Error Identifier: doWhile.alwaysTrue

Every error reported by PHPStan has an error identifier. Here’s a list of all error identifiers. In PHPStan Pro you can see the error identifier next to each error and filter errors by their identifiers.

Code example #

<?php declare(strict_types = 1);

function doFoo(): void
{
	do {
		echo 'looping';
	} while (true);
}

Why is it reported? #

The condition of the do-while loop always evaluates to true, meaning the loop will never terminate through its condition. If the loop body does not contain a break, return, or throw statement, the loop will run indefinitely. Even when an exit point exists, using while (true) may indicate a logic error or unnecessarily obscure code.

PHPStan does not report this error when the loop body contains a break or return statement, as this is a common intentional pattern (infinite loop with explicit exit).

How to fix it #

Introduce a meaningful loop condition that reflects when the loop should terminate:

 <?php declare(strict_types = 1);
 
-function doFoo(): void
+function doFoo(int $max): void
 {
+	$i = 0;
 	do {
 		echo 'looping';
-	} while (true);
+		$i++;
+	} while ($i < $max);
 }

If the loop is intentionally infinite with an exit condition inside, add a break or return statement in the loop body so PHPStan does not report it:

<?php declare(strict_types = 1);

function doFoo(): void
{
	do {
		$result = doSomething();
		if ($result === false) {
			break;
		}
	} while (true);
}

How to ignore this error #

You can use the identifier doWhile.alwaysTrue to ignore this error using a comment:

// @phpstan-ignore doWhile.alwaysTrue
codeThatProducesTheError();

You can also use only the identifier key to ignore all errors of the same type in your configuration file in the ignoreErrors parameter:

parameters:
	ignoreErrors:
		-
			identifier: doWhile.alwaysTrue

Rules that report this error #

PHPStan\Rules\Comparison\DoWhileLoopConstantConditionRule [1]

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