[coll] Add global functions. (#10203)

tests/cpp/common/test_device_helpers.cu

@@ -1,14 +1,16 @@
-/*!
- * Copyright 2017-2021 XGBoost contributors
+/**
+ * Copyright 2017-2024, XGBoost contributors
  */
+#include <thrust/device_vector.h>
+#include <thrust/sort.h>  // for is_sorted
+#include <xgboost/base.h>
+
 #include <cstddef>
 #include <cstdint>
-#include <thrust/device_vector.h>
 #include <vector>
-#include <xgboost/base.h>
+
 #include "../../../src/common/device_helpers.cuh"
 #include "../../../src/common/quantile.h"
-#include "../helpers.h"
 #include "gtest/gtest.h"
 
 TEST(SumReduce, Test) {

tests/cpp/common/test_io.cc

@@ -1,10 +1,11 @@
 /**
- * Copyright 2019-2023, XGBoost Contributors
+ * Copyright 2019-2024, XGBoost Contributors
  */
 #include <gtest/gtest.h>
 
 #include <cstddef>  // for size_t
 #include <fstream>  // for ofstream
+#include <numeric>  // for iota
 
 #include "../../../src/common/io.h"
 #include "../filesystem.h"  // dmlc::TemporaryDirectory

tests/cpp/common/test_json.cc

@@ -4,10 +4,10 @@
 #include <gtest/gtest.h>
 
 #include <fstream>
-#include <iterator>  // for back_inserter
+#include <limits>  // for numeric_limits
 #include <map>
+#include <numeric>  // for iota
 
-#include "../../../src/common/charconv.h"
 #include "../../../src/common/io.h"
 #include "../../../src/common/json_utils.h"
 #include "../../../src/common/threading_utils.h"  // for ParallelFor