Unwrapping nested generics yields incorrect result

[muglug]

In the example below this works:

/**
 * @template TInnerPackage of InnerPackage
 * @template TGenericPackage of GenericPackage<TInnerPackage>
 * @param  class-string<TGenericPackage> $class  FQCN to be instantiated
 * @return TInnerPackage
 */
function loadWithDirectUnwrap(string $class) {
    $package = new $class();
    return $package->unwrap();
}

but the indirect unwrapping fails to produce the templated inner class

/**
 * @template TInnerPackage of InnerPackage
 * @template TGenericPackage of GenericPackage<TInnerPackage>
 * @param  class-string<TGenericPackage> $class  FQCN to be instantiated
 * @return TInnerPackage
 */
function loadWithIndirectUnwrap(string $class) {
    $package = new $class();
    return unwrapGeneric($package);
}

https://psalm.dev/r/abe64b4671

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/abe64b4671

<?php

interface BasePackage {}

interface InnerPackage extends BasePackage {}

/**
 * @template TInnerPackage of InnerPackage
 */
interface GenericPackage extends BasePackage {
    /** @return TInnerPackage */
    public function unwrap() : InnerPackage;
}

interface SomeInnerPackage extends InnerPackage {}

/**
 * @extends GenericPackage<SomeInnerPackage>
 */
interface SomePackage extends GenericPackage {}

/**
 * @template TInnerPackage of InnerPackage
 * @template TGenericPackage of GenericPackage<TInnerPackage>
 * @param TGenericPackage $package
 * @return TInnerPackage
 */
function unwrapGeneric(GenericPackage $package) {
    return $package->unwrap();
}

/**
 * @template TInnerPackage of InnerPackage
 * @template TGenericPackage of GenericPackage<TInnerPackage>
 * @param  class-string<TGenericPackage> $class  FQCN to be instantiated
 * @return TInnerPackage
 */
function loadWithDirectUnwrap(string $class) {
    $package = new $class();
    return $package->unwrap();
}

/**
 * @template TInnerPackage of InnerPackage
 * @template TGenericPackage of GenericPackage<TInnerPackage>
 * @param  class-string<TGenericPackage> $class  FQCN to be instantiated
 * @return TInnerPackage
 */
function loadWithIndirectUnwrap(string $class) {
    $package = new $class();
    return unwrapGeneric($package);
}

$result = loadWithDirectUnwrap(SomePackage::class);
/** @psalm-trace $result */
// expected: SomePackage|SomeInnerPackage

Psalm output (using commit bca09d7):

ERROR: InvalidReturnStatement - 51:12 - The inferred type 'InnerPackage' does not match the declared return type 'TInnerPackage:fn-loadwithindirectunwrap as InnerPackage' for loadWithIndirectUnwrap

ERROR: InvalidReturnType - 47:12 - The declared return type 'TInnerPackage:fn-loadwithindirectunwrap as InnerPackage' for loadWithIndirectUnwrap is incorrect, got 'InnerPackage'

ERROR: InvalidArgument - 54:32 - Argument 1 of loadWithDirectUnwrap expects class-string<GenericPackage<TInnerPackage>>, SomePackage::class provided

INFO: Trace - 56:42 - $result: InnerPackage

INFO: UnusedVariable - 54:1 - $result is never referenced or the value is not used