diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/librustc_traits/lowering.rs | 32 |
1 files changed, 32 insertions, 0 deletions
diff --git a/src/librustc_traits/lowering.rs b/src/librustc_traits/lowering.rs index a69f9988f37..1092e826a35 100644 --- a/src/librustc_traits/lowering.rs +++ b/src/librustc_traits/lowering.rs @@ -12,6 +12,7 @@ use rustc::hir::{self, ImplPolarity}; use rustc::hir::def_id::DefId; use rustc::hir::intravisit::{self, NestedVisitorMap, Visitor}; use rustc::ty::{self, TyCtxt}; +use rustc::ty::subst::Substs; use rustc::traits::{QuantifierKind, Goal, DomainGoal, Clause, WhereClauseAtom}; use syntax::ast; use rustc_data_structures::sync::Lrc; @@ -104,6 +105,7 @@ crate fn program_clauses_for<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefI let node_id = tcx.hir.as_local_node_id(def_id).unwrap(); let item = tcx.hir.expect_item(node_id); match item.node { + hir::ItemTrait(..) => program_clauses_for_trait(tcx, def_id), hir::ItemImpl(..) => program_clauses_for_impl(tcx, def_id), // FIXME: other constructions e.g. traits, associated types... @@ -111,6 +113,36 @@ crate fn program_clauses_for<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefI } } +fn program_clauses_for_trait<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) + -> Lrc<Vec<Clause<'tcx>>> +{ + // Rule Implemented-From-Env (see rustc guide) + // + // `trait Trait<P1..Pn> where WC { .. } // P0 == Self` + // + // ``` + // forall<Self, P1..Pn> { + // Implemented(Self: Trait<P1..Pn>) :- FromEnv(Self: Trait<P1..Pn>) + // } + // ``` + + // `Self: Trait<P1..Pn>` + let trait_pred = ty::TraitPredicate { + trait_ref: ty::TraitRef { + def_id, + substs: Substs::identity_for_item(tcx, def_id) + } + }; + // `FromEnv(Self: Trait<P1..Pn>)` + let from_env = Goal::DomainGoal(DomainGoal::FromEnv(trait_pred.lower())); + // `Implemented(Self: Trait<P1..Pn>)` + let impl_trait = DomainGoal::Holds(WhereClauseAtom::Implemented(trait_pred)); + + // `Implemented(Self: Trait<P1..Pn>) :- FromEnv(Self: Trait<P1..Pn>)` + let clause = Clause::Implies(vec![from_env], impl_trait); + Lrc::new(vec![clause]) +} + fn program_clauses_for_impl<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> Lrc<Vec<Clause<'tcx>>> { |