| use crate::ich::{self, StableHashingContext}; |
| use crate::traits::specialization_graph; |
| use crate::ty::fast_reject; |
| use crate::ty::fold::TypeFoldable; |
| use crate::ty::{Ty, TyCtxt}; |
| use rustc_hir as hir; |
| use rustc_hir::def_id::{CrateNum, DefId}; |
| use rustc_hir::definitions::DefPathHash; |
| use rustc_hir::HirId; |
| |
| use rustc_data_structures::fx::FxHashMap; |
| use rustc_data_structures::stable_hasher::{HashStable, StableHasher}; |
| use rustc_errors::ErrorReported; |
| use rustc_macros::HashStable; |
| use std::collections::BTreeMap; |
| |
| /// A trait's definition with type information. |
| #[derive(HashStable)] |
| pub struct TraitDef { |
| // We already have the def_path_hash below, no need to hash it twice |
| #[stable_hasher(ignore)] |
| 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, |
| |
| /// Used to determine whether the standard library is allowed to specialize |
| /// on this trait. |
| pub specialization_kind: TraitSpecializationKind, |
| |
| /// 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, |
| } |
| |
| /// Whether this trait is treated specially by the standard library |
| /// specialization lint. |
| #[derive(HashStable, PartialEq, Clone, Copy, RustcEncodable, RustcDecodable)] |
| pub enum TraitSpecializationKind { |
| /// The default. Specializing on this trait is not allowed. |
| None, |
| /// Specializing on this trait is allowed because it doesn't have any |
| /// methods. For example `Sized` or `FusedIterator`. |
| /// Applies to traits with the `rustc_unsafe_specialization_marker` |
| /// attribute. |
| Marker, |
| /// Specializing on this trait is allowed because all of the impls of this |
| /// trait are "always applicable". Always applicable means that if |
| /// `X<'x>: T<'y>` for any lifetimes, then `for<'a, 'b> X<'a>: T<'b>`. |
| /// Applies to traits with the `rustc_specialization_trait` attribute. |
| AlwaysApplicable, |
| } |
| |
| #[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<'tcx> TraitDef { |
| pub fn new( |
| def_id: DefId, |
| unsafety: hir::Unsafety, |
| paren_sugar: bool, |
| has_auto_impl: bool, |
| is_marker: bool, |
| specialization_kind: TraitSpecializationKind, |
| def_path_hash: DefPathHash, |
| ) -> TraitDef { |
| TraitDef { |
| def_id, |
| unsafety, |
| paren_sugar, |
| has_auto_impl, |
| is_marker, |
| specialization_kind, |
| def_path_hash, |
| } |
| } |
| |
| pub fn ancestors( |
| &self, |
| tcx: TyCtxt<'tcx>, |
| of_impl: DefId, |
| ) -> Result<specialization_graph::Ancestors<'tcx>, ErrorReported> { |
| specialization_graph::ancestors(tcx, self.def_id, of_impl) |
| } |
| } |
| |
| impl<'tcx> TyCtxt<'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); |
| } |
| } |
| } |
| |
| /// Returns a vector containing all impls |
| pub fn all_impls(self, def_id: DefId) -> impl Iterator<Item = DefId> + 'tcx { |
| let TraitImpls { blanket_impls, non_blanket_impls } = self.trait_impls_of(def_id); |
| |
| blanket_impls.iter().chain(non_blanket_impls.iter().map(|(_, v)| v).flatten()).cloned() |
| } |
| } |
| |
| // Query provider for `all_local_trait_impls`. |
| pub(super) fn all_local_trait_impls<'tcx>( |
| tcx: TyCtxt<'tcx>, |
| krate: CrateNum, |
| ) -> &'tcx BTreeMap<DefId, Vec<HirId>> { |
| &tcx.hir_crate(krate).trait_impls |
| } |
| |
| // Query provider for `trait_impls_of`. |
| pub(super) fn trait_impls_of_provider(tcx: TyCtxt<'_>, trait_id: DefId) -> TraitImpls { |
| let mut impls = TraitImpls::default(); |
| |
| { |
| let mut add_impl = |impl_def_id: DefId| { |
| 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 &hir_id in tcx.hir().trait_impls(trait_id) { |
| add_impl(tcx.hir().local_def_id(hir_id).to_def_id()); |
| } |
| } |
| |
| impls |
| } |
| |
| impl<'a> HashStable<StableHashingContext<'a>> for TraitImpls { |
| fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) { |
| let TraitImpls { ref blanket_impls, ref non_blanket_impls } = *self; |
| |
| ich::hash_stable_trait_impls(hcx, hasher, blanket_impls, non_blanket_impls); |
| } |
| } |