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Error Identifier: booleanNot.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(int $i): void
{
    $zero = 0;
    if (!$zero) {
        // always entered
    }
}

Why is it reported? #

The negated boolean expression (!$zero) always evaluates to true because the operand is always falsy. In this example, the variable $zero is always 0, which is falsy in PHP, so !$zero is always true. This means the condition will always be entered, which usually indicates a logic error or a redundant check.

How to fix it #

Remove the redundant condition if it is always evaluating to the same value:

<?php declare(strict_types = 1);

function doFoo(int $i): void
{
    $zero = 0;
    // Execute the code unconditionally instead of wrapping in if (!$zero)
}

Or fix the logic to check the correct variable:

 <?php declare(strict_types = 1);
 
 function doFoo(int $i): void
 {
-    $zero = 0;
-    if (!$zero) {
+    if (!$i) {
         // now depends on the actual input
     }
 }

How to ignore this error #

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

// @phpstan-ignore booleanNot.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: booleanNot.alwaysTrue

Rules that report this error #

• PHPStan\Rules\Comparison\BooleanNotConstantConditionRule [1]

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