Error Identifier: varTag.trait

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);

trait FooTrait
{
}

class Foo
{
    public function doFoo(): void
    {
        /** @var FooTrait $test */
        $test = new self();
    }
}

Why is it reported? #

The @var PHPDoc tag references a trait as a type. Traits cannot be used as types in PHP because they are not instantiable and cannot be used in instanceof checks or type declarations. A variable cannot hold a value “of type trait” – traits are only used via the use keyword inside classes.

How to fix it #

Use an interface or a class instead of a trait in the @var tag:

 <?php declare(strict_types = 1);
 
+interface FooInterface
+{
+}
+
 trait FooTrait
 {
 }

 class Foo
 {
     public function doFoo(): void
     {
-        /** @var FooTrait $test */
+        /** @var FooInterface $test */
         $test = new self();
     }
 }

Or use the concrete class type that uses the trait:

 <?php declare(strict_types = 1);
 
 class Foo
 {
     use FooTrait;

     public function doFoo(): void
     {
-        /** @var FooTrait $test */
+        /** @var Foo $test */
         $test = new self();
     }
 }

How to ignore this error #

You can use the identifier varTag.trait to ignore this error using a comment:

// @phpstan-ignore varTag.trait
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: varTag.trait

Rules that report this error #

PHPStan\Rules\PhpDoc\InvalidPhpDocVarTagTypeRule [1]

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