while-true-try: Variable might not be defined

Bug report

When using a try block inside a while (true), PHPStan fails to see the variable as defined.

For simple cases such as the following PHPStan correctly deduce that the variable is defined and its type:

<?php declare(strict_types = 1);

function produceInt(): int { return 1; }

while (true) {
	$a = produceInt();
	break;
}

\PHPStan\DumpType($a); // Dumped type: int

Code snippet that reproduces the problem

https://phpstan.org/r/fb9bc3ad-1256-46ae-beb5-24e918dd07f7

Expected output

<?php declare(strict_types = 1);

/**
 * @throws \Exception
 */
function produceInt(): int
{
	return 1;
}

while (true) {
	try {
		$a = produceInt();
		break;
	} catch (\Throwable) {}
}

\PHPStan\DumpType($a); // Dumped type: int

Did PHPStan help you today? Did it make you happy in any way?

I think I cannot count the amount of issues that didn't reach production thanks to PHPStan. It also helps a lot when reviewing code as I can focus on the core logic instead of the possible mistakes here and there.

Similar case without try/catch: https://phpstan.org/r/2bb8d587-d9cb-4d11-b164-d6133dc87731

function foo(int $max): void {
	$i = 0;
	while (true) {
		if ($i > $max) {
			$result = 'done';
			break;
		}
		++$i;
	}
	print $result;  // Variable `$result` might not be defined.
}

The same happens with for(;;).

The reason to use while (true) or for (;;) would be if the entry point of the loop is the wrong place for an exit condition.

@homersimpsons

@homersimpsons After the latest push in 2.0.x, PHPStan now reports different result with your code snippet:

@@ @@
-PHP 8.0 – 8.3 (2 errors)
+PHP 8.0 – 8.3 (3 errors)
 ==========
 
+ 6: Function produceInt() has Exception in PHPDoc @throws tag but it's not thrown.
 18: Dumped type: mixed
 18: Variable $a might not be defined.
 
-PHP 7.2 – 7.4 (3 errors)
+PHP 7.2 – 7.4 (4 errors)
 ==========
 
+ 6: Function produceInt() has Exception in PHPDoc @throws tag but it's not thrown.
 15: Non-capturing catch is supported only on PHP 8.0 and later.
 18: Dumped type: mixed
 18: Variable $a might not be defined.

Full report

PHP 8.0 – 8.3 (3 errors)

Line	Error
6	`Function produceInt() has Exception in PHPDoc @throws tag but it's not thrown.`
18	`Dumped type: mixed`
18	`Variable $a might not be defined.`

PHP 7.2 – 7.4 (4 errors)

Line	Error
6	`Function produceInt() has Exception in PHPDoc @throws tag but it's not thrown.`
15	`Non-capturing catch is supported only on PHP 8.0 and later.`
18	`Dumped type: mixed`
18	`Variable $a might not be defined.`

Add regression tests for #11545, #10245, #5919, #5477

Add regression test for #10245

Add regression tests for #11545, #10245, phpstan#5919, phpstan#5477

Closed via merging phpstan/phpstan-src#5118

This thread has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.

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while-true-try: Variable might not be defined #10245

Bug report

Code snippet that reproduces the problem

Expected output

Did PHPStan help you today? Did it make you happy in any way?

PHP 8.0 – 8.3 (3 errors)

PHP 7.2 – 7.4 (4 errors)

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while-true-try: Variable might not be defined #10245

Description

Bug report

Code snippet that reproduces the problem

Expected output

Did PHPStan help you today? Did it make you happy in any way?

Activity

donquixote commented on Aug 22, 2024

phpstan-bot commented on Sep 30, 2024

PHP 8.0 – 8.3 (3 errors)

PHP 7.2 – 7.4 (4 errors)

phpstan-bot commented on Mar 3, 2026

github-actions commented on Apr 4, 2026

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