FMU with CVODE without states failes

[Andreas Heuermann]

FMUs simulating with CVODE can't handle systems with zero states:

loadString("
  model InputValues
    output Real v;
  equation
    when time >= 0.5 then
      v = 1;
    end when;
  end InputValues;
"); getErrorString();

setCommandLineOptions("--fmiFlags=s:cvode"); getErrorString();

translateModelFMU(InputValues, version="2.0", fmuType="cs"); getErrorString();

system("OMSimulator InputValues.fmu"); getErrorString();

[Andreas Heuermann]

We need to do the same as in the C runtime. If no states are present just use Euler's method. There is nothing to happen any way.

[Andreas Heuermann]

See PR ​https://github.com/OpenModelica/OpenModelica/pull/6688

[Andreas Heuermann]

Merged with ​https://github.com/OpenModelica/OpenModelica/commit/dbb0b7aefeefa9dab002c358c646a12e059efab3