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Error Identifier: interface.duplicateMethod

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);

interface Foo
{
	public function doSomething(): void;

	public function doSomething(): int;
}

Why is it reported? #

The interface declares the same method name more than once. PHP does not allow redeclaring methods within a single interface (or class/enum) definition, and this will cause a fatal error. Method names are compared case-insensitively, so doSomething() and DoSomething() are considered the same method.

How to fix it #

Remove the duplicate method declaration:

 interface Foo
 {
 	public function doSomething(): void;
-
-	public function doSomething(): int;
 }

If two different methods are intended, give them distinct names:

 interface Foo
 {
 	public function doSomething(): void;

-	public function doSomething(): int;
+	public function doSomethingElse(): int;
 }

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\Classes\DuplicateDeclarationRule [1]

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