From 680a1b36f3d951f5a14358db236670c259fa2839 Mon Sep 17 00:00:00 2001
From: Hajime Morrita <omo@dodgson.org>
Date: Sat, 30 Mar 2019 09:02:29 -0700
Subject: [PATCH] Get rid of a few trivial compiler warnings. (#4312)

---
 src/c_api/c_api.cc               | 2 +-
 src/data/sparse_page_dmatrix.cc  | 4 ++--
 src/tree/updater_basemaker-inl.h | 1 -
 src/tree/updater_colmaker.cc     | 1 -
 src/tree/updater_skmaker.cc      | 2 +-
 5 files changed, 4 insertions(+), 6 deletions(-)

diff --git a/src/c_api/c_api.cc b/src/c_api/c_api.cc
index 909291803..2aee319c7 100644
--- a/src/c_api/c_api.cc
+++ b/src/c_api/c_api.cc
@@ -624,7 +624,7 @@ XGB_DLL int XGDMatrixCreateFromDT(void** data, const char** feature_stypes,
 #pragma omp parallel num_threads(nthread)
   {
     // Count elements per row, column by column
-    for (auto j = 0; j < ncol; ++j) {
+    for (auto j = 0u; j < ncol; ++j) {
       DTType dtype = DTGetType(feature_stypes[j]);
 #pragma omp for schedule(static)
       for (omp_ulong i = 0; i < nrow; ++i) {
diff --git a/src/data/sparse_page_dmatrix.cc b/src/data/sparse_page_dmatrix.cc
index cb4ad5406..b69d6eb52 100644
--- a/src/data/sparse_page_dmatrix.cc
+++ b/src/data/sparse_page_dmatrix.cc
@@ -81,12 +81,12 @@ float SparsePageDMatrix::GetColDensity(size_t cidx) {
   if (col_density_.empty()) {
     std::vector<size_t> column_size(this->Info().num_col_);
     for (const auto &batch : this->GetColumnBatches()) {
-      for (int i = 0; i < batch.Size(); i++) {
+      for (auto i = 0u; i < batch.Size(); i++) {
         column_size[i] += batch[i].size();
       }
     }
     col_density_.resize(column_size.size());
-    for (int i = 0; i < col_density_.size(); i++) {
+    for (auto i = 0u; i < col_density_.size(); i++) {
       size_t nmiss = this->Info().num_row_ - column_size[i];
       col_density_[i] =
           1.0f - (static_cast<float>(nmiss)) / this->Info().num_row_;
diff --git a/src/tree/updater_basemaker-inl.h b/src/tree/updater_basemaker-inl.h
index 123e6c489..6e7b49acb 100644
--- a/src/tree/updater_basemaker-inl.h
+++ b/src/tree/updater_basemaker-inl.h
@@ -331,7 +331,6 @@ class BaseMaker: public TreeUpdater {
                            std::vector< std::vector<TStats> > *p_thread_temp,
                            std::vector<TStats> *p_node_stats) {
     std::vector< std::vector<TStats> > &thread_temp = *p_thread_temp;
-    const MetaInfo &info = fmat.Info();
     thread_temp.resize(omp_get_max_threads());
     p_node_stats->resize(tree.param.num_nodes);
 #pragma omp parallel
diff --git a/src/tree/updater_colmaker.cc b/src/tree/updater_colmaker.cc
index 32a66df62..462bd5ea6 100644
--- a/src/tree/updater_colmaker.cc
+++ b/src/tree/updater_colmaker.cc
@@ -245,7 +245,6 @@ class ColMaker: public TreeUpdater {
                                  DMatrix *p_fmat,
                                   const std::vector<GradientPair> &gpair) {
       // TODO(tqchen): double check stats order.
-      const MetaInfo& info = p_fmat->Info();
       const bool ind = col.size() != 0 && col[0].fvalue == col[col.size() - 1].fvalue;
       bool need_forward = param_.NeedForwardSearch(p_fmat->GetColDensity(fid), ind);
       bool need_backward = param_.NeedBackwardSearch(p_fmat->GetColDensity(fid), ind);
diff --git a/src/tree/updater_skmaker.cc b/src/tree/updater_skmaker.cc
index dba1a1d5c..f2d7b200c 100644
--- a/src/tree/updater_skmaker.cc
+++ b/src/tree/updater_skmaker.cc
@@ -140,7 +140,7 @@ class SketchMaker: public BaseMaker {
         this->UpdateSketchCol(gpair, batch[fidx], tree,
                               node_stats_,
                               fidx,
-                              batch[fidx].size() == nrows,
+                              static_cast<size_t>(batch[fidx].size()) == nrows,
                               &thread_sketch_[omp_get_thread_num()]);
       }
     }