check for constant expressions while compiling omc

[jfrenkel]

when compiling omc the bootsrapped compiler should be checking for statements like
a = b-b;
and report a warning
"Warning: constant assignment for a = b-b = 0;"

[sjoelund.se]

We do things like lst = {} to initialize a list all the time... The same error would also occur for regular Modelica users where things like inheritance may cause expressions to be constant.

Are you sure you want that warning?

[jfrenkel]

10 minutes ago I found a bug in omc. This bug could be avoided if a warning is reported.

expandsize = size1-size1;
->
expandsize = size1-size;

With this bugfix omc is now able to compile the multibody pendulum with more than 200 bodies. Before he crached by 33.

[sjoelund.se]

Still, most expressions assigned are constant, so I think this should not be a warning as it is legal code, and often what the programmer intended to write.

[dietmarw]

Sorting away the closed as invalid, won't fix and duplicate tickets from Future.