Rollup merge of #61842 - Zoxc:trim-lift, r=eddyb

Remove unnecessary lift calls

Note that some of these might be useful for sanity checking that there's no infer types or regions.

r? @eddyb

Author: Centril

src/librustc/infer/canonical/canonicalizer.rs

@@ -14,7 +14,7 @@ use crate::mir::interpret::ConstValue;
 use std::sync::atomic::Ordering;
 use crate::ty::fold::{TypeFoldable, TypeFolder};
 use crate::ty::subst::Kind;
-use crate::ty::{self, BoundVar, InferConst, Lift, List, Ty, TyCtxt, TypeFlags};
+use crate::ty::{self, BoundVar, InferConst, List, Ty, TyCtxt, TypeFlags};
 use crate::ty::flags::FlagComputation;
 
 use rustc_data_structures::fx::FxHashMap;
@@ -43,7 +43,7 @@ impl<'cx, 'tcx> InferCtxt<'cx, 'tcx> {
         query_state: &mut OriginalQueryValues<'tcx>,
     ) -> Canonicalized<'tcx, V>
     where
-        V: TypeFoldable<'tcx> + Lift<'tcx>,
+        V: TypeFoldable<'tcx>,
     {
         self.tcx
             .sess
@@ -87,7 +87,7 @@ impl<'cx, 'tcx> InferCtxt<'cx, 'tcx> {
     /// [c]: https://rust-lang.github.io/rustc-guide/traits/canonicalization.html#canonicalizing-the-query-result
     pub fn canonicalize_response<V>(&self, value: &V) -> Canonicalized<'tcx, V>
     where
-        V: TypeFoldable<'tcx> + Lift<'tcx>,
+        V: TypeFoldable<'tcx>,
     {
         let mut query_state = OriginalQueryValues::default();
         Canonicalizer::canonicalize(
@@ -101,7 +101,7 @@ impl<'cx, 'tcx> InferCtxt<'cx, 'tcx> {
 
     pub fn canonicalize_user_type_annotation<V>(&self, value: &V) -> Canonicalized<'tcx, V>
     where
-        V: TypeFoldable<'tcx> + Lift<'tcx>,
+        V: TypeFoldable<'tcx>,
     {
         let mut query_state = OriginalQueryValues::default();
         Canonicalizer::canonicalize(
@@ -132,7 +132,7 @@ impl<'cx, 'tcx> InferCtxt<'cx, 'tcx> {
         query_state: &mut OriginalQueryValues<'tcx>,
     ) -> Canonicalized<'tcx, V>
     where
-        V: TypeFoldable<'tcx> + Lift<'tcx>,
+        V: TypeFoldable<'tcx>,
     {
         self.tcx
             .sess
@@ -506,7 +506,7 @@ impl<'cx, 'tcx> Canonicalizer<'cx, 'tcx> {
         query_state: &mut OriginalQueryValues<'tcx>,
     ) -> Canonicalized<'tcx, V>
     where
-        V: TypeFoldable<'tcx> + Lift<'tcx>,
+        V: TypeFoldable<'tcx>,
     {
         let needs_canonical_flags = if canonicalize_region_mode.any() {
             TypeFlags::KEEP_IN_LOCAL_TCX |
@@ -520,20 +520,12 @@ impl<'cx, 'tcx> Canonicalizer<'cx, 'tcx> {
             TypeFlags::HAS_CT_PLACEHOLDER
         };
 
-        let gcx = tcx.global_tcx();
-
         // Fast path: nothing that needs to be canonicalized.
         if !value.has_type_flags(needs_canonical_flags) {
-            let out_value = gcx.lift(value).unwrap_or_else(|| {
-                bug!(
-                    "failed to lift `{:?}` (nothing to canonicalize)",
-                    value
-                )
-            });
             let canon_value = Canonical {
                 max_universe: ty::UniverseIndex::ROOT,
                 variables: List::empty(),
-                value: out_value,
+                value: value.clone(),
             };
             return canon_value;
         }
@@ -553,13 +545,7 @@ impl<'cx, 'tcx> Canonicalizer<'cx, 'tcx> {
         // Once we have canonicalized `out_value`, it should not
         // contain anything that ties it to this inference context
         // anymore, so it should live in the global arena.
-        let out_value = gcx.lift(&out_value).unwrap_or_else(|| {
-            bug!(
-                "failed to lift `{:?}`, canonicalized from `{:?}`",
-                out_value,
-                value
-            )
-        });
+        debug_assert!(!out_value.has_type_flags(TypeFlags::KEEP_IN_LOCAL_TCX));
 
         let canonical_variables = tcx.intern_canonical_var_infos(&canonicalizer.variables);
 

src/librustc/infer/canonical/mod.rs

@@ -194,10 +194,10 @@ pub struct QueryResponse<'tcx, R> {
     pub value: R,
 }
 
-pub type Canonicalized<'tcx, V> = Canonical<'tcx, <V as Lift<'tcx>>::Lifted>;
+pub type Canonicalized<'tcx, V> = Canonical<'tcx, V>;
 
 pub type CanonicalizedQueryResponse<'tcx, T> =
-    &'tcx Canonical<'tcx, QueryResponse<'tcx, <T as Lift<'tcx>>::Lifted>>;
+    &'tcx Canonical<'tcx, QueryResponse<'tcx, T>>;
 
 /// Indicates whether or not we were able to prove the query to be
 /// true.

src/librustc/infer/canonical/query_response.rs

@@ -26,7 +26,7 @@ use crate::traits::TraitEngine;
 use crate::traits::{Obligation, ObligationCause, PredicateObligation};
 use crate::ty::fold::TypeFoldable;
 use crate::ty::subst::{Kind, UnpackedKind};
-use crate::ty::{self, BoundVar, InferConst, Lift, Ty, TyCtxt};
+use crate::ty::{self, BoundVar, InferConst, Ty, TyCtxt};
 use crate::util::captures::Captures;
 
 impl<'tcx> InferCtxtBuilder<'tcx> {
@@ -53,8 +53,8 @@ impl<'tcx> InferCtxtBuilder<'tcx> {
     ) -> Fallible<CanonicalizedQueryResponse<'tcx, R>>
     where
         K: TypeFoldable<'tcx>,
-        R: Debug + Lift<'tcx> + TypeFoldable<'tcx>,
-        Canonical<'tcx, <QueryResponse<'tcx, R> as Lift<'tcx>>::Lifted>: ArenaAllocatable,
+        R: Debug + TypeFoldable<'tcx>,
+        Canonical<'tcx, QueryResponse<'tcx, R>>: ArenaAllocatable,
     {
         self.enter_with_canonical(
             DUMMY_SP,
@@ -99,8 +99,8 @@ impl<'cx, 'tcx> InferCtxt<'cx, 'tcx> {
         fulfill_cx: &mut dyn TraitEngine<'tcx>,
     ) -> Fallible<CanonicalizedQueryResponse<'tcx, T>>
     where
-        T: Debug + Lift<'tcx> + TypeFoldable<'tcx>,
-        Canonical<'tcx, <QueryResponse<'tcx, T> as Lift<'tcx>>::Lifted>: ArenaAllocatable,
+        T: Debug + TypeFoldable<'tcx>,
+        Canonical<'tcx, QueryResponse<'tcx, T>>: ArenaAllocatable,
     {
         let query_response = self.make_query_response(inference_vars, answer, fulfill_cx)?;
         let canonical_result = self.canonicalize_response(&query_response);
@@ -126,9 +126,9 @@ impl<'cx, 'tcx> InferCtxt<'cx, 'tcx> {
         &self,
         inference_vars: CanonicalVarValues<'tcx>,
         answer: T,
-    ) -> Canonical<'tcx, QueryResponse<'tcx, <T as Lift<'tcx>>::Lifted>>
+    ) -> Canonical<'tcx, QueryResponse<'tcx, T>>
     where
-        T: Debug + Lift<'tcx> + TypeFoldable<'tcx>,
+        T: Debug + TypeFoldable<'tcx>,
     {
         self.canonicalize_response(&QueryResponse {
             var_values: inference_vars,
@@ -147,7 +147,7 @@ impl<'cx, 'tcx> InferCtxt<'cx, 'tcx> {
         fulfill_cx: &mut dyn TraitEngine<'tcx>,
     ) -> Result<QueryResponse<'tcx, T>, NoSolution>
     where
-        T: Debug + TypeFoldable<'tcx> + Lift<'tcx>,
+        T: Debug + TypeFoldable<'tcx>,
     {
         let tcx = self.tcx;
 

src/librustc/infer/opaque_types/mod.rs

@@ -469,11 +469,6 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
             definition_ty
         );
 
-        // We can unwrap here because our reverse mapper always
-        // produces things with 'tcx lifetime, though the type folder
-        // obscures that.
-        let definition_ty = gcx.lift(&definition_ty).unwrap();
-
         definition_ty
     }
 }

src/librustc/middle/mem_categorization.rs

@@ -817,10 +817,7 @@ impl<'a, 'tcx> MemCategorizationContext<'a, 'tcx> {
                              .unwrap_or(ty::ClosureKind::LATTICE_BOTTOM),
 
                     None =>
-                        self.tcx.global_tcx()
-                                .lift(&closure_substs)
-                                .expect("no inference cx, but inference variables in closure ty")
-                                .closure_kind(closure_def_id, self.tcx.global_tcx()),
+                        closure_substs.closure_kind(closure_def_id, self.tcx.global_tcx()),
                 }
             }
             _ => span_bug!(span, "unexpected type for fn in mem_categorization: {:?}", ty),

src/librustc/traits/codegen/mod.rs

@@ -141,9 +141,9 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
         &self,
         fulfill_cx: &mut FulfillmentContext<'tcx>,
         result: &T,
-    ) -> T::Lifted
+    ) -> T
     where
-        T: TypeFoldable<'tcx> + ty::Lift<'tcx>,
+        T: TypeFoldable<'tcx>,
     {
         debug!("drain_fulfillment_cx_or_panic()");
 
@@ -155,10 +155,6 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
         }
 
         let result = self.resolve_vars_if_possible(result);
-        let result = self.tcx.erase_regions(&result);
-
-        self.tcx.lift_to_global(&result).unwrap_or_else(||
-            bug!("Uninferred types/regions/consts in `{:?}`", result)
-        )
+        self.tcx.erase_regions(&result)
     }
 }

src/librustc/traits/project.rs

@@ -409,7 +409,6 @@ impl<'a, 'b, 'tcx> TypeFolder<'tcx> for AssocTypeNormalizer<'a, 'b, 'tcx> {
                             promoted: None
                         };
                         if let Ok(evaluated) = tcx.const_eval(param_env.and(cid)) {
-                            let substs = tcx.lift_to_global(&substs).unwrap();
                             let evaluated = evaluated.subst(tcx, substs);
                             return evaluated;
                         }

src/librustc/traits/query/normalize.rs

@@ -203,7 +203,6 @@ impl<'cx, 'tcx> TypeFolder<'tcx> for QueryNormalizer<'cx, 'tcx> {
                             promoted: None,
                         };
                         if let Ok(evaluated) = tcx.const_eval(param_env.and(cid)) {
-                            let substs = tcx.lift_to_global(&substs).unwrap();
                             let evaluated = evaluated.subst(tcx, substs);
                             return evaluated;
                         }

src/librustc/traits/query/type_op/mod.rs

@@ -8,7 +8,7 @@ use std::rc::Rc;
 use crate::traits::query::Fallible;
 use crate::traits::ObligationCause;
 use crate::ty::fold::TypeFoldable;
-use crate::ty::{Lift, ParamEnvAnd, TyCtxt};
+use crate::ty::{ParamEnvAnd, TyCtxt};
 
 pub mod ascribe_user_type;
 pub mod custom;
@@ -44,8 +44,8 @@ pub trait TypeOp<'tcx>: Sized + fmt::Debug {
 /// which produces the resulting query region constraints.
 ///
 /// [c]: https://rust-lang.github.io/rustc-guide/traits/canonicalization.html
-pub trait QueryTypeOp<'tcx>: fmt::Debug + Sized + TypeFoldable<'tcx> + Lift<'tcx> {
-    type QueryResponse: TypeFoldable<'tcx> + Lift<'tcx>;
+pub trait QueryTypeOp<'tcx>: fmt::Debug + Sized + TypeFoldable<'tcx> + 'tcx {
+    type QueryResponse: TypeFoldable<'tcx>;
 
     /// Give query the option for a simple fast path that never
     /// actually hits the tcx cache lookup etc. Return `Some(r)` with

src/librustc/traits/query/type_op/normalize.rs

@@ -20,7 +20,7 @@ where
 
 impl<'tcx, T> super::QueryTypeOp<'tcx> for Normalize<T>
 where
-    T: Normalizable<'tcx>,
+    T: Normalizable<'tcx> + 'tcx,
 {
     type QueryResponse = T;