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Error Identifier: unset.variable

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
{
	unset($undefined);
}

Why is it reported? #

The unset() call targets a variable that does not exist in the current scope. Unsetting an undefined variable is a no-op but usually indicates a bug – the variable name is likely misspelled, or the logic that was supposed to define the variable is missing or unreachable.

How to fix it #

Make sure the variable name is correct and the variable is defined before attempting to unset it:

 <?php declare(strict_types = 1);
 
 function doFoo(): void
 {
-	unset($undefined);
+	$data = getData();
+	// ... use $data ...
+	unset($data);
 }

If the unset() call is no longer needed, remove it:

 <?php declare(strict_types = 1);
 
 function doFoo(): void
 {
-	unset($undefined);
 }

How to ignore this error #

You can use the identifier unset.variable to ignore this error using a comment:

// @phpstan-ignore unset.variable
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: unset.variable

Rules that report this error #

• PHPStan\Rules\Variables\UnsetRule [1]

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