Expand weak alias types before collecting constrained and referenced late bound regions

Author: fmease

compiler/rustc_hir_analysis/src/astconv/bounds.rs

@@ -454,9 +454,9 @@ impl<'tcx> dyn AstConv<'tcx> + '_ {
                     //     for<'a> <T as Iterator>::Item = &'a str // <-- 'a is bad
                     //     for<'a> <T as FnMut<(&'a u32,)>>::Output = &'a str // <-- 'a is ok
                     let late_bound_in_projection_ty =
-                        tcx.collect_constrained_late_bound_regions(&projection_ty);
+                        tcx.collect_constrained_late_bound_regions(projection_ty);
                     let late_bound_in_term =
-                        tcx.collect_referenced_late_bound_regions(&trait_ref.rebind(term));
+                        tcx.collect_referenced_late_bound_regions(trait_ref.rebind(term));
                     debug!(?late_bound_in_projection_ty);
                     debug!(?late_bound_in_term);
 

compiler/rustc_hir_analysis/src/astconv/mod.rs

@@ -2678,9 +2678,9 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
         //     for<'a> fn(&'a String) -> &'a str <-- 'a is ok
         let inputs = bare_fn_ty.inputs();
         let late_bound_in_args =
-            tcx.collect_constrained_late_bound_regions(&inputs.map_bound(|i| i.to_owned()));
+            tcx.collect_constrained_late_bound_regions(inputs.map_bound(|i| i.to_owned()));
         let output = bare_fn_ty.output();
-        let late_bound_in_ret = tcx.collect_referenced_late_bound_regions(&output);
+        let late_bound_in_ret = tcx.collect_referenced_late_bound_regions(output);
 
         self.validate_late_bound_regions(late_bound_in_args, late_bound_in_ret, |br_name| {
             struct_span_code_err!(

compiler/rustc_hir_analysis/src/collect.rs

@@ -520,7 +520,7 @@ fn get_new_lifetime_name<'tcx>(
     generics: &hir::Generics<'tcx>,
 ) -> String {
     let existing_lifetimes = tcx
-        .collect_referenced_late_bound_regions(&poly_trait_ref)
+        .collect_referenced_late_bound_regions(poly_trait_ref)
         .into_iter()
         .filter_map(|lt| {
             if let ty::BoundRegionKind::BrNamed(_, name) = lt {

compiler/rustc_infer/src/infer/error_reporting/nice_region_error/util.rs

@@ -5,7 +5,7 @@ use crate::infer::error_reporting::nice_region_error::NiceRegionError;
 use crate::infer::TyCtxt;
 use rustc_hir as hir;
 use rustc_hir::def_id::LocalDefId;
-use rustc_middle::ty::{self, Binder, Region, Ty, TypeVisitable};
+use rustc_middle::ty::{self, Binder, Region, Ty, TypeFoldable};
 use rustc_span::Span;
 
 /// Information about the anonymous region we are searching for.
@@ -142,10 +142,10 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
 
     fn includes_region(
         &self,
-        ty: Binder<'tcx, impl TypeVisitable<TyCtxt<'tcx>>>,
+        ty: Binder<'tcx, impl TypeFoldable<TyCtxt<'tcx>>>,
         region: ty::BoundRegionKind,
     ) -> bool {
-        let late_bound_regions = self.tcx().collect_referenced_late_bound_regions(&ty);
+        let late_bound_regions = self.tcx().collect_referenced_late_bound_regions(ty);
         // We are only checking is any region meets the condition so order doesn't matter
         #[allow(rustc::potential_query_instability)]
         late_bound_regions.iter().any(|r| *r == region)

compiler/rustc_middle/src/ty/visit.rs

@@ -2,6 +2,7 @@ use crate::ty::{self, Binder, Ty, TyCtxt, TypeFlags};
 
 use rustc_data_structures::fx::FxHashSet;
 use rustc_data_structures::sso::SsoHashSet;
+use rustc_type_ir::fold::TypeFoldable;
 use std::ops::ControlFlow;
 
 pub use rustc_type_ir::visit::{TypeSuperVisitable, TypeVisitable, TypeVisitableExt, TypeVisitor};
@@ -109,36 +110,37 @@ impl<'tcx> TyCtxt<'tcx> {
     /// variables will also be equated.
     pub fn collect_constrained_late_bound_regions<T>(
         self,
-        value: &Binder<'tcx, T>,
+        value: Binder<'tcx, T>,
     ) -> FxHashSet<ty::BoundRegionKind>
     where
-        T: TypeVisitable<TyCtxt<'tcx>>,
+        T: TypeFoldable<TyCtxt<'tcx>>,
     {
         self.collect_late_bound_regions(value, true)
     }
 
     /// Returns a set of all late-bound regions that appear in `value` anywhere.
     pub fn collect_referenced_late_bound_regions<T>(
         self,
-        value: &Binder<'tcx, T>,
+        value: Binder<'tcx, T>,
     ) -> FxHashSet<ty::BoundRegionKind>
     where
-        T: TypeVisitable<TyCtxt<'tcx>>,
+        T: TypeFoldable<TyCtxt<'tcx>>,
     {
         self.collect_late_bound_regions(value, false)
     }
 
     fn collect_late_bound_regions<T>(
         self,
-        value: &Binder<'tcx, T>,
+        value: Binder<'tcx, T>,
         just_constrained: bool,
     ) -> FxHashSet<ty::BoundRegionKind>
     where
-        T: TypeVisitable<TyCtxt<'tcx>>,
+        T: TypeFoldable<TyCtxt<'tcx>>,
     {
-        let mut collector = LateBoundRegionsCollector::new(self, just_constrained);
+        let mut collector = LateBoundRegionsCollector::new(just_constrained);
+        let value = value.skip_binder();
         let value = if just_constrained { self.expand_weak_alias_tys(value) } else { value };
-        let result = value.as_ref().skip_binder().visit_with(&mut collector);
+        let result = value.visit_with(&mut collector);
         assert!(result.is_continue()); // should never have stopped early
         collector.regions
     }
@@ -258,12 +260,8 @@ struct LateBoundRegionsCollector {
 }
 
 impl LateBoundRegionsCollector {
-    fn new(tcx: TyCtxt<'tcx>, just_constrained: bool) -> Self {
-        Self {
-            current_index: ty::INNERMOST,
-            regions: Default::default(),
-            just_constrained,
-        }
+    fn new(just_constrained: bool) -> Self {
+        Self { current_index: ty::INNERMOST, regions: Default::default(), just_constrained }
     }
 }
 
@@ -287,7 +285,7 @@ impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for LateBoundRegionsCollector {
                     return ControlFlow::Continue(());
                 }
                 // All weak alias types should've been expanded beforehand.
-                ty::Alias(ty::Weak, alias) => bug!("unexpected weak alias type"),
+                ty::Alias(ty::Weak, _) => bug!("unexpected weak alias type"),
                 _ => {}
             }
         }

src/librustdoc/clean/auto_trait.rs

@@ -318,15 +318,14 @@ where
     fn extract_for_generics(&self, pred: ty::Clause<'tcx>) -> FxHashSet<GenericParamDef> {
         let bound_predicate = pred.kind();
         let tcx = self.cx.tcx;
-        let regions = match bound_predicate.skip_binder() {
-            ty::ClauseKind::Trait(poly_trait_pred) => {
-                tcx.collect_referenced_late_bound_regions(&bound_predicate.rebind(poly_trait_pred))
-            }
-            ty::ClauseKind::Projection(poly_proj_pred) => {
-                tcx.collect_referenced_late_bound_regions(&bound_predicate.rebind(poly_proj_pred))
-            }
-            _ => return FxHashSet::default(),
-        };
+        let regions =
+            match bound_predicate.skip_binder() {
+                ty::ClauseKind::Trait(poly_trait_pred) => tcx
+                    .collect_referenced_late_bound_regions(bound_predicate.rebind(poly_trait_pred)),
+                ty::ClauseKind::Projection(poly_proj_pred) => tcx
+                    .collect_referenced_late_bound_regions(bound_predicate.rebind(poly_proj_pred)),
+                _ => return FxHashSet::default(),
+            };
 
         regions
             .into_iter()