Use padding instead of alignment attribute, which MaxSizeVector does not respect. This leads to undefined behavior and hard-to-trace bugs.

1 files changed, 4 insertions, 3 deletions

diff --git a/unsupported/Eigen/CXX11/src/ThreadPool/EventCount.h b/unsupported/Eigen/CXX11/src/ThreadPool/EventCount.h
index 22c952ae1..2cac2d0f1 100644
--- a/unsupported/Eigen/CXX11/src/ThreadPool/EventCount.h
+++ b/unsupported/Eigen/CXX11/src/ThreadPool/EventCount.h
@@ -169,9 +169,7 @@ class EventCount {
 
   class Waiter {
     friend class EventCount;
-    // Align to 128 byte boundary to prevent false sharing with other Waiter
-    // objects in the same vector.
-    EIGEN_ALIGN_TO_BOUNDARY(128) std::atomic<Waiter*> next;
+    std::atomic<Waiter*> next;
     std::mutex mu;
     std::condition_variable cv;
     uint64_t epoch;
@@ -181,6 +179,9 @@ class EventCount {
       kWaiting,
       kSignaled,
     };
+    // Pad past 128 byte boundary to prevent false sharing with other Waiter
+    // objects in the same vector.
+    char pad_[128];
   };
 
  private: