From 03bc6e64270d19ffd634aa3009b11d3be42159d4 Mon Sep 17 00:00:00 2001
From: Jiaming Yuan <jm.yuan@outlook.com>
Date: Sun, 28 May 2023 05:24:15 +0800
Subject: [PATCH] Remove unused variables. (#9210)

- remove used variables.
- Remove signed comparison warnings.
---
 src/collective/communicator-inl.h    | 2 +-
 src/common/partition_builder.h       | 3 +--
 src/tree/common_row_partitioner.h    | 2 +-
 src/tree/hist/evaluate_splits.h      | 4 ++--
 tests/cpp/tree/test_quantile_hist.cc | 1 -
 5 files changed, 5 insertions(+), 7 deletions(-)

diff --git a/src/collective/communicator-inl.h b/src/collective/communicator-inl.h
index 8ae96dd8a..59cc4cc45 100644
--- a/src/collective/communicator-inl.h
+++ b/src/collective/communicator-inl.h
@@ -252,7 +252,7 @@ inline AllgatherVResult<T> AllgatherV(std::vector<T> const &inputs,
 
   // Calculate input offsets (std::exclusive_scan).
   std::vector<std::size_t> offsets(all_sizes.size());
-  for (auto i = 1; i < offsets.size(); i++) {
+  for (std::size_t i = 1; i < offsets.size(); i++) {
     offsets[i] = offsets[i - 1] + all_sizes[i - 1];
   }
 
diff --git a/src/common/partition_builder.h b/src/common/partition_builder.h
index cfa2f6a58..53e11bd91 100644
--- a/src/common/partition_builder.h
+++ b/src/common/partition_builder.h
@@ -263,8 +263,7 @@ class PartitionBuilder {
   template <typename ExpandEntry>
   void PartitionByMask(const size_t node_in_set, std::vector<ExpandEntry> const& nodes,
                        const common::Range1d range, GHistIndexMatrix const& gmat,
-                       const common::ColumnMatrix& column_matrix, const RegTree& tree,
-                       const size_t* rid, BitVector const& decision_bits,
+                       const RegTree& tree, const size_t* rid, BitVector const& decision_bits,
                        BitVector const& missing_bits) {
     common::Span<const size_t> rid_span(rid + range.begin(), rid + range.end());
     common::Span<size_t> left = GetLeftBuffer(node_in_set, range.begin(), range.end());
diff --git a/src/tree/common_row_partitioner.h b/src/tree/common_row_partitioner.h
index ef12d0ccc..4360c0b13 100644
--- a/src/tree/common_row_partitioner.h
+++ b/src/tree/common_row_partitioner.h
@@ -67,7 +67,7 @@ class ColumnSplitHelper {
       const int32_t nid = nodes[node_in_set].nid;
       const size_t task_id = partition_builder_->GetTaskIdx(node_in_set, begin);
       partition_builder_->AllocateForTask(task_id);
-      partition_builder_->PartitionByMask(node_in_set, nodes, r, gmat, column_matrix, *p_tree,
+      partition_builder_->PartitionByMask(node_in_set, nodes, r, gmat, *p_tree,
                                           (*row_set_collection_)[nid].begin, decision_bits_,
                                           missing_bits_);
     });
diff --git a/src/tree/hist/evaluate_splits.h b/src/tree/hist/evaluate_splits.h
index c8321b48a..4fb857e06 100644
--- a/src/tree/hist/evaluate_splits.h
+++ b/src/tree/hist/evaluate_splits.h
@@ -298,7 +298,7 @@ class HistEvaluator {
     std::vector<CPUExpandEntry> all_entries(num_entries * world);
     std::vector<uint32_t> cat_bits;
     std::vector<std::size_t> cat_bits_sizes;
-    for (auto i = 0; i < num_entries; i++) {
+    for (std::size_t i = 0; i < num_entries; i++) {
       all_entries[num_entries * rank + i].CopyAndCollect(entries[i], &cat_bits, &cat_bits_sizes);
     }
     collective::Allgather(all_entries.data(), all_entries.size() * sizeof(CPUExpandEntry));
@@ -586,7 +586,7 @@ class HistMultiEvaluator {
     std::vector<uint32_t> cat_bits;
     std::vector<std::size_t> cat_bits_sizes;
     std::vector<GradientPairPrecise> gradients;
-    for (auto i = 0; i < num_entries; i++) {
+    for (std::size_t i = 0; i < num_entries; i++) {
       all_entries[num_entries * rank + i].CopyAndCollect(entries[i], &cat_bits, &cat_bits_sizes,
                                                          &gradients);
     }
diff --git a/tests/cpp/tree/test_quantile_hist.cc b/tests/cpp/tree/test_quantile_hist.cc
index b8d0fd2c0..7b99a5bf2 100644
--- a/tests/cpp/tree/test_quantile_hist.cc
+++ b/tests/cpp/tree/test_quantile_hist.cc
@@ -113,7 +113,6 @@ void VerifyColumnSplitPartitioner(bst_target_t n_targets, size_t n_samples,
 
   for (auto const& page : Xy->GetBatches<SparsePage>()) {
     GHistIndexMatrix gmat(page, {}, cuts, 64, true, 0.5, ctx.Threads());
-    bst_feature_t const split_ind = 0;
     common::ColumnMatrix column_indices;
     column_indices.InitFromSparse(page, gmat, 0.5, ctx.Threads());
     {