2 use crate::hir::def_id::DefId;
3 use crate::hir::map::DefPathHash;
4 use crate::ich::{self, StableHashingContext};
5 use crate::traits::specialization_graph;
6 use crate::ty::fast_reject;
7 use crate::ty::fold::TypeFoldable;
8 use crate::ty::{Ty, TyCtxt};
10 use rustc_data_structures::fx::FxHashMap;
11 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
12 use rustc_macros::HashStable;
14 /// A trait's definition with type information.
17 // We already have the def_path_hash below, no need to hash it twice
18 #[stable_hasher(ignore)]
21 pub unsafety: hir::Unsafety,
23 /// If `true`, then this trait had the `#[rustc_paren_sugar]`
24 /// attribute, indicating that it should be used with `Foo()`
25 /// sugar. This is a temporary thing -- eventually any trait will
26 /// be usable with the sugar (or without it).
27 pub paren_sugar: bool,
29 pub has_auto_impl: bool,
31 /// If `true`, then this trait has the `#[marker]` attribute, indicating
32 /// that all its associated items have defaults that cannot be overridden,
33 /// and thus `impl`s of it are allowed to overlap.
36 /// The ICH of this trait's DefPath, cached here so it doesn't have to be
37 /// recomputed all the time.
38 pub def_path_hash: DefPathHash,
42 pub struct TraitImpls {
43 blanket_impls: Vec<DefId>,
44 /// Impls indexed by their simplified self type, for fast lookup.
45 non_blanket_impls: FxHashMap<fast_reject::SimplifiedType, Vec<DefId>>,
49 pub fn new(def_id: DefId,
50 unsafety: hir::Unsafety,
54 def_path_hash: DefPathHash)
70 ) -> specialization_graph::Ancestors<'tcx> {
71 specialization_graph::ancestors(tcx, self.def_id, of_impl)
75 impl<'tcx> TyCtxt<'tcx> {
76 pub fn for_each_impl<F: FnMut(DefId)>(self, def_id: DefId, mut f: F) {
77 let impls = self.trait_impls_of(def_id);
79 for &impl_def_id in impls.blanket_impls.iter() {
83 for v in impls.non_blanket_impls.values() {
84 for &impl_def_id in v {
90 /// Iterate over every impl that could possibly match the
91 /// self type `self_ty`.
92 pub fn for_each_relevant_impl<F: FnMut(DefId)>(self,
97 let impls = self.trait_impls_of(def_id);
99 for &impl_def_id in impls.blanket_impls.iter() {
103 // simplify_type(.., false) basically replaces type parameters and
104 // projections with infer-variables. This is, of course, done on
105 // the impl trait-ref when it is instantiated, but not on the
106 // predicate trait-ref which is passed here.
108 // for example, if we match `S: Copy` against an impl like
109 // `impl<T:Copy> Copy for Option<T>`, we replace the type variable
110 // in `Option<T>` with an infer variable, to `Option<_>` (this
111 // doesn't actually change fast_reject output), but we don't
112 // replace `S` with anything - this impl of course can't be
113 // selected, and as there are hundreds of similar impls,
114 // considering them would significantly harm performance.
116 // This depends on the set of all impls for the trait. That is
117 // unfortunate. When we get red-green recompilation, we would like
118 // to have a way of knowing whether the set of relevant impls
119 // changed. The most naive
120 // way would be to compute the Vec of relevant impls and see whether
121 // it differs between compilations. That shouldn't be too slow by
122 // itself - we do quite a bit of work for each relevant impl anyway.
124 // If we want to be faster, we could have separate queries for
125 // blanket and non-blanket impls, and compare them separately.
127 // I think we'll cross that bridge when we get to it.
128 if let Some(simp) = fast_reject::simplify_type(self, self_ty, true) {
129 if let Some(impls) = impls.non_blanket_impls.get(&simp) {
130 for &impl_def_id in impls {
135 for &impl_def_id in impls.non_blanket_impls.values().flatten() {
141 /// Returns a vector containing all impls
142 pub fn all_impls(self, def_id: DefId) -> Vec<DefId> {
143 let impls = self.trait_impls_of(def_id);
145 impls.blanket_impls.iter().chain(
146 impls.non_blanket_impls.values().flatten()
151 // Query provider for `trait_impls_of`.
152 pub(super) fn trait_impls_of_provider(
156 let mut impls = TraitImpls::default();
159 let mut add_impl = |impl_def_id| {
160 let impl_self_ty = tcx.type_of(impl_def_id);
161 if impl_def_id.is_local() && impl_self_ty.references_error() {
165 if let Some(simplified_self_ty) =
166 fast_reject::simplify_type(tcx, impl_self_ty, false)
168 impls.non_blanket_impls
169 .entry(simplified_self_ty)
173 impls.blanket_impls.push(impl_def_id);
177 // Traits defined in the current crate can't have impls in upstream
178 // crates, so we don't bother querying the cstore.
179 if !trait_id.is_local() {
180 for &cnum in tcx.crates().iter() {
181 for &def_id in tcx.implementations_of_trait((cnum, trait_id)).iter() {
187 for &hir_id in tcx.hir().trait_impls(trait_id) {
188 add_impl(tcx.hir().local_def_id(hir_id));
192 tcx.arena.alloc(impls)
195 impl<'a> HashStable<StableHashingContext<'a>> for TraitImpls {
196 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
199 ref non_blanket_impls,
202 ich::hash_stable_trait_impls(hcx, hasher, blanket_impls, non_blanket_impls);