csv.rb: fix field_size_limit check

* lib/csv.rb (CSV#shift): the last column is an Array in extended
  column since r55985.  [ruby-dev:49964] [Bug #13149]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@57406 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

lib/csv.rb

@@ -1927,7 +1927,7 @@ class CSV
         if @io.eof?
           raise MalformedCSVError,
                 "Unclosed quoted field on line #{lineno + 1}."
-        elsif @field_size_limit and csv.last.size >= @field_size_limit
+        elsif @field_size_limit and csv.last.sum(&:size) >= @field_size_limit
           raise MalformedCSVError, "Field size exceeded on line #{lineno + 1}."
         end
         # otherwise, we need to loop and pull some more data to complete the row

test/csv/test_csv_parsing.rb

@@ -209,6 +209,28 @@ class TestCSV::Parsing < TestCSV
                              field_size_limit: 2048 )
   end
 
+  def test_field_size_limit_in_extended_column_not_exceeding
+    data = <<~DATA
+      "a","b"
+      "
+      2
+      ",""
+    DATA
+    assert_nothing_raised(CSV::MalformedCSVError) do
+      CSV.parse(data, field_size_limit: 4)
+    end
+  end
+
+  def test_field_size_limit_in_extended_column_exceeding
+    data = <<~DATA
+      "a","b"
+      "
+      2345
+      ",""
+    DATA
+    assert_parse_errors_out(data, field_size_limit: 5)
+  end
+
   private
 
   def assert_parse_errors_out(*args)