[12.x] Incorrect result of MemoizedStore::many with numeric keys and empty prefix (#57862)

* [12.x] MemoizedStoreTest with empty prefix

* [12.x] MemoizedStore fix with empty prefix and numeric keys

Author: vadimonus

src/Illuminate/Cache/MemoizedStore.php

@@ -68,12 +68,9 @@ public function many(array $keys)
 
         if (count($missing) > 0) {
             $retrieved = tap($this->repository->many($missing), function ($values) {
-                $this->cache = [
-                    ...$this->cache,
-                    ...collect($values)->mapWithKeys(fn ($value, $key) => [
-                        $this->prefix($key) => $value,
-                    ]),
-                ];
+                foreach ($values as $key => $value) {
+                    $this->cache[$this->prefix($key)] = $value;
+                }
             });
         }
 

tests/Integration/Cache/MemoizedStoreTest.php

@@ -121,6 +121,21 @@ public function test_it_uses_correct_keys_for_getMultiple()
         $this->assertSame($cacheValue, $memoValue);
     }
 
+    public function test_it_uses_correct_keys_for_getMultiple_with_empty_prefix()
+    {
+        Cache::setPrefix(null);
+
+        $data = [
+            '1' => 'one',
+            0 => 'zero',
+        ];
+        Cache::putMany($data);
+
+        $this->assertSame($data, Cache::memo()->many(array_keys($data)));
+        // ensure correct on the second memoized retrieval
+        $this->assertSame($data, Cache::memo()->many(array_keys($data)));
+    }
+
     public function test_null_values_are_memoized_when_retrieving_multiple_values()
     {
         $live = Cache::getMultiple(['name.0', 'name.1']);