Error Identifier: assert.alreadyNarrowedType
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);
/**
* @phpstan-assert int $i
*/
function assertInt(int $i): void
{
}
Why is it reported? #
The @phpstan-assert tag declares that the function asserts a certain type for a parameter, but the asserted type does not narrow down the parameter’s type any further. In this example, the parameter $i is already typed as int via the native type declaration, so asserting that it is int provides no additional type information. The assertion is redundant because the type is already as narrow as or narrower than the asserted type.
How to fix it #
Either assert a more specific type that actually narrows the parameter type:
<?php declare(strict_types = 1);
/**
- * @phpstan-assert int $i
+ * @phpstan-assert positive-int $i
*/
-function assertInt(int $i): void
+function assertPositiveInt(int $i): void
{
}
Or remove the redundant assertion if no narrowing is needed:
<?php declare(strict_types = 1);
-/**
- * @phpstan-assert int $i
- */
function assertInt(int $i): void
{
}
Or widen the parameter type if the assertion is intended to accept a broader input:
<?php declare(strict_types = 1);
/**
* @phpstan-assert int $i
*/
-function assertInt(int $i): void
+function assertInt(mixed $i): void
{
}
How to ignore this error #
You can use the identifier assert.alreadyNarrowedType to ignore this error using a comment:
// @phpstan-ignore assert.alreadyNarrowedType
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: assert.alreadyNarrowedType