[libc++] Fix non-uglified name in scoped_allocator_adaptor

As mentioned in #78754, the 'base' typedef in scoped_allocator_adaptor
was not uglified properly.

Author: ldionne

libcxx/include/scoped_allocator

@@ -334,12 +334,12 @@ struct __outermost<_Alloc, true> {
 template <class _OuterAlloc, class... _InnerAllocs>
 class _LIBCPP_TEMPLATE_VIS scoped_allocator_adaptor<_OuterAlloc, _InnerAllocs...>
     : public __scoped_allocator_storage<_OuterAlloc, _InnerAllocs...> {
-  typedef __scoped_allocator_storage<_OuterAlloc, _InnerAllocs...> base;
+  typedef __scoped_allocator_storage<_OuterAlloc, _InnerAllocs...> _Base;
   typedef allocator_traits<_OuterAlloc> _OuterTraits;
 
 public:
   typedef _OuterAlloc outer_allocator_type;
-  typedef typename base::inner_allocator_type inner_allocator_type;
+  typedef typename _Base::inner_allocator_type inner_allocator_type;
   typedef typename _OuterTraits::size_type size_type;
   typedef typename _OuterTraits::difference_type difference_type;
   typedef typename _OuterTraits::pointer pointer;
@@ -365,29 +365,29 @@ public:
   template <class _OuterA2, __enable_if_t<is_constructible<outer_allocator_type, _OuterA2>::value, int> = 0>
   _LIBCPP_HIDE_FROM_ABI
   scoped_allocator_adaptor(_OuterA2&& __outer_alloc, const _InnerAllocs&... __inner_allocs) _NOEXCEPT
-      : base(std::forward<_OuterA2>(__outer_alloc), __inner_allocs...) {}
+      : _Base(std::forward<_OuterA2>(__outer_alloc), __inner_allocs...) {}
   // scoped_allocator_adaptor(const scoped_allocator_adaptor& __other) = default;
   template <class _OuterA2, __enable_if_t<is_constructible<outer_allocator_type, const _OuterA2&>::value, int> = 0>
   _LIBCPP_HIDE_FROM_ABI
   scoped_allocator_adaptor(const scoped_allocator_adaptor<_OuterA2, _InnerAllocs...>& __other) _NOEXCEPT
-      : base(__other) {}
+      : _Base(__other) {}
   template <class _OuterA2, __enable_if_t<is_constructible<outer_allocator_type, _OuterA2>::value, int> = 0>
   _LIBCPP_HIDE_FROM_ABI
   scoped_allocator_adaptor(scoped_allocator_adaptor<_OuterA2, _InnerAllocs...>&& __other) _NOEXCEPT
-      : base(std::move(__other)) {}
+      : _Base(std::move(__other)) {}
 
   // scoped_allocator_adaptor& operator=(const scoped_allocator_adaptor&) = default;
   // scoped_allocator_adaptor& operator=(scoped_allocator_adaptor&&) = default;
   // ~scoped_allocator_adaptor() = default;
 
-  _LIBCPP_HIDE_FROM_ABI inner_allocator_type& inner_allocator() _NOEXCEPT { return base::inner_allocator(); }
+  _LIBCPP_HIDE_FROM_ABI inner_allocator_type& inner_allocator() _NOEXCEPT { return _Base::inner_allocator(); }
   _LIBCPP_HIDE_FROM_ABI const inner_allocator_type& inner_allocator() const _NOEXCEPT {
-    return base::inner_allocator();
+    return _Base::inner_allocator();
   }
 
-  _LIBCPP_HIDE_FROM_ABI outer_allocator_type& outer_allocator() _NOEXCEPT { return base::outer_allocator(); }
+  _LIBCPP_HIDE_FROM_ABI outer_allocator_type& outer_allocator() _NOEXCEPT { return _Base::outer_allocator(); }
   _LIBCPP_HIDE_FROM_ABI const outer_allocator_type& outer_allocator() const _NOEXCEPT {
-    return base::outer_allocator();
+    return _Base::outer_allocator();
   }
 
   _LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_HIDE_FROM_ABI pointer allocate(size_type __n) {
@@ -472,13 +472,13 @@ public:
   }
 
   _LIBCPP_HIDE_FROM_ABI scoped_allocator_adaptor select_on_container_copy_construction() const _NOEXCEPT {
-    return base::select_on_container_copy_construction();
+    return _Base::select_on_container_copy_construction();
   }
 
 private:
   template <class _OuterA2, __enable_if_t<is_constructible<outer_allocator_type, _OuterA2>::value, int> = 0>
   _LIBCPP_HIDE_FROM_ABI scoped_allocator_adaptor(_OuterA2&& __o, const inner_allocator_type& __i) _NOEXCEPT
-      : base(std::forward<_OuterA2>(__o), __i) {}
+      : _Base(std::forward<_OuterA2>(__o), __i) {}
 
   template <class _Tp, class... _Args>
   _LIBCPP_HIDE_FROM_ABI void __construct(integral_constant<int, 0>, _Tp* __p, _Args&&... __args) {

libcxx/test/std/utilities/allocator.adaptor/base-is-uglified.compile.pass.cpp

@@ -0,0 +1,27 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03
+
+// <memory>
+
+// This test ensures that we don't use a non-uglified name 'base' in the
+// implementation of scoped_allocator_adaptor.
+//
+// See https://github.com/llvm/llvm-project/issues/78754.
+
+#include <memory>
+#include <scoped_allocator>
+
+using ScopedAlloc = std::scoped_allocator_adaptor<std::allocator<int>, std::allocator<int>>;
+struct MyBase {
+  using base = MyBase;
+};
+struct MyDerived : ScopedAlloc, MyBase {};
+
+using T = MyDerived::base; // Should be well-formed