staticMethod.resultUnused

Code example

<?php declare(strict_types = 1);

class Foo
{
    public function doFoo(): void
    {
        \DateTimeImmutable::createFromFormat('Y-m-d', '2024-01-15');
    }
}

Why is it reported?

The static method call on a separate line has no side effects, and its return value is not used. This means the call is pointless -- it computes a result that is immediately thrown away, without changing any state.

PHPStan detects this by checking whether the method has known side effects. Methods on immutable objects like DateTimeImmutable are pure and produce no side effects, so calling them without using the result serves no purpose.

How to fix it

Assign the return value to a variable or use it in an expression:

 <?php declare(strict_types = 1);

 class Foo
 {
     public function doFoo(): void
     {
-        \DateTimeImmutable::createFromFormat('Y-m-d', '2024-01-15');
+        $date = \DateTimeImmutable::createFromFormat('Y-m-d', '2024-01-15');
     }
 }

If the method call is truly unnecessary, remove it:

 <?php declare(strict_types = 1);

 class Foo
 {
     public function doFoo(): void
     {
-        \DateTimeImmutable::createFromFormat('Y-m-d', '2024-01-15');
     }
 }