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Error Identifier: method.tentativeReturnType

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 MyIterator implements Iterator
{
	public function current(): void
	{
	}

	public function next(): void
	{
	}

	public function key(): void
	{
	}

	public function valid(): void
	{
	}

	public function rewind(): void
	{
	}
}

Why is it reported? #

The return type of the method is not covariant with the tentative return type declared by the parent method in a PHP built-in class. Since PHP 8.1, many built-in methods have “tentative return types” that signal what the return type will become mandatory in a future PHP version. If your overriding method declares an incompatible return type, PHP emits a deprecation notice.

The error message includes a tip: “Make it covariant, or use the #[\ReturnTypeWillChange] attribute to temporarily suppress the error.”

How to fix it #

Declare a return type that is covariant (the same type or a subtype) with the tentative return type of the parent method.

 <?php declare(strict_types = 1);
 
 class MyIterator implements Iterator
 {
-	public function current(): void
+	public function current(): mixed
 	{
+		return null;
 	}

 	public function next(): void
 	{
 	}

-	public function key(): void
+	public function key(): mixed
 	{
+		return null;
 	}

-	public function valid(): void
+	public function valid(): bool
 	{
+		return false;
 	}

 	public function rewind(): void
 	{
 	}
 }

If you need to support older PHP versions that do not allow these return types, you can temporarily use the #[\ReturnTypeWillChange] attribute:

 <?php declare(strict_types = 1);
 
 class MyIterator implements Iterator
 {
+	#[\ReturnTypeWillChange]
 	public function current()
 	{
+		return null;
 	}

 	// ...
 }

How to ignore this error #

You can use the identifier method.tentativeReturnType to ignore this error using a comment:

// @phpstan-ignore method.tentativeReturnType
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: method.tentativeReturnType

Rules that report this error #

• PHPStan\Rules\Methods\OverridingMethodRule [1]

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