Weird QuestaSim Base Error

[Nigel]

Got a bit of a strange one here. I finally had to bite the bullet and let go of ModelSim DE and upgrade to QuestaSim Base. Straight away I ran into a problem with my simulations that use OSVVM (my sims that don’t use OSVVM work fine). When running the sim, Questa reports the following error:

** Error: ../Test_Benches/LTC2380_CTRL_DAT_IF_tb.vhd(7): (vopt-1659) Mixing VHDL 2019 with earlier versions is not allowed.

This obviously causes the sim to not run.

Has anyone else seen this and any ideas on how to resolve?

[Jim Lewis]

Hi Nigel,
In the OSVVM 2024.09 and 2025.02 releases, the 2019 compile switch was turned on if the Questa release is greater than 2024.2. With the OSVVM 2025.04a release and beyond the 2019 switch it is turned back off again. So I recommend getting the newest release of OSVVM (2025.06a) and this problem is resolved.

In Questa, your issue is happening because OSVVM was compiled with 2019 and your project was compiled with a different version. So in Questa, when you turn on VHDL-2019, you must turn it on for your whole project. You should be able to compile other parts of your project with 2019 as the VHDL-2019 standard should be backward compatible with older versions.

If you do not want to change your OSVVM revision, simply add the following to either your scripts or to your OsvvmSettingsLocal.tcl file:
SetVHDLVersion 2008

So how did this happened? In 2024.2 release of Questa, Questa claimed 2019 support. So I tested the VHDL-2019 based RandomPkg2019.vhd package. It passed all of our regressions and worked fine on Questa 2024.2 and 2024.3. In 2025 releases, the Questa started flagging the VHDL-2019 code in RandomPkg2019.vhd as unsupported.

Best Regards,
Jim

[Jim Lewis]

Hi Nigel,
In the OSVVM 2024.09 and 2025.02 releases, the 2019 compile switch was turned on if the Questa release is greater than 2024.2. With the OSVVM 2025.04a release and beyond the 2019 switch it is turned back off again. So I recommend getting the newest release of OSVVM (2025.06a) and this problem is resolved.

In Questa, your issue is happening because OSVVM was compiled with 2019 and your project was compiled with a different version. So in Questa, when you turn on VHDL-2019, you must turn it on for your whole project. You should be able to compile other parts of your project with 2019 as the VHDL-2019 standard should be backward compatible with older versions.

If you do not want to change your OSVVM revision, simply add the following to either your scripts or to your OsvvmSettingsLocal.tcl file:
SetVHDLVersion 2008

So how did this happened? In 2024.2 release of Questa, Questa claimed 2019 support. So I tested the VHDL-2019 based RandomPkg2019.vhd package. It passed all of our regressions and worked fine on Questa 2024.2 and 2024.3. In 2025 releases, the Questa started flagging the VHDL-2019 code in RandomPkg2019.vhd as unsupported.

Best Regards,
Jim

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