The "Show Line numbers" option is selected under the ISE Text Editor preferences and HDL files correctly show line numbers.
However, line numbers do not show up on report files and log files (.log, par, twr, etc...) opened in Design Summary.
Report files and log files opened in Design Summary are opened in a separateReport Viewer application and therefore the "Show Line Numbers" option for ISE Text Editor has no effect.
In ISE 12.1 software there is no option to show line numbers in the Report viewer. Changing the file extension to a value such as .txt will allow any file to be opened in the ISE Text Editor instead of the report viewer in order to see line numbers.
In ISE 12.2software a user will be able to right click in a report opened in the report viewer and view line numbers.