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string cast might throw exception #4555

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string cast might throw exception #4555

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029c183
string cast might throw exception
canvural Nov 14, 2025
cff8c29
add more tests and add PHP version check
canvural Nov 14, 2025
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8 changes: 8 additions & 0 deletions src/Analyser/NodeScopeResolver.php
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Original file line number Diff line number Diff line change
Expand Up @@ -3619,6 +3619,14 @@ static function (): void {
$exprType = $scope->getType($expr->expr);
$toStringMethod = $scope->getMethodReflection($exprType, '__toString');
if ($toStringMethod !== null) {
if ($this->phpVersion->throwsOnStringCast()) {
if ($toStringMethod->getThrowType() !== null) {
$throwPoints[] = InternalThrowPoint::createExplicit($scope, $toStringMethod->getThrowType(), $expr, false);
} else {
$throwPoints[] = InternalThrowPoint::createImplicit($scope, $expr);
}
}

if (!$toStringMethod->hasSideEffects()->no()) {
$impurePoints[] = new ImpurePoint(
$scope,
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5 changes: 5 additions & 0 deletions src/Php/PhpVersion.php
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Expand Up @@ -479,4 +479,9 @@ public function deprecatesIncOnNonNumericString(): bool
return $this->versionId >= 80500;
}

public function throwsOnStringCast(): bool
{
return $this->versionId >= 70400;
}

}
10 changes: 10 additions & 0 deletions tests/PHPStan/Rules/Exceptions/CatchWithUnthrownExceptionRuleTest.php
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Expand Up @@ -643,4 +643,14 @@ public function testPropertyHooks(): void
]);
}

public function testBug13806(): void
{
$this->analyse([__DIR__ . '/data/bug-13806.php'], [
[
'Dead catch - InvalidArgumentException is never thrown in the try block.',
16,
],
]);
}

}
38 changes: 38 additions & 0 deletions tests/PHPStan/Rules/Exceptions/data/bug-13806.php
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@@ -0,0 +1,38 @@
<?php

namespace Bug13806;
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@VincentLanglet VincentLanglet Nov 14, 2025

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I feel like this lack of test,

It should add a test for

function doFoo(Stringable $myVariable): void

to check the implicit throw tag

and a test for

class MyStringVoid {
	/** @throws void */
	public function __toString() {
		throw new \InvalidArgumentException();
	}
}

to check in this case the catch is reported as dead catch


function doFoo(MyString $myVariable, MyStringVoid $string, $mixed): void
{
try {
(string) $myVariable;
} catch (\InvalidArgumentException $e) {
// Reported as dead catch, even though the `__toString()` method
// in `$myVariable` might throw an exception.
}

try {
(string) $string;
} catch (\InvalidArgumentException $e) {
}

try {
(string) $mixed;
} catch (\InvalidArgumentException $e) {
}
}

class MyString {
/** @throws \InvalidArgumentException */
public function __toString() {
throw new \InvalidArgumentException();
}
}

class MyStringVoid {
/** @throws void */
public function __toString()
{
throw new \InvalidArgumentException();
}
}
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