diff options
Diffstat (limited to 'compiler/rustc_infer/src')
| -rw-r--r-- | compiler/rustc_infer/src/infer/outlives/components.rs | 266 | ||||
| -rw-r--r-- | compiler/rustc_infer/src/infer/outlives/mod.rs | 1 | ||||
| -rw-r--r-- | compiler/rustc_infer/src/infer/outlives/obligations.rs | 4 | ||||
| -rw-r--r-- | compiler/rustc_infer/src/infer/outlives/verify.rs | 6 | ||||
| -rw-r--r-- | compiler/rustc_infer/src/traits/util.rs | 2 |
5 files changed, 6 insertions, 273 deletions
diff --git a/compiler/rustc_infer/src/infer/outlives/components.rs b/compiler/rustc_infer/src/infer/outlives/components.rs deleted file mode 100644 index 6bab3ad6ba3..00000000000 --- a/compiler/rustc_infer/src/infer/outlives/components.rs +++ /dev/null @@ -1,266 +0,0 @@ -// The outlines relation `T: 'a` or `'a: 'b`. This code frequently -// refers to rules defined in RFC 1214 (`OutlivesFooBar`), so see that -// RFC for reference. - -use rustc_data_structures::sso::SsoHashSet; -use rustc_middle::ty::{self, Ty, TyCtxt, TypeVisitableExt}; -use rustc_middle::ty::{GenericArg, GenericArgKind}; -use smallvec::{smallvec, SmallVec}; - -#[derive(Debug)] -pub enum Component<'tcx> { - Region(ty::Region<'tcx>), - Param(ty::ParamTy), - Placeholder(ty::PlaceholderType), - UnresolvedInferenceVariable(ty::InferTy), - - // Projections like `T::Foo` are tricky because a constraint like - // `T::Foo: 'a` can be satisfied in so many ways. There may be a - // where-clause that says `T::Foo: 'a`, or the defining trait may - // include a bound like `type Foo: 'static`, or -- in the most - // conservative way -- we can prove that `T: 'a` (more generally, - // that all components in the projection outlive `'a`). This code - // is not in a position to judge which is the best technique, so - // we just product the projection as a component and leave it to - // the consumer to decide (but see `EscapingProjection` below). - Alias(ty::AliasTy<'tcx>), - - // In the case where a projection has escaping regions -- meaning - // regions bound within the type itself -- we always use - // the most conservative rule, which requires that all components - // outlive the bound. So for example if we had a type like this: - // - // for<'a> Trait1< <T as Trait2<'a,'b>>::Foo > - // ~~~~~~~~~~~~~~~~~~~~~~~~~ - // - // then the inner projection (underlined) has an escaping region - // `'a`. We consider that outer trait `'c` to meet a bound if `'b` - // outlives `'b: 'c`, and we don't consider whether the trait - // declares that `Foo: 'static` etc. Therefore, we just return the - // free components of such a projection (in this case, `'b`). - // - // However, in the future, we may want to get smarter, and - // actually return a "higher-ranked projection" here. Therefore, - // we mark that these components are part of an escaping - // projection, so that implied bounds code can avoid relying on - // them. This gives us room to improve the regionck reasoning in - // the future without breaking backwards compat. - EscapingAlias(Vec<Component<'tcx>>), -} - -/// Push onto `out` all the things that must outlive `'a` for the condition -/// `ty0: 'a` to hold. Note that `ty0` must be a **fully resolved type**. -pub fn push_outlives_components<'tcx>( - tcx: TyCtxt<'tcx>, - ty0: Ty<'tcx>, - out: &mut SmallVec<[Component<'tcx>; 4]>, -) { - let mut visited = SsoHashSet::new(); - compute_components(tcx, ty0, out, &mut visited); - debug!("components({:?}) = {:?}", ty0, out); -} - -fn compute_components<'tcx>( - tcx: TyCtxt<'tcx>, - ty: Ty<'tcx>, - out: &mut SmallVec<[Component<'tcx>; 4]>, - visited: &mut SsoHashSet<GenericArg<'tcx>>, -) { - // Descend through the types, looking for the various "base" - // components and collecting them into `out`. This is not written - // with `collect()` because of the need to sometimes skip subtrees - // in the `subtys` iterator (e.g., when encountering a - // projection). - match *ty.kind() { - ty::FnDef(_, args) => { - // HACK(eddyb) ignore lifetimes found shallowly in `args`. - // This is inconsistent with `ty::Adt` (including all args) - // and with `ty::Closure` (ignoring all args other than - // upvars, of which a `ty::FnDef` doesn't have any), but - // consistent with previous (accidental) behavior. - // See https://github.com/rust-lang/rust/issues/70917 - // for further background and discussion. - for child in args { - match child.unpack() { - GenericArgKind::Type(ty) => { - compute_components(tcx, ty, out, visited); - } - GenericArgKind::Lifetime(_) => {} - GenericArgKind::Const(_) => { - compute_components_recursive(tcx, child, out, visited); - } - } - } - } - - ty::Pat(element, _) | - ty::Array(element, _) => { - // Don't look into the len const as it doesn't affect regions - compute_components(tcx, element, out, visited); - } - - ty::Closure(_, args) => { - let tupled_ty = args.as_closure().tupled_upvars_ty(); - compute_components(tcx, tupled_ty, out, visited); - } - - ty::CoroutineClosure(_, args) => { - let tupled_ty = args.as_coroutine_closure().tupled_upvars_ty(); - compute_components(tcx, tupled_ty, out, visited); - } - - ty::Coroutine(_, args) => { - // Same as the closure case - let tupled_ty = args.as_coroutine().tupled_upvars_ty(); - compute_components(tcx, tupled_ty, out, visited); - - // We ignore regions in the coroutine interior as we don't - // want these to affect region inference - } - - // All regions are bound inside a witness - ty::CoroutineWitness(..) => (), - - // OutlivesTypeParameterEnv -- the actual checking that `X:'a` - // is implied by the environment is done in regionck. - ty::Param(p) => { - out.push(Component::Param(p)); - } - - ty::Placeholder(p) => { - out.push(Component::Placeholder(p)); - } - - // For projections, we prefer to generate an obligation like - // `<P0 as Trait<P1...Pn>>::Foo: 'a`, because this gives the - // regionck more ways to prove that it holds. However, - // regionck is not (at least currently) prepared to deal with - // higher-ranked regions that may appear in the - // trait-ref. Therefore, if we see any higher-ranked regions, - // we simply fallback to the most restrictive rule, which - // requires that `Pi: 'a` for all `i`. - ty::Alias(_, alias_ty) => { - if !alias_ty.has_escaping_bound_vars() { - // best case: no escaping regions, so push the - // projection and skip the subtree (thus generating no - // constraints for Pi). This defers the choice between - // the rules OutlivesProjectionEnv, - // OutlivesProjectionTraitDef, and - // OutlivesProjectionComponents to regionck. - out.push(Component::Alias(alias_ty)); - } else { - // fallback case: hard code - // OutlivesProjectionComponents. Continue walking - // through and constrain Pi. - let mut subcomponents = smallvec![]; - let mut subvisited = SsoHashSet::new(); - compute_alias_components_recursive(tcx, ty, &mut subcomponents, &mut subvisited); - out.push(Component::EscapingAlias(subcomponents.into_iter().collect())); - } - } - - // We assume that inference variables are fully resolved. - // So, if we encounter an inference variable, just record - // the unresolved variable as a component. - ty::Infer(infer_ty) => { - out.push(Component::UnresolvedInferenceVariable(infer_ty)); - } - - // Most types do not introduce any region binders, nor - // involve any other subtle cases, and so the WF relation - // simply constraints any regions referenced directly by - // the type and then visits the types that are lexically - // contained within. (The comments refer to relevant rules - // from RFC1214.) - ty::Bool | // OutlivesScalar - ty::Char | // OutlivesScalar - ty::Int(..) | // OutlivesScalar - ty::Uint(..) | // OutlivesScalar - ty::Float(..) | // OutlivesScalar - ty::Never | // ... - ty::Adt(..) | // OutlivesNominalType - ty::Foreign(..) | // OutlivesNominalType - ty::Str | // OutlivesScalar (ish) - ty::Slice(..) | // ... - ty::RawPtr(..) | // ... - ty::Ref(..) | // OutlivesReference - ty::Tuple(..) | // ... - ty::FnPtr(_) | // OutlivesFunction (*) - ty::Dynamic(..) | // OutlivesObject, OutlivesFragment (*) - ty::Bound(..) | - ty::Error(_) => { - // (*) Function pointers and trait objects are both binders. - // In the RFC, this means we would add the bound regions to - // the "bound regions list". In our representation, no such - // list is maintained explicitly, because bound regions - // themselves can be readily identified. - compute_components_recursive(tcx, ty.into(), out, visited); - } - } -} - -/// Collect [Component]s for *all* the args of `parent`. -/// -/// This should not be used to get the components of `parent` itself. -/// Use [push_outlives_components] instead. -pub(super) fn compute_alias_components_recursive<'tcx>( - tcx: TyCtxt<'tcx>, - alias_ty: Ty<'tcx>, - out: &mut SmallVec<[Component<'tcx>; 4]>, - visited: &mut SsoHashSet<GenericArg<'tcx>>, -) { - let ty::Alias(kind, alias_ty) = alias_ty.kind() else { - unreachable!("can only call `compute_alias_components_recursive` on an alias type") - }; - let opt_variances = if *kind == ty::Opaque { tcx.variances_of(alias_ty.def_id) } else { &[] }; - for (index, child) in alias_ty.args.iter().enumerate() { - if opt_variances.get(index) == Some(&ty::Bivariant) { - continue; - } - if !visited.insert(child) { - continue; - } - match child.unpack() { - GenericArgKind::Type(ty) => { - compute_components(tcx, ty, out, visited); - } - GenericArgKind::Lifetime(lt) => { - // Ignore higher ranked regions. - if !lt.is_bound() { - out.push(Component::Region(lt)); - } - } - GenericArgKind::Const(_) => { - compute_components_recursive(tcx, child, out, visited); - } - } - } -} - -/// Collect [Component]s for *all* the args of `parent`. -/// -/// This should not be used to get the components of `parent` itself. -/// Use [push_outlives_components] instead. -fn compute_components_recursive<'tcx>( - tcx: TyCtxt<'tcx>, - parent: GenericArg<'tcx>, - out: &mut SmallVec<[Component<'tcx>; 4]>, - visited: &mut SsoHashSet<GenericArg<'tcx>>, -) { - for child in parent.walk_shallow(visited) { - match child.unpack() { - GenericArgKind::Type(ty) => { - compute_components(tcx, ty, out, visited); - } - GenericArgKind::Lifetime(lt) => { - // Ignore higher ranked regions. - if !lt.is_bound() { - out.push(Component::Region(lt)); - } - } - GenericArgKind::Const(_) => { - compute_components_recursive(tcx, child, out, visited); - } - } - } -} diff --git a/compiler/rustc_infer/src/infer/outlives/mod.rs b/compiler/rustc_infer/src/infer/outlives/mod.rs index 48d006e7fbc..89ff4604560 100644 --- a/compiler/rustc_infer/src/infer/outlives/mod.rs +++ b/compiler/rustc_infer/src/infer/outlives/mod.rs @@ -8,7 +8,6 @@ use crate::infer::lexical_region_resolve; use rustc_middle::traits::query::{NoSolution, OutlivesBound}; use rustc_middle::ty; -pub mod components; pub mod env; pub mod for_liveness; pub mod obligations; diff --git a/compiler/rustc_infer/src/infer/outlives/obligations.rs b/compiler/rustc_infer/src/infer/outlives/obligations.rs index 32c790523b6..9bb5f775e4a 100644 --- a/compiler/rustc_infer/src/infer/outlives/obligations.rs +++ b/compiler/rustc_infer/src/infer/outlives/obligations.rs @@ -59,7 +59,6 @@ //! might later infer `?U` to something like `&'b u32`, which would //! imply that `'b: 'a`. -use crate::infer::outlives::components::{push_outlives_components, Component}; use crate::infer::outlives::env::RegionBoundPairs; use crate::infer::outlives::verify::VerifyBoundCx; use crate::infer::resolve::OpportunisticRegionResolver; @@ -75,6 +74,7 @@ use rustc_middle::ty::{ }; use rustc_middle::ty::{GenericArgKind, PolyTypeOutlivesPredicate}; use rustc_span::DUMMY_SP; +use rustc_type_ir::outlives::{push_outlives_components, Component}; use smallvec::smallvec; use super::env::OutlivesEnvironment; @@ -291,7 +291,7 @@ where fn components_must_outlive( &mut self, origin: infer::SubregionOrigin<'tcx>, - components: &[Component<'tcx>], + components: &[Component<TyCtxt<'tcx>>], region: ty::Region<'tcx>, category: ConstraintCategory<'tcx>, ) { diff --git a/compiler/rustc_infer/src/infer/outlives/verify.rs b/compiler/rustc_infer/src/infer/outlives/verify.rs index 7e977b9b954..ad102dfcc1f 100644 --- a/compiler/rustc_infer/src/infer/outlives/verify.rs +++ b/compiler/rustc_infer/src/infer/outlives/verify.rs @@ -1,10 +1,10 @@ -use crate::infer::outlives::components::{compute_alias_components_recursive, Component}; use crate::infer::outlives::env::RegionBoundPairs; use crate::infer::region_constraints::VerifyIfEq; use crate::infer::{GenericKind, VerifyBound}; use rustc_data_structures::sso::SsoHashSet; use rustc_middle::ty::GenericArg; use rustc_middle::ty::{self, OutlivesPredicate, Ty, TyCtxt}; +use rustc_type_ir::outlives::{compute_alias_components_recursive, Component}; use smallvec::smallvec; @@ -139,7 +139,7 @@ impl<'cx, 'tcx> VerifyBoundCx<'cx, 'tcx> { fn bound_from_components( &self, - components: &[Component<'tcx>], + components: &[Component<TyCtxt<'tcx>>], visited: &mut SsoHashSet<GenericArg<'tcx>>, ) -> VerifyBound<'tcx> { let mut bounds = components @@ -158,7 +158,7 @@ impl<'cx, 'tcx> VerifyBoundCx<'cx, 'tcx> { fn bound_from_single_component( &self, - component: &Component<'tcx>, + component: &Component<TyCtxt<'tcx>>, visited: &mut SsoHashSet<GenericArg<'tcx>>, ) -> VerifyBound<'tcx> { match *component { diff --git a/compiler/rustc_infer/src/traits/util.rs b/compiler/rustc_infer/src/traits/util.rs index 18d36c3a5df..b269bfcbfeb 100644 --- a/compiler/rustc_infer/src/traits/util.rs +++ b/compiler/rustc_infer/src/traits/util.rs @@ -1,12 +1,12 @@ use smallvec::smallvec; -use crate::infer::outlives::components::{push_outlives_components, Component}; use crate::traits::{self, Obligation, ObligationCauseCode, PredicateObligation}; use rustc_data_structures::fx::FxHashSet; use rustc_middle::ty::ToPolyTraitRef; use rustc_middle::ty::{self, Ty, TyCtxt, Upcast}; use rustc_span::symbol::Ident; use rustc_span::Span; +use rustc_type_ir::outlives::{push_outlives_components, Component}; pub fn anonymize_predicate<'tcx>( tcx: TyCtxt<'tcx>, |