BlockArena, a bit of allocator rework

src/basic/basic_array.h

@@ -214,7 +214,7 @@ void Reserve(Array<T> *arr, int64_t size) {
         T *new_data = AllocArray(arr->allocator, T, size);
         Assert(new_data);
         memcpy(new_data, arr->data, arr->len * sizeof(T));
-        Dealloc(arr->allocator, &arr->data);
+        Dealloc(arr->allocator, arr->data);
 
         arr->data = new_data;
         arr->cap  = size;
@@ -393,7 +393,10 @@ T Get(Array<T> &arr, int64_t i, T default_value = {}) {
 
 template <class T>
 void Dealloc(Array<T> *arr) {
-    if (arr->data) Dealloc(arr->allocator, &arr->data);
+    if (arr->data) {
+        Dealloc(arr->allocator, arr->data);
+        arr->data = NULL;
+    }
     arr->len = arr->cap = 0;
 }