Define the new device parameter. (#9362)

src/common/error_msg.cc

@@ -3,23 +3,18 @@
  */
 #include "error_msg.h"
 
+#include "../collective/communicator-inl.h"  // for GetRank
 #include "xgboost/logging.h"
 
 namespace xgboost::error {
 void WarnDeprecatedGPUHist() {
-  bool static thread_local logged{false};
-  if (logged) {
-    return;
-  }
   auto msg =
       "The tree method `gpu_hist` is deprecated since 2.0.0. To use GPU training, set the `device` "
       R"(parameter to CUDA instead.
 
     E.g. tree_method = "hist", device = "CUDA"
-
 )";
   LOG(WARNING) << msg;
-  logged = true;
 }
 
 void WarnManualUpdater() {
@@ -33,4 +28,23 @@ void WarnManualUpdater() {
          "behavior. For common uses, we recommend using `tree_method` parameter instead.";
   logged = true;
 }
+
+void WarnDeprecatedGPUId() {
+  static thread_local bool logged{false};
+  if (logged) {
+    return;
+  }
+  LOG(WARNING) << "`gpu_id` is deprecated in favor of the new `device` parameter: "
+               << "device = cpu/cuda/cuda:0";
+  logged = true;
+}
+
+void WarnEmptyDataset() {
+  static thread_local bool logged{false};
+  if (logged) {
+    return;
+  }
+  LOG(WARNING) << "Empty dataset at worker: " << collective::GetRank();
+  logged = true;
+}
 }  // namespace xgboost::error

src/common/error_msg.h

@@ -82,5 +82,9 @@ inline void WarnOldSerialization() {
 void WarnDeprecatedGPUHist();
 
 void WarnManualUpdater();
+
+void WarnDeprecatedGPUId();
+
+void WarnEmptyDataset();
 }  // namespace xgboost::error
 #endif  // XGBOOST_COMMON_ERROR_MSG_H_