[NF] Handling of parameters (fixed=false, start=value) with annotation(Evaluate=true)

[adrpo]

It seems that in MSL we have final parameters with fixed=false, a start value and annotation(Evaluate=true).

The question is how do we handle these?

• Do we give an warning that it has no binding?
• Do we just ignore that it has no binding?
• Do we use the start value as a binding, they are final!?

[adrpo]

Modelica Spec says:

If Evaluate = true, the model developer proposes to utilize the value for the symbolic
processing. In that case, it is not possible to change the parameter value after symbolic 
pre-processing.

This would imply that the parameter should have a value.

[adrpo]

I will add a warning if we have a parameter Type p(fixed=true) annotation(Evaluate=true); with no binding.

I've seen some discussion on making parameters without binding an error, if we decide on that it will be easy to add (#5051).

[casella]

Replying to adrpo:

It seems that in MSL we have final parameters with fixed=false, a start value and annotation(Evaluate=true).

This sounds really odd to me. The front-end should be able to analyze and solve the initial equations in order to compute the value, which seems quite far-fetched.

Can you point out where are these parameters found?

[adrpo]

Fixed with: ​https://github.com/OpenModelica/OMCompiler/pull/2600

[adrpo]

See:
​https://github.com/modelica/ModelicaStandardLibrary/blob/master/Modelica/Mechanics/MultiBody/Joints.mo#L6181
Also there is a small related discussion here:
​https://github.com/modelica/ModelicaStandardLibrary/issues/1116