Export of internal Abseil changes

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9e8b4a286d70df9487bff080816bd07ae38af5f8 by Evan Brown <ezb@google.com>:

Add btree_node::transfer_n/transfer_n_backward and replace usage of uninitialized_move_n and value_destroy_n.

PiperOrigin-RevId: 314600027

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6c452aa1ee7e46ab941ba7d1fa636da8ea3d7370 by Laramie Leavitt <lar@google.com>:

Remove the MockingBitGenBase base class in favor of type-erasure in BitGenRef.

In Abseil random, mocking was split across two different classes,
MockingBitGenBase and MockingBitGen. This split existed because Google Mock is a
test-only library that we don't link into production, so MockingBitGenBase
provided a low-overhead scaffold used to lookup mocks when in test code, but
which is unused in production code.

That has been replaced by type-erasure which looks for a method named
CallImpl with the correct signature.

Weaken the coupling between MockingBitGen, DistributionCaller, and MockOverloadSet.

Rename CallImpl to InvokeMock()

Previously, the implementation of DistributionCaller was also split across different files using explicit instantiation of the DistributionCaller struct and some details in the Mocking classes. Now Distribution caller uses the presence of the InvokeMock() method to choose whether to use the mockable call path or the default call path.

PiperOrigin-RevId: 314584095

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07853c47dc98698d67d65a3b9b662a65ab9def0a by Abseil Team <absl-team@google.com>:

Add PC / backtrace / symbolization support for Apple platforms.

Full backtrace support requires iOS 9+

PiperOrigin-RevId: 314415072

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43889f17a132b31f6558c6482721cbbc776128fd by Gennadiy Rozental <rogeeff@google.com>:

Consolidate all reflection interface in the new module 'reflection' and expose interface to locate reflection handle by name.

PiperOrigin-RevId: 314390358
GitOrigin-RevId: 9e8b4a286d70df9487bff080816bd07ae38af5f8
Change-Id: I8e0910437740cf9ea9da5000adddfcef127e1158

1 files changed, 47 insertions, 4 deletions

diff --git a/absl/random/internal/distribution_caller.h b/absl/random/internal/distribution_caller.h
index 4e072444..87a76845 100644
--- a/absl/random/internal/distribution_caller.h
+++ b/absl/random/internal/distribution_caller.h
@@ -20,6 +20,8 @@
 #include <utility>
 
 #include "absl/base/config.h"
+#include "absl/base/internal/fast_type_id.h"
+#include "absl/utility/utility.h"
 
 namespace absl {
 ABSL_NAMESPACE_BEGIN
@@ -30,14 +32,55 @@ namespace random_internal {
 // to intercept such calls.
 template <typename URBG>
 struct DistributionCaller {
-  // Call the provided distribution type. The parameters are expected
-  // to be explicitly specified.
-  // DistrT is the distribution type.
+  // SFINAE to detect whether the URBG type includes a member matching
+  // bool InvokeMock(base_internal::FastTypeIdType, void*, void*).
+  //
+  // These live inside BitGenRef so that they have friend access
+  // to MockingBitGen. (see similar methods in DistributionCaller).
+  template <template <class...> class Trait, class AlwaysVoid, class... Args>
+  struct detector : std::false_type {};
+  template <template <class...> class Trait, class... Args>
+  struct detector<Trait, absl::void_t<Trait<Args...>>, Args...>
+      : std::true_type {};
+
+  template <class T>
+  using invoke_mock_t = decltype(std::declval<T*>()->InvokeMock(
+      std::declval<::absl::base_internal::FastTypeIdType>(),
+      std::declval<void*>(), std::declval<void*>()));
+
+  using HasInvokeMock = typename detector<invoke_mock_t, void, URBG>::type;
+
+  // Default implementation of distribution caller.
   template <typename DistrT, typename... Args>
-  static typename DistrT::result_type Call(URBG* urbg, Args&&... args) {
+  static inline typename DistrT::result_type Impl(std::false_type, URBG* urbg,
+                                                  Args&&... args) {
     DistrT dist(std::forward<Args>(args)...);
     return dist(*urbg);
   }
+
+  // Mock implementation of distribution caller.
+  template <typename DistrT, typename... Args>
+  static inline typename DistrT::result_type Impl(std::true_type, URBG* urbg,
+                                                  Args&&... args) {
+    using ResultT = typename DistrT::result_type;
+    using ArgTupleT = std::tuple<absl::decay_t<Args>...>;
+    ArgTupleT arg_tuple(std::forward<Args>(args)...);
+    ResultT result;
+    if (!urbg->InvokeMock(
+            ::absl::base_internal::FastTypeId<ResultT(DistrT, ArgTupleT)>(),
+            &arg_tuple, &result)) {
+      auto dist = absl::make_from_tuple<DistrT>(arg_tuple);
+      result = dist(*urbg);
+    }
+    return result;
+  }
+
+  // Default implementation of distribution caller.
+  template <typename DistrT, typename... Args>
+  static inline typename DistrT::result_type Call(URBG* urbg, Args&&... args) {
+    return Impl<DistrT, Args...>(HasInvokeMock{}, urbg,
+                                 std::forward<Args>(args)...);
+  }
 };
 
 }  // namespace random_internal