Fix reading of CSV files with blank second row

cpp/src/io/csv/reader_impl.cu

@@ -134,7 +134,6 @@ std::vector<std::string> get_column_names(std::vector<char> const& header,
   if (header.size() <= 1) { return col_names; }
 
   std::vector<char> first_row = header;
-  int num_cols                = 0;
 
   bool quotation = false;
   for (size_t pos = 0, prev = 0; pos < first_row.size(); ++pos) {
@@ -163,17 +162,16 @@ std::vector<std::string> get_column_names(std::vector<char> const& header,
 
         const string new_col_name(first_row.data() + prev, col_name_len);
         col_names.push_back(removeQuotes(new_col_name, parse_opts.quotechar));
-
-        // Stop parsing when we hit the line terminator; relevant when there is
-        // a blank line following the header. In this case, first_row includes
-        // multiple line terminators at the end, as the new recStart belongs to
-        // a line that comes after the blank line(s)
-        if (!quotation && first_row[pos] == parse_opts.terminator) { break; }
       } else {
         // This is the first data row, add the automatically generated name
-        col_names.push_back(prefix + std::to_string(num_cols));
+        col_names.push_back(prefix + std::to_string(col_names.size()));
       }
-      num_cols++;
+
+      // Stop parsing when we hit the line terminator; relevant when there is
+      // a blank line following the header. In this case, first_row includes
+      // multiple line terminators at the end, as the new recStart belongs to
+      // a line that comes after the blank line(s)
+      if (!quotation && first_row[pos] == parse_opts.terminator) { break; }
 
       // Skip adjacent delimiters if delim_whitespace is set
       while (parse_opts.multi_delimiter && pos < first_row.size() &&

cpp/tests/io/csv_test.cpp

@@ -2244,4 +2244,29 @@ TEST_F(CsvReaderTest, CsvDefaultOptionsWriteReadMatch)
   EXPECT_EQ(new_table_and_metadata.metadata.column_names[1], "1");
 }
 
+TEST_F(CsvReaderTest, BlankLineAfterFirstRow)
+{
+  std::string csv_in{"12,9., 10\n\n"};
+
+  {
+    cudf::io::csv_reader_options no_header_opts =
+      cudf::io::csv_reader_options::builder(cudf::io::source_info{csv_in.c_str(), csv_in.size()})
+        .header(-1);
+    // No header, getting column names/count from first row
+    auto result = cudf::io::read_csv(no_header_opts);
+
+    const auto result_table = result.tbl->view();
+    ASSERT_EQ(result_table.num_columns(), 3);
+  }
+  {
+    cudf::io::csv_reader_options header_opts =
+      cudf::io::csv_reader_options::builder(cudf::io::source_info{csv_in.c_str(), csv_in.size()});
+    // Getting column names/count from header
+    auto result = cudf::io::read_csv(header_opts);
+
+    const auto result_table = result.tbl->view();
+    ASSERT_EQ(result_table.num_columns(), 3);
+  }
+}
+
 CUDF_TEST_PROGRAM_MAIN()