3 files changed, 22 insertions, 29 deletions

diff --git a/absl/synchronization/internal/mutex_nonprod.inc b/absl/synchronization/internal/mutex_nonprod.inc
index 85dae0ff5f49..a1502e727da4 100644
--- a/absl/synchronization/internal/mutex_nonprod.inc
+++ b/absl/synchronization/internal/mutex_nonprod.inc
@@ -252,8 +252,8 @@ class SynchronizationStorage {
 
   absl::once_flag once_;
 
-  // An aligned space for T.
-  typename std::aligned_storage<sizeof(T), alignof(T)>::type space_;
+  // An aligned space for the T.
+  alignas(T) unsigned char space_[sizeof(T)];
 };
 
 }  // namespace synchronization_internal
diff --git a/absl/synchronization/internal/waiter.cc b/absl/synchronization/internal/waiter.cc
index ddd6081ed00c..2949f5a84c8f 100644
--- a/absl/synchronization/internal/waiter.cc
+++ b/absl/synchronization/internal/waiter.cc
@@ -368,31 +368,29 @@ class Waiter::WinHelper {
     return reinterpret_cast<CONDITION_VARIABLE *>(&w->cv_storage_);
   }
 
-  static_assert(sizeof(SRWLOCK) == sizeof(Waiter::SRWLockStorage),
-                "SRWLockStorage does not have the same size as SRWLOCK");
+  static_assert(sizeof(SRWLOCK) == sizeof(void *),
+                "`mu_storage_` does not have the same size as SRWLOCK");
+  static_assert(alignof(SRWLOCK) == alignof(void *),
+                "`mu_storage_` does not have the same alignment as SRWLOCK");
+
+  static_assert(sizeof(CONDITION_VARIABLE) == sizeof(void *),
+                "`ABSL_CONDITION_VARIABLE_STORAGE` does not have the same size "
+                "as `CONDITION_VARIABLE`");
   static_assert(
-      alignof(SRWLOCK) == alignof(Waiter::SRWLockStorage),
-      "SRWLockStorage does not have the same alignment as SRWLOCK");
-
-  static_assert(sizeof(CONDITION_VARIABLE) ==
-                    sizeof(Waiter::ConditionVariableStorage),
-                "ABSL_CONDITION_VARIABLE_STORAGE does not have the same size "
-                "as CONDITION_VARIABLE");
-  static_assert(alignof(CONDITION_VARIABLE) ==
-                    alignof(Waiter::ConditionVariableStorage),
-                "ConditionVariableStorage does not have the same "
-                "alignment as CONDITION_VARIABLE");
+      alignof(CONDITION_VARIABLE) == alignof(void *),
+      "`cv_storage_` does not have the same alignment as `CONDITION_VARIABLE`");
 
   // The SRWLOCK and CONDITION_VARIABLE types must be trivially constructible
   // and destructible because we never call their constructors or destructors.
   static_assert(std::is_trivially_constructible<SRWLOCK>::value,
-                "The SRWLOCK type must be trivially constructible");
-  static_assert(std::is_trivially_constructible<CONDITION_VARIABLE>::value,
-                "The CONDITION_VARIABLE type must be trivially constructible");
+                "The `SRWLOCK` type must be trivially constructible");
+  static_assert(
+      std::is_trivially_constructible<CONDITION_VARIABLE>::value,
+      "The `CONDITION_VARIABLE` type must be trivially constructible");
   static_assert(std::is_trivially_destructible<SRWLOCK>::value,
-                "The SRWLOCK type must be trivially destructible");
+                "The `SRWLOCK` type must be trivially destructible");
   static_assert(std::is_trivially_destructible<CONDITION_VARIABLE>::value,
-                "The CONDITION_VARIABLE type must be trivially destructible");
+                "The `CONDITION_VARIABLE` type must be trivially destructible");
 };
 
 class LockHolder {
diff --git a/absl/synchronization/internal/waiter.h b/absl/synchronization/internal/waiter.h
index 5af5c282ff2e..a6e6d4c7eed4 100644
--- a/absl/synchronization/internal/waiter.h
+++ b/absl/synchronization/internal/waiter.h
@@ -133,13 +133,6 @@ class Waiter {
   std::atomic<int> wakeups_;
 
 #elif ABSL_WAITER_MODE == ABSL_WAITER_MODE_WIN32
-  // We can't include Windows.h in our headers, so we use aligned storage
-  // buffers to define the storage of SRWLOCK and CONDITION_VARIABLE.
-  using SRWLockStorage =
-      typename std::aligned_storage<sizeof(void*), alignof(void*)>::type;
-  using ConditionVariableStorage =
-      typename std::aligned_storage<sizeof(void*), alignof(void*)>::type;
-
   // WinHelper - Used to define utilities for accessing the lock and
   // condition variable storage once the types are complete.
   class WinHelper;
@@ -147,8 +140,10 @@ class Waiter {
   // REQUIRES: WinHelper::GetLock(this) must be held.
   void InternalCondVarPoke();
 
-  SRWLockStorage mu_storage_;
-  ConditionVariableStorage cv_storage_;
+  // We can't include Windows.h in our headers, so we use aligned charachter
+  // buffers to define the storage of SRWLOCK and CONDITION_VARIABLE.
+  alignas(void*) unsigned char mu_storage_[sizeof(void*)];
+  alignas(void*) unsigned char cv_storage_[sizeof(void*)];
   int waiter_count_;
   int wakeup_count_;