matching case? allows multiple arms with the same pattern

[nathanaelhuffman]

This is accepted by nvc and runs, I believe this should be compile error, otherwise I'm not sure what the return value would be expected to be.

library ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;

package pack is
    function matching_cases (
        opcode: std_logic_vector
    ) return natural;
   
end package;

package body pack is

    function matching_cases (
        opcode: std_logic_vector
    ) return natural is

        variable bytes : natural := 0;

    begin
        case? opcode is
            when "00000000" =>
                bytes := 1;
            when "00000001" =>
                bytes := 1;
            when "010000--" =>
                bytes := 1;
            when "010000--" =>  -- SAME CONDITION AS ABOVE ARM!!!
                bytes := 2; -
            when others =>
                bytes := 4; 
        end case?;
        return bytes;
    end;

end package body;

[nickg]

Bounds checks were missing for case? statements. Now it reports:

** Error: duplicate choice in case statement
    > ../test/bounds/issue966.vhd:27
    |
 25 |             when "010000--" =>
    |                  ^^^^^^^^^^ previous choice for this value
 26 |                 bytes := 1;
 27 |             when "010000--" =>  -- SAME CONDITION AS ABOVE ARM!!!
    |                  ^^^^^^^^^^ repeated here
    |
    = Note: each value of the subtype of the expression must be represented once and only 
            once in the set of choices
    = Help: IEEE Std 1076-2008 section 10.9 "Case statement"