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Do binder folding eagerly in bound_coroutine_hidden_types

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I refuse to fix this in the old solver; its lazy instantiation of
binders will be the end of me.
This commit is contained in:
Michael Goulet 2024-03-14 11:51:22 -04:00
parent 67f1c53c05
commit bca708b9fa
3 changed files with 42 additions and 37 deletions
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36
compiler/rustc_middle/src/ty/util.rs
View file

@ -682,6 +682,9 @@ impl<'tcx> TyCtxt<'tcx> {
/// Return the set of types that should be taken into account when checking
/// trait bounds on a coroutine's internal state.
// FIXME(compiler-errors): We should remove this when the old solver goes away;
// and all other usages of this function should go through `bound_coroutine_hidden_types`
// instead.
pub fn coroutine_hidden_types(
self,
def_id: DefId,
@ -694,6 +697,33 @@ impl<'tcx> TyCtxt<'tcx> {
.map(|decl| ty::EarlyBinder::bind(decl.ty))
}
/// Return the set of types that should be taken into account when checking
/// trait bounds on a coroutine's internal state. This properly replaces
/// `ReErased` with new existential bound lifetimes.
pub fn bound_coroutine_hidden_types(
self,
def_id: DefId,
) -> impl Iterator<Item = ty::EarlyBinder<ty::Binder<'tcx, Ty<'tcx>>>> {
let coroutine_layout = self.mir_coroutine_witnesses(def_id);
coroutine_layout
.as_ref()
.map_or_else(|| [].iter(), |l| l.field_tys.iter())
.filter(|decl| !decl.ignore_for_traits)
.map(move |decl| {
let mut vars = vec![];
let ty = self.fold_regions(decl.ty, |re, debruijn| {
assert_eq!(re, self.lifetimes.re_erased);
let var = ty::BoundVar::from_usize(vars.len());
vars.push(ty::BoundVariableKind::Region(ty::BrAnon));
ty::Region::new_bound(self, debruijn, ty::BoundRegion { var, kind: ty::BrAnon })
});
ty::EarlyBinder::bind(ty::Binder::bind_with_vars(
ty,
self.mk_bound_variable_kinds(&vars),
))
})
}
/// Expands the given impl trait type, stopping if the type is recursive.
#[instrument(skip(self), level = "debug", ret)]
pub fn try_expand_impl_trait_type(
@ -998,8 +1028,10 @@ impl<'tcx> OpaqueTypeExpander<'tcx> {
Some(expanded_ty) => *expanded_ty,
None => {
if matches!(self.inspect_coroutine_fields, InspectCoroutineFields::Yes) {
for bty in self.tcx.coroutine_hidden_types(def_id) {
let hidden_ty = bty.instantiate(self.tcx, args);
for bty in self.tcx.bound_coroutine_hidden_types(def_id) {
let hidden_ty = self.tcx.instantiate_bound_regions_with_erased(
bty.instantiate(self.tcx, args),
);
self.fold_ty(hidden_ty);
}
}

35
compiler/rustc_trait_selection/src/solve/assembly/structural_traits.rs
View file

@ -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`.
@ -93,26 +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>> {
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>,
@ -240,13 +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()),
}
}

8
compiler/rustc_trait_selection/src/traits/select/confirmation.rs
View file

@ -14,7 +14,7 @@ use rustc_infer::infer::{DefineOpaqueTypes, InferOk};
use rustc_middle::traits::{BuiltinImplSource, SignatureMismatchData};
use rustc_middle::ty::{
self, GenericArgs, GenericArgsRef, GenericParamDefKind, ToPolyTraitRef, ToPredicate,
TraitPredicate, Ty, TyCtxt, TypeVisitableExt,
TraitPredicate, Ty, TyCtxt,
};
use rustc_span::def_id::DefId;
@ -1438,10 +1438,8 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
}
ty::CoroutineWitness(def_id, args) => {
let tcx = self.tcx();
stack.extend(tcx.coroutine_hidden_types(def_id).map(|bty| {
let ty = bty.instantiate(tcx, args);
debug_assert!(!ty.has_bound_regions());
ty
stack.extend(tcx.bound_coroutine_hidden_types(def_id).map(|bty| {
self.infcx.enter_forall_and_leak_universe(bty.instantiate(tcx, args))
}))
}