diff options
Diffstat (limited to 'compiler/rustc_trait_selection/src/solve/assembly')
| -rw-r--r-- | compiler/rustc_trait_selection/src/solve/assembly/mod.rs | 11 | ||||
| -rw-r--r-- | compiler/rustc_trait_selection/src/solve/assembly/structural_traits.rs | 60 |
2 files changed, 33 insertions, 38 deletions
diff --git a/compiler/rustc_trait_selection/src/solve/assembly/mod.rs b/compiler/rustc_trait_selection/src/solve/assembly/mod.rs index 9c7fa5216d7..d92bae2528f 100644 --- a/compiler/rustc_trait_selection/src/solve/assembly/mod.rs +++ b/compiler/rustc_trait_selection/src/solve/assembly/mod.rs @@ -128,7 +128,7 @@ pub(super) trait GoalKind<'tcx>: goal: Goal<'tcx, Self>, ) -> QueryResult<'tcx>; - /// A type is `Copy` or `Clone` if its components are `Sized`. + /// A type is `Sized` if its tail component is `Sized`. /// /// These components are given by built-in rules from /// [`structural_traits::instantiate_constituent_tys_for_sized_trait`]. @@ -215,6 +215,13 @@ pub(super) trait GoalKind<'tcx>: goal: Goal<'tcx, Self>, ) -> QueryResult<'tcx>; + /// A coroutine (that comes from a `gen` desugaring) is known to implement + /// `FusedIterator` + fn consider_builtin_fused_iterator_candidate( + ecx: &mut EvalCtxt<'_, 'tcx>, + goal: Goal<'tcx, Self>, + ) -> QueryResult<'tcx>; + fn consider_builtin_async_iterator_candidate( ecx: &mut EvalCtxt<'_, 'tcx>, goal: Goal<'tcx, Self>, @@ -497,6 +504,8 @@ impl<'tcx> EvalCtxt<'_, 'tcx> { G::consider_builtin_future_candidate(self, goal) } else if lang_items.iterator_trait() == Some(trait_def_id) { G::consider_builtin_iterator_candidate(self, goal) + } else if lang_items.fused_iterator_trait() == Some(trait_def_id) { + G::consider_builtin_fused_iterator_candidate(self, goal) } else if lang_items.async_iterator_trait() == Some(trait_def_id) { G::consider_builtin_async_iterator_candidate(self, goal) } else if lang_items.coroutine_trait() == Some(trait_def_id) { diff --git a/compiler/rustc_trait_selection/src/solve/assembly/structural_traits.rs b/compiler/rustc_trait_selection/src/solve/assembly/structural_traits.rs index 2bfb86b592b..80c31831462 100644 --- a/compiler/rustc_trait_selection/src/solve/assembly/structural_traits.rs +++ b/compiler/rustc_trait_selection/src/solve/assembly/structural_traits.rs @@ -6,7 +6,7 @@ use rustc_hir::{def_id::DefId, Movability, Mutability}; use rustc_infer::traits::query::NoSolution; use rustc_middle::traits::solve::Goal; use rustc_middle::ty::{ - self, ToPredicate, Ty, TyCtxt, TypeFoldable, TypeFolder, TypeSuperFoldable, TypeVisitableExt, + self, ToPredicate, Ty, TyCtxt, TypeFoldable, TypeFolder, TypeSuperFoldable, }; use rustc_span::sym; @@ -73,8 +73,8 @@ pub(in crate::solve) fn instantiate_constituent_tys_for_auto_trait<'tcx>( ty::CoroutineWitness(def_id, args) => Ok(ecx .tcx() - .coroutine_hidden_types(def_id) - .map(|bty| replace_erased_lifetimes_with_bound_vars(tcx, bty.instantiate(tcx, args))) + .bound_coroutine_hidden_types(def_id) + .map(|bty| bty.instantiate(tcx, args)) .collect()), // For `PhantomData<T>`, we pass `T`. @@ -93,27 +93,6 @@ pub(in crate::solve) fn instantiate_constituent_tys_for_auto_trait<'tcx>( } } -pub(in crate::solve) fn replace_erased_lifetimes_with_bound_vars<'tcx>( - tcx: TyCtxt<'tcx>, - ty: Ty<'tcx>, -) -> ty::Binder<'tcx, Ty<'tcx>> { - debug_assert!(!ty.has_bound_regions()); - let mut counter = 0; - let ty = tcx.fold_regions(ty, |r, current_depth| match r.kind() { - ty::ReErased => { - let br = ty::BoundRegion { var: ty::BoundVar::from_u32(counter), kind: ty::BrAnon }; - counter += 1; - ty::Region::new_bound(tcx, current_depth, br) - } - // All free regions should be erased here. - r => bug!("unexpected region: {r:?}"), - }); - let bound_vars = tcx.mk_bound_variable_kinds_from_iter( - (0..counter).map(|_| ty::BoundVariableKind::Region(ty::BrAnon)), - ); - ty::Binder::bind_with_vars(ty, bound_vars) -} - #[instrument(level = "debug", skip(ecx), ret)] pub(in crate::solve) fn instantiate_constituent_tys_for_sized_trait<'tcx>( ecx: &EvalCtxt<'_, 'tcx>, @@ -154,13 +133,25 @@ pub(in crate::solve) fn instantiate_constituent_tys_for_sized_trait<'tcx>( bug!("unexpected type `{ty}`") } - // impl Sized for (T1, T2, .., Tn) where T1: Sized, T2: Sized, .. Tn: Sized - ty::Tuple(tys) => Ok(tys.iter().map(ty::Binder::dummy).collect()), - - // impl Sized for Adt where T: Sized forall T in field types + // impl Sized for () + // impl Sized for (T1, T2, .., Tn) where Tn: Sized if n >= 1 + ty::Tuple(tys) => Ok(tys.last().map_or_else(Vec::new, |&ty| vec![ty::Binder::dummy(ty)])), + + // impl Sized for Adt<Args...> where sized_constraint(Adt)<Args...>: Sized + // `sized_constraint(Adt)` is the deepest struct trail that can be determined + // by the definition of `Adt`, independent of the generic args. + // impl Sized for Adt<Args...> if sized_constraint(Adt) == None + // As a performance optimization, `sized_constraint(Adt)` can return `None` + // if the ADTs definition implies that it is sized by for all possible args. + // In this case, the builtin impl will have no nested subgoals. This is a + // "best effort" optimization and `sized_constraint` may return `Some`, even + // if the ADT is sized for all possible args. ty::Adt(def, args) => { - let sized_crit = def.sized_constraint(ecx.tcx()); - Ok(sized_crit.iter_instantiated(ecx.tcx(), args).map(ty::Binder::dummy).collect()) + if let Some(sized_crit) = def.sized_constraint(ecx.tcx()) { + Ok(vec![ty::Binder::dummy(sized_crit.instantiate(ecx.tcx(), args))]) + } else { + Ok(vec![]) + } } } } @@ -229,13 +220,8 @@ pub(in crate::solve) fn instantiate_constituent_tys_for_copy_clone_trait<'tcx>( // impl Copy/Clone for CoroutineWitness where T: Copy/Clone forall T in coroutine_hidden_types ty::CoroutineWitness(def_id, args) => Ok(ecx .tcx() - .coroutine_hidden_types(def_id) - .map(|bty| { - replace_erased_lifetimes_with_bound_vars( - ecx.tcx(), - bty.instantiate(ecx.tcx(), args), - ) - }) + .bound_coroutine_hidden_types(def_id) + .map(|bty| bty.instantiate(ecx.tcx(), args)) .collect()), } } |