bjoernager/rust
bjoernager/rust
1
Fork 0
Code Activity

reviews + rebase

Browse source
This commit is contained in:
Boxy 2024-02-08 13:19:20 +00:00
parent b181a12623
commit f867742be8
11 changed files with 101 additions and 114 deletions
Download patch file Download diff file Expand all files Collapse all files

2
compiler/rustc_infer/src/infer/mod.rs
View file

@ -1032,7 +1032,6 @@ impl<'tcx> InferCtxt<'tcx> {
_ => {}
}
// FIXME(tree_universes): leaking placeholders
self.enter_forall(predicate, |ty::SubtypePredicate { a_is_expected, a, b }| {
Ok(self.at(cause, param_env).sub_exp(DefineOpaqueTypes::No, a_is_expected, a, b))
})
@ -1043,7 +1042,6 @@ impl<'tcx> InferCtxt<'tcx> {
cause: &traits::ObligationCause<'tcx>,
predicate: ty::PolyRegionOutlivesPredicate<'tcx>,
) {
// FIXME(tree_universes): leaking placeholders
self.enter_forall(predicate, |ty::OutlivesPredicate(r_a, r_b)| {
let origin = SubregionOrigin::from_obligation_cause(cause, || {
RelateRegionParamBound(cause.span)

15
compiler/rustc_infer/src/infer/relate/higher_ranked.rs
View file

@ -49,7 +49,6 @@ impl<'a, 'tcx> CombineFields<'a, 'tcx> {
debug!("b_prime={:?}", sup_prime);
// Compare types now that bound regions have been replaced.
// FIXME(tree_universes): leaked universes
let result = self.sub(sub_is_expected).relate(sub_prime, sup_prime);
if result.is_ok() {
debug!("OK result={result:?}");
@ -70,7 +69,7 @@ impl<'tcx> InferCtxt<'tcx> {
/// This is the first step of checking subtyping when higher-ranked things are involved.
/// For more details visit the relevant sections of the [rustc dev guide].
///
/// `enter_forall` should be preferred over this method.
/// `fn enter_forall` should be preferred over this method.
///
/// [rustc dev guide]: https://rustc-dev-guide.rust-lang.org/traits/hrtb.html
#[instrument(level = "debug", skip(self), ret)]
@ -111,14 +110,14 @@ impl<'tcx> InferCtxt<'tcx> {
}
/// Replaces all bound variables (lifetimes, types, and constants) bound by
/// `binder` with placeholder variables in a new universe. This means that the
/// new placeholders can only be named by inference variables created after
/// this method has been called.
/// `binder` with placeholder variables in a new universe and then calls the
/// closure `f` with the instantiated value. The new placeholders can only be
/// named by inference variables created inside of the closure `f` or afterwards.
///
/// This is the first step of checking subtyping when higher-ranked things are involved.
/// For more details visit the relevant sections of the [rustc dev guide].
///
/// This method should be preferred over `enter_forall_and_leak_universe`.
/// This method should be preferred over `fn enter_forall_and_leak_universe`.
///
/// [rustc dev guide]: https://rustc-dev-guide.rust-lang.org/traits/hrtb.html
#[instrument(level = "debug", skip(self, f))]
@ -126,6 +125,10 @@ impl<'tcx> InferCtxt<'tcx> {
where
T: TypeFoldable<TyCtxt<'tcx>> + Copy,
{
// FIXME: currently we do nothing to prevent placeholders with the new universe being
// used after exiting `f`. For example region subtyping can result in outlives constraints
// that name placeholders created in this function. Nested goals from type relations can
// also contain placeholders created by this function.
let value = self.enter_forall_and_leak_universe(forall);
debug!("?value");
f(value)

89
compiler/rustc_infer/src/infer/relate/nll.rs
View file

@ -261,54 +261,6 @@ where
Ok(a)
}
#[instrument(skip(self), level = "debug")]
fn enter_forall_and_leak_universe<T>(&mut self, binder: ty::Binder<'tcx, T>) -> T
where
T: ty::TypeFoldable<TyCtxt<'tcx>> + Copy,
{
if let Some(inner) = binder.no_bound_vars() {
return inner;
}
let mut next_region = {
let nll_delegate = &mut self.delegate;
let mut lazy_universe = None;
move |br: ty::BoundRegion| {
// The first time this closure is called, create a
// new universe for the placeholders we will make
// from here out.
let universe = lazy_universe.unwrap_or_else(|| {
let universe = nll_delegate.create_next_universe();
lazy_universe = Some(universe);
universe
});
let placeholder = ty::PlaceholderRegion { universe, bound: br };
debug!(?placeholder);
let placeholder_reg = nll_delegate.next_placeholder_region(placeholder);
debug!(?placeholder_reg);
placeholder_reg
}
};
let delegate = FnMutDelegate {
regions: &mut next_region,
types: &mut |_bound_ty: ty::BoundTy| {
unreachable!("we only replace regions in nll_relate, not types")
},
consts: &mut |_bound_var: ty::BoundVar, _ty| {
unreachable!("we only replace regions in nll_relate, not consts")
},
};
let replaced = self.infcx.tcx.replace_bound_vars_uncached(binder, delegate);
debug!(?replaced);
replaced
}
fn enter_forall<T, U>(
&mut self,
binder: ty::Binder<'tcx, T>,
@ -317,7 +269,46 @@ where
where
T: ty::TypeFoldable<TyCtxt<'tcx>> + Copy,
{
let value = self.enter_forall_and_leak_universe(binder);
let value = if let Some(inner) = binder.no_bound_vars() {
inner
} else {
let mut next_region = {
let nll_delegate = &mut self.delegate;
let mut lazy_universe = None;
move |br: ty::BoundRegion| {
// The first time this closure is called, create a
// new universe for the placeholders we will make
// from here out.
let universe = lazy_universe.unwrap_or_else(|| {
let universe = nll_delegate.create_next_universe();
lazy_universe = Some(universe);
universe
});
let placeholder = ty::PlaceholderRegion { universe, bound: br };
debug!(?placeholder);
let placeholder_reg = nll_delegate.next_placeholder_region(placeholder);
debug!(?placeholder_reg);
placeholder_reg
}
};
let delegate = FnMutDelegate {
regions: &mut next_region,
types: &mut |_bound_ty: ty::BoundTy| {
unreachable!("we only replace regions in nll_relate, not types")
},
consts: &mut |_bound_var: ty::BoundVar, _ty| {
unreachable!("we only replace regions in nll_relate, not consts")
},
};
self.infcx.tcx.replace_bound_vars_uncached(binder, delegate)
};
debug!(?value);
f(self, value)
}