From d240463b38b1074d68896832a1a4541c309180f1 Mon Sep 17 00:00:00 2001
From: Jiaming Yuan <jm.yuan@outlook.com>
Date: Mon, 17 Aug 2020 20:10:15 +0800
Subject: [PATCH] Revert "Remove warning about memset. (#6003)" (#6020)

This reverts commit 12e3fb6a6cb601c58d39ed54253e6e50f1513ccc.
---
 src/common/hist_util.cc | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/src/common/hist_util.cc b/src/common/hist_util.cc
index 7f4912317..efd62d701 100644
--- a/src/common/hist_util.cc
+++ b/src/common/hist_util.cc
@@ -500,13 +500,13 @@ void GHistIndexBlockMatrix::Init(const GHistIndexMatrix& gmat,
  */
 template<typename GradientSumT>
 void InitilizeHistByZeroes(GHistRow<GradientSumT> hist, size_t begin, size_t end) {
-  static_assert(sizeof(xgboost::detail::GradientPairInternal<GradientSumT>) %
-                        sizeof(GradientSumT) ==
-                    0,
-                "");
-  auto p_data = reinterpret_cast<GradientSumT*>(hist.data());
-  memset(p_data + begin, '\0', (end-begin)*
+#if defined(XGBOOST_STRICT_R_MODE) && XGBOOST_STRICT_R_MODE == 1
+  std::fill(hist.begin() + begin, hist.begin() + end,
+            xgboost::detail::GradientPairInternal<GradientSumT>());
+#else  // defined(XGBOOST_STRICT_R_MODE) && XGBOOST_STRICT_R_MODE == 1
+  memset(hist.data() + begin, '\0', (end-begin)*
          sizeof(xgboost::detail::GradientPairInternal<GradientSumT>));
+#endif  // defined(XGBOOST_STRICT_R_MODE) && XGBOOST_STRICT_R_MODE == 1
 }
 template void InitilizeHistByZeroes(GHistRow<float> hist, size_t begin,
                                     size_t end);