5 files changed, 57 insertions, 7 deletions
diff --git a/absl/container/internal/btree.h b/absl/container/internal/btree.h
index adf49f81c571..4504e9ce6659 100644
--- a/absl/container/internal/btree.h
+++ b/absl/container/internal/btree.h
@@ -937,8 +937,13 @@ struct btree_iterator {
   }
 
   // Accessors for the key/value the iterator is pointing at.
-  reference operator*() const { return node->value(position); }
-  pointer operator->() const { return &node->value(position); }
+  reference operator*() const {
+    ABSL_HARDENING_ASSERT(node != nullptr);
+    ABSL_HARDENING_ASSERT(node->start() <= position);
+    ABSL_HARDENING_ASSERT(node->finish() > position);
+    return node->value(position);
+  }
+  pointer operator->() const { return &operator*(); }
 
   btree_iterator &operator++() {
     increment();
@@ -1769,6 +1774,7 @@ void btree_iterator<N, R, P>::increment_slow() {
       position = node->position();
       node = node->parent();
     }
+    // TODO(ezb): assert we aren't incrementing end() instead of handling.
     if (position == node->finish()) {
       *this = save;
     }
@@ -1792,6 +1798,7 @@ void btree_iterator<N, R, P>::decrement_slow() {
       position = node->position() - 1;
       node = node->parent();
     }
+    // TODO(ezb): assert we aren't decrementing begin() instead of handling.
     if (position < node->start()) {
       *this = save;
     }
diff --git a/absl/container/internal/common.h b/absl/container/internal/common.h
index 5037d80316cc..8990f2947273 100644
--- a/absl/container/internal/common.h
+++ b/absl/container/internal/common.h
@@ -138,6 +138,7 @@ class node_handle<Policy, PolicyTraits, Alloc,
                   absl::void_t<typename Policy::mapped_type>>
     : public node_handle_base<PolicyTraits, Alloc> {
   using Base = node_handle_base<PolicyTraits, Alloc>;
+  using slot_type = typename PolicyTraits::slot_type;
 
  public:
   using key_type = typename Policy::key_type;
@@ -145,7 +146,7 @@ class node_handle<Policy, PolicyTraits, Alloc,
 
   constexpr node_handle() {}
 
-  auto key() const -> decltype(PolicyTraits::key(this->slot())) {
+  auto key() const -> decltype(PolicyTraits::key(std::declval<slot_type*>())) {
     return PolicyTraits::key(this->slot());
   }
 
diff --git a/absl/container/internal/container_memory.h b/absl/container/internal/container_memory.h
index d24b0f841384..55b59c7ff313 100644
--- a/absl/container/internal/container_memory.h
+++ b/absl/container/internal/container_memory.h
@@ -37,6 +37,9 @@ namespace absl {
 ABSL_NAMESPACE_BEGIN
 namespace container_internal {
 
+template <size_t Alignment>
+struct alignas(Alignment) AlignedType {};
+
 // Allocates at least n bytes aligned to the specified alignment.
 // Alignment must be a power of 2. It must be positive.
 //
@@ -48,7 +51,7 @@ template <size_t Alignment, class Alloc>
 void* Allocate(Alloc* alloc, size_t n) {
   static_assert(Alignment > 0, "");
   assert(n && "n must be positive");
-  struct alignas(Alignment) M {};
+  using M = AlignedType<Alignment>;
   using A = typename absl::allocator_traits<Alloc>::template rebind_alloc<M>;
   using AT = typename absl::allocator_traits<Alloc>::template rebind_traits<M>;
   A mem_alloc(*alloc);
@@ -64,7 +67,7 @@ template <size_t Alignment, class Alloc>
 void Deallocate(Alloc* alloc, void* p, size_t n) {
   static_assert(Alignment > 0, "");
   assert(n && "n must be positive");
-  struct alignas(Alignment) M {};
+  using M = AlignedType<Alignment>;
   using A = typename absl::allocator_traits<Alloc>::template rebind_alloc<M>;
   using AT = typename absl::allocator_traits<Alloc>::template rebind_traits<M>;
   A mem_alloc(*alloc);
diff --git a/absl/container/internal/container_memory_test.cc b/absl/container/internal/container_memory_test.cc
index 7942c7be4831..e3262e3c884a 100644
--- a/absl/container/internal/container_memory_test.cc
+++ b/absl/container/internal/container_memory_test.cc
@@ -16,6 +16,8 @@
 
 #include <cstdint>
 #include <tuple>
+#include <typeindex>
+#include <typeinfo>
 #include <utility>
 
 #include "gmock/gmock.h"
@@ -27,6 +29,9 @@ ABSL_NAMESPACE_BEGIN
 namespace container_internal {
 namespace {
 
+using ::testing::Gt;
+using ::testing::_;
+using ::testing::ElementsAre;
 using ::testing::Pair;
 
 TEST(Memory, AlignmentLargerThanBase) {
@@ -45,6 +50,39 @@ TEST(Memory, AlignmentSmallerThanBase) {
   Deallocate<2>(&alloc, mem, 3);
 }
 
+std::map<std::type_index, int>& AllocationMap() {
+  static auto* map = new std::map<std::type_index, int>;
+  return *map;
+}
+
+template <typename T>
+struct TypeCountingAllocator {
+  TypeCountingAllocator() = default;
+  template <typename U>
+  TypeCountingAllocator(const TypeCountingAllocator<U>&) {}  // NOLINT
+
+  using value_type = T;
+
+  T* allocate(size_t n, const void* = nullptr) {
+    AllocationMap()[typeid(T)] += n;
+    return std::allocator<T>().allocate(n);
+  }
+  void deallocate(T* p, std::size_t n) {
+    AllocationMap()[typeid(T)] -= n;
+    return std::allocator<T>().deallocate(p, n);
+  }
+};
+
+TEST(Memory, AllocateDeallocateMatchType) {
+  TypeCountingAllocator<int> alloc;
+  void* mem = Allocate<1>(&alloc, 1);
+  // Verify that it was allocated
+  EXPECT_THAT(AllocationMap(), ElementsAre(Pair(_, Gt(0))));
+  Deallocate<1>(&alloc, mem, 1);
+  // Verify that the deallocation matched.
+  EXPECT_THAT(AllocationMap(), ElementsAre(Pair(_, 0)));
+}
+
 class Fixture : public ::testing::Test {
   using Alloc = std::allocator<std::string>;
 
diff --git a/absl/container/internal/raw_hash_set.h b/absl/container/internal/raw_hash_set.h
index fb47f62f4e7d..e47e1fedf725 100644
--- a/absl/container/internal/raw_hash_set.h
+++ b/absl/container/internal/raw_hash_set.h
@@ -104,6 +104,7 @@
 
 #include "absl/base/internal/bits.h"
 #include "absl/base/internal/endian.h"
+#include "absl/base/macros.h"
 #include "absl/base/port.h"
 #include "absl/container/internal/common.h"
 #include "absl/container/internal/compressed_tuple.h"
@@ -651,9 +652,9 @@ class raw_hash_set {
     iterator(ctrl_t* ctrl) : ctrl_(ctrl) {}  // for end()
     iterator(ctrl_t* ctrl, slot_type* slot) : ctrl_(ctrl), slot_(slot) {}
 
-    void assert_is_full() const { assert(IsFull(*ctrl_)); }
+    void assert_is_full() const { ABSL_HARDENING_ASSERT(IsFull(*ctrl_)); }
     void assert_is_valid() const {
-      assert(!ctrl_ || IsFull(*ctrl_) || *ctrl_ == kSentinel);
+      ABSL_HARDENING_ASSERT(!ctrl_ || IsFull(*ctrl_) || *ctrl_ == kSentinel);
     }
 
     void skip_empty_or_deleted() {