There might be a silent bug in the Python module which directly reads from this type_set field; in particular, it does so when reading all controlling type variables, which all seem to be free variables (i.e. no parent typevar). So imitate this behavior here, until we're sure there are no other meta generators that rely on this.
This crate contains the core Cranelift code generator. It translates code from an intermediate representation into executable machine code.