Fix compiler warnings. (#8022)

- Remove/fix unused parameters
- Remove deprecated code in rabit.
- Update dmlc-core.

src/metric/auc.cu

@@ -201,8 +201,7 @@ void Transpose(common::Span<float const> in, common::Span<float> out, size_t m,
   });
 }
 
-double ScaleClasses(common::Span<double> results,
-                    common::Span<double> local_area, common::Span<double> fp,
+double ScaleClasses(common::Span<double> results, common::Span<double> local_area,
                     common::Span<double> tp, common::Span<double> auc,
                     std::shared_ptr<DeviceAUCCache> cache, size_t n_classes) {
   dh::XGBDeviceAllocator<char> alloc;
@@ -333,10 +332,9 @@ double GPUMultiClassAUCOVR(MetaInfo const &info, int32_t device, common::Span<ui
     dh::LaunchN(n_classes * 4,
                 [=] XGBOOST_DEVICE(size_t i) { d_results[i] = 0.0f; });
     auto local_area = d_results.subspan(0, n_classes);
-    auto fp = d_results.subspan(n_classes, n_classes);
     auto tp = d_results.subspan(2 * n_classes, n_classes);
     auto auc = d_results.subspan(3 * n_classes, n_classes);
-    return ScaleClasses(d_results, local_area, fp, tp, auc, cache, n_classes);
+    return ScaleClasses(d_results, local_area, tp, auc, cache, n_classes);
   }
 
   /**
@@ -440,7 +438,7 @@ double GPUMultiClassAUCOVR(MetaInfo const &info, int32_t device, common::Span<ui
       tp[c] = 1.0f;
     }
   });
-  return ScaleClasses(d_results, local_area, fp, tp, auc, cache, n_classes);
+  return ScaleClasses(d_results, local_area, tp, auc, cache, n_classes);
 }
 
 void MultiClassSortedIdx(common::Span<float const> predts,

src/metric/elementwise_metric.cu

@@ -376,40 +376,40 @@ struct EvalEWiseBase : public Metric {
 };
 
 XGBOOST_REGISTER_METRIC(RMSE, "rmse")
-.describe("Rooted mean square error.")
-.set_body([](const char* param) { return new EvalEWiseBase<EvalRowRMSE>(); });
+    .describe("Rooted mean square error.")
+    .set_body([](const char*) { return new EvalEWiseBase<EvalRowRMSE>(); });
 
 XGBOOST_REGISTER_METRIC(RMSLE, "rmsle")
-.describe("Rooted mean square log error.")
-.set_body([](const char* param) { return new EvalEWiseBase<EvalRowRMSLE>(); });
+    .describe("Rooted mean square log error.")
+    .set_body([](const char*) { return new EvalEWiseBase<EvalRowRMSLE>(); });
 
-XGBOOST_REGISTER_METRIC(MAE, "mae")
-.describe("Mean absolute error.")
-.set_body([](const char* param) { return new EvalEWiseBase<EvalRowMAE>(); });
+XGBOOST_REGISTER_METRIC(MAE, "mae").describe("Mean absolute error.").set_body([](const char*) {
+  return new EvalEWiseBase<EvalRowMAE>();
+});
 
 XGBOOST_REGISTER_METRIC(MAPE, "mape")
     .describe("Mean absolute percentage error.")
-    .set_body([](const char* param) { return new EvalEWiseBase<EvalRowMAPE>(); });
+    .set_body([](const char*) { return new EvalEWiseBase<EvalRowMAPE>(); });
 
 XGBOOST_REGISTER_METRIC(LogLoss, "logloss")
-.describe("Negative loglikelihood for logistic regression.")
-.set_body([](const char* param) { return new EvalEWiseBase<EvalRowLogLoss>(); });
+    .describe("Negative loglikelihood for logistic regression.")
+    .set_body([](const char*) { return new EvalEWiseBase<EvalRowLogLoss>(); });
 
 XGBOOST_REGISTER_METRIC(PseudoErrorLoss, "mphe")
     .describe("Mean Pseudo-huber error.")
-    .set_body([](const char* param) { return new PseudoErrorLoss{}; });
+    .set_body([](const char*) { return new PseudoErrorLoss{}; });
 
 XGBOOST_REGISTER_METRIC(PossionNegLoglik, "poisson-nloglik")
-.describe("Negative loglikelihood for poisson regression.")
-.set_body([](const char* param) { return new EvalEWiseBase<EvalPoissonNegLogLik>(); });
+    .describe("Negative loglikelihood for poisson regression.")
+    .set_body([](const char*) { return new EvalEWiseBase<EvalPoissonNegLogLik>(); });
 
 XGBOOST_REGISTER_METRIC(GammaDeviance, "gamma-deviance")
-.describe("Residual deviance for gamma regression.")
-.set_body([](const char* param) { return new EvalEWiseBase<EvalGammaDeviance>(); });
+    .describe("Residual deviance for gamma regression.")
+    .set_body([](const char*) { return new EvalEWiseBase<EvalGammaDeviance>(); });
 
 XGBOOST_REGISTER_METRIC(GammaNLogLik, "gamma-nloglik")
-.describe("Negative log-likelihood for gamma regression.")
-.set_body([](const char* param) { return new EvalEWiseBase<EvalGammaNLogLik>(); });
+    .describe("Negative log-likelihood for gamma regression.")
+    .set_body([](const char*) { return new EvalEWiseBase<EvalGammaNLogLik>(); });
 
 XGBOOST_REGISTER_METRIC(Error, "error")
 .describe("Binary classification error.")

src/metric/multiclass_metric.cu

@@ -230,9 +230,7 @@ struct EvalMultiLogLoss : public EvalMClassBase<EvalMultiLogLoss> {
   const char* Name() const override {
     return "mlogloss";
   }
-  XGBOOST_DEVICE static bst_float EvalRow(int label,
-                                          const bst_float *pred,
-                                          size_t nclass) {
+  XGBOOST_DEVICE static bst_float EvalRow(int label, const bst_float* pred, size_t /*nclass*/) {
     const bst_float eps = 1e-16f;
     auto k = static_cast<size_t>(label);
     if (pred[k] > eps) {
@@ -244,11 +242,11 @@ struct EvalMultiLogLoss : public EvalMClassBase<EvalMultiLogLoss> {
 };
 
 XGBOOST_REGISTER_METRIC(MatchError, "merror")
-.describe("Multiclass classification error.")
-.set_body([](const char* param) { return new EvalMatchError(); });
+    .describe("Multiclass classification error.")
+    .set_body([](const char*) { return new EvalMatchError(); });
 
 XGBOOST_REGISTER_METRIC(MultiLogLoss, "mlogloss")
-.describe("Multiclass negative loglikelihood.")
-.set_body([](const char* param) { return new EvalMultiLogLoss(); });
+    .describe("Multiclass negative loglikelihood.")
+    .set_body([](const char*) { return new EvalMultiLogLoss(); });
 }  // namespace metric
 }  // namespace xgboost

src/metric/survival_metric.cu

@@ -153,7 +153,7 @@ class ElementWiseSurvivalMetricsReduction {
 };
 
 struct EvalIntervalRegressionAccuracy {
-  void Configure(const Args& args) {}
+  void Configure(const Args&) {}
 
   const char* Name() const {
     return "interval-regression-accuracy";
@@ -277,18 +277,15 @@ struct AFTNLogLikDispatcher : public Metric {
   std::unique_ptr<Metric> metric_;
 };
 
-
 XGBOOST_REGISTER_METRIC(AFTNLogLik, "aft-nloglik")
-.describe("Negative log likelihood of Accelerated Failure Time model.")
-.set_body([](const char* param) {
-  return new AFTNLogLikDispatcher();
-});
+    .describe("Negative log likelihood of Accelerated Failure Time model.")
+    .set_body([](const char*) { return new AFTNLogLikDispatcher(); });
 
 XGBOOST_REGISTER_METRIC(IntervalRegressionAccuracy, "interval-regression-accuracy")
-.describe("")
-.set_body([](const char* param) {
-  return new EvalEWiseSurvivalBase<EvalIntervalRegressionAccuracy>();
-});
+    .describe("")
+    .set_body([](const char*) {
+      return new EvalEWiseSurvivalBase<EvalIntervalRegressionAccuracy>();
+    });
 
 }  // namespace metric
 }  // namespace xgboost