1 files changed, 57 insertions, 14 deletions

diff --git a/compiler/rustc_borrowck/src/renumber.rs b/compiler/rustc_borrowck/src/renumber.rs
index 084754830..016f6f78d 100644
--- a/compiler/rustc_borrowck/src/renumber.rs
+++ b/compiler/rustc_borrowck/src/renumber.rs
@@ -1,18 +1,20 @@
 #![deny(rustc::untranslatable_diagnostic)]
 #![deny(rustc::diagnostic_outside_of_impl)]
+use crate::BorrowckInferCtxt;
 use rustc_index::vec::IndexVec;
-use rustc_infer::infer::{InferCtxt, NllRegionVariableOrigin};
+use rustc_infer::infer::NllRegionVariableOrigin;
 use rustc_middle::mir::visit::{MutVisitor, TyContext};
 use rustc_middle::mir::Constant;
 use rustc_middle::mir::{Body, Location, Promoted};
 use rustc_middle::ty::subst::SubstsRef;
 use rustc_middle::ty::{self, Ty, TyCtxt, TypeFoldable};
+use rustc_span::{Span, Symbol};
 
 /// Replaces all free regions appearing in the MIR with fresh
 /// inference variables, returning the number of variables created.
 #[instrument(skip(infcx, body, promoted), level = "debug")]
 pub fn renumber_mir<'tcx>(
-    infcx: &InferCtxt<'tcx>,
+    infcx: &BorrowckInferCtxt<'_, 'tcx>,
     body: &mut Body<'tcx>,
     promoted: &mut IndexVec<Promoted, Body<'tcx>>,
 ) {
@@ -29,27 +31,68 @@ pub fn renumber_mir<'tcx>(
 
 /// Replaces all regions appearing in `value` with fresh inference
 /// variables.
-#[instrument(skip(infcx), level = "debug")]
-pub fn renumber_regions<'tcx, T>(infcx: &InferCtxt<'tcx>, value: T) -> T
+#[instrument(skip(infcx, get_ctxt_fn), level = "debug")]
+pub(crate) fn renumber_regions<'tcx, T, F>(
+    infcx: &BorrowckInferCtxt<'_, 'tcx>,
+    value: T,
+    get_ctxt_fn: F,
+) -> T
 where
-    T: TypeFoldable<'tcx>,
+    T: TypeFoldable<TyCtxt<'tcx>>,
+    F: Fn() -> RegionCtxt,
 {
     infcx.tcx.fold_regions(value, |_region, _depth| {
         let origin = NllRegionVariableOrigin::Existential { from_forall: false };
-        infcx.next_nll_region_var(origin)
+        infcx.next_nll_region_var(origin, || get_ctxt_fn())
     })
 }
 
+#[derive(Copy, Clone, Debug, Eq, PartialEq, Hash)]
+pub(crate) enum BoundRegionInfo {
+    Name(Symbol),
+    Span(Span),
+}
+
+#[derive(Copy, Clone, Debug, Eq, PartialEq, Hash)]
+pub(crate) enum RegionCtxt {
+    Location(Location),
+    TyContext(TyContext),
+    Free(Symbol),
+    Bound(BoundRegionInfo),
+    LateBound(BoundRegionInfo),
+    Existential(Option<Symbol>),
+    Placeholder(BoundRegionInfo),
+    Unknown,
+}
+
+impl RegionCtxt {
+    /// Used to determine the representative of a component in the strongly connected
+    /// constraint graph
+    pub(crate) fn preference_value(self) -> usize {
+        let _anon = Symbol::intern("anon");
+
+        match self {
+            RegionCtxt::Unknown => 1,
+            RegionCtxt::Existential(None) => 2,
+            RegionCtxt::Existential(Some(_anon)) | RegionCtxt::Free(_anon) => 2,
+            RegionCtxt::Location(_) => 3,
+            RegionCtxt::TyContext(_) => 4,
+            _ => 5,
+        }
+    }
+}
+
 struct NllVisitor<'a, 'tcx> {
-    infcx: &'a InferCtxt<'tcx>,
+    infcx: &'a BorrowckInferCtxt<'a, 'tcx>,
 }
 
 impl<'a, 'tcx> NllVisitor<'a, 'tcx> {
-    fn renumber_regions<T>(&mut self, value: T) -> T
+    fn renumber_regions<T, F>(&mut self, value: T, region_ctxt_fn: F) -> T
     where
-        T: TypeFoldable<'tcx>,
+        T: TypeFoldable<TyCtxt<'tcx>>,
+        F: Fn() -> RegionCtxt,
     {
-        renumber_regions(self.infcx, value)
+        renumber_regions(self.infcx, value, region_ctxt_fn)
     }
 }
 
@@ -60,14 +103,14 @@ impl<'a, 'tcx> MutVisitor<'tcx> for NllVisitor<'a, 'tcx> {
 
     #[instrument(skip(self), level = "debug")]
     fn visit_ty(&mut self, ty: &mut Ty<'tcx>, ty_context: TyContext) {
-        *ty = self.renumber_regions(*ty);
+        *ty = self.renumber_regions(*ty, || RegionCtxt::TyContext(ty_context));
 
         debug!(?ty);
     }
 
     #[instrument(skip(self), level = "debug")]
     fn visit_substs(&mut self, substs: &mut SubstsRef<'tcx>, location: Location) {
-        *substs = self.renumber_regions(*substs);
+        *substs = self.renumber_regions(*substs, || RegionCtxt::Location(location));
 
         debug!(?substs);
     }
@@ -75,7 +118,7 @@ impl<'a, 'tcx> MutVisitor<'tcx> for NllVisitor<'a, 'tcx> {
     #[instrument(skip(self), level = "debug")]
     fn visit_region(&mut self, region: &mut ty::Region<'tcx>, location: Location) {
         let old_region = *region;
-        *region = self.renumber_regions(old_region);
+        *region = self.renumber_regions(old_region, || RegionCtxt::Location(location));
 
         debug!(?region);
     }
@@ -83,7 +126,7 @@ impl<'a, 'tcx> MutVisitor<'tcx> for NllVisitor<'a, 'tcx> {
     #[instrument(skip(self), level = "debug")]
     fn visit_constant(&mut self, constant: &mut Constant<'tcx>, _location: Location) {
         let literal = constant.literal;
-        constant.literal = self.renumber_regions(literal);
+        constant.literal = self.renumber_regions(literal, || RegionCtxt::Location(_location));
         debug!("constant: {:#?}", constant);
     }
 }