Squashed 'third_party/abseil_cpp/' changes from 768eb2ca2..ccdbb5941

ccdbb5941 Export of internal Abseil changes
01f5f81f9 Export of internal Abseil changes
2c92bdc7c Export of internal Abseil changes
e7ebf9803 Export of internal Abseil changes
2eba343b5 Export of internal Abseil changes
a8b03d90e Export of internal Abseil changes
1d31b5c36 Export of internal Abseil changes
da3a87690 Export of internal Abseil changes
8faf20461 Exclude empty directories (#697)
2069dc796 Export of internal Abseil changes
4832bf6bf Added a BUILD file in root to expose license. (#695)
af8f994af Export of internal Abseil changes
33caf1097 Export of internal Abseil changes
cf1a02e2d Export of internal Abseil changes

git-subtree-dir: third_party/abseil_cpp
git-subtree-split: ccdbb5941f992fabda7eae3ce72f55efc17c826a

1 files changed, 68 insertions, 39 deletions

diff --git a/absl/random/bit_gen_ref.h b/absl/random/bit_gen_ref.h
index 59591a479d8c..9555460fd491 100644
--- a/absl/random/bit_gen_ref.h
+++ b/absl/random/bit_gen_ref.h
@@ -24,11 +24,11 @@
 #ifndef ABSL_RANDOM_BIT_GEN_REF_H_
 #define ABSL_RANDOM_BIT_GEN_REF_H_
 
+#include "absl/base/internal/fast_type_id.h"
 #include "absl/base/macros.h"
 #include "absl/meta/type_traits.h"
 #include "absl/random/internal/distribution_caller.h"
 #include "absl/random/internal/fast_uniform_bits.h"
-#include "absl/random/internal/mocking_bit_gen_base.h"
 
 namespace absl {
 ABSL_NAMESPACE_BEGIN
@@ -51,6 +51,10 @@ struct is_urbg<
         typename std::decay<decltype(std::declval<URBG>()())>::type>::value>>
     : std::true_type {};
 
+template <typename>
+struct DistributionCaller;
+class MockHelpers;
+
 }  // namespace random_internal
 
 // -----------------------------------------------------------------------------
@@ -77,23 +81,50 @@ struct is_urbg<
 //    }
 //
 class BitGenRef {
- public:
-  using result_type = uint64_t;
+  // 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<base_internal::FastTypeIdType>(), std::declval<void*>(),
+      std::declval<void*>()));
+
+  template <typename T>
+  using HasInvokeMock = typename detector<invoke_mock_t, void, T>::type;
 
-  BitGenRef(const absl::BitGenRef&) = default;
-  BitGenRef(absl::BitGenRef&&) = default;
-  BitGenRef& operator=(const absl::BitGenRef&) = default;
-  BitGenRef& operator=(absl::BitGenRef&&) = default;
+ public:
+  BitGenRef(const BitGenRef&) = default;
+  BitGenRef(BitGenRef&&) = default;
+  BitGenRef& operator=(const BitGenRef&) = default;
+  BitGenRef& operator=(BitGenRef&&) = default;
+
+  template <typename URBG, typename absl::enable_if_t<
+                               (!std::is_same<URBG, BitGenRef>::value &&
+                                random_internal::is_urbg<URBG>::value &&
+                                !HasInvokeMock<URBG>::value)>* = nullptr>
+  BitGenRef(URBG& gen)  // NOLINT
+      : t_erased_gen_ptr_(reinterpret_cast<uintptr_t>(&gen)),
+        mock_call_(NotAMock),
+        generate_impl_fn_(ImplFn<URBG>) {}
 
   template <typename URBG,
-            typename absl::enable_if_t<
-                (!std::is_same<URBG, BitGenRef>::value &&
-                 random_internal::is_urbg<URBG>::value)>* = nullptr>
+            typename absl::enable_if_t<(!std::is_same<URBG, BitGenRef>::value &&
+                                        random_internal::is_urbg<URBG>::value &&
+                                        HasInvokeMock<URBG>::value)>* = nullptr>
   BitGenRef(URBG& gen)  // NOLINT
-      : mocked_gen_ptr_(MakeMockPointer(&gen)),
-        t_erased_gen_ptr_(reinterpret_cast<uintptr_t>(&gen)),
-        generate_impl_fn_(ImplFn<URBG>) {
-  }
+      : t_erased_gen_ptr_(reinterpret_cast<uintptr_t>(&gen)),
+        mock_call_(&MockCall<URBG>),
+        generate_impl_fn_(ImplFn<URBG>) {}
+
+  using result_type = uint64_t;
 
   static constexpr result_type(min)() {
     return (std::numeric_limits<result_type>::min)();
@@ -106,14 +137,9 @@ class BitGenRef {
   result_type operator()() { return generate_impl_fn_(t_erased_gen_ptr_); }
 
  private:
-  friend struct absl::random_internal::DistributionCaller<absl::BitGenRef>;
   using impl_fn = result_type (*)(uintptr_t);
-  using mocker_base_t = absl::random_internal::MockingBitGenBase;
-
-  // Convert an arbitrary URBG pointer into either a valid mocker_base_t
-  // pointer or a nullptr.
-  static inline mocker_base_t* MakeMockPointer(mocker_base_t* t) { return t; }
-  static inline mocker_base_t* MakeMockPointer(void*) { return nullptr; }
+  using mock_call_fn = bool (*)(uintptr_t, base_internal::FastTypeIdType, void*,
+                                void*);
 
   template <typename URBG>
   static result_type ImplFn(uintptr_t ptr) {
@@ -123,29 +149,32 @@ class BitGenRef {
     return fast_uniform_bits(*reinterpret_cast<URBG*>(ptr));
   }
 
-  mocker_base_t* mocked_gen_ptr_;
+  // Get a type-erased InvokeMock pointer.
+  template <typename URBG>
+  static bool MockCall(uintptr_t gen_ptr, base_internal::FastTypeIdType type,
+                       void* result, void* arg_tuple) {
+    return reinterpret_cast<URBG*>(gen_ptr)->InvokeMock(type, result,
+                                                        arg_tuple);
+  }
+  static bool NotAMock(uintptr_t, base_internal::FastTypeIdType, void*, void*) {
+    return false;
+  }
+
+  inline bool InvokeMock(base_internal::FastTypeIdType type, void* args_tuple,
+                         void* result) {
+    if (mock_call_ == NotAMock) return false;  // avoids an indirect call.
+    return mock_call_(t_erased_gen_ptr_, type, args_tuple, result);
+  }
+
   uintptr_t t_erased_gen_ptr_;
+  mock_call_fn mock_call_;
   impl_fn generate_impl_fn_;
-};
-
-namespace random_internal {
 
-template <>
-struct DistributionCaller<absl::BitGenRef> {
-  template <typename DistrT, typename... Args>
-  static typename DistrT::result_type Call(absl::BitGenRef* gen_ref,
-                                           Args&&... args) {
-    auto* mock_ptr = gen_ref->mocked_gen_ptr_;
-    if (mock_ptr == nullptr) {
-      DistrT dist(std::forward<Args>(args)...);
-      return dist(*gen_ref);
-    } else {
-      return mock_ptr->template Call<DistrT>(std::forward<Args>(args)...);
-    }
-  }
+  template <typename>
+  friend struct ::absl::random_internal::DistributionCaller;  // for InvokeMock
+  friend class ::absl::random_internal::MockHelpers;          // for InvokeMock
 };
 
-}  // namespace random_internal
 ABSL_NAMESPACE_END
 }  // namespace absl