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Error Identifier: generics.callSiteVarianceConflict

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);

/**
 * @template-covariant T
 */
interface Collection
{
    /** @return T */
    public function first(): mixed;
}

/**
 * @param Collection<contravariant string> $collection
 */
function process(Collection $collection): void
{
}

Why is it reported? #

A call-site variance annotation (such as covariant or contravariant) on a generic type argument conflicts with the variance declared on the template type parameter of the class or interface. In this example, the template parameter T of Collection is declared as @template-covariant, but the call-site annotation uses contravariant, which is not a valid position for a covariant template type.

Call-site variance annotations (also called “use-site variance” or “type projections”) must be compatible with the declaration-site variance of the template parameter.

How to fix it #

Remove the conflicting call-site variance annotation, or use one that is compatible with the declaration-site variance:

 <?php declare(strict_types = 1);
 
 /**
- * @param Collection<contravariant string> $collection
+ * @param Collection<covariant string> $collection
  */
 function process(Collection $collection): void
 {
 }

Or simply use the type without a call-site variance annotation:

 <?php declare(strict_types = 1);
 
 /**
- * @param Collection<contravariant string> $collection
+ * @param Collection<string> $collection
  */
 function process(Collection $collection): void
 {
 }

How to ignore this error #

You can use the identifier generics.callSiteVarianceConflict to ignore this error using a comment:

// @phpstan-ignore generics.callSiteVarianceConflict
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: generics.callSiteVarianceConflict

Rules that report this error #

• PHPStan\Rules\Classes\LocalTypeAliasesRule [1]
• PHPStan\Rules\Classes\LocalTypeTraitAliasesRule [1]
• PHPStan\Rules\Classes\LocalTypeTraitUseAliasesRule [1]
• PHPStan\Rules\Classes\MethodTagRule [1]
• PHPStan\Rules\Classes\MethodTagTraitRule [1]
• PHPStan\Rules\Classes\MethodTagTraitUseRule [1]
• PHPStan\Rules\Classes\MixinRule [1]
• PHPStan\Rules\Classes\MixinTraitRule [1]
• PHPStan\Rules\Classes\MixinTraitUseRule [1]
• PHPStan\Rules\Classes\PropertyTagRule [1]
• PHPStan\Rules\Classes\PropertyTagTraitRule [1]
• PHPStan\Rules\Classes\PropertyTagTraitUseRule [1]
• PHPStan\Rules\Generics\ClassAncestorsRule [1]
• PHPStan\Rules\Generics\ClassTemplateTypeRule [1]
• PHPStan\Rules\Generics\EnumAncestorsRule [1]
• PHPStan\Rules\Generics\FunctionTemplateTypeRule [1]
• PHPStan\Rules\Generics\InterfaceAncestorsRule [1]
• PHPStan\Rules\Generics\InterfaceTemplateTypeRule [1]
• PHPStan\Rules\Generics\MethodTagTemplateTypeRule [1]
• PHPStan\Rules\Generics\MethodTagTemplateTypeTraitRule [1]
• PHPStan\Rules\Generics\MethodTemplateTypeRule [1]
• PHPStan\Rules\Generics\TraitTemplateTypeRule [1]
• PHPStan\Rules\Generics\UsedTraitsRule [1]
• PHPStan\Rules\PhpDoc\FunctionAssertRule [1]
• PHPStan\Rules\PhpDoc\IncompatibleClassConstantPhpDocTypeRule [1]
• PHPStan\Rules\PhpDoc\IncompatiblePhpDocTypeRule [1]
• PHPStan\Rules\PhpDoc\IncompatiblePropertyHookPhpDocTypeRule [1]
• PHPStan\Rules\PhpDoc\IncompatiblePropertyPhpDocTypeRule [1]
• PHPStan\Rules\PhpDoc\IncompatibleSelfOutTypeRule [1]
• PHPStan\Rules\PhpDoc\InvalidPhpDocVarTagTypeRule [1]
• PHPStan\Rules\PhpDoc\MethodAssertRule [1]

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