Export of internal Abseil changes

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00f5301405423005d9129935c05f20155536cc1a by CJ Johnson <johnsoncj@google.com>:

Removes usage of std::aligned_storage from Abseil implementation details

PiperOrigin-RevId: 296492301

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fc11d15f91764612fba080669d2381dc181df52b by Abseil Team <absl-team@google.com>:

Fix absl::bind_front documentation.

PiperOrigin-RevId: 296482945

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0164c595c129c46bf21ae74eba5399a1da5f140b by Gennadiy Rozental <rogeeff@google.com>:

Automated g4 rollback of changelist 296320700.

PiperOrigin-RevId: 296439968

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1eb295700758ca0894d872b2de7c675b4ad679af by Abseil Team <absl-team@google.com>:

Removes duplicate comments.

PiperOrigin-RevId: 296433214

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c30c01caae02d2fa4ef783d988de6bebb9757c39 by Derek Mauro <dmauro@google.com>:

Merge GitHub #621: Add RISCV support to GetProgramCounter()

Fixes #621

PiperOrigin-RevId: 296351174

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95d4498167596fd7543e025bdfe9a8da9e2ca3c8 by Abseil Team <absl-team@google.com>:

Automated g4 rollback of changelist 296320700.

PiperOrigin-RevId: 296348701

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b193f0543e0cec54dddb2ed51f45dc489c8d06d5 by Gennadiy Rozental <rogeeff@google.com>:

Change TryParse interface to return managed value.

In addition introduce companion StoreValue routine which consumes pointer to source value and stores the value inside of FlagImpl. In a follow up CL we will change StoreValue implementation to behave differently depending on "value storage kind".
We also rename default_src_ to default_value_.

PiperOrigin-RevId: 296320700

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57e942b485d12912a0a8d0d0b35fa2a62847020f by Derek Mauro <dmauro@google.com>:

Merge GitHub #622
 * Add missing #ifdef conditionals for ABSL_HAVE_VDSO_SUPPORT

PiperOrigin-RevId: 296272830
GitOrigin-RevId: 00f5301405423005d9129935c05f20155536cc1a
Change-Id: I1b05eeaf1280f95fb0a2c5f3654995a87c792893

3 files changed, 7 insertions, 13 deletions

diff --git a/absl/container/fixed_array_test.cc b/absl/container/fixed_array_test.cc
index 2b1cf47e..c960fe51 100644
--- a/absl/container/fixed_array_test.cc
+++ b/absl/container/fixed_array_test.cc
@@ -604,19 +604,16 @@ TEST(FixedArrayTest, Fill) {
   empty.fill(fill_val);
 }
 
-// TODO(johnsoncj): Investigate InlinedStorage default initialization in GCC 4.x
 #ifndef __GNUC__
 TEST(FixedArrayTest, DefaultCtorDoesNotValueInit) {
   using T = char;
   constexpr auto capacity = 10;
   using FixedArrType = absl::FixedArray<T, capacity>;
-  using FixedArrBuffType =
-      absl::aligned_storage_t<sizeof(FixedArrType), alignof(FixedArrType)>;
   constexpr auto scrubbed_bits = 0x95;
   constexpr auto length = capacity / 2;
 
-  FixedArrBuffType buff;
-  std::memset(std::addressof(buff), scrubbed_bits, sizeof(FixedArrBuffType));
+  alignas(FixedArrType) unsigned char buff[sizeof(FixedArrType)];
+  std::memset(std::addressof(buff), scrubbed_bits, sizeof(FixedArrType));
 
   FixedArrType* arr =
       ::new (static_cast<void*>(std::addressof(buff))) FixedArrType(length);
diff --git a/absl/container/internal/common.h b/absl/container/internal/common.h
index 853a5b21..5037d803 100644
--- a/absl/container/internal/common.h
+++ b/absl/container/internal/common.h
@@ -56,7 +56,7 @@ class node_handle_base {
  public:
   using allocator_type = Alloc;
 
-  constexpr node_handle_base() {}
+  constexpr node_handle_base() = default;
   node_handle_base(node_handle_base&& other) noexcept {
     *this = std::move(other);
   }
@@ -109,9 +109,8 @@ class node_handle_base {
   allocator_type* alloc() { return std::addressof(*alloc_); }
 
  private:
-  absl::optional<allocator_type> alloc_;
-  mutable absl::aligned_storage_t<sizeof(slot_type), alignof(slot_type)>
-      slot_space_;
+  absl::optional<allocator_type> alloc_ = {};
+  alignas(slot_type) mutable unsigned char slot_space_[sizeof(slot_type)] = {};
 };
 
 // For sets.
diff --git a/absl/container/internal/raw_hash_set.h b/absl/container/internal/raw_hash_set.h
index 0d3d604c..ca7be8d8 100644
--- a/absl/container/internal/raw_hash_set.h
+++ b/absl/container/internal/raw_hash_set.h
@@ -1067,8 +1067,7 @@ class raw_hash_set {
   template <class... Args, typename std::enable_if<
                                !IsDecomposable<Args...>::value, int>::type = 0>
   std::pair<iterator, bool> emplace(Args&&... args) {
-    typename std::aligned_storage<sizeof(slot_type), alignof(slot_type)>::type
-        raw;
+    alignas(slot_type) unsigned char raw[sizeof(slot_type)];
     slot_type* slot = reinterpret_cast<slot_type*>(&raw);
 
     PolicyTraits::construct(&alloc_ref(), slot, std::forward<Args>(args)...);
@@ -1556,8 +1555,7 @@ class raw_hash_set {
     //       mark target as FULL
     //       repeat procedure for current slot with moved from element (target)
     ConvertDeletedToEmptyAndFullToDeleted(ctrl_, capacity_);
-    typename std::aligned_storage<sizeof(slot_type), alignof(slot_type)>::type
-        raw;
+    alignas(slot_type) unsigned char raw[sizeof(slot_type)];
     size_t total_probe_length = 0;
     slot_type* slot = reinterpret_cast<slot_type*>(&raw);
     for (size_t i = 0; i != capacity_; ++i) {