Questa/Modelsim: don't force compilation unit settings

I discovered an issue today while trying to simulate a medium-sized project (several files) which uses SystemVerilog packages for constant and property definitions; it complained about multiple declarations of the same properties through wildcard imports.

# ** Error: /path/to/file.sv(line): Identifier 'C_ABCDE' is not directly visible.
#    Found multiple Declaration of 'C_ABCDE' through wildcard imports from these packages : component_defs, component_defs, component_defs, component_defs, component_defs, component_defs, component_defs, component_defs, component_defs, component_defs, component_defs, component_defs

I fixed this by modifying the cocotb/makefiles/simulators/Makefile.questa file to remove the -mfcu option at line 98, allowing QuestaSim to treat each file as a separate compile unit (using the -sfcu option instead). If you want I could submit a pull request with this change.

[cmarqu]

So basically, if you need to replace default settings you should override the DEFAULT_COMPILE_ARGS. If you need to pass additional settings, you just define COMPILE_ARGS.

One small UX comment here - intuitively, I would have assumed that just by setting COMPILE_ARGS, I would completely override DEFAULT_COMPILE_ARGS, while your code example does not do this. Of course, one can get used to it, but this may be a small trap for users.

[tovine]

@mciepluc Just to clarify: I did not set VSIM_ARGS, it was correctly applied from the EXTRA_ARGS variable in the makefile so that problem has already been solved.

Using overridable DEFAULT_COMPILE_ARGS could be an idea.

@forensicgarlic I agree, it’s a mystery to me why it was deemed necessary to set the defaults like this - possibly to ensure consistent behavior across different compiler/simulator backends?

However it is a bit problematic as long as the compiler freaks out if both opposing arguments are applied at the same time, failing to execute instead of allowing the user to override the (perhaps wrongfully assumed) cocotb defaults.