class), true);
 	}
 
 	public function testThrowTypesInPhpVersionRange(): void

tests/PHPStan/Rules/Exceptions/CatchWithUnthrownExceptionRuleGetClassConfigPhpTest.php

@@ -2,6 +2,7 @@
 
 namespace PHPStan\Rules\Exceptions;
 
+use PHPStan\Rules\Comparison\ConstantConditionInTraitHelper;
 use PHPStan\Rules\Rule;
 use PHPStan\Testing\RuleTestCase;
 
@@ -19,7 +20,7 @@ protected function getRule(): Rule
 			[],
 			[],
 			[],
-		), true);
+		), self::getContainer()->getByType(ConstantConditionInTraitHelper::class), true);
 	}
 
 	public function testGetClassThrowTypeInPhpVersionRange(): void

tests/PHPStan/Rules/Exceptions/CatchWithUnthrownExceptionRuleStubsTest.php

@@ -2,6 +2,7 @@
 
 namespace PHPStan\Rules\Exceptions;
 
+use PHPStan\Rules\Comparison\ConstantConditionInTraitHelper;
 use PHPStan\Rules\Rule;
 use PHPStan\Testing\RuleTestCase;
 
@@ -19,7 +20,7 @@ protected function getRule(): Rule
 			[],
 			[],
 			[],
-		), true);
+		), self::getContainer()->getByType(ConstantConditionInTraitHelper::class), true);
 	}
 
 	public function testRule(): void