[libc++] Don't instantiate allocators in __tree on an incomplete type

Author: philnik777

libcxx/include/map

@@ -911,8 +911,7 @@ public:
 private:
   typedef std::__value_type<key_type, mapped_type> __value_type;
   typedef __map_value_compare<key_type, value_type, key_compare> __vc;
-  typedef __rebind_alloc<allocator_traits<allocator_type>, __value_type> __allocator_type;
-  typedef __tree<__value_type, __vc, __allocator_type> __base;
+  typedef __tree<__value_type, __vc, allocator_type> __base;
   typedef typename __base::__node_traits __node_traits;
   typedef allocator_traits<allocator_type> __alloc_traits;
 
@@ -1596,8 +1595,7 @@ public:
 private:
   typedef std::__value_type<key_type, mapped_type> __value_type;
   typedef __map_value_compare<key_type, value_type, key_compare> __vc;
-  typedef __rebind_alloc<allocator_traits<allocator_type>, __value_type> __allocator_type;
-  typedef __tree<__value_type, __vc, __allocator_type> __base;
+  typedef __tree<__value_type, __vc, allocator_type> __base;
   typedef typename __base::__node_traits __node_traits;
   typedef allocator_traits<allocator_type> __alloc_traits;
 

libcxx/test/support/min_allocator.h

@@ -390,6 +390,9 @@ class min_allocator
     typedef T value_type;
     typedef min_pointer<T> pointer;
 
+    // Make sure that value_type is a complete when min_allocator is instantiated
+    static_assert(alignof(value_type) != 0);
+
     min_allocator() = default;
     template <class U>
     TEST_CONSTEXPR_CXX20 min_allocator(min_allocator<U>) {}