message: Forwardprop: Switch to a deque-backed stack to avoid element invalidation on reallocation
  Fixes an asan use-after-free issue
diff: @@ -334,8 +334,9 @@ class ForwardAccumulator {
  // executions not forwarded to backward_tape should be ignored.
  bool accumulating;
  };
  - std::stack<AccumulatorCallState, std::vector<AccumulatorCallState>>
  - call_state_;
  + // A deque-backed stack, whose element references are not invalidated by
  + // pushes and pops at the back.
  + std::stack<AccumulatorCallState> call_state_;
  };
  // Template instantiations here
  