Redundant "others"


If a case statement contains all the possible choices (usually in an enumerated datatype), you can safely remove the when others clause. Sigasi Studio warns about this:

Case statement contains all choices explicitly. You can safely remove the redundant others.

case bits is
  when "00" => -- code
  when "01" => -- code
  when "10" => -- code
  when "11" => -- code
  when others => -- never reached: all cases are covered
end case;

There is some debate on this coding rule. However, the vast majority of synthesis tools do not take the others into account if all choices are enumerated. If the synthesis tool is set up to generate fault-tolerant hardware, the fallback state is the same as the reset state (for most synthesis tools). Check the manual of your synthesis tools and run some experiments. For more information, see VHDL case statements can do without the “others”.

Project specific setting of this rule

This rule can be disabled for your project, or its severity can be modified in the project linting settings.

Manual configuration in ${project location}/.settings/com.sigasi.hdt.vhdl.linting.prefs:

13/severity/<project>=IGNORE