Error Identifier: classConstant.inTrait

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 FooBar
{
	const FOO = 'foo';
	public const BAR = 'bar';
}

class Consumer
{
	use FooBar;
}

Why is it reported? #

Constants in traits are only supported starting from PHP 8.2. If the project targets an earlier PHP version, declaring a constant inside a trait will cause a syntax error at runtime. This error is reported when PHPStan detects that the configured PHP version is lower than 8.2.

How to fix it #

Move the constants to the class that uses the trait, or to an interface:

 <?php declare(strict_types = 1);
 
 trait FooBar
 {
-	const FOO = 'foo';
-	public const BAR = 'bar';
 }

 class Consumer
 {
 	use FooBar;
+
+	const FOO = 'foo';
+	public const BAR = 'bar';
 }

Or upgrade the minimum PHP version of the project to 8.2 or later.

Non-ignorable error #

This error cannot be ignored using @phpstan-ignore or the ignoreErrors configuration. Non-ignorable errors indicate code that would cause a crash or a fatal error at runtime, or a fundamental problem in the analysed code that must be addressed.

Rules that report this error #

PHPStan\Rules\Traits\ConstantsInTraitsRule [1]

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