Make C++ unit tests run and pass on Windows (#3869)

* Make C++ unit tests run and pass on Windows

* Fix logic for external memory. The letter ':' is part of drive letter,
so remove the drive letter before splitting on ':'.
* Cosmetic syntax changes to keep MSVC happy.

* Fix lint

* Add Windows guard

src/data/sparse_page_source.cc

@@ -6,19 +6,43 @@
 #include <dmlc/timer.h>
 #include <xgboost/logging.h>
 #include <memory>
+#include <vector>
+#include <string>
+#include <locale>
 
 #if DMLC_ENABLE_STD_THREAD
 #include "./sparse_page_source.h"
 #include "../common/common.h"
 
+namespace {
+
+// Split a cache info string with delimiter ':'
+// If cache info string contains drive letter (e.g. C:), exclude it before splitting
+inline std::vector<std::string>
+GetCacheShards(const std::string& cache_info) {
+#if (defined _WIN32) || (defined __CYGWIN__)
+  if (cache_info.length() >= 2
+      && std::isalpha(cache_info[0], std::locale::classic())
+      && cache_info[1] == ':') {
+    std::vector<std::string> cache_shards
+      = xgboost::common::Split(cache_info.substr(2), ':');
+    cache_shards[0] = cache_info.substr(0, 2) + cache_shards[0];
+    return cache_shards;
+  }
+#endif
+  return xgboost::common::Split(cache_info, ':');
+}
+
+}  // anonymous namespace
+
 namespace xgboost {
 namespace data {
 
 SparsePageSource::SparsePageSource(const std::string& cache_info,
                                    const std::string& page_type)
     : base_rowid_(0), page_(nullptr), clock_ptr_(0) {
   // read in the info files
-  std::vector<std::string> cache_shards = common::Split(cache_info, ':');
+  std::vector<std::string> cache_shards = GetCacheShards(cache_info);
   CHECK_NE(cache_shards.size(), 0U);
   {
     std::string name_info = cache_shards[0];
@@ -86,7 +110,7 @@ const SparsePage& SparsePageSource::Value() const {
 
 bool SparsePageSource::CacheExist(const std::string& cache_info,
                                   const std::string& page_type) {
-  std::vector<std::string> cache_shards = common::Split(cache_info, ':');
+  std::vector<std::string> cache_shards = GetCacheShards(cache_info);
   CHECK_NE(cache_shards.size(), 0U);
   {
     std::string name_info = cache_shards[0];
@@ -104,7 +128,7 @@ bool SparsePageSource::CacheExist(const std::string& cache_info,
 void SparsePageSource::CreateRowPage(dmlc::Parser<uint32_t>* src,
                               const std::string& cache_info) {
   const std::string page_type = ".row.page";
-  std::vector<std::string> cache_shards = common::Split(cache_info, ':');
+  std::vector<std::string> cache_shards = GetCacheShards(cache_info);
   CHECK_NE(cache_shards.size(), 0U);
   // read in the info files.
   std::string name_info = cache_shards[0];
@@ -198,7 +222,7 @@ void SparsePageSource::CreateRowPage(dmlc::Parser<uint32_t>* src,
 void SparsePageSource::CreatePageFromDMatrix(DMatrix* src,
                                              const std::string& cache_info,
                                              const std::string& page_type) {
-  std::vector<std::string> cache_shards = common::Split(cache_info, ':');
+  std::vector<std::string> cache_shards = GetCacheShards(cache_info);
   CHECK_NE(cache_shards.size(), 0U);
   // read in the info files.
   std::string name_info = cache_shards[0];

tests/cpp/common/test_transform_range.cc

@@ -50,7 +50,9 @@ TEST(Transform, DeclareUnifiedTest(Basic)) {
   HostDeviceVector<bst_float> out_vec{h_out, TRANSFORM_GPU_DIST};
   out_vec.Fill(0);
 
-  Transform<>::Init(TestTransformRange<bst_float>{}, Range{0, size}, TRANSFORM_GPU_RANGE)
+  Transform<>::Init(TestTransformRange<bst_float>{},
+	                Range{0, static_cast<Range::DifferenceType>(size)},
+	                TRANSFORM_GPU_RANGE)
       .Eval(&out_vec, &in_vec);
   std::vector<bst_float> res = out_vec.HostVector();
 

tests/cpp/helpers.cc

@@ -5,12 +5,12 @@
 #include "xgboost/c_api.h"
 #include <random>
 
-bool FileExists(const std::string name) {
+bool FileExists(const std::string& filename) {
   struct stat st;
-  return stat(name.c_str(), &st) == 0;
+  return stat(filename.c_str(), &st) == 0;
 }
 
-long GetFileSize(const std::string filename) {
+long GetFileSize(const std::string& filename) {
   struct stat st;
   stat(filename.c_str(), &st);
   return st.st_size;

tests/cpp/helpers.h

@@ -24,9 +24,9 @@
 #define DeclareUnifiedTest(name) name
 #endif
 
-bool FileExists(const std::string name);
+bool FileExists(const std::string& filename);
 
-long GetFileSize(const std::string filename);
+long GetFileSize(const std::string& filename);
 
 void CreateSimpleTestData(const std::string& filename);
 

tests/cpp/objective/test_multiclass_obj.cc

@@ -10,11 +10,11 @@ TEST(Objective, DeclareUnifiedTest(SoftmaxMultiClassObjGPair)) {
   std::vector<std::pair<std::string, std::string>> args {{"num_class", "3"}};
   obj->Configure(args);
   CheckObjFunction(obj,
-		   {1, 0, 2, 2, 0, 1}, // preds
-		   {1.0, 0.0},	       // labels
-		   {1.0, 1.0},	       // weights
+		   {1.0f, 0.0f, 2.0f, 2.0f, 0.0f, 1.0f}, // preds
+		   {1.0f, 0.0f},	       // labels
+		   {1.0f, 1.0f},	       // weights
 		   {0.24f, -0.91f, 0.66f, -0.33f, 0.09f, 0.24f}, // grad
-		   {0.36, 0.16, 0.44, 0.45, 0.16, 0.37});	 // hess
+		   {0.36f, 0.16f, 0.44f, 0.45f, 0.16f, 0.37f});	 // hess
 
   ASSERT_NO_THROW(obj->DefaultEvalMetric());
 

tests/cpp/tree/test_gpu_hist.cu

@@ -24,16 +24,16 @@ void BuildGidx(DeviceShard* shard, int n_rows, int n_cols,
 
   common::HistCutMatrix cmat;
   cmat.row_ptr = {0, 3, 6, 9, 12, 15, 18, 21, 24};
-  cmat.min_val = {0.1, 0.2, 0.3, 0.1, 0.2, 0.3, 0.2, 0.2};
+  cmat.min_val = {0.1f, 0.2f, 0.3f, 0.1f, 0.2f, 0.3f, 0.2f, 0.2f};
   // 24 cut fields, 3 cut fields for each feature (column).
-  cmat.cut = {0.30, 0.67, 1.64,
-              0.32, 0.77, 1.95,
-              0.29, 0.70, 1.80,
-              0.32, 0.75, 1.85,
-              0.18, 0.59, 1.69,
-              0.25, 0.74, 2.00,
-              0.26, 0.74, 1.98,
-              0.26, 0.71, 1.83};
+  cmat.cut = {0.30f, 0.67f, 1.64f,
+              0.32f, 0.77f, 1.95f,
+              0.29f, 0.70f, 1.80f,
+              0.32f, 0.75f, 1.85f,
+              0.18f, 0.59f, 1.69f,
+              0.25f, 0.74f, 2.00f,
+              0.26f, 0.74f, 1.98f,
+              0.26f, 0.71f, 1.83f};
 
   shard->InitRowPtrs(batch);
   shard->InitCompressedData(cmat, batch);
@@ -110,14 +110,14 @@ TEST(GpuHist, BuildGidxSparse) {
 std::vector<GradientPairPrecise> GetHostHistGpair() {
   // 24 bins, 3 bins for each feature (column).
   std::vector<GradientPairPrecise> hist_gpair = {
-    {0.8314, 0.7147}, {1.7989, 3.7312}, {3.3846, 3.4598},
-    {2.9277, 3.5886}, {1.8429, 2.4152}, {1.2443, 1.9019},
-    {1.6380, 2.9174}, {1.5657, 2.5107}, {2.8111, 2.4776},
-    {2.1322, 3.0651}, {3.2927, 3.8540}, {0.5899, 0.9866},
-    {1.5185, 1.6263}, {2.0686, 3.1844}, {2.4278, 3.0950},
-    {1.5105, 2.1403}, {2.6922, 4.2217}, {1.8122, 1.5437},
-    {0.0000, 0.0000}, {4.3245, 5.7955}, {1.6903, 2.1103},
-    {2.4012, 4.4754}, {3.6136, 3.4303}, {0.0000, 0.0000}
+    {0.8314f, 0.7147f}, {1.7989f, 3.7312f}, {3.3846f, 3.4598f},
+    {2.9277f, 3.5886f}, {1.8429f, 2.4152f}, {1.2443f, 1.9019f},
+    {1.6380f, 2.9174f}, {1.5657f, 2.5107f}, {2.8111f, 2.4776f},
+    {2.1322f, 3.0651f}, {3.2927f, 3.8540f}, {0.5899f, 0.9866f},
+    {1.5185f, 1.6263f}, {2.0686f, 3.1844f}, {2.4278f, 3.0950f},
+    {1.5105f, 2.1403f}, {2.6922f, 4.2217f}, {1.8122f, 1.5437f},
+    {0.0000f, 0.0000f}, {4.3245f, 5.7955f}, {1.6903f, 2.1103f},
+    {2.4012f, 4.4754f}, {3.6136f, 3.4303f}, {0.0000f, 0.0000f}
   };
   return hist_gpair;
 }
@@ -198,17 +198,17 @@ TEST(GpuHist, BuildHistSharedMem) {
 common::HistCutMatrix GetHostCutMatrix () {
   common::HistCutMatrix cmat;
   cmat.row_ptr = {0, 3, 6, 9, 12, 15, 18, 21, 24};
-  cmat.min_val = {0.1, 0.2, 0.3, 0.1, 0.2, 0.3, 0.2, 0.2};
+  cmat.min_val = {0.1f, 0.2f, 0.3f, 0.1f, 0.2f, 0.3f, 0.2f, 0.2f};
   // 24 cut fields, 3 cut fields for each feature (column).
   // Each row of the cut represents the cuts for a data column.
-  cmat.cut = {0.30, 0.67, 1.64,
-              0.32, 0.77, 1.95,
-              0.29, 0.70, 1.80,
-              0.32, 0.75, 1.85,
-              0.18, 0.59, 1.69,
-              0.25, 0.74, 2.00,
-              0.26, 0.74, 1.98,
-              0.26, 0.71, 1.83};
+  cmat.cut = {0.30f, 0.67f, 1.64f,
+              0.32f, 0.77f, 1.95f,
+              0.29f, 0.70f, 1.80f,
+              0.32f, 0.75f, 1.85f,
+              0.18f, 0.59f, 1.69f,
+              0.25f, 0.74f, 2.00f,
+              0.26f, 0.74f, 1.98f,
+              0.26f, 0.71f, 1.83f};
   return cmat;
 }
 
@@ -238,7 +238,7 @@ TEST(GpuHist, EvaluateSplits) {
   // Initialize DeviceShard
   std::unique_ptr<DeviceShard> shard {new DeviceShard(0, 0, n_rows, param)};
   // Initialize DeviceShard::node_sum_gradients
-  shard->node_sum_gradients = {{6.4, 12.8}};
+  shard->node_sum_gradients = {{6.4f, 12.8f}};
 
   // Initialize DeviceShard::cut
   common::HistCutMatrix cmat = GetHostCutMatrix();