1 // Copyright 2012-2015 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 use dep_graph::DepNode;
12 use hir::def_id::{DefId, LOCAL_CRATE};
13 use traits::{self, specialization_graph};
16 use ty::{Ty, TyCtxt, TraitRef};
17 use std::cell::{Cell, RefCell};
19 use util::nodemap::FxHashMap;
22 use syntax_pos::DUMMY_SP;
24 /// A trait's definition with type information.
28 pub unsafety: hir::Unsafety,
30 /// If `true`, then this trait had the `#[rustc_paren_sugar]`
31 /// attribute, indicating that it should be used with `Foo()`
32 /// sugar. This is a temporary thing -- eventually any trait will
33 /// be usable with the sugar (or without it).
34 pub paren_sugar: bool,
36 // Impls of a trait. To allow for quicker lookup, the impls are indexed by a
37 // simplified version of their `Self` type: impls with a simplifiable `Self`
38 // are stored in `nonblanket_impls` keyed by it, while all other impls are
39 // stored in `blanket_impls`.
41 // A similar division is used within `specialization_graph`, but the ones
42 // here are (1) stored as a flat list for the trait and (2) populated prior
43 // to -- and used while -- determining specialization order.
45 // FIXME: solve the reentrancy issues and remove these lists in favor of the
46 // ones in `specialization_graph`.
48 // These lists are tracked by `DepNode::TraitImpls`; we don't use
49 // a DepTrackingMap but instead have the `TraitDef` insert the
50 // required reads/writes.
52 /// Impls of the trait.
53 nonblanket_impls: RefCell<
54 FxHashMap<fast_reject::SimplifiedType, Vec<DefId>>
57 /// Blanket impls associated with the trait.
58 blanket_impls: RefCell<Vec<DefId>>,
60 /// The specialization order for impls of this trait.
61 pub specialization_graph: RefCell<traits::specialization_graph::Graph>,
64 pub flags: Cell<TraitFlags>,
66 /// The number of impls we've added from the local crate.
67 /// When this number matches up the list in the HIR map,
68 /// we're done, and the specialization graph is correct.
69 local_impl_count: Cell<usize>,
71 /// The ICH of this trait's DefPath, cached here so it doesn't have to be
72 /// recomputed all the time.
73 pub def_path_hash: u64,
76 impl<'a, 'gcx, 'tcx> TraitDef {
77 pub fn new(def_id: DefId,
78 unsafety: hir::Unsafety,
84 paren_sugar: paren_sugar,
86 nonblanket_impls: RefCell::new(FxHashMap()),
87 blanket_impls: RefCell::new(vec![]),
88 flags: Cell::new(ty::TraitFlags::NO_TRAIT_FLAGS),
89 local_impl_count: Cell::new(0),
90 specialization_graph: RefCell::new(traits::specialization_graph::Graph::new()),
91 def_path_hash: def_path_hash,
95 // returns None if not yet calculated
96 pub fn object_safety(&self) -> Option<bool> {
97 if self.flags.get().intersects(TraitFlags::OBJECT_SAFETY_VALID) {
98 Some(self.flags.get().intersects(TraitFlags::IS_OBJECT_SAFE))
104 pub fn set_object_safety(&self, is_safe: bool) {
105 assert!(self.object_safety().map(|cs| cs == is_safe).unwrap_or(true));
107 self.flags.get() | if is_safe {
108 TraitFlags::OBJECT_SAFETY_VALID | TraitFlags::IS_OBJECT_SAFE
110 TraitFlags::OBJECT_SAFETY_VALID
115 fn write_trait_impls(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) {
116 tcx.dep_graph.write(DepNode::TraitImpls(self.def_id));
119 fn read_trait_impls(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) {
120 tcx.dep_graph.read(DepNode::TraitImpls(self.def_id));
123 /// Records a basic trait-to-implementation mapping.
125 /// Returns `true` iff the impl has not previously been recorded.
126 fn record_impl(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>,
128 impl_trait_ref: TraitRef<'tcx>)
130 debug!("TraitDef::record_impl for {:?}, from {:?}",
131 self, impl_trait_ref);
133 // Record the write into the impl set, but only for local
134 // impls: external impls are handled differently.
135 if impl_def_id.is_local() {
136 self.write_trait_impls(tcx);
139 // We don't want to borrow_mut after we already populated all impls,
140 // so check if an impl is present with an immutable borrow first.
141 if let Some(sty) = fast_reject::simplify_type(tcx,
142 impl_trait_ref.self_ty(), false) {
143 if let Some(is) = self.nonblanket_impls.borrow().get(&sty) {
144 if is.contains(&impl_def_id) {
145 return false; // duplicate - skip
149 self.nonblanket_impls.borrow_mut().entry(sty).or_insert(vec![]).push(impl_def_id)
151 if self.blanket_impls.borrow().contains(&impl_def_id) {
152 return false; // duplicate - skip
154 self.blanket_impls.borrow_mut().push(impl_def_id)
160 /// Records a trait-to-implementation mapping for a crate-local impl.
161 pub fn record_local_impl(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>,
163 impl_trait_ref: TraitRef<'tcx>) {
164 assert!(impl_def_id.is_local());
165 let was_new = self.record_impl(tcx, impl_def_id, impl_trait_ref);
168 self.local_impl_count.set(self.local_impl_count.get() + 1);
171 /// Records a trait-to-implementation mapping.
172 pub fn record_has_default_impl(&self) {
173 self.flags.set(self.flags.get() | TraitFlags::HAS_DEFAULT_IMPL);
176 /// Records a trait-to-implementation mapping for a non-local impl.
178 /// The `parent_impl` is the immediately-less-specialized impl, or the
179 /// trait's def ID if the impl is not a specialization -- information that
180 /// should be pulled from the metadata.
181 pub fn record_remote_impl(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>,
183 impl_trait_ref: TraitRef<'tcx>,
184 parent_impl: DefId) {
185 assert!(!impl_def_id.is_local());
187 // if the impl has not previously been recorded
188 if self.record_impl(tcx, impl_def_id, impl_trait_ref) {
189 // if the impl is non-local, it's placed directly into the
190 // specialization graph using parent information drawn from metadata.
191 self.specialization_graph.borrow_mut()
192 .record_impl_from_cstore(tcx, parent_impl, impl_def_id)
196 /// Adds a local impl into the specialization graph, returning an error with
197 /// overlap information if the impl overlaps but does not specialize an
199 pub fn add_impl_for_specialization(&self,
200 tcx: TyCtxt<'a, 'gcx, 'tcx>,
202 -> Result<(), traits::OverlapError> {
203 assert!(impl_def_id.is_local());
205 self.specialization_graph.borrow_mut()
206 .insert(tcx, impl_def_id)
209 pub fn ancestors(&'a self, of_impl: DefId) -> specialization_graph::Ancestors<'a> {
210 specialization_graph::ancestors(self, of_impl)
213 /// Whether the impl set and specialization graphs are complete.
214 pub fn is_complete(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> bool {
215 tcx.populate_implementations_for_trait_if_necessary(self.def_id);
216 ty::queries::coherent_trait::try_get(tcx, DUMMY_SP, (LOCAL_CRATE, self.def_id)).is_ok()
219 /// If any local impls haven't been added yet, returns
220 /// Some(list of local impls for this trait).
221 fn missing_local_impls(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>)
222 -> Option<&'gcx [ast::NodeId]> {
223 if self.flags.get().intersects(TraitFlags::HAS_LOCAL_IMPLS) {
227 if self.is_complete(tcx) {
228 self.flags.set(self.flags.get() | TraitFlags::HAS_LOCAL_IMPLS);
232 let impls = tcx.hir.trait_impls(self.def_id);
233 assert!(self.local_impl_count.get() <= impls.len());
234 if self.local_impl_count.get() == impls.len() {
235 self.flags.set(self.flags.get() | TraitFlags::HAS_LOCAL_IMPLS);
242 pub fn for_each_impl<F: FnMut(DefId)>(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, mut f: F) {
243 self.read_trait_impls(tcx);
244 tcx.populate_implementations_for_trait_if_necessary(self.def_id);
246 let local_impls = self.missing_local_impls(tcx);
247 if let Some(impls) = local_impls {
249 f(tcx.hir.local_def_id(id));
252 let mut f = |def_id: DefId| {
253 if !(local_impls.is_some() && def_id.is_local()) {
258 for &impl_def_id in self.blanket_impls.borrow().iter() {
262 for v in self.nonblanket_impls.borrow().values() {
263 for &impl_def_id in v {
269 /// Iterate over every impl that could possibly match the
270 /// self-type `self_ty`.
271 pub fn for_each_relevant_impl<F: FnMut(DefId)>(&self,
272 tcx: TyCtxt<'a, 'gcx, 'tcx>,
276 self.read_trait_impls(tcx);
277 tcx.populate_implementations_for_trait_if_necessary(self.def_id);
279 let local_impls = self.missing_local_impls(tcx);
280 if let Some(impls) = local_impls {
282 f(tcx.hir.local_def_id(id));
285 let mut f = |def_id: DefId| {
286 if !(local_impls.is_some() && def_id.is_local()) {
291 for &impl_def_id in self.blanket_impls.borrow().iter() {
295 // simplify_type(.., false) basically replaces type parameters and
296 // projections with infer-variables. This is, of course, done on
297 // the impl trait-ref when it is instantiated, but not on the
298 // predicate trait-ref which is passed here.
300 // for example, if we match `S: Copy` against an impl like
301 // `impl<T:Copy> Copy for Option<T>`, we replace the type variable
302 // in `Option<T>` with an infer variable, to `Option<_>` (this
303 // doesn't actually change fast_reject output), but we don't
304 // replace `S` with anything - this impl of course can't be
305 // selected, and as there are hundreds of similar impls,
306 // considering them would significantly harm performance.
307 if let Some(simp) = fast_reject::simplify_type(tcx, self_ty, true) {
308 if let Some(impls) = self.nonblanket_impls.borrow().get(&simp) {
309 for &impl_def_id in impls {
314 for v in self.nonblanket_impls.borrow().values() {
315 for &impl_def_id in v {
324 flags TraitFlags: u32 {
325 const NO_TRAIT_FLAGS = 0,
326 const HAS_DEFAULT_IMPL = 1 << 0,
327 const IS_OBJECT_SAFE = 1 << 1,
328 const OBJECT_SAFETY_VALID = 1 << 2,
329 const HAS_REMOTE_IMPLS = 1 << 3,
330 const HAS_LOCAL_IMPLS = 1 << 4,