diff options
Diffstat (limited to 'compiler/rustc_infer/src/infer/outlives/verify.rs')
| -rw-r--r-- | compiler/rustc_infer/src/infer/outlives/verify.rs | 111 |
1 files changed, 38 insertions, 73 deletions
diff --git a/compiler/rustc_infer/src/infer/outlives/verify.rs b/compiler/rustc_infer/src/infer/outlives/verify.rs index 752334950..f470b2eb8 100644 --- a/compiler/rustc_infer/src/infer/outlives/verify.rs +++ b/compiler/rustc_infer/src/infer/outlives/verify.rs @@ -2,11 +2,10 @@ use crate::infer::outlives::components::{compute_components_recursive, Component use crate::infer::outlives::env::RegionBoundPairs; use crate::infer::region_constraints::VerifyIfEq; use crate::infer::{GenericKind, VerifyBound}; -use rustc_data_structures::captures::Captures; use rustc_data_structures::sso::SsoHashSet; use rustc_hir::def_id::DefId; -use rustc_middle::ty::subst::{GenericArg, Subst}; -use rustc_middle::ty::{self, EarlyBinder, OutlivesPredicate, Ty, TyCtxt}; +use rustc_middle::ty::GenericArg; +use rustc_middle::ty::{self, EarlyBinder, OutlivesPredicate, SubstsRef, Ty, TyCtxt}; use smallvec::smallvec; @@ -38,20 +37,8 @@ impl<'cx, 'tcx> VerifyBoundCx<'cx, 'tcx> { Self { tcx, region_bound_pairs, implicit_region_bound, param_env } } - /// Returns a "verify bound" that encodes what we know about - /// `generic` and the regions it outlives. - pub fn generic_bound(&self, generic: GenericKind<'tcx>) -> VerifyBound<'tcx> { - let mut visited = SsoHashSet::new(); - match generic { - GenericKind::Param(param_ty) => self.param_bound(param_ty), - GenericKind::Projection(projection_ty) => { - self.projection_bound(projection_ty, &mut visited) - } - } - } - #[instrument(level = "debug", skip(self))] - fn param_bound(&self, param_ty: ty::ParamTy) -> VerifyBound<'tcx> { + pub fn param_bound(&self, param_ty: ty::ParamTy) -> VerifyBound<'tcx> { // Start with anything like `T: 'a` we can scrape from the // environment. If the environment contains something like // `for<'a> T: 'a`, then we know that `T` outlives everything. @@ -105,41 +92,31 @@ impl<'cx, 'tcx> VerifyBoundCx<'cx, 'tcx> { /// the clause from the environment only applies if `'0 = 'a`, /// which we don't know yet. But we would still include `'b` in /// this list. - pub fn projection_approx_declared_bounds_from_env( + pub fn approx_declared_bounds_from_env( &self, - projection_ty: ty::ProjectionTy<'tcx>, + generic: GenericKind<'tcx>, ) -> Vec<ty::Binder<'tcx, ty::OutlivesPredicate<Ty<'tcx>, ty::Region<'tcx>>>> { - let projection_ty = GenericKind::Projection(projection_ty).to_ty(self.tcx); + let projection_ty = generic.to_ty(self.tcx); let erased_projection_ty = self.tcx.erase_regions(projection_ty); self.declared_generic_bounds_from_env_for_erased_ty(erased_projection_ty) } - /// Searches the where-clauses in scope for regions that - /// `projection_ty` is known to outlive. Currently requires an - /// exact match. - pub fn projection_declared_bounds_from_trait( + #[instrument(level = "debug", skip(self, visited))] + pub fn projection_opaque_bounds( &self, - projection_ty: ty::ProjectionTy<'tcx>, - ) -> impl Iterator<Item = ty::Region<'tcx>> + 'cx + Captures<'tcx> { - self.declared_projection_bounds_from_trait(projection_ty) - } - - pub fn projection_bound( - &self, - projection_ty: ty::ProjectionTy<'tcx>, + generic: GenericKind<'tcx>, + def_id: DefId, + substs: SubstsRef<'tcx>, visited: &mut SsoHashSet<GenericArg<'tcx>>, ) -> VerifyBound<'tcx> { - debug!("projection_bound(projection_ty={:?})", projection_ty); - - let projection_ty_as_ty = - self.tcx.mk_projection(projection_ty.item_def_id, projection_ty.substs); + let generic_ty = generic.to_ty(self.tcx); // Search the env for where clauses like `P: 'a`. - let env_bounds = self - .projection_approx_declared_bounds_from_env(projection_ty) + let projection_opaque_bounds = self + .approx_declared_bounds_from_env(generic) .into_iter() .map(|binder| { - if let Some(ty::OutlivesPredicate(ty, r)) = binder.no_bound_vars() && ty == projection_ty_as_ty { + if let Some(ty::OutlivesPredicate(ty, r)) = binder.no_bound_vars() && ty == generic_ty { // Micro-optimize if this is an exact match (this // occurs often when there are no region variables // involved). @@ -149,21 +126,19 @@ impl<'cx, 'tcx> VerifyBoundCx<'cx, 'tcx> { VerifyBound::IfEq(verify_if_eq_b) } }); - // Extend with bounds that we can find from the trait. - let trait_bounds = self - .projection_declared_bounds_from_trait(projection_ty) - .map(|r| VerifyBound::OutlivedBy(r)); + let trait_bounds = + self.declared_region_bounds(def_id, substs).map(|r| VerifyBound::OutlivedBy(r)); // see the extensive comment in projection_must_outlive let recursive_bound = { let mut components = smallvec![]; - let ty = self.tcx.mk_projection(projection_ty.item_def_id, projection_ty.substs); - compute_components_recursive(self.tcx, ty.into(), &mut components, visited); + compute_components_recursive(self.tcx, generic_ty.into(), &mut components, visited); self.bound_from_components(&components, visited) }; - VerifyBound::AnyBound(env_bounds.chain(trait_bounds).collect()).or(recursive_bound) + VerifyBound::AnyBound(projection_opaque_bounds.chain(trait_bounds).collect()) + .or(recursive_bound) } fn bound_from_components( @@ -195,7 +170,18 @@ impl<'cx, 'tcx> VerifyBoundCx<'cx, 'tcx> { match *component { Component::Region(lt) => VerifyBound::OutlivedBy(lt), Component::Param(param_ty) => self.param_bound(param_ty), - Component::Projection(projection_ty) => self.projection_bound(projection_ty, visited), + Component::Opaque(did, substs) => self.projection_opaque_bounds( + GenericKind::Opaque(did, substs), + did, + substs, + visited, + ), + Component::Projection(projection_ty) => self.projection_opaque_bounds( + GenericKind::Projection(projection_ty), + projection_ty.item_def_id, + projection_ty.substs, + visited, + ), Component::EscapingProjection(ref components) => { self.bound_from_components(components, visited) } @@ -293,30 +279,6 @@ impl<'cx, 'tcx> VerifyBoundCx<'cx, 'tcx> { /// } /// ``` /// - /// then this function would return `'x`. This is subject to the - /// limitations around higher-ranked bounds described in - /// `region_bounds_declared_on_associated_item`. - fn declared_projection_bounds_from_trait( - &self, - projection_ty: ty::ProjectionTy<'tcx>, - ) -> impl Iterator<Item = ty::Region<'tcx>> + 'cx + Captures<'tcx> { - debug!("projection_bounds(projection_ty={:?})", projection_ty); - let tcx = self.tcx; - self.region_bounds_declared_on_associated_item(projection_ty.item_def_id) - .map(move |r| EarlyBinder(r).subst(tcx, projection_ty.substs)) - } - - /// Given the `DefId` of an associated item, returns any region - /// bounds attached to that associated item from the trait definition. - /// - /// For example: - /// - /// ```rust - /// trait Foo<'a> { - /// type Bar: 'a; - /// } - /// ``` - /// /// If we were given the `DefId` of `Foo::Bar`, we would return /// `'a`. You could then apply the substitutions from the /// projection to convert this into your namespace. This also @@ -336,17 +298,20 @@ impl<'cx, 'tcx> VerifyBoundCx<'cx, 'tcx> { /// /// This is for simplicity, and because we are not really smart /// enough to cope with such bounds anywhere. - fn region_bounds_declared_on_associated_item( + pub fn declared_region_bounds( &self, - assoc_item_def_id: DefId, + def_id: DefId, + substs: SubstsRef<'tcx>, ) -> impl Iterator<Item = ty::Region<'tcx>> { let tcx = self.tcx; - let bounds = tcx.item_bounds(assoc_item_def_id); + let bounds = tcx.item_bounds(def_id); + trace!("{:#?}", bounds); bounds .into_iter() .filter_map(|p| p.to_opt_type_outlives()) .filter_map(|p| p.no_bound_vars()) .map(|b| b.1) + .map(move |r| EarlyBinder(r).subst(tcx, substs)) } /// Searches through a predicate list for a predicate `T: 'a`. |