fix: Collection::transform() and Paginator::through() return types (#56273)

Author: calebdw

src/Illuminate/Collections/Collection.php

@@ -1732,7 +1732,9 @@ public function takeWhile($value)
      * @template TMapValue
      *
      * @param  callable(TValue, TKey): TMapValue  $callback
-     * @return $this<TKey, TMapValue>
+     * @return $this
+     *
+     * @phpstan-this-out static<TKey, TMapValue>
      */
     public function transform(callable $callback)
     {

src/Illuminate/Pagination/AbstractCursorPaginator.php

@@ -406,7 +406,7 @@ public function items()
      * @template TThroughValue
      *
      * @param  callable(TValue, TKey): TThroughValue  $callback
-     * @return $this<TKey, TThroughValue>
+     * @return $this
      *
      * @phpstan-this-out static<TKey, TThroughValue>
      */

src/Illuminate/Pagination/AbstractPaginator.php

@@ -356,7 +356,9 @@ public function lastItem()
      * @template TMapValue
      *
      * @param  callable(TValue, TKey): TMapValue  $callback
-     * @return $this<TKey, TMapValue>
+     * @return $this
+     *
+     * @phpstan-this-out static<TKey, TMapValue>
      */
     public function through(callable $callback)
     {

types/Support/Collection.php

@@ -1049,18 +1049,18 @@ function ($collection, $count) {
 assertType('Illuminate\Support\Collection<int, User>', $collection->splice(1));
 assertType('Illuminate\Support\Collection<int, User>', $collection->splice(1, 1, [new User]));
 
-assertType('mixed', $collection->transform(function ($user, $int) {
+assertType('Illuminate\Support\Collection<int, int>', $collection->transform(function ($user, $int): int {
     assertType('User', $user);
     assertType('int', $int);
 
-    return new User;
+    return $int * 2;
 }));
 
-assertType('mixed', $collection->transform(function ($user, $int): int {
-    assertType('User', $user);
-    assertType('int', $int);
+assertType('Illuminate\Support\Collection<int, User>', $collection->transform(function ($value, $key) {
+    assertType('int', $value);
+    assertType('int', $key);
 
-    return $int * 2;
+    return new User;
 }));
 
 assertType('Illuminate\Support\Collection<int, User>', $collection->add(new User));