| // Copyright 2012-2015 The Rust Project Developers. See the COPYRIGHT |
| // file at the top-level directory of this distribution and at |
| // http://rust-lang.org/COPYRIGHT. |
| // |
| // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or |
| // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license |
| // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your |
| // option. This file may not be copied, modified, or distributed |
| // except according to those terms. |
| |
| use hir; |
| use hir::def_id::DefId; |
| use hir::map::DefPathHash; |
| use ich::{self, StableHashingContext}; |
| use traits::specialization_graph; |
| use ty::fast_reject; |
| use ty::fold::TypeFoldable; |
| use ty::{Ty, TyCtxt}; |
| |
| use rustc_data_structures::fx::FxHashMap; |
| use rustc_data_structures::stable_hasher::{HashStable, StableHasher, |
| StableHasherResult}; |
| use rustc_data_structures::sync::Lrc; |
| |
| /// A trait's definition with type information. |
| pub struct TraitDef { |
| pub def_id: DefId, |
| |
| pub unsafety: hir::Unsafety, |
| |
| /// If `true`, then this trait had the `#[rustc_paren_sugar]` |
| /// attribute, indicating that it should be used with `Foo()` |
| /// sugar. This is a temporary thing -- eventually any trait will |
| /// be usable with the sugar (or without it). |
| pub paren_sugar: bool, |
| |
| pub has_auto_impl: bool, |
| |
| /// If `true`, then this trait has the `#[marker]` attribute, indicating |
| /// that all its associated items have defaults that cannot be overridden, |
| /// and thus `impl`s of it are allowed to overlap. |
| pub is_marker: bool, |
| |
| /// The ICH of this trait's DefPath, cached here so it doesn't have to be |
| /// recomputed all the time. |
| pub def_path_hash: DefPathHash, |
| } |
| |
| #[derive(Default)] |
| pub struct TraitImpls { |
| blanket_impls: Vec<DefId>, |
| /// Impls indexed by their simplified self-type, for fast lookup. |
| non_blanket_impls: FxHashMap<fast_reject::SimplifiedType, Vec<DefId>>, |
| } |
| |
| impl<'a, 'gcx, 'tcx> TraitDef { |
| pub fn new(def_id: DefId, |
| unsafety: hir::Unsafety, |
| paren_sugar: bool, |
| has_auto_impl: bool, |
| is_marker: bool, |
| def_path_hash: DefPathHash) |
| -> TraitDef { |
| TraitDef { |
| def_id, |
| unsafety, |
| paren_sugar, |
| has_auto_impl, |
| is_marker, |
| def_path_hash, |
| } |
| } |
| |
| pub fn ancestors(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, |
| of_impl: DefId) |
| -> specialization_graph::Ancestors { |
| specialization_graph::ancestors(tcx, self.def_id, of_impl) |
| } |
| } |
| |
| impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> { |
| pub fn for_each_impl<F: FnMut(DefId)>(self, def_id: DefId, mut f: F) { |
| let impls = self.trait_impls_of(def_id); |
| |
| for &impl_def_id in impls.blanket_impls.iter() { |
| f(impl_def_id); |
| } |
| |
| for v in impls.non_blanket_impls.values() { |
| for &impl_def_id in v { |
| f(impl_def_id); |
| } |
| } |
| } |
| |
| /// Iterate over every impl that could possibly match the |
| /// self-type `self_ty`. |
| pub fn for_each_relevant_impl<F: FnMut(DefId)>(self, |
| def_id: DefId, |
| self_ty: Ty<'tcx>, |
| mut f: F) |
| { |
| let impls = self.trait_impls_of(def_id); |
| |
| for &impl_def_id in impls.blanket_impls.iter() { |
| f(impl_def_id); |
| } |
| |
| // simplify_type(.., false) basically replaces type parameters and |
| // projections with infer-variables. This is, of course, done on |
| // the impl trait-ref when it is instantiated, but not on the |
| // predicate trait-ref which is passed here. |
| // |
| // for example, if we match `S: Copy` against an impl like |
| // `impl<T:Copy> Copy for Option<T>`, we replace the type variable |
| // in `Option<T>` with an infer variable, to `Option<_>` (this |
| // doesn't actually change fast_reject output), but we don't |
| // replace `S` with anything - this impl of course can't be |
| // selected, and as there are hundreds of similar impls, |
| // considering them would significantly harm performance. |
| |
| // This depends on the set of all impls for the trait. That is |
| // unfortunate. When we get red-green recompilation, we would like |
| // to have a way of knowing whether the set of relevant impls |
| // changed. The most naive |
| // way would be to compute the Vec of relevant impls and see whether |
| // it differs between compilations. That shouldn't be too slow by |
| // itself - we do quite a bit of work for each relevant impl anyway. |
| // |
| // If we want to be faster, we could have separate queries for |
| // blanket and non-blanket impls, and compare them separately. |
| // |
| // I think we'll cross that bridge when we get to it. |
| if let Some(simp) = fast_reject::simplify_type(self, self_ty, true) { |
| if let Some(impls) = impls.non_blanket_impls.get(&simp) { |
| for &impl_def_id in impls { |
| f(impl_def_id); |
| } |
| } |
| } else { |
| for &impl_def_id in impls.non_blanket_impls.values().flatten() { |
| f(impl_def_id); |
| } |
| } |
| } |
| |
| /// Return a vector containing all impls |
| pub fn all_impls(self, def_id: DefId) -> Vec<DefId> { |
| let impls = self.trait_impls_of(def_id); |
| |
| impls.blanket_impls.iter().chain( |
| impls.non_blanket_impls.values().flatten() |
| ).cloned().collect() |
| } |
| } |
| |
| // Query provider for `trait_impls_of`. |
| pub(super) fn trait_impls_of_provider<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, |
| trait_id: DefId) |
| -> Lrc<TraitImpls> { |
| let mut impls = TraitImpls::default(); |
| |
| { |
| let mut add_impl = |impl_def_id| { |
| let impl_self_ty = tcx.type_of(impl_def_id); |
| if impl_def_id.is_local() && impl_self_ty.references_error() { |
| return; |
| } |
| |
| if let Some(simplified_self_ty) = |
| fast_reject::simplify_type(tcx, impl_self_ty, false) |
| { |
| impls.non_blanket_impls |
| .entry(simplified_self_ty) |
| .or_default() |
| .push(impl_def_id); |
| } else { |
| impls.blanket_impls.push(impl_def_id); |
| } |
| }; |
| |
| // Traits defined in the current crate can't have impls in upstream |
| // crates, so we don't bother querying the cstore. |
| if !trait_id.is_local() { |
| for &cnum in tcx.crates().iter() { |
| for &def_id in tcx.implementations_of_trait((cnum, trait_id)).iter() { |
| add_impl(def_id); |
| } |
| } |
| } |
| |
| for &node_id in tcx.hir.trait_impls(trait_id) { |
| add_impl(tcx.hir.local_def_id(node_id)); |
| } |
| } |
| |
| Lrc::new(impls) |
| } |
| |
| impl<'a> HashStable<StableHashingContext<'a>> for TraitImpls { |
| fn hash_stable<W: StableHasherResult>(&self, |
| hcx: &mut StableHashingContext<'a>, |
| hasher: &mut StableHasher<W>) { |
| let TraitImpls { |
| ref blanket_impls, |
| ref non_blanket_impls, |
| } = *self; |
| |
| ich::hash_stable_trait_impls(hcx, hasher, blanket_impls, non_blanket_impls); |
| } |
| } |