Add test for invalid categorical data values. (#7380)

* Add test for invalid categorical data values.

* Add check during sketching.

src/common/categorical.h

@@ -42,9 +42,9 @@ inline XGBOOST_DEVICE bool Decision(common::Span<uint32_t const> cats, bst_cat_t
   return !s_cats.Check(cat);
 }
 
-inline void CheckCat(bst_cat_t cat) {
-  CHECK_GE(cat, 0) << "Invalid categorical value detected.  Categorical value "
-                      "should be non-negative.";
+inline void InvalidCategory() {
+  LOG(FATAL) << "Invalid categorical value detected.  Categorical value "
+                "should be non-negative.";
 }
 
 struct IsCatOp {

src/common/quantile.cu

@@ -580,6 +580,19 @@ void SketchContainer::AllReduce() {
   timer_.Stop(__func__);
 }
 
+namespace {
+struct InvalidCat {
+  Span<float const> values;
+  Span<uint32_t const> ptrs;
+  Span<FeatureType const> ft;
+
+  XGBOOST_DEVICE bool operator()(size_t i) {
+    auto fidx = dh::SegmentId(ptrs, i);
+    return IsCat(ft, fidx) && values[i] < 0;
+  }
+};
+}  // anonymous namespace
+
 void SketchContainer::MakeCuts(HistogramCuts* p_cuts) {
   timer_.Start(__func__);
   dh::safe_cuda(cudaSetDevice(device_));
@@ -669,6 +682,19 @@ void SketchContainer::MakeCuts(HistogramCuts* p_cuts) {
     assert(idx+1 < in_column.size());
     out_column[idx] = in_column[idx+1].value;
   });
+
+  if (has_categorical_) {
+    dh::XGBCachingDeviceAllocator<char> alloc;
+    auto ptrs = p_cuts->cut_ptrs_.ConstDeviceSpan();
+    auto it = thrust::make_counting_iterator(0ul);
+    CHECK_EQ(p_cuts->Ptrs().back(), out_cut_values.size());
+    auto invalid =
+        thrust::any_of(thrust::cuda::par(alloc), it, it + out_cut_values.size(),
+                       InvalidCat{out_cut_values, ptrs, d_ft});
+    if (invalid) {
+      InvalidCategory();
+    }
+  }
   timer_.Stop(__func__);
 }
 }  // namespace common