Error Identifier: staticClassAccess.privateConstant

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);

class Foo
{
    private const FOO = 1;

    public function doFoo(): int
    {
        return static::FOO;
    }
}

Why is it reported? #

Accessing a private constant through static:: is unsafe in a non-final class. The static keyword uses late static binding, which resolves to the actual class at runtime. If a child class extends Foo, static::FOO in the child’s context would try to access Foo::FOO, but private constants are not visible to child classes. This leads to a fatal error at runtime.

How to fix it #

Use self:: instead of static:: to access private constants, since they cannot be overridden in child classes:

 <?php declare(strict_types = 1);
 
 class Foo
 {
     private const FOO = 1;

     public function doFoo(): int
     {
-        return static::FOO;
+        return self::FOO;
     }
 }

Alternatively, make the class final if it is not intended to be extended:

 <?php declare(strict_types = 1);
 
-class Foo
+final class Foo
 {
     private const FOO = 1;

     public function doFoo(): int
     {
         return static::FOO;
     }
 }

How to ignore this error #

You can use the identifier staticClassAccess.privateConstant to ignore this error using a comment:

// @phpstan-ignore staticClassAccess.privateConstant
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: staticClassAccess.privateConstant

Rules that report this error #

PHPStan\Rules\Classes\AccessPrivateConstantThroughStaticRule [1]

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