Rollup merge of #65660 - varkor:canonical-const-to-bound-const, r=eddyb

Rename `ConstValue::Infer(InferConst::Canonical(..))` to `ConstValue::Bound(..)`

It already has the right form, so this is just a renaming. Fixes #65655.

r? @eddyb

src/librustc/infer/canonical/canonicalizer.rs

@@ -468,7 +468,7 @@ impl<'cx, 'tcx> TypeFolder<'tcx> for Canonicalizer<'cx, 'tcx> {
             ConstValue::Infer(InferConst::Fresh(_)) => {
                 bug!("encountered a fresh const during canonicalization")
             }
-            ConstValue::Infer(InferConst::Canonical(debruijn, _)) => {
+            ConstValue::Bound(debruijn, _) => {
                 if debruijn >= self.binder_index {
                     bug!("escaping bound type during canonicalization")
                 } else {
@@ -700,7 +700,7 @@ impl<'cx, 'tcx> Canonicalizer<'cx, 'tcx> {
             let var = self.canonical_var(info, const_var.into());
             self.tcx().mk_const(
                 ty::Const {
-                    val: ConstValue::Infer(InferConst::Canonical(self.binder_index, var.into())),
+                    val: ConstValue::Bound(self.binder_index, var.into()),
                     ty: self.fold_ty(const_var.ty),
                 }
             )

src/librustc/infer/canonical/mod.rs

@@ -33,7 +33,7 @@ use std::ops::Index;
 use syntax::source_map::Span;
 use crate::ty::fold::TypeFoldable;
 use crate::ty::subst::GenericArg;
-use crate::ty::{self, BoundVar, InferConst, Lift, List, Region, TyCtxt};
+use crate::ty::{self, BoundVar, Lift, List, Region, TyCtxt};
 
 mod canonicalizer;
 
@@ -510,9 +510,7 @@ impl<'tcx> CanonicalVarValues<'tcx> {
                     GenericArgKind::Const(ct) => {
                         tcx.mk_const(ty::Const {
                             ty: ct.ty,
-                            val: ConstValue::Infer(
-                                InferConst::Canonical(ty::INNERMOST, ty::BoundVar::from_u32(i))
-                            ),
+                            val: ConstValue::Bound(ty::INNERMOST, ty::BoundVar::from_u32(i)),
                         }).into()
                     }
                 })

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::{GenericArg, GenericArgKind};
-use crate::ty::{self, BoundVar, InferConst, Ty, TyCtxt};
+use crate::ty::{self, BoundVar, Ty, TyCtxt};
 use crate::util::captures::Captures;
 
 impl<'tcx> InferCtxtBuilder<'tcx> {
@@ -493,10 +493,7 @@ impl<'cx, 'tcx> InferCtxt<'cx, 'tcx> {
                     }
                 }
                 GenericArgKind::Const(result_value) => {
-                    if let ty::Const {
-                        val: ConstValue::Infer(InferConst::Canonical(debrujin, b)),
-                        ..
-                    } = result_value {
+                    if let ty::Const { val: ConstValue::Bound(debrujin, b), .. } = result_value {
                         // ...in which case we would set `canonical_vars[0]` to `Some(const X)`.
 
                         // We only allow a `ty::INNERMOST` index in substitutions.

src/librustc/infer/freshen.rs

@@ -252,7 +252,7 @@ impl<'a, 'tcx> TypeFolder<'tcx> for TypeFreshener<'a, 'tcx> {
                 return ct;
             }
 
-            ConstValue::Infer(ty::InferConst::Canonical(..)) |
+            ConstValue::Bound(..) |
             ConstValue::Placeholder(_) => {
                 bug!("unexpected const {:?}", ct)
             }

src/librustc/infer/nll_relate/mod.rs

@@ -27,7 +27,7 @@ use crate::ty::error::TypeError;
 use crate::ty::fold::{TypeFoldable, TypeVisitor};
 use crate::ty::relate::{self, Relate, RelateResult, TypeRelation};
 use crate::ty::subst::GenericArg;
-use crate::ty::{self, Ty, TyCtxt, InferConst};
+use crate::ty::{self, Ty, TyCtxt};
 use crate::mir::interpret::ConstValue;
 use rustc_data_structures::fx::FxHashMap;
 use std::fmt::Debug;
@@ -618,7 +618,7 @@ where
         a: &'tcx ty::Const<'tcx>,
         b: &'tcx ty::Const<'tcx>,
     ) -> RelateResult<'tcx, &'tcx ty::Const<'tcx>> {
-        if let ty::Const { val: ConstValue::Infer(InferConst::Canonical(_, _)), .. } = a {
+        if let ty::Const { val: ConstValue::Bound(..), .. } = a {
             // FIXME(const_generics): I'm unsure how this branch should actually be handled,
             // so this is probably not correct.
             self.infcx.super_combine_consts(self, a, b)
@@ -993,7 +993,7 @@ where
     ) -> RelateResult<'tcx, &'tcx ty::Const<'tcx>> {
         debug!("TypeGeneralizer::consts(a={:?})", a);
 
-        if let ty::Const { val: ConstValue::Infer(InferConst::Canonical(_, _)), .. } = a {
+        if let ty::Const { val: ConstValue::Bound(..), .. } = a {
             bug!(
                 "unexpected inference variable encountered in NLL generalization: {:?}",
                 a

src/librustc/mir/interpret/value.rs

@@ -5,6 +5,7 @@ use rustc_apfloat::{Float, ieee::{Double, Single}};
 use crate::ty::{Ty, InferConst, ParamConst, layout::{HasDataLayout, Size}, subst::SubstsRef};
 use crate::ty::PlaceholderConst;
 use crate::hir::def_id::DefId;
+use crate::ty::{BoundVar, DebruijnIndex};
 
 use super::{InterpResult, Pointer, PointerArithmetic, Allocation, AllocId, sign_extend, truncate};
 
@@ -28,6 +29,9 @@ pub enum ConstValue<'tcx> {
     /// Infer the value of the const.
     Infer(InferConst<'tcx>),
 
+    /// Bound const variable, used only when preparing a trait query.
+    Bound(DebruijnIndex, BoundVar),
+
     /// A placeholder const - universally quantified higher-ranked const.
     Placeholder(PlaceholderConst),
 
@@ -66,8 +70,9 @@ impl<'tcx> ConstValue<'tcx> {
         match *self {
             ConstValue::Param(_) |
             ConstValue::Infer(_) |
+            ConstValue::Bound(..) |
             ConstValue::Placeholder(_) |
-            ConstValue::ByRef{ .. } |
+            ConstValue::ByRef { .. } |
             ConstValue::Unevaluated(..) |
             ConstValue::Slice { .. } => None,
             ConstValue::Scalar(val) => Some(val),

src/librustc/ty/context.rs

@@ -882,7 +882,7 @@ impl CanonicalUserType<'tcx> {
                         },
 
                         GenericArgKind::Const(ct) => match ct.val {
-                            ConstValue::Infer(InferConst::Canonical(debruijn, b)) => {
+                            ConstValue::Bound(debruijn, b) => {
                                 // We only allow a `ty::INNERMOST` index in substitutions.
                                 assert_eq!(debruijn, ty::INNERMOST);
                                 cvar == b

src/librustc/ty/flags.rs

@@ -240,10 +240,10 @@ impl FlagComputation {
                 self.add_flags(TypeFlags::HAS_FREE_LOCAL_NAMES | TypeFlags::HAS_CT_INFER);
                 match infer {
                     InferConst::Fresh(_) => {}
-                    InferConst::Canonical(debruijn, _) => self.add_binder(debruijn),
                     InferConst::Var(_) => self.add_flags(TypeFlags::KEEP_IN_LOCAL_TCX),
                 }
             }
+            ConstValue::Bound(debruijn, _) => self.add_binder(debruijn),
             ConstValue::Param(_) => {
                 self.add_flags(TypeFlags::HAS_FREE_LOCAL_NAMES | TypeFlags::HAS_PARAMS);
             }

src/librustc/ty/fold.rs

@@ -521,10 +521,7 @@ impl<'a, 'tcx> TypeFolder<'tcx> for BoundVarReplacer<'a, 'tcx> {
     }
 
     fn fold_const(&mut self, ct: &'tcx ty::Const<'tcx>) -> &'tcx ty::Const<'tcx> {
-        if let ty::Const {
-            val: ConstValue::Infer(ty::InferConst::Canonical(debruijn, bound_const)),
-            ty,
-        } = *ct {
+        if let ty::Const { val: ConstValue::Bound(debruijn, bound_const), ty } = *ct {
             if debruijn == self.current_index {
                 let fld_c = &mut self.fld_c;
                 let ct = fld_c(bound_const, ty);
@@ -570,7 +567,10 @@ impl<'tcx> TyCtxt<'tcx> {
         // identity for bound types and consts
         let fld_t = |bound_ty| self.mk_ty(ty::Bound(ty::INNERMOST, bound_ty));
         let fld_c = |bound_ct, ty| {
-            self.mk_const_infer(ty::InferConst::Canonical(ty::INNERMOST, bound_ct), ty)
+            self.mk_const(ty::Const {
+                val: ConstValue::Bound(ty::INNERMOST, bound_ct),
+                ty,
+            })
         };
         self.replace_escaping_bound_vars(value.skip_binder(), fld_r, fld_t, fld_c)
     }
@@ -801,10 +801,7 @@ impl TypeFolder<'tcx> for Shifter<'tcx> {
     }
 
     fn fold_const(&mut self, ct: &'tcx ty::Const<'tcx>) -> &'tcx ty::Const<'tcx> {
-        if let ty::Const {
-            val: ConstValue::Infer(ty::InferConst::Canonical(debruijn, bound_const)),
-            ty,
-        } = *ct {
+        if let ty::Const { val: ConstValue::Bound(debruijn, bound_ct), ty } = *ct {
             if self.amount == 0 || debruijn < self.current_index {
                 ct
             } else {
@@ -815,7 +812,10 @@ impl TypeFolder<'tcx> for Shifter<'tcx> {
                         debruijn.shifted_out(self.amount)
                     }
                 };
-                self.tcx.mk_const_infer(ty::InferConst::Canonical(debruijn, bound_const), ty)
+                self.tcx.mk_const(ty::Const {
+                    val: ConstValue::Bound(debruijn, bound_ct),
+                    ty,
+                })
             }
         } else {
             ct.super_fold_with(self)
@@ -919,8 +919,7 @@ impl<'tcx> TypeVisitor<'tcx> for HasEscapingVarsVisitor {
         // const, as it has types/regions embedded in a lot of other
         // places.
         match ct.val {
-            ConstValue::Infer(ty::InferConst::Canonical(debruijn, _))
-                if debruijn >= self.outer_index => true,
+            ConstValue::Bound(debruijn, _) if debruijn >= self.outer_index => true,
             _ => ct.super_visit_with(self),
         }
     }

src/librustc/ty/structural_impls.rs

@@ -1379,27 +1379,23 @@ impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::Const<'tcx> {
 impl<'tcx> TypeFoldable<'tcx> for ConstValue<'tcx> {
     fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self {
         match *self {
-            ConstValue::ByRef { alloc, offset } =>
-                ConstValue::ByRef { alloc, offset },
             ConstValue::Infer(ic) => ConstValue::Infer(ic.fold_with(folder)),
             ConstValue::Param(p) => ConstValue::Param(p.fold_with(folder)),
-            ConstValue::Placeholder(p) => ConstValue::Placeholder(p),
-            ConstValue::Scalar(a) => ConstValue::Scalar(a),
-            ConstValue::Slice { data, start, end } => ConstValue::Slice { data, start, end },
             ConstValue::Unevaluated(did, substs)
                 => ConstValue::Unevaluated(did, substs.fold_with(folder)),
+            ConstValue::ByRef { .. } | ConstValue::Bound(..) | ConstValue::Placeholder(..)
+            | ConstValue::Scalar(..) | ConstValue::Slice { .. } => *self,
+
         }
     }
 
     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
         match *self {
-            ConstValue::ByRef { .. } => false,
             ConstValue::Infer(ic) => ic.visit_with(visitor),
             ConstValue::Param(p) => p.visit_with(visitor),
-            ConstValue::Placeholder(_) => false,
-            ConstValue::Scalar(_) => false,
-            ConstValue::Slice { .. } => false,
             ConstValue::Unevaluated(_, substs) => substs.visit_with(visitor),
+            ConstValue::ByRef { .. } | ConstValue::Bound(..) | ConstValue::Placeholder(_)
+            | ConstValue::Scalar(_) | ConstValue::Slice { .. } => false,
         }
     }
 }

src/librustc/ty/sty.rs

@@ -2371,6 +2371,4 @@ pub enum InferConst<'tcx> {
     Var(ConstVid<'tcx>),
     /// A fresh const variable. See `infer::freshen` for more details.
     Fresh(u32),
-    /// Canonicalized const variable, used only when preparing a trait query.
-    Canonical(DebruijnIndex, BoundVar),
 }

src/librustc/ty/subst.rs

@@ -2,7 +2,7 @@
 
 use crate::hir::def_id::DefId;
 use crate::infer::canonical::Canonical;
-use crate::ty::{self, Lift, List, Ty, TyCtxt, InferConst, ParamConst};
+use crate::ty::{self, Lift, List, Ty, TyCtxt, ParamConst};
 use crate::ty::fold::{TypeFoldable, TypeFolder, TypeVisitor};
 use crate::mir::interpret::ConstValue;
 use crate::ty::sty::{ClosureSubsts, GeneratorSubsts};
@@ -234,9 +234,7 @@ impl<'a, 'tcx> InternalSubsts<'tcx> {
 
                 ty::GenericParamDefKind::Const => {
                     tcx.mk_const(ty::Const {
-                        val: ConstValue::Infer(
-                            InferConst::Canonical(ty::INNERMOST, ty::BoundVar::from(param.index))
-                        ),
+                        val: ConstValue::Bound(ty::INNERMOST, ty::BoundVar::from(param.index)),
                         ty: tcx.type_of(def_id),
                     }).into()
                 }

src/librustc_codegen_ssa/mir/operand.rs

@@ -79,6 +79,7 @@ impl<'a, 'tcx, V: CodegenObject> OperandRef<'tcx, V> {
             ConstValue::Unevaluated(..) => bug!("unevaluated constant in `OperandRef::from_const`"),
             ConstValue::Param(_) => bug!("encountered a ConstValue::Param in codegen"),
             ConstValue::Infer(_) => bug!("encountered a ConstValue::Infer in codegen"),
+            ConstValue::Bound(..) => bug!("encountered a ConstValue::Bound in codegen"),
             ConstValue::Placeholder(_) => bug!("encountered a ConstValue::Placeholder in codegen"),
             ConstValue::Scalar(x) => {
                 let scalar = match layout.abi {

src/librustc_mir/interpret/operand.rs

@@ -589,8 +589,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                 let ptr = self.tag_static_base_pointer(Pointer::new(id, offset));
                 Operand::Indirect(MemPlace::from_ptr(ptr, layout.align.abi))
             },
-            ConstValue::Scalar(x) =>
-                Operand::Immediate(tag_scalar(x).into()),
+            ConstValue::Scalar(x) => Operand::Immediate(tag_scalar(x).into()),
             ConstValue::Slice { data, start, end } => {
                 // We rely on mutability being set correctly in `data` to prevent writes
                 // where none should happen.
@@ -606,6 +605,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
             }
             ConstValue::Param(..) |
             ConstValue::Infer(..) |
+            ConstValue::Bound(..) |
             ConstValue::Placeholder(..) |
             ConstValue::Unevaluated(..) =>
                 bug!("eval_const_to_op: Unexpected ConstValue {:?}", val),

src/librustc_traits/chalk_context/mod.rs

@@ -33,7 +33,7 @@ use rustc::traits::{
     InEnvironment,
     ChalkCanonicalGoal,
 };
-use rustc::ty::{self, TyCtxt, InferConst};
+use rustc::ty::{self, TyCtxt};
 use rustc::ty::fold::{TypeFoldable, TypeFolder, TypeVisitor};
 use rustc::ty::query::Providers;
 use rustc::ty::subst::{GenericArg, GenericArgKind};
@@ -286,7 +286,7 @@ impl context::ContextOps<ChalkArenas<'tcx>> for ChalkContext<'tcx> {
                     _ => false,
                 },
                 GenericArgKind::Const(ct) => match ct.val {
-                    ConstValue::Infer(InferConst::Canonical(debruijn, bound_ct)) => {
+                    ConstValue::Bound(debruijn, bound_ct) => {
                         debug_assert_eq!(debruijn, ty::INNERMOST);
                         cvar == bound_ct
                     }

src/librustc_traits/chalk_context/resolvent_ops.rs

@@ -16,7 +16,7 @@ use rustc::traits::{
     Environment,
     InEnvironment,
 };
-use rustc::ty::{self, Ty, TyCtxt, InferConst};
+use rustc::ty::{self, Ty, TyCtxt};
 use rustc::ty::subst::GenericArg;
 use rustc::ty::relate::{Relate, RelateResult, TypeRelation};
 use rustc::mir::interpret::ConstValue;
@@ -287,10 +287,7 @@ impl TypeRelation<'tcx> for AnswerSubstitutor<'cx, 'tcx> {
         a: &'tcx ty::Const<'tcx>,
         b: &'tcx ty::Const<'tcx>,
     ) -> RelateResult<'tcx, &'tcx ty::Const<'tcx>> {
-        if let ty::Const {
-            val: ConstValue::Infer(InferConst::Canonical(debruijn, bound_ct)),
-            ..
-        } = a {
+        if let ty::Const { val: ConstValue::Bound(debruijn, bound_ct), .. } = a {
             if *debruijn == self.binder_index {
                 self.unify_free_answer_var(*bound_ct, b.into())?;
                 return Ok(b);
@@ -299,14 +296,8 @@ impl TypeRelation<'tcx> for AnswerSubstitutor<'cx, 'tcx> {
 
         match (a, b) {
             (
-                ty::Const {
-                    val: ConstValue::Infer(InferConst::Canonical(a_debruijn, a_bound)),
-                    ..
-                },
-                ty::Const {
-                    val: ConstValue::Infer(InferConst::Canonical(b_debruijn, b_bound)),
-                    ..
-                },
+                ty::Const { val: ConstValue::Bound(a_debruijn, a_bound), .. },
+                ty::Const { val: ConstValue::Bound(b_debruijn, b_bound), .. },
             ) => {
                 assert_eq!(a_debruijn, b_debruijn);
                 assert_eq!(a_bound, b_bound);

src/test/ui/symbol-names/impl1.legacy.stderr

@@ -46,13 +46,13 @@ error: def-path(bar::<impl foo::Foo>::baz)
 LL |         #[rustc_def_path]
    |         ^^^^^^^^^^^^^^^^^
 
-error: symbol-name(_ZN209_$LT$$u5b$$RF$dyn$u20$impl1..Foo$u2b$Assoc$u20$$u3d$$u20$extern$u20$$u22$C$u22$$u20$fn$LP$$RF$u8$C$$u20$...$RP$$u2b$impl1..AutoTrait$u3b$$u20$_$u5d$$u20$as$u20$impl1..main..$u7b$$u7b$closure$u7d$$u7d$..Bar$GT$6method17h059bf53000885489E)
+error: symbol-name(_ZN209_$LT$$u5b$$RF$dyn$u20$impl1..Foo$u2b$Assoc$u20$$u3d$$u20$extern$u20$$u22$C$u22$$u20$fn$LP$$RF$u8$C$$u20$...$RP$$u2b$impl1..AutoTrait$u3b$$u20$_$u5d$$u20$as$u20$impl1..main..$u7b$$u7b$closure$u7d$$u7d$..Bar$GT$6method17h636bc933fc62ee2fE)
   --> $DIR/impl1.rs:61:13
    |
 LL |             #[rustc_symbol_name]
    |             ^^^^^^^^^^^^^^^^^^^^
 
-error: demangling(<[&dyn impl1::Foo+Assoc = extern "C" fn(&u8, ::.)+impl1::AutoTrait; _] as impl1::main::{{closure}}::Bar>::method::h059bf53000885489)
+error: demangling(<[&dyn impl1::Foo+Assoc = extern "C" fn(&u8, ::.)+impl1::AutoTrait; _] as impl1::main::{{closure}}::Bar>::method::h636bc933fc62ee2f)
   --> $DIR/impl1.rs:61:13
    |
 LL |             #[rustc_symbol_name]