Export of internal Abseil changes

--
730bb88bee556aa11fa19aa33e1434cb6fa78985 by Evan Brown <ezb@google.com>:

Support missing allocator-related constructors in b-tree. See [reference](https://en.cppreference.com/w/cpp/container/set/set).

Also use allocator_traits::select_on_container_copy_construction() to get allocator for copy construction.

PiperOrigin-RevId: 339058322

--
b6cc121689ae3e452d1db2d66122cb198d25142b by Derek Mauro <dmauro@google.com>:

Fix more sign-compare warnings

PiperOrigin-RevId: 339057920

--
0e2c62da1dcaf6529abab952bdcc96c6de2d9506 by Abseil Team <absl-team@google.com>:

Add missing <limits> include

PiperOrigin-RevId: 339054753

--
d5a9ec2d1e40fe6359e720942e4955009ee415ec by Derek Mauro <dmauro@google.com>:

Stop disabling sign-compare warnings for non-test targets.
Our users complain about these.

This does not catch issues in header-only libraries (like btree.h)
but we may work on those in the future

PiperOrigin-RevId: 338967089

--
0c062c542a4c61ea0f65d25811827c0858e3adde by Abseil Team <absl-team@google.com>:

Improve cache-locality for ThreadIdentity and PerThreadSynch.

This is a change based on an observation in RPC benchmarks that shows
significant cycles being spent in waking up a thread, 99.8% of which
was on cache misses. Investigating this a bit more, it turns out to
be due to sharing the cache line with the waiter state.

To fix this issue, the following changes are introduced:
- Reorder fields in PerThreadSync so that it fits in a single cache line
  The size of this structure was 80 bytes before this change.
  Note: Manually inspected all booleans to make sure they are not modified by
        multiple threads concurrently.

PiperOrigin-RevId: 338852058

--
a90d6f2b2346385017e32dd8ae1b5ca691a5863f by Derek Mauro <dmauro@google.com>:

Delete GCC 4.9 test script. It is no longer supported

PiperOrigin-RevId: 338779452

--
7274008d4757e88869110be9db39d03d911ae2b5 by Abseil Team <absl-team@google.com>:

Fix the usage example in which SetFlag should take a pointer.

PiperOrigin-RevId: 338744529
GitOrigin-RevId: 730bb88bee556aa11fa19aa33e1434cb6fa78985
Change-Id: Iff99594c4022e60e482a392d334b376c7ae8883e

15 files changed, 203 insertions, 179 deletions

diff --git a/absl/base/internal/thread_identity.h b/absl/base/internal/thread_identity.h
index ceb109b4..c61d1feb 100644
--- a/absl/base/internal/thread_identity.h
+++ b/absl/base/internal/thread_identity.h
@@ -32,6 +32,7 @@
 
 #include "absl/base/config.h"
 #include "absl/base/internal/per_thread_tls.h"
+#include "absl/base/optimization.h"
 
 namespace absl {
 ABSL_NAMESPACE_BEGIN
@@ -69,30 +70,28 @@ struct PerThreadSynch {
                          // is using this PerThreadSynch as a terminator.  Its
                          // skip field must not be filled in because the loop
                          // might then skip over the terminator.
-
-  // The wait parameters of the current wait.  waitp is null if the
-  // thread is not waiting. Transitions from null to non-null must
-  // occur before the enqueue commit point (state = kQueued in
-  // Enqueue() and CondVarEnqueue()). Transitions from non-null to
-  // null must occur after the wait is finished (state = kAvailable in
-  // Mutex::Block() and CondVar::WaitCommon()). This field may be
-  // changed only by the thread that describes this PerThreadSynch.  A
-  // special case is Fer(), which calls Enqueue() on another thread,
-  // but with an identical SynchWaitParams pointer, thus leaving the
-  // pointer unchanged.
-  SynchWaitParams *waitp;
-
-  bool suppress_fatal_errors;  // If true, try to proceed even in the face of
-                               // broken invariants.  This is used within fatal
-                               // signal handlers to improve the chances of
-                               // debug logging information being output
-                               // successfully.
-
-  intptr_t readers;     // Number of readers in mutex.
-  int priority;         // Priority of thread (updated every so often).
-
-  // When priority will next be read (cycles).
-  int64_t next_priority_read_cycles;
+  bool wake;             // This thread is to be woken from a Mutex.
+  // If "x" is on a waiter list for a mutex, "x->cond_waiter" is true iff the
+  // waiter is waiting on the mutex as part of a CV Wait or Mutex Await.
+  //
+  // The value of "x->cond_waiter" is meaningless if "x" is not on a
+  // Mutex waiter list.
+  bool cond_waiter;
+  bool maybe_unlocking;  // Valid at head of Mutex waiter queue;
+                         // true if UnlockSlow could be searching
+                         // for a waiter to wake.  Used for an optimization
+                         // in Enqueue().  true is always a valid value.
+                         // Can be reset to false when the unlocker or any
+                         // writer releases the lock, or a reader fully
+                         // releases the lock.  It may not be set to false
+                         // by a reader that decrements the count to
+                         // non-zero. protected by mutex spinlock
+  bool suppress_fatal_errors;  // If true, try to proceed even in the face
+                               // of broken invariants.  This is used within
+                               // fatal signal handlers to improve the
+                               // chances of debug logging information being
+                               // output successfully.
+  int priority;                // Priority of thread (updated every so often).
 
   // State values:
   //   kAvailable: This PerThreadSynch is available.
@@ -111,30 +110,30 @@ struct PerThreadSynch {
   };
   std::atomic<State> state;
 
-  bool maybe_unlocking;  // Valid at head of Mutex waiter queue;
-                         // true if UnlockSlow could be searching
-                         // for a waiter to wake.  Used for an optimization
-                         // in Enqueue().  true is always a valid value.
-                         // Can be reset to false when the unlocker or any
-                         // writer releases the lock, or a reader fully releases
-                         // the lock.  It may not be set to false by a reader
-                         // that decrements the count to non-zero.
-                         // protected by mutex spinlock
+  // The wait parameters of the current wait.  waitp is null if the
+  // thread is not waiting. Transitions from null to non-null must
+  // occur before the enqueue commit point (state = kQueued in
+  // Enqueue() and CondVarEnqueue()). Transitions from non-null to
+  // null must occur after the wait is finished (state = kAvailable in
+  // Mutex::Block() and CondVar::WaitCommon()). This field may be
+  // changed only by the thread that describes this PerThreadSynch.  A
+  // special case is Fer(), which calls Enqueue() on another thread,
+  // but with an identical SynchWaitParams pointer, thus leaving the
+  // pointer unchanged.
+  SynchWaitParams* waitp;
 
-  bool wake;  // This thread is to be woken from a Mutex.
+  intptr_t readers;     // Number of readers in mutex.
 
-  // If "x" is on a waiter list for a mutex, "x->cond_waiter" is true iff the
-  // waiter is waiting on the mutex as part of a CV Wait or Mutex Await.
-  //
-  // The value of "x->cond_waiter" is meaningless if "x" is not on a
-  // Mutex waiter list.
-  bool cond_waiter;
+  // When priority will next be read (cycles).
+  int64_t next_priority_read_cycles;
 
   // Locks held; used during deadlock detection.
   // Allocated in Synch_GetAllLocks() and freed in ReclaimThreadIdentity().
   SynchLocksHeld *all_locks;
 };
 
+// The instances of this class are allocated in NewThreadIdentity() with an
+// alignment of PerThreadSynch::kAlignment.
 struct ThreadIdentity {
   // Must be the first member.  The Mutex implementation requires that
   // the PerThreadSynch object associated with each thread is
diff --git a/absl/container/btree_test.cc b/absl/container/btree_test.cc
index 7fa5d4f3..4a495067 100644
--- a/absl/container/btree_test.cc
+++ b/absl/container/btree_test.cc
@@ -2709,6 +2709,101 @@ TEST(Btree, MultiKeyEqualRange) {
   }
 }
 
+TEST(Btree, AllocConstructor) {
+  using Alloc = CountingAllocator<int>;
+  using Set = absl::btree_set<int, std::less<int>, Alloc>;
+  int64_t bytes_used = 0;
+  Alloc alloc(&bytes_used);
+  Set set(alloc);
+
+  set.insert({1, 2, 3});
+
+  EXPECT_THAT(set, ElementsAre(1, 2, 3));
+  EXPECT_GT(bytes_used, set.size() * sizeof(int));
+}
+
+TEST(Btree, AllocInitializerListConstructor) {
+  using Alloc = CountingAllocator<int>;
+  using Set = absl::btree_set<int, std::less<int>, Alloc>;
+  int64_t bytes_used = 0;
+  Alloc alloc(&bytes_used);
+  Set set({1, 2, 3}, alloc);
+
+  EXPECT_THAT(set, ElementsAre(1, 2, 3));
+  EXPECT_GT(bytes_used, set.size() * sizeof(int));
+}
+
+TEST(Btree, AllocRangeConstructor) {
+  using Alloc = CountingAllocator<int>;
+  using Set = absl::btree_set<int, std::less<int>, Alloc>;
+  int64_t bytes_used = 0;
+  Alloc alloc(&bytes_used);
+  std::vector<int> v = {1, 2, 3};
+  Set set(v.begin(), v.end(), alloc);
+
+  EXPECT_THAT(set, ElementsAre(1, 2, 3));
+  EXPECT_GT(bytes_used, set.size() * sizeof(int));
+}
+
+TEST(Btree, AllocCopyConstructor) {
+  using Alloc = CountingAllocator<int>;
+  using Set = absl::btree_set<int, std::less<int>, Alloc>;
+  int64_t bytes_used1 = 0;
+  Alloc alloc1(&bytes_used1);
+  Set set1(alloc1);
+
+  set1.insert({1, 2, 3});
+
+  int64_t bytes_used2 = 0;
+  Alloc alloc2(&bytes_used2);
+  Set set2(set1, alloc2);
+
+  EXPECT_THAT(set1, ElementsAre(1, 2, 3));
+  EXPECT_THAT(set2, ElementsAre(1, 2, 3));
+  EXPECT_GT(bytes_used1, set1.size() * sizeof(int));
+  EXPECT_EQ(bytes_used1, bytes_used2);
+}
+
+TEST(Btree, AllocMoveConstructor_SameAlloc) {
+  using Alloc = CountingAllocator<int>;
+  using Set = absl::btree_set<int, std::less<int>, Alloc>;
+  int64_t bytes_used = 0;
+  Alloc alloc(&bytes_used);
+  Set set1(alloc);
+
+  set1.insert({1, 2, 3});
+
+  const int64_t original_bytes_used = bytes_used;
+  EXPECT_GT(original_bytes_used, set1.size() * sizeof(int));
+
+  Set set2(std::move(set1), alloc);
+
+  EXPECT_THAT(set2, ElementsAre(1, 2, 3));
+  EXPECT_EQ(bytes_used, original_bytes_used);
+}
+
+TEST(Btree, AllocMoveConstructor_DifferentAlloc) {
+  using Alloc = CountingAllocator<int>;
+  using Set = absl::btree_set<int, std::less<int>, Alloc>;
+  int64_t bytes_used1 = 0;
+  Alloc alloc1(&bytes_used1);
+  Set set1(alloc1);
+
+  set1.insert({1, 2, 3});
+
+  const int64_t original_bytes_used = bytes_used1;
+  EXPECT_GT(original_bytes_used, set1.size() * sizeof(int));
+
+  int64_t bytes_used2 = 0;
+  Alloc alloc2(&bytes_used2);
+  Set set2(std::move(set1), alloc2);
+
+  EXPECT_THAT(set2, ElementsAre(1, 2, 3));
+  // We didn't free these bytes allocated by `set1` yet.
+  EXPECT_EQ(bytes_used1, original_bytes_used);
+  EXPECT_EQ(bytes_used2, original_bytes_used);
+}
+
 }  // namespace
 }  // namespace container_internal
 ABSL_NAMESPACE_END
diff --git a/absl/container/internal/btree.h b/absl/container/internal/btree.h
index a82b5177..8547d68e 100644
--- a/absl/container/internal/btree.h
+++ b/absl/container/internal/btree.h
@@ -1141,21 +1141,35 @@ class btree {
   // before this method is called. This method is used in copy construction,
   // copy assignment, and move assignment.
   template <typename Btree>
-  void copy_or_move_values_in_order(Btree *other);
+  void copy_or_move_values_in_order(Btree &other);
 
   // Validates that various assumptions/requirements are true at compile time.
   constexpr static bool static_assert_validation();
 
  public:
-  btree(const key_compare &comp, const allocator_type &alloc);
+  btree(const key_compare &comp, const allocator_type &alloc)
+      : root_(comp, alloc, EmptyNode()), rightmost_(EmptyNode()), size_(0) {}
 
-  btree(const btree &other);
+  btree(const btree &other) : btree(other, other.allocator()) {}
+  btree(const btree &other, const allocator_type &alloc)
+      : btree(other.key_comp(), alloc) {
+    copy_or_move_values_in_order(other);
+  }
   btree(btree &&other) noexcept
       : root_(std::move(other.root_)),
         rightmost_(absl::exchange(other.rightmost_, EmptyNode())),
         size_(absl::exchange(other.size_, 0)) {
     other.mutable_root() = EmptyNode();
   }
+  btree(btree &&other, const allocator_type &alloc)
+      : btree(other.key_comp(), alloc) {
+    if (alloc == other.allocator()) {
+      swap(other);
+    } else {
+      // Move values from `other` one at a time when allocators are different.
+      copy_or_move_values_in_order(other);
+    }
+  }
 
   ~btree() {
     // Put static_asserts in destructor to avoid triggering them before the type
@@ -1851,7 +1865,7 @@ void btree_iterator<N, R, P>::decrement_slow() {
 // btree methods
 template <typename P>
 template <typename Btree>
-void btree<P>::copy_or_move_values_in_order(Btree *other) {
+void btree<P>::copy_or_move_values_in_order(Btree &other) {
   static_assert(std::is_same<btree, Btree>::value ||
                     std::is_same<const btree, Btree>::value,
                 "Btree type must be same or const.");
@@ -1859,11 +1873,11 @@ void btree<P>::copy_or_move_values_in_order(Btree *other) {
 
   // We can avoid key comparisons because we know the order of the
   // values is the same order we'll store them in.
-  auto iter = other->begin();
-  if (iter == other->end()) return;
+  auto iter = other.begin();
+  if (iter == other.end()) return;
   insert_multi(maybe_move_from_iterator(iter));
   ++iter;
-  for (; iter != other->end(); ++iter) {
+  for (; iter != other.end(); ++iter) {
     // If the btree is not empty, we can just insert the new value at the end
     // of the tree.
     internal_emplace(end(), maybe_move_from_iterator(iter));
@@ -1902,16 +1916,6 @@ constexpr bool btree<P>::static_assert_validation() {
 }
 
 template <typename P>
-btree<P>::btree(const key_compare &comp, const allocator_type &alloc)
-    : root_(comp, alloc, EmptyNode()), rightmost_(EmptyNode()), size_(0) {}
-
-template <typename P>
-btree<P>::btree(const btree &other)
-    : btree(other.key_comp(), other.allocator()) {
-  copy_or_move_values_in_order(&other);
-}
-
-template <typename P>
 template <typename K>
 auto btree<P>::equal_range(const K &key) -> std::pair<iterator, iterator> {
   const iterator lower = lower_bound(key);
@@ -2068,7 +2072,7 @@ auto btree<P>::operator=(const btree &other) -> btree & {
       *mutable_allocator() = other.allocator();
     }
 
-    copy_or_move_values_in_order(&other);
+    copy_or_move_values_in_order(other);
   }
   return *this;
 }
@@ -2098,7 +2102,7 @@ auto btree<P>::operator=(btree &&other) noexcept -> btree & {
         // comparator while moving the values so we can't swap the key
         // comparators.
         *mutable_key_comp() = other.key_comp();
-        copy_or_move_values_in_order(&other);
+        copy_or_move_values_in_order(other);
       }
     }
   }
diff --git a/absl/container/internal/btree_container.h b/absl/container/internal/btree_container.h
index 2322e7c7..3792bc21 100644
--- a/absl/container/internal/btree_container.h
+++ b/absl/container/internal/btree_container.h
@@ -23,6 +23,7 @@
 #include "absl/base/internal/throw_delegate.h"
 #include "absl/container/internal/btree.h"  // IWYU pragma: export
 #include "absl/container/internal/common.h"
+#include "absl/memory/memory.h"
 #include "absl/meta/type_traits.h"
 
 namespace absl {
@@ -68,8 +69,21 @@ class btree_container {
   explicit btree_container(const key_compare &comp,
                            const allocator_type &alloc = allocator_type())
       : tree_(comp, alloc) {}
-  btree_container(const btree_container &other) = default;
-  btree_container(btree_container &&other) noexcept = default;
+  explicit btree_container(const allocator_type &alloc)
+      : tree_(key_compare(), alloc) {}
+
+  btree_container(const btree_container &other)
+      : btree_container(other, absl::allocator_traits<allocator_type>::
+                                   select_on_container_copy_construction(
+                                       other.get_allocator())) {}
+  btree_container(const btree_container &other, const allocator_type &alloc)
+      : tree_(other.tree_, alloc) {}
+
+  btree_container(btree_container &&other) noexcept(
+      std::is_nothrow_move_constructible<Tree>::value) = default;
+  btree_container(btree_container &&other, const allocator_type &alloc)
+      : tree_(std::move(other.tree_), alloc) {}
+
   btree_container &operator=(const btree_container &other) = default;
   btree_container &operator=(btree_container &&other) noexcept(
       std::is_nothrow_move_assignable<Tree>::value) = default;
@@ -234,7 +248,7 @@ class btree_set_container : public btree_container<Tree> {
   using super_type::super_type;
   btree_set_container() {}
 
-  // Range constructor.
+  // Range constructors.
   template <class InputIterator>
   btree_set_container(InputIterator b, InputIterator e,
                       const key_compare &comp = key_compare(),
@@ -242,12 +256,19 @@ class btree_set_container : public btree_container<Tree> {
       : super_type(comp, alloc) {
     insert(b, e);
   }
+  template <class InputIterator>
+  btree_set_container(InputIterator b, InputIterator e,
+                      const allocator_type &alloc)
+      : btree_set_container(b, e, key_compare(), alloc) {}
 
-  // Initializer list constructor.
+  // Initializer list constructors.
   btree_set_container(std::initializer_list<init_type> init,
                       const key_compare &comp = key_compare(),
                       const allocator_type &alloc = allocator_type())
       : btree_set_container(init.begin(), init.end(), comp, alloc) {}
+  btree_set_container(std::initializer_list<init_type> init,
+                      const allocator_type &alloc)
+      : btree_set_container(init.begin(), init.end(), alloc) {}
 
   // Lookup routines.
   template <typename K = key_type>
@@ -535,7 +556,7 @@ class btree_multiset_container : public btree_container<Tree> {
   using super_type::super_type;
   btree_multiset_container() {}
 
-  // Range constructor.
+  // Range constructors.
   template <class InputIterator>
   btree_multiset_container(InputIterator b, InputIterator e,
                            const key_compare &comp = key_compare(),
@@ -543,12 +564,19 @@ class btree_multiset_container : public btree_container<Tree> {
       : super_type(comp, alloc) {
     insert(b, e);
   }
+  template <class InputIterator>
+  btree_multiset_container(InputIterator b, InputIterator e,
+                           const allocator_type &alloc)
+      : btree_multiset_container(b, e, key_compare(), alloc) {}
 
-  // Initializer list constructor.
+  // Initializer list constructors.
   btree_multiset_container(std::initializer_list<init_type> init,
                            const key_compare &comp = key_compare(),
                            const allocator_type &alloc = allocator_type())
       : btree_multiset_container(init.begin(), init.end(), comp, alloc) {}
+  btree_multiset_container(std::initializer_list<init_type> init,
+                           const allocator_type &alloc)
+      : btree_multiset_container(init.begin(), init.end(), alloc) {}
 
   // Lookup routines.
   template <typename K = key_type>
diff --git a/absl/copts/GENERATED_AbseilCopts.cmake b/absl/copts/GENERATED_AbseilCopts.cmake
index 97bd283e..beb3799e 100644
--- a/absl/copts/GENERATED_AbseilCopts.cmake
+++ b/absl/copts/GENERATED_AbseilCopts.cmake
@@ -16,7 +16,6 @@ list(APPEND ABSL_CLANG_CL_FLAGS
     "-Wno-extra-semi-stmt"
     "-Wno-packed"
     "-Wno-padded"
-    "-Wno-sign-compare"
     "-Wno-float-conversion"
     "-Wno-float-equal"
     "-Wno-format-nonliteral"
@@ -88,7 +87,6 @@ list(APPEND ABSL_GCC_FLAGS
     "-Wvla"
     "-Wwrite-strings"
     "-Wno-missing-field-initializers"
-    "-Wno-sign-compare"
     "-DNOMINMAX"
 )
 
@@ -117,7 +115,6 @@ list(APPEND ABSL_LLVM_FLAGS
     "-Wno-extra-semi-stmt"
     "-Wno-packed"
     "-Wno-padded"
-    "-Wno-sign-compare"
     "-Wno-float-conversion"
     "-Wno-float-equal"
     "-Wno-format-nonliteral"
diff --git a/absl/copts/GENERATED_copts.bzl b/absl/copts/GENERATED_copts.bzl
index bcdd61ef..ff729d74 100644
--- a/absl/copts/GENERATED_copts.bzl
+++ b/absl/copts/GENERATED_copts.bzl
@@ -17,7 +17,6 @@ ABSL_CLANG_CL_FLAGS = [
     "-Wno-extra-semi-stmt",
     "-Wno-packed",
     "-Wno-padded",
-    "-Wno-sign-compare",
     "-Wno-float-conversion",
     "-Wno-float-equal",
     "-Wno-format-nonliteral",
@@ -89,7 +88,6 @@ ABSL_GCC_FLAGS = [
     "-Wvla",
     "-Wwrite-strings",
     "-Wno-missing-field-initializers",
-    "-Wno-sign-compare",
     "-DNOMINMAX",
 ]
 
@@ -118,7 +116,6 @@ ABSL_LLVM_FLAGS = [
     "-Wno-extra-semi-stmt",
     "-Wno-packed",
     "-Wno-padded",
-    "-Wno-sign-compare",
     "-Wno-float-conversion",
     "-Wno-float-equal",
     "-Wno-format-nonliteral",
diff --git a/absl/copts/copts.py b/absl/copts/copts.py
index a3437c1b..55b5fb10 100644
--- a/absl/copts/copts.py
+++ b/absl/copts/copts.py
@@ -41,10 +41,6 @@ LLVM_DISABLE_WARNINGS_FLAGS = [
     "-Wno-packed",
     "-Wno-padded",
     ###
-    # Google style does not use unsigned integers, though STL containers
-    # have unsigned types.
-    "-Wno-sign-compare",
-    ###
     "-Wno-float-conversion",
     "-Wno-float-equal",
     "-Wno-format-nonliteral",
@@ -138,9 +134,6 @@ COPT_VARS = {
         # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=36750
         # Remove when gcc-4.x is no longer supported.
         "-Wno-missing-field-initializers",
-        # Google style does not use unsigned integers, though STL containers
-        # have unsigned types.
-        "-Wno-sign-compare",
         # Don't define min and max macros (Build on Windows using gcc)
         "-DNOMINMAX",
     ],
diff --git a/absl/debugging/symbolize_elf.inc b/absl/debugging/symbolize_elf.inc
index 7c36fd13..f4d5727b 100644
--- a/absl/debugging/symbolize_elf.inc
+++ b/absl/debugging/symbolize_elf.inc
@@ -1281,7 +1281,7 @@ static bool MaybeInitializeObjFile(ObjFile *obj) {
     const int phnum = obj->elf_header.e_phnum;
     const int phentsize = obj->elf_header.e_phentsize;
     size_t phoff = obj->elf_header.e_phoff;
-    int num_executable_load_segments = 0;
+    size_t num_executable_load_segments = 0;
     for (int j = 0; j < phnum; j++) {
       ElfW(Phdr) phdr;
       if (!ReadFromOffsetExact(obj->fd, &phdr, sizeof(phdr), phoff)) {
@@ -1342,7 +1342,7 @@ const char *Symbolizer::GetSymbol(const void *const pc) {
         // Note: some binaries have multiple "rx" LOAD segments. We must
         // find the right one.
         ElfW(Phdr) *phdr = nullptr;
-        for (int j = 0; j < obj->phdr.size(); j++) {
+        for (size_t j = 0; j < obj->phdr.size(); j++) {
           ElfW(Phdr) &p = obj->phdr[j];
           if (p.p_type != PT_LOAD) {
             // We only expect PT_LOADs. This must be PT_NULL that we didn't
diff --git a/absl/flags/reflection.h b/absl/flags/reflection.h
index 4ce0ab6c..e6baf5de 100644
--- a/absl/flags/reflection.h
+++ b/absl/flags/reflection.h
@@ -64,7 +64,7 @@ absl::flat_hash_map<absl::string_view, absl::CommandLineFlag*> GetAllFlags();
 //   void MyFunc() {
 //    absl::FlagSaver fs;
 //    ...
-//    absl::SetFlag(FLAGS_myFlag, otherValue);
+//    absl::SetFlag(&FLAGS_myFlag, otherValue);
 //    ...
 //  } // scope of FlagSaver left, flags return to previous state
 //
diff --git a/absl/strings/internal/charconv_parse.cc b/absl/strings/internal/charconv_parse.cc
index a368845f..8b11868c 100644
--- a/absl/strings/internal/charconv_parse.cc
+++ b/absl/strings/internal/charconv_parse.cc
@@ -246,8 +246,8 @@ constexpr int DigitMagnitude<16>() {
 // ConsumeDigits does not protect against overflow on *out; max_digits must
 // be chosen with respect to type T to avoid the possibility of overflow.
 template <int base, typename T>
-std::size_t ConsumeDigits(const char* begin, const char* end, int max_digits,
-                          T* out, bool* dropped_nonzero_digit) {
+int ConsumeDigits(const char* begin, const char* end, int max_digits, T* out,
+                  bool* dropped_nonzero_digit) {
   if (base == 10) {
     assert(max_digits <= std::numeric_limits<T>::digits10);
   } else if (base == 16) {
@@ -282,7 +282,7 @@ std::size_t ConsumeDigits(const char* begin, const char* end, int max_digits,
     *dropped_nonzero_digit = true;
   }
   *out = accumulator;
-  return begin - original_begin;
+  return static_cast<int>(begin - original_begin);
 }
 
 // Returns true if `v` is one of the chars allowed inside parentheses following
@@ -372,7 +372,7 @@ strings_internal::ParsedFloat ParseFloat(const char* begin, const char* end,
 
   int exponent_adjustment = 0;
   bool mantissa_is_inexact = false;
-  std::size_t pre_decimal_digits = ConsumeDigits<base>(
+  int pre_decimal_digits = ConsumeDigits<base>(
       begin, end, MantissaDigitsMax<base>(), &mantissa, &mantissa_is_inexact);
   begin += pre_decimal_digits;
   int digits_left;
@@ -398,14 +398,14 @@ strings_internal::ParsedFloat ParseFloat(const char* begin, const char* end,
       while (begin < end && *begin == '0') {
         ++begin;
       }
-      std::size_t zeros_skipped = begin - begin_zeros;
+      int zeros_skipped = static_cast<int>(begin - begin_zeros);
       if (zeros_skipped >= DigitLimit<base>()) {
         // refuse to parse pathological inputs
         return result;
       }
       exponent_adjustment -= static_cast<int>(zeros_skipped);
     }
-    int64_t post_decimal_digits = ConsumeDigits<base>(
+    int post_decimal_digits = ConsumeDigits<base>(
         begin, end, digits_left, &mantissa, &mantissa_is_inexact);
     begin += post_decimal_digits;
 
diff --git a/absl/strings/internal/str_format/bind.cc b/absl/strings/internal/str_format/bind.cc
index 194e21af..4e68b90b 100644
--- a/absl/strings/internal/str_format/bind.cc
+++ b/absl/strings/internal/str_format/bind.cc
@@ -235,7 +235,7 @@ int FprintF(std::FILE* output, const UntypedFormatSpecImpl format,
     errno = sink.error();
     return -1;
   }
-  if (sink.count() > std::numeric_limits<int>::max()) {
+  if (sink.count() > static_cast<size_t>(std::numeric_limits<int>::max())) {
     errno = EFBIG;
     return -1;
   }
diff --git a/absl/strings/internal/str_format/float_conversion.cc b/absl/strings/internal/str_format/float_conversion.cc
index d3c5f0a7..0ded0a66 100644
--- a/absl/strings/internal/str_format/float_conversion.cc
+++ b/absl/strings/internal/str_format/float_conversion.cc
@@ -134,7 +134,7 @@ class BinaryToDecimal {
     assert(exp > 0);
     assert(exp <= std::numeric_limits<long double>::max_exponent);
     static_assert(
-        StackArray::kMaxCapacity >=
+        static_cast<int>(StackArray::kMaxCapacity) >=
             ChunksNeeded(std::numeric_limits<long double>::max_exponent),
         "");
 
diff --git a/absl/synchronization/internal/graphcycles.cc b/absl/synchronization/internal/graphcycles.cc
index 19f9aab5..27fec216 100644
--- a/absl/synchronization/internal/graphcycles.cc
+++ b/absl/synchronization/internal/graphcycles.cc
@@ -37,6 +37,7 @@
 
 #include <algorithm>
 #include <array>
+#include <limits>
 #include "absl/base/internal/hide_ptr.h"
 #include "absl/base/internal/raw_logging.h"
 #include "absl/base/internal/spinlock.h"
diff --git a/ci/linux_docker_containers.sh b/ci/linux_docker_containers.sh
index b96fe890..afad301e 100644
--- a/ci/linux_docker_containers.sh
+++ b/ci/linux_docker_containers.sh
@@ -19,4 +19,3 @@ readonly LINUX_ALPINE_CONTAINER="gcr.io/google.com/absl-177019/alpine:20191016"
 readonly LINUX_CLANG_LATEST_CONTAINER="gcr.io/google.com/absl-177019/linux_hybrid-latest:20201008"
 readonly LINUX_GCC_LATEST_CONTAINER="gcr.io/google.com/absl-177019/linux_hybrid-latest:20201008"
 readonly LINUX_GCC_FLOOR_CONTAINER="gcr.io/google.com/absl-177019/linux_gcc-floor:20201015"
-readonly LINUX_GCC_49_CONTAINER="gcr.io/google.com/absl-177019/linux_gcc-4.9:20191018"
diff --git a/ci/linux_gcc-4.9_libstdcxx_bazel.sh b/ci/linux_gcc-4.9_libstdcxx_bazel.sh
deleted file mode 100755
index 16f927bd..00000000
--- a/ci/linux_gcc-4.9_libstdcxx_bazel.sh
+++ /dev/null
@@ -1,89 +0,0 @@
-#!/bin/bash
-#
-# Copyright 2019 The Abseil Authors.
-#
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-#    https://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-
-# This script that can be invoked to test abseil-cpp in a hermetic environment
-# using a Docker image on Linux. You must have Docker installed to use this
-# script.
-
-set -euox pipefail
-
-if [[ -z ${ABSEIL_ROOT:-} ]]; then
-  ABSEIL_ROOT="$(realpath $(dirname ${0})/..)"
-fi
-
-if [[ -z ${STD:-} ]]; then
-  STD="c++11 c++14"
-fi
-
-if [[ -z ${COMPILATION_MODE:-} ]]; then
-  COMPILATION_MODE="fastbuild opt"
-fi
-
-if [[ -z ${EXCEPTIONS_MODE:-} ]]; then
-  EXCEPTIONS_MODE="-fno-exceptions -fexceptions"
-fi
-
-source "${ABSEIL_ROOT}/ci/linux_docker_containers.sh"
-readonly DOCKER_CONTAINER=${LINUX_GCC_49_CONTAINER}
-
-# USE_BAZEL_CACHE=1 only works on Kokoro.
-# Without access to the credentials this won't work.
-if [[ ${USE_BAZEL_CACHE:-0} -ne 0 ]]; then
-  DOCKER_EXTRA_ARGS="--mount type=bind,source=${KOKORO_KEYSTORE_DIR},target=/keystore,readonly ${DOCKER_EXTRA_ARGS:-}"
-  # Bazel doesn't track changes to tools outside of the workspace
-  # (e.g. /usr/bin/gcc), so by appending the docker container to the
-  # remote_http_cache url, we make changes to the container part of
-  # the cache key. Hashing the key is to make it shorter and url-safe.
-  container_key=$(echo ${DOCKER_CONTAINER} | sha256sum | head -c 16)
-  BAZEL_EXTRA_ARGS="--remote_http_cache=https://storage.googleapis.com/absl-bazel-remote-cache/${container_key} --google_credentials=/keystore/73103_absl-bazel-remote-cache ${BAZEL_EXTRA_ARGS:-}"
-fi
-
-# Avoid depending on external sites like GitHub by checking --distdir for
-# external dependencies first.
-# https://docs.bazel.build/versions/master/guide.html#distdir
-if [[ ${KOKORO_GFILE_DIR:-} ]] && [[ -d "${KOKORO_GFILE_DIR}/distdir" ]]; then
-  DOCKER_EXTRA_ARGS="--mount type=bind,source=${KOKORO_GFILE_DIR}/distdir,target=/distdir,readonly ${DOCKER_EXTRA_ARGS:-}"
-  BAZEL_EXTRA_ARGS="--distdir=/distdir ${BAZEL_EXTRA_ARGS:-}"
-fi
-
-for std in ${STD}; do
-  for compilation_mode in ${COMPILATION_MODE}; do
-    for exceptions_mode in ${EXCEPTIONS_MODE}; do
-      echo "--------------------------------------------------------------------"
-      time docker run \
-        --mount type=bind,source="${ABSEIL_ROOT}",target=/abseil-cpp,readonly \
-        --workdir=/abseil-cpp \
-        --cap-add=SYS_PTRACE \
-        --rm \
-        -e CC="/usr/bin/gcc-4.9" \
-        -e BAZEL_CXXOPTS="-std=${std}" \
-        ${DOCKER_EXTRA_ARGS:-} \
-        ${DOCKER_CONTAINER} \
-        /usr/local/bin/bazel test ... \
-          --compilation_mode="${compilation_mode}" \
-          --copt="${exceptions_mode}" \
-          --copt=-Werror \
-          --define="absl=1" \
-          --keep_going \
-          --show_timestamps \
-          --test_env="GTEST_INSTALL_FAILURE_SIGNAL_HANDLER=1" \
-          --test_env="TZDIR=/abseil-cpp/absl/time/internal/cctz/testdata/zoneinfo" \
-          --test_output=errors \
-          --test_tag_filters=-benchmark \
-          ${BAZEL_EXTRA_ARGS:-}
-    done
-  done
-done