empty.variable

Code example

<?php declare(strict_types = 1);

function doFoo(): void
{
	empty($undefined);
}

Why is it reported?

The variable used inside empty() is never defined in the current scope. The empty() language construct is intended to check whether a variable exists and has a non-empty value. When used on a variable that is never defined, the result is always true (because undefined variables are treated as empty). This usually indicates a logic error, such as a typo in the variable name or a missing assignment.

How to fix it

Define the variable before using it with empty(), or fix the variable name if it is a typo:

 <?php declare(strict_types = 1);

 function doFoo(): void
 {
-	empty($undefined);
+	$value = getValue();
+	if (empty($value)) {
+		// handle empty case
+	}
 }

If the intent is to check whether an optional variable has been set, use isset() instead with proper variable initialization:

 <?php declare(strict_types = 1);

-function doFoo(): void
+function doFoo(?string $value = null): void
 {
-	empty($undefined);
+	if ($value === null || $value === '') {
+		// handle missing/empty case
+	}
 }