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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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6 changes: 6 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 +3619,12 @@ static function (): void {
$exprType = $scope->getType($expr->expr);
$toStringMethod = $scope->getMethodReflection($exprType, '__toString');
if ($toStringMethod !== null) {
if ($toStringMethod->getThrowType() !== null) {
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@staabm staabm Nov 14, 2025 •
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the rfc is PHP 7.4+, meaning this logic should be gated via PHPVersion class.

note though, that NodeScopeResolver is undergoing a major refactoring atm, so this might conflict easily

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@ondrejmirtes ondrejmirtes Nov 14, 2025

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It won't conflict, I'm not doing any major changes in NodeScopeResolver that I'm not pushing.

But it's possible that the same change also needs to happen in PHPStan\Analyser\Generator namespace. In this case it doesn't because there's no StringCastHandler ported yet.

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@canvural canvural Nov 14, 2025

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I thought the minimum version PHPStan supports was 7.4 Is it 7.1?

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@staabm staabm Nov 14, 2025 •
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there are 2 things.

the php version PHPStan can analyze against, configured in the .neon config:

phpstan-src/conf/parametersSchema.neon

Line 103 in 5afb019

schema(int(), min(70100), max(80599)),

and the PHP runtime version you use to run PHPStan itself:
https://github.com/phpstan/phpstan/blob/5afb019da9f70ae5a2b4247a1830b5103423a325/composer.json#L7

$throwPoints[] = InternalThrowPoint::createExplicit($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 tests/PHPStan/Rules/Exceptions/CatchWithUnthrownExceptionRuleTest.php
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Expand Up @@ -643,4 +643,9 @@ public function testPropertyHooks(): void
]);
}

public function testBug13806(): void
{
$this->analyse([__DIR__ . '/data/bug-13806.php'], []);
}

}
20 changes: 20 additions & 0 deletions tests/PHPStan/Rules/Exceptions/data/bug-13806.php
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@@ -0,0 +1,20 @@
<?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): void
{
try {
(string) $myVariable;
} catch (\InvalidArgumentException) {
// Reported as dead catch, even though the `__toString()` method
// in `$myVariable` might throw an exception.
}
}

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