Error Identifier: instanceof.deprecatedTrait

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);

/** @deprecated Use NewHelperInterface instead */
trait OldHelperTrait
{
	public function help(): void {}
}

function doFoo(object $obj): void
{
	if ($obj instanceof OldHelperTrait) { // ERROR: Instanceof references deprecated trait OldHelperTrait.
		// ...
	}
}

Why is it reported? #

This error is reported by phpstan/phpstan-deprecation-rules.

The instanceof check references a trait that has been marked with the @deprecated PHPDoc tag. Deprecated traits are scheduled for removal or replacement, and any usage – including in instanceof checks – should be migrated to the recommended alternative. Additionally, instanceof checks against traits always evaluate to false at runtime because PHP does not support trait-based type checks.

How to fix it #

Replace the deprecated trait with the recommended replacement type in the instanceof check:

 <?php declare(strict_types = 1);
 
 function doFoo(object $obj): void
 {
-	if ($obj instanceof OldHelperTrait) {
+	if ($obj instanceof NewHelperInterface) {
 		// ...
 	}
 }

How to ignore this error #

You can use the identifier instanceof.deprecatedTrait to ignore this error using a comment:

// @phpstan-ignore instanceof.deprecatedTrait
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: instanceof.deprecatedTrait

Rules that report this error #

PHPStan\Rules\Deprecations\RestrictedDeprecatedClassNameUsageExtension [1] phpstan/phpstan-deprecation-rules

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