This commit fixes issue #1631. However, it is not a perfect solution.
This commit improves the predicate that checks whether a definition is
noncomputable or not. This predicate was implemented before we had
a code generator.
We should refactor the code and use the code generator to check
whether a definition is noncomputable or not. Otherwise, we will
keep finding mismatches between the predicate at noncomputable.cpp
and what the code generator implements.