Accommodate libc++ upgrade and C++20

C++20 removes the `pointer` member from std::allocator, and it also
removes the `allocate` method which takes a hint parameter. Newer
versions of libc++ implement these removals for -std=c++20 and up.

The hint version of the `allocate` method is optional for satisfying
the allocator requirement, even as far back as C++11, so remove the
`hint` parameter, not just the `hint` argument to
std::allocator<T>::allocate.

base::Value needs to be a complete type in value_iterators.cc to
satisfy a `requires` clause.

Bug: 175635923
Test: m libchrome libmojo MODULES-IN-external-libchrome
Change-Id: I28408f1f1be3e02e28187e2f8ad6ac4d20a73bd6

2 files changed, 5 insertions, 3 deletions

diff --git a/base/containers/stack_container.h b/base/containers/stack_container.h
index c775744305..980da077c1 100644
--- a/base/containers/stack_container.h
+++ b/base/containers/stack_container.h
@@ -35,7 +35,7 @@ namespace base {
 template<typename T, size_t stack_capacity>
 class StackAllocator : public std::allocator<T> {
  public:
-  typedef typename std::allocator<T>::pointer pointer;
+  typedef T* pointer;
   typedef typename std::allocator<T>::size_type size_type;
 
   // Backing store for the allocator. The container owner is responsible for
@@ -102,13 +102,13 @@ class StackAllocator : public std::allocator<T> {
   // Actually do the allocation. Use the stack buffer if nobody has used it yet
   // and the size requested fits. Otherwise, fall through to the standard
   // allocator.
-  pointer allocate(size_type n, void* hint = 0) {
+  pointer allocate(size_type n) {
     if (source_ != NULL && !source_->used_stack_buffer_
         && n <= stack_capacity) {
       source_->used_stack_buffer_ = true;
       return source_->stack_buffer();
     } else {
-      return std::allocator<T>::allocate(n, hint);
+      return std::allocator<T>::allocate(n);
     }
   }
 
diff --git a/base/value_iterators.cc b/base/value_iterators.cc
index ba9c73072f..4765f73fdf 100644
--- a/base/value_iterators.cc
+++ b/base/value_iterators.cc
@@ -4,6 +4,8 @@
 
 #include "base/value_iterators.h"
 
+#include "base/values.h"
+
 namespace base {
 
 namespace detail {