Fix #2281 - allow lists to accept list types

src/Psalm/Type/Atomic/TList.php

@@ -144,6 +144,12 @@ class TList extends \Psalm\Type\Atomic
                 } else {
                     $input_type_param = $input_type->getGenericValueType();
                 }
+            } elseif ($input_type instanceof Atomic\TList) {
+                if ($offset === 0) {
+                    continue;
+                }
+
+                $input_type_param = clone $input_type->type_param;
             }
 
             $type_param->replaceTemplateTypesWithStandins(

tests/Template/ClassTemplateTest.php

@@ -1864,6 +1864,33 @@ class ClassTemplateTest extends TestCase
                     /** @param Foo<array> $_ */
                     function takesFooArray($_): void {}',
             ],
+            'allowListAcceptance' => [
+                '<?php
+                    /** @template T */
+                    class Collection
+                    {
+                        /** @var list<T> */
+                        public $values;
+
+                        /** @param list<T> $values */
+                        function __construct(array $values)
+                        {
+                            $this->values = $values;
+                        }
+                    }
+
+                    /** @return Collection<string> */
+                    function makeStringCollection()
+                    {
+                        return new Collection(getStringList()); // gets typed as Collection<mixed> for some reason
+                    }
+
+                    /** @return list<string> */
+                    function getStringList(): array
+                    {
+                        return ["foo", "baz"];
+                    }'
+            ],
         ];
     }