Merging upstream version 1.76.0+dfsg1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 0 insertions, 136 deletions

diff --git a/compiler/rustc_infer/src/infer/higher_ranked/mod.rs b/compiler/rustc_infer/src/infer/higher_ranked/mod.rs
deleted file mode 100644
index 510b1797d..000000000
--- a/compiler/rustc_infer/src/infer/higher_ranked/mod.rs
+++ /dev/null
@@ -1,136 +0,0 @@
-//! Helper routines for higher-ranked things. See the `doc` module at
-//! the end of the file for details.
-
-use super::combine::CombineFields;
-use super::{HigherRankedType, InferCtxt};
-use crate::infer::CombinedSnapshot;
-use rustc_middle::ty::fold::FnMutDelegate;
-use rustc_middle::ty::relate::{Relate, RelateResult, TypeRelation};
-use rustc_middle::ty::{self, Binder, Ty, TyCtxt, TypeFoldable};
-
-impl<'a, 'tcx> CombineFields<'a, 'tcx> {
-    /// Checks whether `for<..> sub <: for<..> sup` holds.
-    ///
-    /// For this to hold, **all** instantiations of the super type
-    /// have to be a super type of **at least one** instantiation of
-    /// the subtype.
-    ///
-    /// This is implemented by first entering a new universe.
-    /// We then replace all bound variables in `sup` with placeholders,
-    /// and all bound variables in `sub` with inference vars.
-    /// We can then just relate the two resulting types as normal.
-    ///
-    /// Note: this is a subtle algorithm. For a full explanation, please see
-    /// the [rustc dev guide][rd]
-    ///
-    /// [rd]: https://rustc-dev-guide.rust-lang.org/borrow_check/region_inference/placeholders_and_universes.html
-    #[instrument(skip(self), level = "debug")]
-    pub fn higher_ranked_sub<T>(
-        &mut self,
-        sub: Binder<'tcx, T>,
-        sup: Binder<'tcx, T>,
-        sub_is_expected: bool,
-    ) -> RelateResult<'tcx, ()>
-    where
-        T: Relate<'tcx>,
-    {
-        let span = self.trace.cause.span;
-        // First, we instantiate each bound region in the supertype with a
-        // fresh placeholder region. Note that this automatically creates
-        // a new universe if needed.
-        let sup_prime = self.infcx.instantiate_binder_with_placeholders(sup);
-
-        // Next, we instantiate each bound region in the subtype
-        // with a fresh region variable. These region variables --
-        // but no other preexisting region variables -- can name
-        // the placeholders.
-        let sub_prime = self.infcx.instantiate_binder_with_fresh_vars(span, HigherRankedType, sub);
-
-        debug!("a_prime={:?}", sub_prime);
-        debug!("b_prime={:?}", sup_prime);
-
-        // Compare types now that bound regions have been replaced.
-        let result = self.sub(sub_is_expected).relate(sub_prime, sup_prime)?;
-
-        debug!("OK result={result:?}");
-        // NOTE: returning the result here would be dangerous as it contains
-        // placeholders which **must not** be named afterwards.
-        Ok(())
-    }
-}
-
-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.
-    ///
-    /// 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].
-    ///
-    /// [rustc dev guide]: https://rustc-dev-guide.rust-lang.org/traits/hrtb.html
-    #[instrument(level = "debug", skip(self), ret)]
-    pub fn instantiate_binder_with_placeholders<T>(&self, binder: ty::Binder<'tcx, T>) -> T
-    where
-        T: TypeFoldable<TyCtxt<'tcx>> + Copy,
-    {
-        if let Some(inner) = binder.no_bound_vars() {
-            return inner;
-        }
-
-        let next_universe = self.create_next_universe();
-
-        let delegate = FnMutDelegate {
-            regions: &mut |br: ty::BoundRegion| {
-                ty::Region::new_placeholder(
-                    self.tcx,
-                    ty::PlaceholderRegion { universe: next_universe, bound: br },
-                )
-            },
-            types: &mut |bound_ty: ty::BoundTy| {
-                Ty::new_placeholder(
-                    self.tcx,
-                    ty::PlaceholderType { universe: next_universe, bound: bound_ty },
-                )
-            },
-            consts: &mut |bound_var: ty::BoundVar, ty| {
-                ty::Const::new_placeholder(
-                    self.tcx,
-                    ty::PlaceholderConst { universe: next_universe, bound: bound_var },
-                    ty,
-                )
-            },
-        };
-
-        debug!(?next_universe);
-        self.tcx.replace_bound_vars_uncached(binder, delegate)
-    }
-
-    /// See [RegionConstraintCollector::leak_check][1]. We only check placeholder
-    /// leaking into `outer_universe`, i.e. placeholders which cannot be named by that
-    /// universe.
-    ///
-    /// [1]: crate::infer::region_constraints::RegionConstraintCollector::leak_check
-    pub fn leak_check(
-        &self,
-        outer_universe: ty::UniverseIndex,
-        only_consider_snapshot: Option<&CombinedSnapshot<'tcx>>,
-    ) -> RelateResult<'tcx, ()> {
-        // If the user gave `-Zno-leak-check`, or we have been
-        // configured to skip the leak check, then skip the leak check
-        // completely. The leak check is deprecated. Any legitimate
-        // subtyping errors that it would have caught will now be
-        // caught later on, during region checking. However, we
-        // continue to use it for a transition period.
-        if self.tcx.sess.opts.unstable_opts.no_leak_check || self.skip_leak_check {
-            return Ok(());
-        }
-
-        self.inner.borrow_mut().unwrap_region_constraints().leak_check(
-            self.tcx,
-            outer_universe,
-            self.universe(),
-            only_consider_snapshot,
-        )
-    }
-}