Fix phpstan/phpstan#5952: Track __toString() throws in echo statements

- Added __toString() throw point tracking to echo statement handling in NodeScopeResolver
- Reuses existing CastStringHandler pattern: checks PhpVersion::throwsOnStringCast() and MethodThrowPointHelper
- New regression test in tests/PHPStan/Rules/Exceptions/data/bug-5952.php
- The root cause was that echo $obj did not consider implicit __toString() calls when collecting throw points

Author: VincentLanglet

src/Analyser/NodeScopeResolver.php

@@ -110,6 +110,7 @@
 use PHPStan\Parser\ImmediatelyInvokedClosureVisitor;
 use PHPStan\Parser\LineAttributesVisitor;
 use PHPStan\Parser\Parser;
+use PHPStan\Php\PhpVersion;
 use PHPStan\PhpDoc\PhpDocInheritanceResolver;
 use PHPStan\PhpDoc\ResolvedPhpDocBlock;
 use PHPStan\PhpDoc\Tag\VarTag;
@@ -862,9 +863,26 @@ public function processStmtNode(
 			$hasYield = false;
 			$throwPoints = [];
 			$isAlwaysTerminating = false;
+			$phpVersion = $this->container->getByType(PhpVersion::class);
+			$methodThrowPointHelper = $this->container->getByType(ExprHandler\Helper\MethodThrowPointHelper::class);
 			foreach ($stmt->exprs as $echoExpr) {
 				$result = $this->processExprNode($stmt, $echoExpr, $scope, $storage, $nodeCallback, ExpressionContext::createDeep());
 				$throwPoints = array_merge($throwPoints, $result->getThrowPoints());
+				if ($phpVersion->throwsOnStringCast()) {
+					$exprType = $scope->getType($echoExpr);
+					$toStringMethod = $scope->getMethodReflection($exprType, '__toString');
+					if ($toStringMethod !== null) {
+						$throwPoint = $methodThrowPointHelper->getThrowPoint(
+							$toStringMethod,
+							$toStringMethod->getOnlyVariant(),
+							new Expr\MethodCall($echoExpr, new Identifier('__toString')),
+							$scope,
+						);
+						if ($throwPoint !== null) {
+							$throwPoints[] = $throwPoint;
+						}
+					}
+				}
 				$scope = $result->getScope();
 				$hasYield = $hasYield || $result->hasYield();
 				$isAlwaysTerminating = $isAlwaysTerminating || $result->isAlwaysTerminating();

tests/PHPStan/Rules/Exceptions/CatchWithUnthrownExceptionRuleTest.php

@@ -748,4 +748,18 @@ public function testBug13806(): void
 		]);
 	}
 
+	public function testBug5952(): void
+	{
+		$this->analyse([__DIR__ . '/data/bug-5952.php'], [
+			[
+				'Dead catch - Exception is never thrown in the try block.',
+				51,
+			],
+			[
+				'Dead catch - Exception is never thrown in the try block.',
+				57,
+			],
+		]);
+	}
+
 }

tests/PHPStan/Rules/Exceptions/data/bug-5952.php

@@ -0,0 +1,59 @@
+<?php // lint >= 7.4
+
+namespace Bug5952;
+
+class Foo
+{
+	public function __toString(): string
+	{
+		throw new \Exception();
+	}
+}
+
+$foo = new Foo();
+
+try {
+	echo $foo;
+} catch (\Exception $e) {
+	echo "Should be printed";
+}
+
+class Bar
+{
+	/** @throws \Exception */
+	public function __toString(): string
+	{
+		throw new \Exception();
+	}
+}
+
+$bar = new Bar();
+
+try {
+	echo $bar;
+} catch (\Exception $e) {
+	echo "Should be printed";
+}
+
+class Baz
+{
+	/** @throws void */
+	public function __toString(): string
+	{
+		return 'hello';
+	}
+}
+
+$baz = new Baz();
+
+try {
+	echo $baz;
+} catch (\Exception $e) {
+	echo "Should not be printed";
+}
+
+try {
+	echo 123;
+} catch (\Exception $e) {
+	echo "Should not be printed";
+}