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
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
For more information, see VHDL case statements can do without the “others”.
This rule can be disabled for your project, or its severity and parameters can be modified in the project linting settings. Alternatively, it can be manually configured with the following template: