Export of internal Abseil changes

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1bc4d36e13fb9175ea8cdaa00213aa9d4417c669 by Andy Getzendanner <durandal@google.com>:

Fix pointer format specifier in documentation

Import of https://github.com/abseil/abseil-cpp/pull/614

PiperOrigin-RevId: 293227540

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c7b43b30493c4fb5f2ec3264672b08bfe1ea3709 by Abseil Team <absl-team@google.com>:

Internal change.

PiperOrigin-RevId: 293160245

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64439365e2b4a0b5e51ae0a7dafdb15912402dfd by Shahriar Rouf <nafi@google.com>:

Add benchmarks for string_view: BM_CompareFirstOneLess and BM_CompareSecondOneLess.

PiperOrigin-RevId: 293031676

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b273b420cab24a6e3f487430987e09f4eb1caec4 by Greg Falcon <gfalcon@google.com>:

Remove an unreachable line from charconv.cc.

Fixes github issue #613.

PiperOrigin-RevId: 292980167

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70babb5f7a3d9fdd00a2b3085c3c2b9fe0265c79 by Gennadiy Rozental <rogeeff@google.com>:

Move GetFlag implementation into FlagImpl.

This change will allow us to hide details of GetFlag overloads inside implementation detais. Eventually we'll migrate to a different implementation. No semantic changes in this CL.

PiperOrigin-RevId: 292930847

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94bee7b7cc31e0167ee4b953281c1e78c96a574a by Abseil Team <absl-team@google.com>:

Clarification in absl::Exponential documentation.

PiperOrigin-RevId: 292912672

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d6916d30c5c1d3ee9ae46d69ec0a166a760c99c7 by Derek Mauro <dmauro@google.com>:

Make AtomicHook constant-initializable on Clang for Windows.

Only mark AtomicHook as constant-initializable on platforms where it
is actually constant-initializable.

PiperOrigin-RevId: 292655939
GitOrigin-RevId: 1bc4d36e13fb9175ea8cdaa00213aa9d4417c669
Change-Id: I090b231a0ca0d92868e494ab5b3fa86c902889d5

2 files changed, 27 insertions, 34 deletions

diff --git a/absl/flags/flag.h b/absl/flags/flag.h
index bd61668f..fcfdd58c 100644
--- a/absl/flags/flag.h
+++ b/absl/flags/flag.h
@@ -186,15 +186,17 @@ class Flag {
 //
 //   // FLAGS_firstname is a Flag of type `std::string`
 //   std::string first_name = absl::GetFlag(FLAGS_firstname);
+template <typename T>
+ABSL_MUST_USE_RESULT T GetFlag(const absl::Flag<T>& flag) {
+  return flag.Get();
+}
+
 #ifndef NDEBUG
 // We want to validate the type mismatch between type definition and
 // declaration. The lock-free implementation does not allow us to do it,
 // so in debug builds we always use the slower implementation, which always
 // validates the type.
-template <typename T>
-ABSL_MUST_USE_RESULT T GetFlag(const absl::Flag<T>& flag) {
-  return flag.Get();
-}
+
 // We currently need an external linkage for built-in types because shared
 // libraries have different addresses of flags_internal::FlagOps<T> which
 // might cause log spam when checking the same flag type.
@@ -202,29 +204,6 @@ ABSL_MUST_USE_RESULT T GetFlag(const absl::Flag<T>& flag) {
   ABSL_MUST_USE_RESULT T GetFlag(const absl::Flag<T>& flag);
 ABSL_FLAGS_INTERNAL_BUILTIN_TYPES(ABSL_FLAGS_INTERNAL_BUILT_IN_EXPORT)
 #undef ABSL_FLAGS_INTERNAL_BUILT_IN_EXPORT
-#else
-template <typename T,
-          typename std::enable_if<
-              !flags_internal::IsAtomicFlagTypeTrait<T>::value, int>::type = 0>
-ABSL_MUST_USE_RESULT T GetFlag(const absl::Flag<T>& flag) {
-  return flag.Get();
-}
-// Overload for `GetFlag()` for types that support lock-free reads.
-template <typename T,
-          typename std::enable_if<
-              flags_internal::IsAtomicFlagTypeTrait<T>::value, int>::type = 0>
-ABSL_MUST_USE_RESULT T GetFlag(const absl::Flag<T>& flag) {
-  // T might not be default constructible.
-  union U {
-    T value;
-    U() {}
-  };
-  U result;
-  if (flag.AtomicGet(&result.value)) {
-    return result.value;
-  }
-  return flag.Get();
-}
 #endif
 
 // SetFlag()
diff --git a/absl/flags/internal/flag.h b/absl/flags/internal/flag.h
index ec467c31..4341f113 100644
--- a/absl/flags/internal/flag.h
+++ b/absl/flags/internal/flag.h
@@ -244,16 +244,32 @@ class FlagImpl {
   bool TryParse(void** dst, absl::string_view value, std::string* err) const
       ABSL_EXCLUSIVE_LOCKS_REQUIRED(*DataGuard());
 
+#ifndef NDEBUG
   template <typename T>
-  bool AtomicGet(T* v) const {
+  void Get(T* dst) const {
+    Read(dst, &flags_internal::FlagOps<T>);
+  }
+#else
+  template <typename T, typename std::enable_if<
+                            !flags_internal::IsAtomicFlagTypeTrait<T>::value,
+                            int>::type = 0>
+  void Get(T* dst) const {
+    Read(dst, &flags_internal::FlagOps<T>);
+  }
+  // Overload for `GetFlag()` for types that support lock-free reads.
+  template <typename T,
+            typename std::enable_if<
+                flags_internal::IsAtomicFlagTypeTrait<T>::value, int>::type = 0>
+  void Get(T* dst) const {
     using U = flags_internal::BestAtomicType<T>;
     const typename U::type r = atomics_.template load<T>();
     if (r != U::AtomicInit()) {
-      std::memcpy(static_cast<void*>(v), &r, sizeof(T));
-      return true;
+      std::memcpy(static_cast<void*>(dst), &r, sizeof(T));
+    } else {
+      Read(dst, &flags_internal::FlagOps<T>);
     }
-    return false;
   }
+#endif
 
   // Mutating access methods
   void Write(const void* src, const flags_internal::FlagOpFn src_op)
@@ -397,12 +413,10 @@ class Flag final : public flags_internal::CommandLineFlag {
     };
     U u;
 
-    impl_.Read(&u.value, &flags_internal::FlagOps<T>);
+    impl_.Get(&u.value);
     return std::move(u.value);
   }
 
-  bool AtomicGet(T* v) const { return impl_.AtomicGet(v); }
-
   void Set(const T& v) { impl_.Write(&v, &flags_internal::FlagOps<T>); }
 
   void SetCallback(const flags_internal::FlagCallback mutation_callback) {