Export of internal Abseil changes

--
0e867881e4b9f388a13d6fa8ed715192460130ab by Abseil Team <absl-team@google.com>:

Minor wording change to header comment for Mutex::AwaitWithDeadline(). No functional changes.

PiperOrigin-RevId: 306729491

--
fc64361fb831003fa5e6fbb84a9a89338fd2838c by Derek Mauro <dmauro@google.com>:

Uses C++20 compatible allocator traits in Abseil types

This merges both instances of CountingAllocator in the Abseil codebase.
Makes the presubmits test C++20 mode.

Fixes #651

PiperOrigin-RevId: 306728102

--
d759e5681b9dd6b7339fc019ed58fb5fdececdc3 by Derek Mauro <dmauro@google.com>:

Makes btree's iterator comparisons C++20 compatible

See https://stackoverflow.com/questions/60386792/c20-comparison-warning-about-ambiguous-reversed-operator

PiperOrigin-RevId: 306702048

--
e9da5f409bc5ddb1bad308f9d8c41213c67a1d1e by Derek Mauro <dmauro@google.com>:

Switch a few uses of at() that should have been data() in the implementation of InlinedVector.
Use ABSL_HARDENING_ASSERT in resize().

PiperOrigin-RevId: 306670992
GitOrigin-RevId: 0e867881e4b9f388a13d6fa8ed715192460130ab
Change-Id: If431f3e5d77097e9901654773552dcc01dface87

8 files changed, 85 insertions, 103 deletions

diff --git a/absl/container/BUILD.bazel b/absl/container/BUILD.bazel
index 3606faa7..06921235 100644
--- a/absl/container/BUILD.bazel
+++ b/absl/container/BUILD.bazel
@@ -73,6 +73,7 @@ cc_test(
     copts = ABSL_TEST_COPTS,
     linkopts = ABSL_DEFAULT_LINKOPTS,
     deps = [
+        ":counting_allocator",
         ":fixed_array",
         "//absl/base:config",
         "//absl/base:exception_testing",
diff --git a/absl/container/CMakeLists.txt b/absl/container/CMakeLists.txt
index 392f3284..13d96957 100644
--- a/absl/container/CMakeLists.txt
+++ b/absl/container/CMakeLists.txt
@@ -147,6 +147,7 @@ absl_cc_test(
     ${ABSL_TEST_COPTS}
   DEPS
     absl::fixed_array
+    absl::counting_allocator
     absl::config
     absl::exception_testing
     absl::hash_testing
diff --git a/absl/container/fixed_array.h b/absl/container/fixed_array.h
index 796dd629..adf0dc80 100644
--- a/absl/container/fixed_array.h
+++ b/absl/container/fixed_array.h
@@ -106,13 +106,13 @@ class FixedArray {
 
  public:
   using allocator_type = typename AllocatorTraits::allocator_type;
-  using value_type = typename allocator_type::value_type;
-  using pointer = typename allocator_type::pointer;
-  using const_pointer = typename allocator_type::const_pointer;
-  using reference = typename allocator_type::reference;
-  using const_reference = typename allocator_type::const_reference;
-  using size_type = typename allocator_type::size_type;
-  using difference_type = typename allocator_type::difference_type;
+  using value_type = typename AllocatorTraits::value_type;
+  using pointer = typename AllocatorTraits::pointer;
+  using const_pointer = typename AllocatorTraits::const_pointer;
+  using reference = value_type&;
+  using const_reference = const value_type&;
+  using size_type = typename AllocatorTraits::size_type;
+  using difference_type = typename AllocatorTraits::difference_type;
   using iterator = pointer;
   using const_iterator = const_pointer;
   using reverse_iterator = std::reverse_iterator<iterator>;
diff --git a/absl/container/fixed_array_test.cc b/absl/container/fixed_array_test.cc
index 9b1c224f..90e950c7 100644
--- a/absl/container/fixed_array_test.cc
+++ b/absl/container/fixed_array_test.cc
@@ -29,6 +29,7 @@
 #include "gtest/gtest.h"
 #include "absl/base/internal/exception_testing.h"
 #include "absl/base/options.h"
+#include "absl/container/internal/counting_allocator.h"
 #include "absl/hash/hash_testing.h"
 #include "absl/memory/memory.h"
 
@@ -638,70 +639,9 @@ TEST(FixedArrayTest, DefaultCtorDoesNotValueInit) {
 }
 #endif  // __GNUC__
 
-// This is a stateful allocator, but the state lives outside of the
-// allocator (in whatever test is using the allocator). This is odd
-// but helps in tests where the allocator is propagated into nested
-// containers - that chain of allocators uses the same state and is
-// thus easier to query for aggregate allocation information.
-template <typename T>
-class CountingAllocator : public std::allocator<T> {
- public:
-  using Alloc = std::allocator<T>;
-  using pointer = typename Alloc::pointer;
-  using size_type = typename Alloc::size_type;
-
-  CountingAllocator() : bytes_used_(nullptr), instance_count_(nullptr) {}
-  explicit CountingAllocator(int64_t* b)
-      : bytes_used_(b), instance_count_(nullptr) {}
-  CountingAllocator(int64_t* b, int64_t* a)
-      : bytes_used_(b), instance_count_(a) {}
-
-  template <typename U>
-  explicit CountingAllocator(const CountingAllocator<U>& x)
-      : Alloc(x),
-        bytes_used_(x.bytes_used_),
-        instance_count_(x.instance_count_) {}
-
-  pointer allocate(size_type n, const void* const hint = nullptr) {
-    assert(bytes_used_ != nullptr);
-    *bytes_used_ += n * sizeof(T);
-    return Alloc::allocate(n, hint);
-  }
-
-  void deallocate(pointer p, size_type n) {
-    Alloc::deallocate(p, n);
-    assert(bytes_used_ != nullptr);
-    *bytes_used_ -= n * sizeof(T);
-  }
-
-  template <typename... Args>
-  void construct(pointer p, Args&&... args) {
-    Alloc::construct(p, absl::forward<Args>(args)...);
-    if (instance_count_) {
-      *instance_count_ += 1;
-    }
-  }
-
-  void destroy(pointer p) {
-    Alloc::destroy(p);
-    if (instance_count_) {
-      *instance_count_ -= 1;
-    }
-  }
-
-  template <typename U>
-  class rebind {
-   public:
-    using other = CountingAllocator<U>;
-  };
-
-  int64_t* bytes_used_;
-  int64_t* instance_count_;
-};
-
 TEST(AllocatorSupportTest, CountInlineAllocations) {
   constexpr size_t inlined_size = 4;
-  using Alloc = CountingAllocator<int>;
+  using Alloc = absl::container_internal::CountingAllocator<int>;
   using AllocFxdArr = absl::FixedArray<int, inlined_size, Alloc>;
 
   int64_t allocated = 0;
@@ -722,7 +662,7 @@ TEST(AllocatorSupportTest, CountInlineAllocations) {
 
 TEST(AllocatorSupportTest, CountOutoflineAllocations) {
   constexpr size_t inlined_size = 4;
-  using Alloc = CountingAllocator<int>;
+  using Alloc = absl::container_internal::CountingAllocator<int>;
   using AllocFxdArr = absl::FixedArray<int, inlined_size, Alloc>;
 
   int64_t allocated = 0;
@@ -743,7 +683,7 @@ TEST(AllocatorSupportTest, CountOutoflineAllocations) {
 
 TEST(AllocatorSupportTest, CountCopyInlineAllocations) {
   constexpr size_t inlined_size = 4;
-  using Alloc = CountingAllocator<int>;
+  using Alloc = absl::container_internal::CountingAllocator<int>;
   using AllocFxdArr = absl::FixedArray<int, inlined_size, Alloc>;
 
   int64_t allocated1 = 0;
@@ -771,7 +711,7 @@ TEST(AllocatorSupportTest, CountCopyInlineAllocations) {
 
 TEST(AllocatorSupportTest, CountCopyOutoflineAllocations) {
   constexpr size_t inlined_size = 4;
-  using Alloc = CountingAllocator<int>;
+  using Alloc = absl::container_internal::CountingAllocator<int>;
   using AllocFxdArr = absl::FixedArray<int, inlined_size, Alloc>;
 
   int64_t allocated1 = 0;
@@ -803,7 +743,7 @@ TEST(AllocatorSupportTest, SizeValAllocConstructor) {
   using testing::SizeIs;
 
   constexpr size_t inlined_size = 4;
-  using Alloc = CountingAllocator<int>;
+  using Alloc = absl::container_internal::CountingAllocator<int>;
   using AllocFxdArr = absl::FixedArray<int, inlined_size, Alloc>;
 
   {
diff --git a/absl/container/inlined_vector.h b/absl/container/inlined_vector.h
index 5f6f6154..36f388ae 100644
--- a/absl/container/inlined_vector.h
+++ b/absl/container/inlined_vector.h
@@ -351,14 +351,14 @@ class InlinedVector {
   // Returns a `reference` to the first element of the inlined vector.
   reference front() {
     ABSL_HARDENING_ASSERT(!empty());
-    return at(0);
+    return data()[0];
   }
 
   // Overload of `InlinedVector::front()` that returns a `const_reference` to
   // the first element of the inlined vector.
   const_reference front() const {
     ABSL_HARDENING_ASSERT(!empty());
-    return at(0);
+    return data()[0];
   }
 
   // `InlinedVector::back()`
@@ -366,14 +366,14 @@ class InlinedVector {
   // Returns a `reference` to the last element of the inlined vector.
   reference back() {
     ABSL_HARDENING_ASSERT(!empty());
-    return at(size() - 1);
+    return data()[size() - 1];
   }
 
   // Overload of `InlinedVector::back()` that returns a `const_reference` to the
   // last element of the inlined vector.
   const_reference back() const {
     ABSL_HARDENING_ASSERT(!empty());
-    return at(size() - 1);
+    return data()[size() - 1];
   }
 
   // `InlinedVector::begin()`
@@ -524,7 +524,7 @@ class InlinedVector {
   void assign(InputIterator first, InputIterator last) {
     size_type i = 0;
     for (; i < size() && first != last; ++i, static_cast<void>(++first)) {
-      at(i) = *first;
+      data()[i] = *first;
     }
 
     erase(data() + i, data() + size());
@@ -537,7 +537,10 @@ class InlinedVector {
   //
   // NOTE: if `n` is smaller than `size()`, extra elements are destroyed. If `n`
   // is larger than `size()`, new elements are value-initialized.
-  void resize(size_type n) { storage_.Resize(DefaultValueAdapter(), n); }
+  void resize(size_type n) {
+    ABSL_HARDENING_ASSERT(n <= max_size());
+    storage_.Resize(DefaultValueAdapter(), n);
+  }
 
   // Overload of `InlinedVector::resize(...)` that resizes the inlined vector to
   // contain `n` elements.
@@ -545,6 +548,7 @@ class InlinedVector {
   // NOTE: if `n` is smaller than `size()`, extra elements are destroyed. If `n`
   // is larger than `size()`, new elements are copied-constructed from `v`.
   void resize(size_type n, const_reference v) {
+    ABSL_HARDENING_ASSERT(n <= max_size());
     storage_.Resize(CopyValueAdapter(v), n);
   }
 
diff --git a/absl/container/internal/btree.h b/absl/container/internal/btree.h
index 4504e9ce..b23138f0 100644
--- a/absl/container/internal/btree.h
+++ b/absl/container/internal/btree.h
@@ -929,9 +929,15 @@ struct btree_iterator {
   void decrement_slow();
 
  public:
+  bool operator==(const iterator &other) const {
+    return node == other.node && position == other.position;
+  }
   bool operator==(const const_iterator &other) const {
     return node == other.node && position == other.position;
   }
+  bool operator!=(const iterator &other) const {
+    return node != other.node || position != other.position;
+  }
   bool operator!=(const const_iterator &other) const {
     return node != other.node || position != other.position;
   }
diff --git a/absl/container/internal/counting_allocator.h b/absl/container/internal/counting_allocator.h
index 9efdc662..927cf082 100644
--- a/absl/container/internal/counting_allocator.h
+++ b/absl/container/internal/counting_allocator.h
@@ -15,7 +15,6 @@
 #ifndef ABSL_CONTAINER_INTERNAL_COUNTING_ALLOCATOR_H_
 #define ABSL_CONTAINER_INTERNAL_COUNTING_ALLOCATOR_H_
 
-#include <cassert>
 #include <cstdint>
 #include <memory>
 
@@ -31,33 +30,63 @@ namespace container_internal {
 // containers - that chain of allocators uses the same state and is
 // thus easier to query for aggregate allocation information.
 template <typename T>
-class CountingAllocator : public std::allocator<T> {
+class CountingAllocator {
  public:
-  using Alloc = std::allocator<T>;
-  using pointer = typename Alloc::pointer;
-  using size_type = typename Alloc::size_type;
+  using Allocator = std::allocator<T>;
+  using AllocatorTraits = std::allocator_traits<Allocator>;
+  using value_type = typename AllocatorTraits::value_type;
+  using pointer = typename AllocatorTraits::pointer;
+  using const_pointer = typename AllocatorTraits::const_pointer;
+  using size_type = typename AllocatorTraits::size_type;
+  using difference_type = typename AllocatorTraits::difference_type;
 
-  CountingAllocator() : bytes_used_(nullptr) {}
-  explicit CountingAllocator(int64_t* b) : bytes_used_(b) {}
+  CountingAllocator() = default;
+  explicit CountingAllocator(int64_t* bytes_used) : bytes_used_(bytes_used) {}
+  CountingAllocator(int64_t* bytes_used, int64_t* instance_count)
+      : bytes_used_(bytes_used), instance_count_(instance_count) {}
 
   template <typename U>
   CountingAllocator(const CountingAllocator<U>& x)
-      : Alloc(x), bytes_used_(x.bytes_used_) {}
+      : bytes_used_(x.bytes_used_), instance_count_(x.instance_count_) {}
 
-  pointer allocate(size_type n,
-                   std::allocator<void>::const_pointer hint = nullptr) {
-    assert(bytes_used_ != nullptr);
-    *bytes_used_ += n * sizeof(T);
-    return Alloc::allocate(n, hint);
+  pointer allocate(
+      size_type n,
+      typename AllocatorTraits::const_void_pointer hint = nullptr) {
+    Allocator allocator;
+    pointer ptr = AllocatorTraits::allocate(allocator, n, hint);
+    if (bytes_used_ != nullptr) {
+      *bytes_used_ += n * sizeof(T);
+    }
+    return ptr;
   }
 
   void deallocate(pointer p, size_type n) {
-    Alloc::deallocate(p, n);
-    assert(bytes_used_ != nullptr);
-    *bytes_used_ -= n * sizeof(T);
+    Allocator allocator;
+    AllocatorTraits::deallocate(allocator, p, n);
+    if (bytes_used_ != nullptr) {
+      *bytes_used_ -= n * sizeof(T);
+    }
   }
 
-  template<typename U>
+  template <typename U, typename... Args>
+  void construct(U* p, Args&&... args) {
+    Allocator allocator;
+    AllocatorTraits::construct(allocator, p, std::forward<Args>(args)...);
+    if (instance_count_ != nullptr) {
+      *instance_count_ += 1;
+    }
+  }
+
+  template <typename U>
+  void destroy(U* p) {
+    Allocator allocator;
+    AllocatorTraits::destroy(allocator, p);
+    if (instance_count_ != nullptr) {
+      *instance_count_ -= 1;
+    }
+  }
+
+  template <typename U>
   class rebind {
    public:
     using other = CountingAllocator<U>;
@@ -65,7 +94,8 @@ class CountingAllocator : public std::allocator<T> {
 
   friend bool operator==(const CountingAllocator& a,
                          const CountingAllocator& b) {
-    return a.bytes_used_ == b.bytes_used_;
+    return a.bytes_used_ == b.bytes_used_ &&
+           a.instance_count_ == b.instance_count_;
   }
 
   friend bool operator!=(const CountingAllocator& a,
@@ -73,7 +103,8 @@ class CountingAllocator : public std::allocator<T> {
     return !(a == b);
   }
 
-  int64_t* bytes_used_;
+  int64_t* bytes_used_ = nullptr;
+  int64_t* instance_count_ = nullptr;
 };
 
 }  // namespace container_internal
diff --git a/absl/synchronization/mutex.h b/absl/synchronization/mutex.h
index 8c70c4ce..961ff52b 100644
--- a/absl/synchronization/mutex.h
+++ b/absl/synchronization/mutex.h
@@ -331,17 +331,16 @@ class ABSL_LOCKABLE Mutex {
   // Mutex::AwaitWithTimeout()
   // Mutex::AwaitWithDeadline()
   //
-  // If `cond` is initially true, do nothing, or act as though `cond` is
-  // initially false.
-  //
-  // If `cond` is initially false, unlock this `Mutex` and block until
-  // simultaneously:
+  // Unlocks this `Mutex` and blocks until simultaneously:
   //   - either `cond` is true or the {timeout has expired, deadline has passed}
   //     and
   //   - this `Mutex` can be reacquired,
   // then reacquire this `Mutex` in the same mode in which it was previously
   // held, returning `true` iff `cond` is `true` on return.
   //
+  // If the condition is initially `true`, the implementation *may* skip the
+  // release/re-acquire step and return immediately.
+  //
   // Deadlines in the past are equivalent to an immediate deadline.
   // Negative timeouts are equivalent to a zero timeout.
   //