Arbitrary identifier accepted as message parameter

[senier]

The following specification should be rejected as the parameter passed to the message type does not exist:

package Test is
   type T is mod 2 ** 8;
   type M1 (P : Boolean) is
      message
         F : T;
      end message;
   type M2 is
      message
         F : M1 (P => Blubber);
      end message;
end Test;

Currently rflx check succeeds on this specification.

[treiher]

The actual problem is that P is unused in M1. The use of message types as field types is just some form of syntactic sugar. The message model does not contain that information. Blubber just gets lost during merging M1 into M2. Only the resulting message is verified, where no Blubber exists anymore. I think the best solution would be to just add a check for unused message parameters here:

https://github.com/Componolit/RecordFlux/blob/5e894e44a07d3d6d26b745bff00add009ac9f8da/rflx/model/message.py#L796-L802