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Error Identifier: return.nestedUnusedType

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);

/**
 * @return array<int|string>
 */
function doFoo(): array
{
	return [1, 2, 3];
}

Why is it reported? #

The declared return type contains a nested type that is wider than necessary based on the actual return values. In the example above, the function is declared to return array<int|string>, but it only ever returns arrays containing int values. The string part of the nested union type is unused and can be narrowed.

How to fix it #

Narrow the return type to match the actual return values:

 <?php declare(strict_types = 1);
 
 /**
- * @return array<int|string>
+ * @return array<int>
  */
 function doFoo(): array
 {
 	return [1, 2, 3];
 }

How to ignore this error #

You can use the identifier return.nestedUnusedType to ignore this error using a comment:

// @phpstan-ignore return.nestedUnusedType
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: return.nestedUnusedType

Rules that report this error #

• PHPStan\Rules\TooWideTypehints\TooWideArrowFunctionReturnTypehintRule [1]
• PHPStan\Rules\TooWideTypehints\TooWideClosureReturnTypehintRule [1]
• PHPStan\Rules\TooWideTypehints\TooWideFunctionParameterOutTypeRule [1]
• PHPStan\Rules\TooWideTypehints\TooWideFunctionReturnTypehintRule [1]
• PHPStan\Rules\TooWideTypehints\TooWideMethodParameterOutTypeRule [1]
• PHPStan\Rules\TooWideTypehints\TooWideMethodReturnTypehintRule [1]
• PHPStan\Rules\TooWideTypehints\TooWidePropertyTypeRule [1]

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