Constructor symbols are not in the known_map of Compile.Translate.module_ outputs
mod_known of compiled program modules (
Mltree.pmodule) does not contain the constructor symbols, which are present in the known_map of the pmodules passed as parameters to
Compile.Translate.module_ (and point to the type declaration in which they are introduced).
This can be worked around, as the old known_map is included in the
mod_from field, but they should be included at some point.