When combining templated class-string and Generics, the concrete class is missing.

Bug report

Classes instantiated from a class string do not have a generic type. The use case in this case is a typed collection class factory function.

Code snippet that reproduces the problem

https://phpstan.org/r/b8d7d149-be06-42bd-941d-67758ffbd708

/**
 * @template T
 * @template K of IFoo
 * @param T $v
 * @param class-string<K> $class
 * @return K<T>
 */
function make2($v, string $class)
{
    return new $class($v);
}


$obj2 = make2(1, Foo::class); // I want to type Foo<int>
\PHPStan\dumpType($obj2); // Kept generic type "int", but unexpected typed as "IFoo" interface

Expected output

Type as Foo<int> and no error will be printed.

Possibly the same issue? https://phpstan.org/r/89101459-ba3b-4f20-b833-fcf7124a3223

@zonuexe

@zonuexe After the latest commit in dev-master, PHPStan now reports different result with your code snippet:

@@ @@
-50: Function make2() should return IFoo<T> but returns K of IFoo.
-54: Dumped type: Foo
-57: Dumped type: IFoo<int>
+-1: Internal error: PHPStan\Rules\Methods\WrongCaseOfInheritedMethodRule::findMethod(): Argument #2 ($classReflection) must be of type PHPStan\Reflection\ClassReflection, null given, called in /var/task/vendor/phpstan/phpstan-strict-rules/src/Rules/Methods/WrongCaseOfInheritedMethodRule.php on line 40
+Run PHPStan with --debug option and post the stack trace to:
+https://github.com/phpstan/phpstan/issues/new?template=Bug_report.md

Full report

Line	Error
-1	`Internal error: PHPStan\Rules\Methods\WrongCaseOfInheritedMethodRule::findMethod(): Argument #2 ($classReflection) must be of type PHPStan\Reflection\ClassReflection, null given, called in /var/task/vendor/phpstan/phpstan-strict-rules/src/Rules/Methods/WrongCaseOfInheritedMethodRule.php on line 40Run PHPStan with --debug option and post the stack trace to:https://github.com/phpstan/phpstan/issues/new?template=Bug_report.md`

@zonuexe

@zonuexe After the latest commit in dev-master, PHPStan now reports different result with your code snippet:

@@ @@
-50: Function make2() should return IFoo<T> but returns K of IFoo.
 54: Dumped type: Foo
 57: Dumped type: IFoo<int>

Full report

Line	Error
54	`Dumped type: Foo`
57	`Dumped type: IFoo<int>`

@zonuexe

@zonuexe Just solved the same issue: https://phpstan.org/r/9f25afc8-fad9-4005-b2d1-7de847cf2181

Line 31 should have a IFoo<T> to let phpstan know what type is inside the IFoo

Fix class-string template resolution with generic args

I think I have a similar issue with the following snippet: https://phpstan.org/r/5c4a72d8-e23a-4e4c-acc7-9db4b8c9577a. In particular this method does not seem to be correctly handled by phpstan:

    /**
     * @param class-string<TLinq> $linqClass
     *
     * @return TLinq<TKey, TValue>
     *
     * @template TLinq of Linq
     */
    public function to(string $linqClass): self
    {
        return new $linqClass($this);
    }

For the record the snippet should still report an error as we would create a BarIterator<int, Foo>. I have other methods to do the cast but adding them here would add a lot of noise.

Thanks a lot to PHPStan maintainers though as this tool really improves code quality.

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When combining templated class-string and Generics, the concrete class is missing. #4971

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When combining templated class-string and Generics, the concrete class is missing. #4971

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rohm1 commented on May 22, 2021

phpstan-bot commented on Sep 23, 2021

phpstan-bot commented on Feb 7, 2022

biozshock commented on Mar 30, 2022

homersimpsons commented on Jun 30, 2026

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