Unwrap the results of type folders

Author: LeSeulArtichaut

compiler/rustc_infer/src/infer/canonical/canonicalizer.rs

@@ -519,7 +519,7 @@ impl<'cx, 'tcx> Canonicalizer<'cx, 'tcx> {
             indices: FxHashMap::default(),
             binder_index: ty::INNERMOST,
         };
-        let out_value = value.fold_with(&mut canonicalizer);
+        let out_value = value.fold_with(&mut canonicalizer).into_ok();
 
         // Once we have canonicalized `out_value`, it should not
         // contain anything that ties it to this inference context
@@ -637,7 +637,7 @@ impl<'cx, 'tcx> Canonicalizer<'cx, 'tcx> {
         let infcx = self.infcx.expect("encountered ty-var without infcx");
         let bound_to = infcx.shallow_resolve(ty_var);
         if bound_to != ty_var {
-            self.fold_ty(bound_to)
+            self.fold_ty(bound_to).into_ok()
         } else {
             let var = self.canonical_var(info, ty_var.into());
             self.tcx().mk_ty(ty::Bound(self.binder_index, var.into()))
@@ -656,12 +656,12 @@ impl<'cx, 'tcx> Canonicalizer<'cx, 'tcx> {
         let infcx = self.infcx.expect("encountered const-var without infcx");
         let bound_to = infcx.shallow_resolve(const_var);
         if bound_to != const_var {
-            self.fold_const(bound_to)
+            self.fold_const(bound_to).into_ok()
         } else {
             let var = self.canonical_var(info, const_var.into());
             self.tcx().mk_const(ty::Const {
                 val: ty::ConstKind::Bound(self.binder_index, var),
-                ty: self.fold_ty(const_var.ty),
+                ty: self.fold_ty(const_var.ty).into_ok(),
             })
         }
     }

compiler/rustc_infer/src/infer/freshen.rs

@@ -70,7 +70,7 @@ impl<'a, 'tcx> TypeFreshener<'a, 'tcx> {
         F: FnOnce(u32) -> ty::InferTy,
     {
         if let Some(ty) = opt_ty {
-            return ty.fold_with(self);
+            return ty.fold_with(self).into_ok();
         }
 
         match self.ty_freshen_map.entry(key) {
@@ -96,7 +96,7 @@ impl<'a, 'tcx> TypeFreshener<'a, 'tcx> {
         F: FnOnce(u32) -> ty::InferConst<'tcx>,
     {
         if let Some(ct) = opt_ct {
-            return ct.fold_with(self);
+            return ct.fold_with(self).into_ok();
         }
 
         match self.const_freshen_map.entry(key) {

compiler/rustc_infer/src/infer/fudge.rs

@@ -162,7 +162,7 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
         {
             Ok(value)
         } else {
-            Ok(value.fold_with(&mut fudger))
+            Ok(value.fold_with(&mut fudger).into_ok())
         }
     }
 }

compiler/rustc_infer/src/infer/mod.rs

@@ -635,7 +635,7 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
     }
 
     pub fn freshen<T: TypeFoldable<'tcx>>(&self, t: T) -> T {
-        t.fold_with(&mut self.freshener())
+        t.fold_with(&mut self.freshener()).into_ok()
     }
 
     pub fn type_var_diverges(&'a self, ty: Ty<'_>) -> bool {
@@ -1287,7 +1287,7 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
     where
         T: TypeFoldable<'tcx>,
     {
-        value.fold_with(&mut ShallowResolver { infcx: self })
+        value.fold_with(&mut ShallowResolver { infcx: self }).into_ok()
     }
 
     pub fn root_var(&self, var: ty::TyVid) -> ty::TyVid {
@@ -1308,7 +1308,7 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
             return value; // Avoid duplicated subst-folding.
         }
         let mut r = resolve::OpportunisticVarResolver::new(self);
-        value.fold_with(&mut r)
+        value.fold_with(&mut r).into_ok()
     }
 
     /// Returns the first unresolved variable contained in `T`. In the

compiler/rustc_infer/src/infer/resolve.rs

@@ -177,7 +177,7 @@ where
     T: TypeFoldable<'tcx>,
 {
     let mut full_resolver = FullTypeResolver { infcx, err: None };
-    let result = value.fold_with(&mut full_resolver);
+    let result = value.fold_with(&mut full_resolver).into_ok();
     match full_resolver.err {
         None => Ok(result),
         Some(e) => Err(e),

compiler/rustc_infer/src/lib.rs

@@ -24,6 +24,7 @@
 #![feature(control_flow_enum)]
 #![feature(min_specialization)]
 #![feature(trusted_step)]
+#![feature(unwrap_infallible)]
 #![recursion_limit = "512"] // For rustdoc
 
 #[macro_use]

compiler/rustc_middle/src/lib.rs

@@ -51,6 +51,7 @@
 #![feature(iter_zip)]
 #![feature(thread_local_const_init)]
 #![feature(trusted_step)]
+#![feature(unwrap_infallible)]
 #![recursion_limit = "512"]
 
 #[macro_use]

compiler/rustc_middle/src/ty/erase_regions.rs

@@ -9,7 +9,7 @@ pub(super) fn provide(providers: &mut ty::query::Providers) {
 fn erase_regions_ty<'tcx>(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> Ty<'tcx> {
     // N.B., use `super_fold_with` here. If we used `fold_with`, it
     // could invoke the `erase_regions_ty` query recursively.
-    ty.super_fold_with(&mut RegionEraserVisitor { tcx })
+    ty.super_fold_with(&mut RegionEraserVisitor { tcx }).into_ok()
 }
 
 impl<'tcx> TyCtxt<'tcx> {
@@ -25,7 +25,7 @@ impl<'tcx> TyCtxt<'tcx> {
             return value;
         }
         debug!("erase_regions({:?})", value);
-        let value1 = value.fold_with(&mut RegionEraserVisitor { tcx: self });
+        let value1 = value.fold_with(&mut RegionEraserVisitor { tcx: self }).into_ok();
         debug!("erase_regions = {:?}", value1);
         value1
     }

compiler/rustc_middle/src/ty/fold.rs

@@ -282,7 +282,7 @@ impl<'tcx> TyCtxt<'tcx> {
     where
         T: TypeFoldable<'tcx>,
     {
-        value.fold_with(&mut RegionFolder::new(self, skipped_regions, &mut f))
+        value.fold_with(&mut RegionFolder::new(self, skipped_regions, &mut f)).into_ok()
     }
 
     /// Invoke `callback` on every region appearing free in `value`.
@@ -582,7 +582,7 @@ impl<'tcx> TyCtxt<'tcx> {
             value
         } else {
             let mut replacer = BoundVarReplacer::new(self, Some(&mut real_fld_r), None, None);
-            value.fold_with(&mut replacer)
+            value.fold_with(&mut replacer).into_ok()
         };
         (value, region_map)
     }
@@ -608,7 +608,7 @@ impl<'tcx> TyCtxt<'tcx> {
         } else {
             let mut replacer =
                 BoundVarReplacer::new(self, Some(&mut fld_r), Some(&mut fld_t), Some(&mut fld_c));
-            value.fold_with(&mut replacer)
+            value.fold_with(&mut replacer).into_ok()
         }
     }
 
@@ -1051,7 +1051,7 @@ where
 {
     debug!("shift_vars(value={:?}, amount={})", value, amount);
 
-    value.fold_with(&mut Shifter::new(tcx, amount))
+    value.fold_with(&mut Shifter::new(tcx, amount)).into_ok()
 }
 
 #[derive(Debug, PartialEq, Eq, Copy, Clone)]

compiler/rustc_middle/src/ty/instance.rs

@@ -589,7 +589,7 @@ fn polymorphize<'tcx>(
                     // ..and polymorphize any closures/generators captured as upvars.
                     let upvars_ty = upvars_ty.unwrap();
                     let polymorphized_upvars_ty = upvars_ty.fold_with(
-                        &mut PolymorphizationFolder { tcx });
+                        &mut PolymorphizationFolder { tcx }).into_ok();
                     debug!("polymorphize: polymorphized_upvars_ty={:?}", polymorphized_upvars_ty);
                     ty::GenericArg::from(polymorphized_upvars_ty)
                 },

compiler/rustc_middle/src/ty/normalize_erasing_regions.rs

@@ -35,7 +35,9 @@ impl<'tcx> TyCtxt<'tcx> {
         if !value.has_projections() {
             value
         } else {
-            value.fold_with(&mut NormalizeAfterErasingRegionsFolder { tcx: self, param_env })
+            value
+                .fold_with(&mut NormalizeAfterErasingRegionsFolder { tcx: self, param_env })
+                .into_ok()
         }
     }
 

compiler/rustc_middle/src/ty/subst.rs

@@ -431,7 +431,7 @@ impl<'tcx, T: TypeFoldable<'tcx>> Subst<'tcx> for T {
         span: Option<Span>,
     ) -> T {
         let mut folder = SubstFolder { tcx, substs, span, binders_passed: 0 };
-        self.fold_with(&mut folder)
+        self.fold_with(&mut folder).into_ok()
     }
 }
 

compiler/rustc_middle/src/ty/util.rs

@@ -571,14 +571,14 @@ impl<'tcx> OpaqueTypeExpander<'tcx> {
         if self.found_recursion {
             return None;
         }
-        let substs = substs.fold_with(self);
+        let substs = substs.fold_with(self).into_ok();
         if !self.check_recursion || self.seen_opaque_tys.insert(def_id) {
             let expanded_ty = match self.expanded_cache.get(&(def_id, substs)) {
                 Some(expanded_ty) => expanded_ty,
                 None => {
                     let generic_ty = self.tcx.type_of(def_id);
                     let concrete_ty = generic_ty.subst(self.tcx, substs);
-                    let expanded_ty = self.fold_ty(concrete_ty);
+                    let expanded_ty = self.fold_ty(concrete_ty).into_ok();
                     self.expanded_cache.insert((def_id, substs), expanded_ty);
                     expanded_ty
                 }
@@ -1073,7 +1073,7 @@ pub fn normalize_opaque_types(
         check_recursion: false,
         tcx,
     };
-    val.fold_with(&mut visitor)
+    val.fold_with(&mut visitor).into_ok()
 }
 
 pub fn provide(providers: &mut ty::query::Providers) {

compiler/rustc_mir/src/lib.rs

@@ -32,6 +32,7 @@ Rust MIR: a lowered representation of Rust.
 #![feature(once_cell)]
 #![feature(control_flow_enum)]
 #![feature(trusted_step)]
+#![feature(unwrap_infallible)]
 #![recursion_limit = "256"]
 
 #[macro_use]

compiler/rustc_mir/src/transform/validate.rs

@@ -95,7 +95,8 @@ pub fn equal_up_to_regions(
                 // Leave consts and types unchanged.
                 ct_op: |ct| ct,
                 ty_op: |ty| ty,
-            }),
+            })
+            .into_ok(),
         )
     };
     tcx.infer_ctxt().enter(|infcx| infcx.can_eq(param_env, normalize(src), normalize(dest)).is_ok())