Rand_pkg.vhd causes "Range 1 to 0 is null" Warning (vcom-1246)

Good Morning,

i just updated our project UVVM-Folder to v2 2021.10.22 (c2af620)
and found rand_pkg.vhd causes some " Range 1 to 0 is null" Warnings (vcom-1246) in Modelsim.

Cause are the lines 1531…1529 and 6338…6368, because the frist index A is higher then the second B
inside the slv(A to B).

Fixed by : slv(1 to 0) → slv(1 downto 0)

Ord did i misunderstand something?

Hoping i could help / give back something. I am still / just at the beginng ob UVVM usage.

By the way: Would you prefer an Isse at github or a message here in the forum, even if one my not be absolutely shure thats something is a bug?

Kind regards,
Kai Hennigs


These warnings are expected because the arrays need to be initialized to null elements, therefore we use the notation (1 to 0). This is a legal way of initializing a null array even though simulators might report this as a warning. If you want to avoid those warnings you can use the compile directive “-suppress 1246” when compiling the file rand_pkg.vhd.

I think you can use the forum for questions or things that are not completely sure is a bug and might need a discussion. For more concrete bugs you can use Github.


Hi Erik!

Thanks for the quick answer! Now I can suppress the warning without being unsafe.

…and learned something.

Happy holidays and greetings from Germany