diff options
| -rw-r--r-- | src/librustc_typeck/variance.rs | 99 |
1 files changed, 3 insertions, 96 deletions
diff --git a/src/librustc_typeck/variance.rs b/src/librustc_typeck/variance.rs index b83d8fc6af7..a95919c20f3 100644 --- a/src/librustc_typeck/variance.rs +++ b/src/librustc_typeck/variance.rs @@ -644,39 +644,9 @@ impl<'a, 'tcx, 'v> Visitor<'v> for ConstraintContext<'a, 'tcx> { ast::ItemTrait(..) => { let trait_def = ty::lookup_trait_def(tcx, did); - let predicates = ty::lookup_super_predicates(tcx, did); - self.add_constraints_from_predicates(&trait_def.generics, - predicates.predicates.as_slice(), - self.covariant); - - let trait_items = ty::trait_items(tcx, did); - for trait_item in &*trait_items { - match *trait_item { - ty::MethodTraitItem(ref method) => { - self.add_constraints_from_predicates( - &method.generics, - method.predicates.predicates.get_slice(FnSpace), - self.contravariant); - - self.add_constraints_from_sig( - &method.generics, - &method.fty.sig, - self.covariant); - } - ty::TypeTraitItem(ref data) => { - // Any trait with an associated type is - // invariant with respect to all of its - // inputs. See length discussion in the comment - // on this module. - let projection_ty = ty::mk_projection(tcx, - trait_def.trait_ref.clone(), - data.name); - self.add_constraints_from_ty(&trait_def.generics, - projection_ty, - self.invariant); - } - } - } + self.add_constraints_from_trait_ref(&trait_def.generics, + &trait_def.trait_ref, + self.invariant); } ast::ItemExternCrate(_) | @@ -1045,69 +1015,6 @@ impl<'a, 'tcx> ConstraintContext<'a, 'tcx> { } } - fn add_constraints_from_predicates(&mut self, - generics: &ty::Generics<'tcx>, - predicates: &[ty::Predicate<'tcx>], - variance: VarianceTermPtr<'a>) { - debug!("add_constraints_from_generics({})", - generics.repr(self.tcx())); - - for predicate in predicates.iter() { - match *predicate { - ty::Predicate::Trait(ty::Binder(ref data)) => { - self.add_constraints_from_trait_ref(generics, &*data.trait_ref, variance); - } - - ty::Predicate::Equate(ty::Binder(ref data)) => { - // A == B is only true if A and B are the same - // types, not subtypes of one another, so this is - // an invariant position: - self.add_constraints_from_ty(generics, data.0, self.invariant); - self.add_constraints_from_ty(generics, data.1, self.invariant); - } - - ty::Predicate::TypeOutlives(ty::Binder(ref data)) => { - // Why contravariant on both? Let's consider: - // - // Under what conditions is `(T:'t) <: (U:'u)`, - // meaning that `(T:'t) => (U:'u)`. The answer is - // if `U <: T` or `'u <= 't`. Let's see some examples: - // - // (T: 'big) => (T: 'small) - // where 'small <= 'big - // - // (&'small Foo: 't) => (&'big Foo: 't) - // where 'small <= 'big - // note that &'big Foo <: &'small Foo - - let variance_r = self.xform(variance, self.contravariant); - self.add_constraints_from_ty(generics, data.0, variance_r); - self.add_constraints_from_region(generics, data.1, variance_r); - } - - ty::Predicate::RegionOutlives(ty::Binder(ref data)) => { - // `'a : 'b` is still true if 'a gets bigger - self.add_constraints_from_region(generics, data.0, variance); - - // `'a : 'b` is still true if 'b gets smaller - let variance_r = self.xform(variance, self.contravariant); - self.add_constraints_from_region(generics, data.1, variance_r); - } - - ty::Predicate::Projection(ty::Binder(ref data)) => { - self.add_constraints_from_trait_ref(generics, - &*data.projection_ty.trait_ref, - variance); - - // as the equality predicate above, a binder is a - // type equality relation, not a subtyping - // relation - self.add_constraints_from_ty(generics, data.ty, self.invariant); - } - } - } - } - /// Adds constraints appropriate for a function with signature /// `sig` appearing in a context with ambient variance `variance` fn add_constraints_from_sig(&mut self, |