fix naming, static_cast and forgotten asertion

Author: andishgar

cpp/src/arrow/array/array_test.cc

@@ -1004,15 +1004,15 @@ class TestArrayBinaryViewBuilderAppendArraySlice : public TestArray {
   Result<std::shared_ptr<Array>> AppendArraySliceWithSpanOffset(
       const std::shared_ptr<Array>& array) {
     const ArraySpan span(*array->data());
-    for (int i = 0; i < array->length(); i++) {
+    for (int i = 0; i < array->length(); ++i) {
       ARROW_RETURN_NOT_OK(builder_.AppendArraySlice(span, i, 1));
     }
     return builder_.Finish();
   }
 
   Result<std::shared_ptr<Array>> AppendArraySliceWithArrayOffset(
       const std::shared_ptr<Array>& array) {
-    for (int i = 0; i < array->length(); i++) {
+    for (int i = 0; i < array->length(); ++i) {
       auto slice = array->Slice(i, 1);
       const ArraySpan span(*slice->data());
       ARROW_RETURN_NOT_OK(builder_.AppendArraySlice(span, 0, 1));
@@ -1263,6 +1263,10 @@ TEST_F(TestArrayBinaryViewBuilderAppendArraySlice, Reset) {
   view_1 = view_buffer[0];
   view_2 = view_buffer[1];
   view_3 = view_buffer[2];
+
+  ASSERT_EQ(view_1.ref.buffer_index, 0);
+  ASSERT_EQ(view_2.ref.buffer_index, 0);
+  ASSERT_EQ(view_3.ref.buffer_index, 1);
 }
 
 TEST_F(TestArray, ValidateBuffersPrimitive) {

cpp/src/arrow/array/builder_binary.cc

@@ -81,13 +81,13 @@ Status BinaryViewBuilder::AppendArraySlice(const ArraySpan& array, int64_t offse
         if (view.is_inline()) {
           data_builder_.UnsafeAppend(&view, 1);
         } else {
-          auto dst_buffer_index = TryAddBufferAndGetIndex(
+          auto dst_data_buffer_index = TryAddBufferAndGetIndex(
               buffer_index_map, view.ref.buffer_index, data_heap_builder_,
               data_buffers[view.ref.buffer_index]);
           auto dst_view_index = data_builder_.length();
           data_builder_.UnsafeAppend(&view, 1);
           data_builder_.mutable_data()[dst_view_index].ref.buffer_index =
-              dst_buffer_index;
+              dst_data_buffer_index;
         }
       },
       [&]() { UnsafeAppendNull(); });

cpp/src/arrow/array/builder_binary.h

@@ -533,7 +533,7 @@ class ARROW_EXPORT StringHeapBuilder {
       current_offset_ = 0;
       current_out_buffer_ = new_block->mutable_data();
       blocks_.emplace_back(std::move(new_block));
-      current_block_ = static_cast<int32_t>(blocks_.size() - 1);
+      current_block_ = static_cast<int64_t>(blocks_.size() - 1);
     }
     return Status::OK();
   }