mikros/rust
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Remove duplicated code in trait selection

Browse Source
This commit is contained in:
Esteban Küber 2020-03-31 16:50:15 -07:00
parent a5b09d3547
commit 8bedb7eac1
3 changed files with 81 additions and 298 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
src/librustc_infer/traits/mod.rs
View File

@ -6,7 +6,7 @@
pub mod error_reporting;
mod project;
mod structural_impls;
mod util;
pub mod util;
use rustc_hir as hir;
use rustc_middle::ty::error::{ExpectedFound, TypeError};

80
src/librustc_infer/traits/util.rs
View File

@ -2,9 +2,12 @@
use rustc_data_structures::fx::FxHashSet;
use rustc_middle::ty::outlives::Component;
use rustc_middle::ty::{self, ToPolyTraitRef, TyCtxt};
use rustc_middle::ty::{self, ToPolyTraitRef, ToPredicate, TyCtxt, WithConstness};
fn anonymize_predicate<'tcx>(tcx: TyCtxt<'tcx>, pred: &ty::Predicate<'tcx>) -> ty::Predicate<'tcx> {
pub fn anonymize_predicate<'tcx>(
tcx: TyCtxt<'tcx>,
pred: &ty::Predicate<'tcx>,
) -> ty::Predicate<'tcx> {
match *pred {
ty::Predicate::Trait(ref data, constness) => {
ty::Predicate::Trait(tcx.anonymize_late_bound_regions(data), constness)
@ -88,6 +91,21 @@ pub struct Elaborator<'tcx> {
visited: PredicateSet<'tcx>,
}
pub fn elaborate_trait_ref<'tcx>(
tcx: TyCtxt<'tcx>,
trait_ref: ty::PolyTraitRef<'tcx>,
) -> Elaborator<'tcx> {
elaborate_predicates(tcx, vec![trait_ref.without_const().to_predicate()])
}
pub fn elaborate_trait_refs<'tcx>(
tcx: TyCtxt<'tcx>,
trait_refs: impl Iterator<Item = ty::PolyTraitRef<'tcx>>,
) -> Elaborator<'tcx> {
let predicates = trait_refs.map(|trait_ref| trait_ref.without_const().to_predicate()).collect();
elaborate_predicates(tcx, predicates)
}
pub fn elaborate_predicates<'tcx>(
tcx: TyCtxt<'tcx>,
mut predicates: Vec<ty::Predicate<'tcx>>,
@ -98,6 +116,10 @@ pub fn elaborate_predicates<'tcx>(
}
impl Elaborator<'tcx> {
pub fn filter_to_traits(self) -> FilterToTraits<Self> {
FilterToTraits::new(self)
}
fn elaborate(&mut self, predicate: &ty::Predicate<'tcx>) {
let tcx = self.visited.tcx;
match *predicate {
@ -223,3 +245,57 @@ fn next(&mut self) -> Option<ty::Predicate<'tcx>> {
}
}
}
///////////////////////////////////////////////////////////////////////////
// Supertrait iterator
///////////////////////////////////////////////////////////////////////////
pub type Supertraits<'tcx> = FilterToTraits<Elaborator<'tcx>>;
pub fn supertraits<'tcx>(
tcx: TyCtxt<'tcx>,
trait_ref: ty::PolyTraitRef<'tcx>,
) -> Supertraits<'tcx> {
elaborate_trait_ref(tcx, trait_ref).filter_to_traits()
}
pub fn transitive_bounds<'tcx>(
tcx: TyCtxt<'tcx>,
bounds: impl Iterator<Item = ty::PolyTraitRef<'tcx>>,
) -> Supertraits<'tcx> {
elaborate_trait_refs(tcx, bounds).filter_to_traits()
}
///////////////////////////////////////////////////////////////////////////
// Other
///////////////////////////////////////////////////////////////////////////
/// A filter around an iterator of predicates that makes it yield up
/// just trait references.
pub struct FilterToTraits<I> {
base_iterator: I,
}
impl<I> FilterToTraits<I> {
fn new(base: I) -> FilterToTraits<I> {
FilterToTraits { base_iterator: base }
}
}
impl<'tcx, I: Iterator<Item = ty::Predicate<'tcx>>> Iterator for FilterToTraits<I> {
type Item = ty::PolyTraitRef<'tcx>;
fn next(&mut self) -> Option<ty::PolyTraitRef<'tcx>> {
while let Some(pred) = self.base_iterator.next() {
if let ty::Predicate::Trait(data, _) = pred {
return Some(data.to_poly_trait_ref());
}
}
None
}
fn size_hint(&self) -> (usize, Option<usize>) {
let (_, upper) = self.base_iterator.size_hint();
(0, upper)
}
}

297
src/librustc_trait_selection/traits/util.rs
View File

@ -6,270 +6,11 @@
use rustc_data_structures::fx::FxHashSet;
use rustc_hir as hir;
use rustc_hir::def_id::DefId;
use rustc_middle::ty::outlives::Component;
use rustc_middle::ty::subst::{GenericArg, Subst, SubstsRef};
use rustc_middle::ty::{self, ToPolyTraitRef, ToPredicate, Ty, TyCtxt, WithConstness};
use rustc_middle::ty::{self, ToPredicate, Ty, TyCtxt, WithConstness};
use super::{Normalized, Obligation, ObligationCause, PredicateObligation, SelectionContext};
fn anonymize_predicate<'tcx>(tcx: TyCtxt<'tcx>, pred: &ty::Predicate<'tcx>) -> ty::Predicate<'tcx> {
match *pred {
ty::Predicate::Trait(ref data, constness) => {
ty::Predicate::Trait(tcx.anonymize_late_bound_regions(data), constness)
}
ty::Predicate::RegionOutlives(ref data) => {
ty::Predicate::RegionOutlives(tcx.anonymize_late_bound_regions(data))
}
ty::Predicate::TypeOutlives(ref data) => {
ty::Predicate::TypeOutlives(tcx.anonymize_late_bound_regions(data))
}
ty::Predicate::Projection(ref data) => {
ty::Predicate::Projection(tcx.anonymize_late_bound_regions(data))
}
ty::Predicate::WellFormed(data) => ty::Predicate::WellFormed(data),
ty::Predicate::ObjectSafe(data) => ty::Predicate::ObjectSafe(data),
ty::Predicate::ClosureKind(closure_def_id, closure_substs, kind) => {
ty::Predicate::ClosureKind(closure_def_id, closure_substs, kind)
}
ty::Predicate::Subtype(ref data) => {
ty::Predicate::Subtype(tcx.anonymize_late_bound_regions(data))
}
ty::Predicate::ConstEvaluatable(def_id, substs) => {
ty::Predicate::ConstEvaluatable(def_id, substs)
}
}
}
struct PredicateSet<'tcx> {
tcx: TyCtxt<'tcx>,
set: FxHashSet<ty::Predicate<'tcx>>,
}
impl PredicateSet<'tcx> {
fn new(tcx: TyCtxt<'tcx>) -> Self {
Self { tcx, set: Default::default() }
}
fn insert(&mut self, pred: &ty::Predicate<'tcx>) -> bool {
// We have to be careful here because we want
//
// for<'a> Foo<&'a int>
//
// and
//
// for<'b> Foo<&'b int>
//
// to be considered equivalent. So normalize all late-bound
// regions before we throw things into the underlying set.
self.set.insert(anonymize_predicate(self.tcx, pred))
}
}
impl<T: AsRef<ty::Predicate<'tcx>>> Extend<T> for PredicateSet<'tcx> {
fn extend<I: IntoIterator<Item = T>>(&mut self, iter: I) {
for pred in iter {
self.insert(pred.as_ref());
}
}
}
///////////////////////////////////////////////////////////////////////////
// `Elaboration` iterator
///////////////////////////////////////////////////////////////////////////
/// "Elaboration" is the process of identifying all the predicates that
/// are implied by a source predicate. Currently, this basically means
/// walking the "supertraits" and other similar assumptions. For example,
/// if we know that `T: Ord`, the elaborator would deduce that `T: PartialOrd`
/// holds as well. Similarly, if we have `trait Foo: 'static`, and we know that
/// `T: Foo`, then we know that `T: 'static`.
pub struct Elaborator<'tcx> {
stack: Vec<ty::Predicate<'tcx>>,
visited: PredicateSet<'tcx>,
}
pub fn elaborate_trait_ref<'tcx>(
tcx: TyCtxt<'tcx>,
trait_ref: ty::PolyTraitRef<'tcx>,
) -> Elaborator<'tcx> {
elaborate_predicates(tcx, vec![trait_ref.without_const().to_predicate()])
}
pub fn elaborate_trait_refs<'tcx>(
tcx: TyCtxt<'tcx>,
trait_refs: impl Iterator<Item = ty::PolyTraitRef<'tcx>>,
) -> Elaborator<'tcx> {
let predicates = trait_refs.map(|trait_ref| trait_ref.without_const().to_predicate()).collect();
elaborate_predicates(tcx, predicates)
}
pub fn elaborate_predicates<'tcx>(
tcx: TyCtxt<'tcx>,
mut predicates: Vec<ty::Predicate<'tcx>>,
) -> Elaborator<'tcx> {
let mut visited = PredicateSet::new(tcx);
predicates.retain(|pred| visited.insert(pred));
Elaborator { stack: predicates, visited }
}
impl Elaborator<'tcx> {
pub fn filter_to_traits(self) -> FilterToTraits<Self> {
FilterToTraits::new(self)
}
fn elaborate(&mut self, predicate: &ty::Predicate<'tcx>) {
let tcx = self.visited.tcx;
match *predicate {
ty::Predicate::Trait(ref data, _) => {
// Get predicates declared on the trait.
let predicates = tcx.super_predicates_of(data.def_id());
let predicates = predicates
.predicates
.iter()
.map(|(pred, _)| pred.subst_supertrait(tcx, &data.to_poly_trait_ref()));
debug!("super_predicates: data={:?} predicates={:?}", data, predicates.clone());
// Only keep those bounds that we haven't already seen.
// This is necessary to prevent infinite recursion in some
// cases. One common case is when people define
// `trait Sized: Sized { }` rather than `trait Sized { }`.
let visited = &mut self.visited;
let predicates = predicates.filter(|pred| visited.insert(pred));
self.stack.extend(predicates);
}
ty::Predicate::WellFormed(..) => {
// Currently, we do not elaborate WF predicates,
// although we easily could.
}
ty::Predicate::ObjectSafe(..) => {
// Currently, we do not elaborate object-safe
// predicates.
}
ty::Predicate::Subtype(..) => {
// Currently, we do not "elaborate" predicates like `X <: Y`,
// though conceivably we might.
}
ty::Predicate::Projection(..) => {
// Nothing to elaborate in a projection predicate.
}
ty::Predicate::ClosureKind(..) => {
// Nothing to elaborate when waiting for a closure's kind to be inferred.
}
ty::Predicate::ConstEvaluatable(..) => {
// Currently, we do not elaborate const-evaluatable
// predicates.
}
ty::Predicate::RegionOutlives(..) => {
// Nothing to elaborate from `'a: 'b`.
}
ty::Predicate::TypeOutlives(ref data) => {
// We know that `T: 'a` for some type `T`. We can
// often elaborate this. For example, if we know that
// `[U]: 'a`, that implies that `U: 'a`. Similarly, if
// we know `&'a U: 'b`, then we know that `'a: 'b` and
// `U: 'b`.
//
// We can basically ignore bound regions here. So for
// example `for<'c> Foo<'a,'c>: 'b` can be elaborated to
// `'a: 'b`.
// Ignore `for<'a> T: 'a` -- we might in the future
// consider this as evidence that `T: 'static`, but
// I'm a bit wary of such constructions and so for now
// I want to be conservative. --nmatsakis
let ty_max = data.skip_binder().0;
let r_min = data.skip_binder().1;
if r_min.is_late_bound() {
return;
}
let visited = &mut self.visited;
let mut components = smallvec![];
tcx.push_outlives_components(ty_max, &mut components);
self.stack.extend(
components
.into_iter()
.filter_map(|component| match component {
Component::Region(r) => {
if r.is_late_bound() {
None
} else {
Some(ty::Predicate::RegionOutlives(ty::Binder::dummy(
ty::OutlivesPredicate(r, r_min),
)))
}
}
Component::Param(p) => {
let ty = tcx.mk_ty_param(p.index, p.name);
Some(ty::Predicate::TypeOutlives(ty::Binder::dummy(
ty::OutlivesPredicate(ty, r_min),
)))
}
Component::UnresolvedInferenceVariable(_) => None,
Component::Projection(_) | Component::EscapingProjection(_) => {
// We can probably do more here. This
// corresponds to a case like `<T as
// Foo<'a>>::U: 'b`.
None
}
})
.filter(|p| visited.insert(p)),
);
}
}
}
}
impl Iterator for Elaborator<'tcx> {
type Item = ty::Predicate<'tcx>;
fn size_hint(&self) -> (usize, Option<usize>) {
(self.stack.len(), None)
}
fn next(&mut self) -> Option<ty::Predicate<'tcx>> {
// Extract next item from top-most stack frame, if any.
if let Some(pred) = self.stack.pop() {
self.elaborate(&pred);
Some(pred)
} else {
None
}
}
}
///////////////////////////////////////////////////////////////////////////
// Supertrait iterator
///////////////////////////////////////////////////////////////////////////
pub type Supertraits<'tcx> = FilterToTraits<Elaborator<'tcx>>;
pub fn supertraits<'tcx>(
tcx: TyCtxt<'tcx>,
trait_ref: ty::PolyTraitRef<'tcx>,
) -> Supertraits<'tcx> {
elaborate_trait_ref(tcx, trait_ref).filter_to_traits()
}
pub fn transitive_bounds<'tcx>(
tcx: TyCtxt<'tcx>,
bounds: impl Iterator<Item = ty::PolyTraitRef<'tcx>>,
) -> Supertraits<'tcx> {
elaborate_trait_refs(tcx, bounds).filter_to_traits()
}
pub use rustc_infer::traits::util::*;
///////////////////////////////////////////////////////////////////////////
// `TraitAliasExpander` iterator
@ -451,40 +192,6 @@ fn next(&mut self) -> Option<DefId> {
// Other
///////////////////////////////////////////////////////////////////////////
/// A filter around an iterator of predicates that makes it yield up
/// just trait references.
pub struct FilterToTraits<I> {
base_iterator: I,
}
impl<I> FilterToTraits<I> {
fn new(base: I) -> FilterToTraits<I> {
FilterToTraits { base_iterator: base }
}
}
impl<'tcx, I: Iterator<Item = ty::Predicate<'tcx>>> Iterator for FilterToTraits<I> {
type Item = ty::PolyTraitRef<'tcx>;
fn next(&mut self) -> Option<ty::PolyTraitRef<'tcx>> {
while let Some(pred) = self.base_iterator.next() {
if let ty::Predicate::Trait(data, _) = pred {
return Some(data.to_poly_trait_ref());
}
}
None
}
fn size_hint(&self) -> (usize, Option<usize>) {
let (_, upper) = self.base_iterator.size_hint();
(0, upper)
}
}
///////////////////////////////////////////////////////////////////////////
// Other
///////////////////////////////////////////////////////////////////////////
/// Instantiate all bound parameters of the impl with the given substs,
/// returning the resulting trait ref and all obligations that arise.
/// The obligations are closed under normalization.