3 pub fn glb(v1: ty::Variance, v2: ty::Variance) -> ty::Variance {
4 // Greatest lower bound of the variance lattice as
5 // defined in The Paper:
12 (_, ty::Invariant) => ty::Invariant,
14 (ty::Covariant, ty::Contravariant) => ty::Invariant,
15 (ty::Contravariant, ty::Covariant) => ty::Invariant,
17 (ty::Covariant, ty::Covariant) => ty::Covariant,
19 (ty::Contravariant, ty::Contravariant) => ty::Contravariant,
22 (ty::Bivariant, x) => x,