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

1 files changed, 14 insertions, 11 deletions

diff --git a/absl/flags/internal/flag.h b/absl/flags/internal/flag.h
index ec6734870c7e..c1beda8ebc00 100644
--- a/absl/flags/internal/flag.h
+++ b/absl/flags/internal/flag.h
@@ -363,7 +363,7 @@ struct DynValueDeleter {
     if (op != nullptr) Delete(op, ptr);
   }
 
-  const FlagOpFn op;
+  FlagOpFn op;
 };
 
 class FlagImpl {
@@ -380,7 +380,7 @@ class FlagImpl {
         on_command_line_(false),
         counter_(0),
         callback_(nullptr),
-        default_src_(default_value_gen),
+        default_value_(default_value_gen),
         data_guard_{} {}
 
   // Constant access methods
@@ -392,10 +392,6 @@ class FlagImpl {
   std::string DefaultValue() const ABSL_LOCKS_EXCLUDED(*DataGuard());
   std::string CurrentValue() const ABSL_LOCKS_EXCLUDED(*DataGuard());
   void Read(void* dst) const ABSL_LOCKS_EXCLUDED(*DataGuard());
-  // Attempts to parse supplied `value` std::string. If parsing is successful, then
-  // it replaces `dst` with the new value.
-  bool TryParse(void** dst, absl::string_view value, std::string* err) const
-      ABSL_EXCLUSIVE_LOCKS_REQUIRED(*DataGuard());
 
   template <typename T, typename std::enable_if<
                             !IsAtomicFlagTypeTrait<T>::value, int>::type = 0>
@@ -466,8 +462,15 @@ class FlagImpl {
   // Returns heap allocated value of type T initialized with default value.
   std::unique_ptr<void, DynValueDeleter> MakeInitValue() const
       ABSL_EXCLUSIVE_LOCKS_REQUIRED(*DataGuard());
-  // Lazy initialization of the Flag's data.
+  // Flag initialization called via absl::call_once.
   void Init();
+  // Attempts to parse supplied `value` std::string. If parsing is successful,
+  // returns new value. Otherwsie returns nullptr.
+  std::unique_ptr<void, DynValueDeleter> TryParse(absl::string_view value,
+                                                  std::string* err) const
+      ABSL_EXCLUSIVE_LOCKS_REQUIRED(*DataGuard());
+  // Stores the flag value based on the pointer to the source.
+  void StoreValue(const void* src) ABSL_EXCLUSIVE_LOCKS_REQUIRED(*DataGuard());
 
   FlagHelpKind HelpSourceKind() const {
     return static_cast<FlagHelpKind>(help_source_kind_);
@@ -511,7 +514,7 @@ class FlagImpl {
 
   // Mutable flag's state (guarded by `data_guard_`).
 
-  // If def_kind_ == kDynamicValue, default_src_ holds a dynamically allocated
+  // If def_kind_ == kDynamicValue, default_value_ holds a dynamically allocated
   // value.
   uint8_t def_kind_ : 1 ABSL_GUARDED_BY(*DataGuard());
   // Has this flag's value been modified?
@@ -527,7 +530,7 @@ class FlagImpl {
   // value specified in ABSL_FLAG or pointer to the dynamically set default
   // value via SetCommandLineOptionWithMode. def_kind_ is used to distinguish
   // these two cases.
-  FlagDefaultSrc default_src_ ABSL_GUARDED_BY(*DataGuard());
+  FlagDefaultSrc default_value_ ABSL_GUARDED_BY(*DataGuard());
   // Current Flag Value
   FlagValue value_;
 
@@ -542,8 +545,8 @@ class FlagImpl {
 };
 
 ///////////////////////////////////////////////////////////////////////////////
-// The "unspecified" implementation of Flag object parameterized by the
-// flag's value type.
+// The Flag object parameterized by the flag's value type. This class implements
+// flag reflection handle interface.
 
 template <typename T>
 class Flag final : public flags_internal::CommandLineFlag {