Modelsim error when doing: port map(a => not(b))

Hi all,

I'm VERY sorry because I've seen much discussion about globally static expressions and Modelsim, but I cannot find a clear answer to this problem.

When you instantiate an entity, is quite common to negate one of the inputs. It would look something like this:

i_my_entity : MyEntity port map( ena => not(nEN) );

When we pass it to Modelsim for pre-synthesis simulation, it complains: "The actual for formal 'ena' is not a globally static expression".

I don't look for an answer for "why it does not work". I would like to know HOW can I make it work in a convenient way, different from assigning not(nEN) to a signal and passing this signal to the instantiation like this:

signal aNegation : std_logic; ... aNegation aNegation );

Regards. Jose.