rustc: use ty::Const for the length of TyArray.

src/librustc/middle/const_val.rs

@@ -247,18 +247,23 @@ impl<'a, 'gcx, 'tcx> ConstEvalErr<'tcx> {
 }
 
 /// Returns the value of the length-valued expression
-pub fn eval_length(tcx: TyCtxt,
-                   count: hir::BodyId,
-                   reason: &str)
-                   -> Result<ConstUsize, ErrorReported>
+pub fn eval_length<'a, 'gcx, 'tcx>(tcx: TyCtxt<'a, 'gcx, 'tcx>,
+                                   count: hir::BodyId,
+                                   reason: &str)
+                                   -> Result<&'gcx ty::Const<'gcx>, ErrorReported>
 {
     let count_expr = &tcx.hir.body(count).value;
     let count_def_id = tcx.hir.body_owner_def_id(count);
     let param_env = ty::ParamEnv::empty(Reveal::UserFacing);
     let substs = Substs::identity_for_item(tcx.global_tcx(), count_def_id);
     match tcx.at(count_expr.span).const_eval(param_env.and((count_def_id, substs))) {
-        Ok(&ty::Const { val: Integral(Usize(count)), .. }) => Ok(count),
-        Ok(_) | Err(ConstEvalErr { kind: ErrKind::TypeckError, .. }) => Err(ErrorReported),
+        Ok(count) => {
+            // Elsewhere in the compiler this is enforced even in the presence
+            // of erroneous code (type mismatch error has already been emitted).
+            assert_eq!(count.ty, tcx.types.usize);
+            Ok(count)
+        }
+        Err(ConstEvalErr { kind: ErrKind::TypeckError, .. }) => Err(ErrorReported),
         Err(err) => {
             let mut diag = err.struct_error(tcx, count_expr.span, reason);
 

src/librustc/middle/mem_categorization.rs

@@ -876,7 +876,7 @@ impl<'a, 'gcx, 'tcx> MemCategorizationContext<'a, 'gcx, 'tcx> {
 
         // Always promote `[T; 0]` (even when e.g. borrowed mutably).
         let promotable = match expr_ty.sty {
-            ty::TyArray(_, len) if len.as_u64() == 0 => true,
+            ty::TyArray(_, len) if len.val.to_const_int().unwrap().to_u64().unwrap() == 0 => true,
             _ => promotable,
         };
 

src/librustc/mir/tcx.rs

@@ -70,7 +70,8 @@ impl<'a, 'gcx, 'tcx> LvalueTy<'tcx> {
                 LvalueTy::Ty {
                     ty: match ty.sty {
                         ty::TyArray(inner, size) => {
-                            let len = size.as_u64() - (from as u64) - (to as u64);
+                            let size = size.val.to_const_int().unwrap().to_u64().unwrap();
+                            let len = size - (from as u64) - (to as u64);
                             tcx.mk_array(inner, len)
                         }
                         ty::TySlice(..) => ty,
@@ -148,7 +149,7 @@ impl<'tcx> Rvalue<'tcx> {
         match *self {
             Rvalue::Use(ref operand) => operand.ty(local_decls, tcx),
             Rvalue::Repeat(ref operand, count) => {
-                tcx.mk_array(operand.ty(local_decls, tcx), count.as_u64())
+                tcx.mk_array_const_usize(operand.ty(local_decls, tcx), count)
             }
             Rvalue::Ref(reg, bk, ref lv) => {
                 let lv_ty = lv.ty(local_decls, tcx).to_ty(tcx);

src/librustc/ty/context.rs

@@ -21,6 +21,7 @@ use hir::map as hir_map;
 use hir::map::DefPathHash;
 use lint::{self, Lint};
 use ich::{self, StableHashingContext, NodeIdHashingMode};
+use middle::const_val::ConstVal;
 use middle::free_region::FreeRegionMap;
 use middle::lang_items;
 use middle::resolve_lifetime::{self, ObjectLifetimeDefault};
@@ -49,7 +50,7 @@ use rustc_data_structures::stable_hasher::{HashStable, StableHasher,
                                            StableHasherResult};
 
 use arena::{TypedArena, DroplessArena};
-use rustc_const_math::ConstUsize;
+use rustc_const_math::{ConstInt, ConstUsize};
 use rustc_data_structures::indexed_vec::IndexVec;
 use std::borrow::Borrow;
 use std::cell::{Cell, RefCell};
@@ -1757,7 +1758,14 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
 
     pub fn mk_array(self, ty: Ty<'tcx>, n: u64) -> Ty<'tcx> {
         let n = ConstUsize::new(n, self.sess.target.usize_ty).unwrap();
-        self.mk_ty(TyArray(ty, n))
+        self.mk_array_const_usize(ty, n)
+    }
+
+    pub fn mk_array_const_usize(self, ty: Ty<'tcx>, n: ConstUsize) -> Ty<'tcx> {
+        self.mk_ty(TyArray(ty, self.mk_const(ty::Const {
+            val: ConstVal::Integral(ConstInt::Usize(n)),
+            ty: self.types.usize
+        })))
     }
 
     pub fn mk_slice(self, ty: Ty<'tcx>) -> Ty<'tcx> {

src/librustc/ty/error.rs

@@ -10,6 +10,7 @@
 
 use hir::def_id::DefId;
 use infer::type_variable;
+use middle::const_val::ConstVal;
 use ty::{self, BoundRegion, DefIdTree, Region, Ty, TyCtxt};
 
 use std::fmt;
@@ -18,7 +19,7 @@ use syntax::ast;
 use errors::DiagnosticBuilder;
 use syntax_pos::Span;
 
-use rustc_const_math::ConstUsize;
+use rustc_const_math::ConstInt;
 
 use hir;
 
@@ -36,7 +37,7 @@ pub enum TypeError<'tcx> {
     AbiMismatch(ExpectedFound<abi::Abi>),
     Mutability,
     TupleSize(ExpectedFound<usize>),
-    FixedArraySize(ExpectedFound<ConstUsize>),
+    FixedArraySize(ExpectedFound<u64>),
     ArgCount,
 
     RegionsDoesNotOutlive(Region<'tcx>, Region<'tcx>),
@@ -181,7 +182,13 @@ impl<'a, 'gcx, 'lcx, 'tcx> ty::TyS<'tcx> {
             ty::TyTuple(ref tys, _) if tys.is_empty() => self.to_string(),
 
             ty::TyAdt(def, _) => format!("{} `{}`", def.descr(), tcx.item_path_str(def.did)),
-            ty::TyArray(_, n) => format!("array of {} elements", n),
+            ty::TyArray(_, n) => {
+                if let ConstVal::Integral(ConstInt::Usize(n)) = n.val {
+                    format!("array of {} elements", n)
+                } else {
+                    "array".to_string()
+                }
+            }
             ty::TySlice(_) => "slice".to_string(),
             ty::TyRawPtr(_) => "*-ptr".to_string(),
             ty::TyRef(region, tymut) => {

src/librustc/ty/flags.rs

@@ -8,6 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+use middle::const_val::{ConstVal, ConstAggregate};
 use ty::subst::Substs;
 use ty::{self, Ty, TypeFlags, TypeFoldable};
 
@@ -145,7 +146,12 @@ impl FlagComputation {
                 self.add_region(r);
             }
 
-            &ty::TyArray(tt, _) | &ty::TySlice(tt) => {
+            &ty::TyArray(tt, len) => {
+                self.add_ty(tt);
+                self.add_const(len);
+            }
+
+            &ty::TySlice(tt) => {
                 self.add_ty(tt)
             }
 
@@ -202,6 +208,36 @@ impl FlagComputation {
         }
     }
 
+    fn add_const(&mut self, constant: &ty::Const) {
+        self.add_ty(constant.ty);
+        match constant.val {
+            ConstVal::Integral(_) |
+            ConstVal::Float(_) |
+            ConstVal::Str(_) |
+            ConstVal::ByteStr(_) |
+            ConstVal::Bool(_) |
+            ConstVal::Char(_) |
+            ConstVal::Variant(_) => {}
+            ConstVal::Function(_, substs) => {
+                self.add_substs(substs);
+            }
+            ConstVal::Aggregate(ConstAggregate::Struct(fields)) => {
+                for &(_, v) in fields {
+                    self.add_const(v);
+                }
+            }
+            ConstVal::Aggregate(ConstAggregate::Tuple(fields)) |
+            ConstVal::Aggregate(ConstAggregate::Array(fields)) => {
+                for v in fields {
+                    self.add_const(v);
+                }
+            }
+            ConstVal::Aggregate(ConstAggregate::Repeat(v, _)) => {
+                self.add_const(v);
+            }
+        }
+    }
+
     fn add_existential_projection(&mut self, projection: &ty::ExistentialProjection) {
         self.add_substs(projection.substs);
         self.add_ty(projection.ty);

src/librustc/ty/inhabitedness/mod.rs

@@ -205,7 +205,7 @@ impl<'a, 'gcx, 'tcx> TyS<'tcx> {
                 }))
             },
             TyArray(ty, len) => {
-                if len.as_u64() == 0 {
+                if len.val.to_const_int().unwrap().to_u64().unwrap() == 0 {
                     DefIdForest::empty()
                 } else {
                     ty.uninhabited_from(visited, tcx)

src/librustc/ty/layout.rs

@@ -837,7 +837,7 @@ impl<'a, 'tcx> Struct {
 
             // Is this a fixed-size array of something non-zero
             // with at least one element?
-            (_, &ty::TyArray(ety, d)) if d.as_u64() > 0 => {
+            (_, &ty::TyArray(ety, d)) if d.val.to_const_int().unwrap().to_u64().unwrap() != 0 => {
                 Struct::non_zero_field_paths(
                     tcx,
                     param_env,
@@ -1177,7 +1177,7 @@ impl<'a, 'tcx> Layout {
             ty::TyArray(element, count) => {
                 let element = element.layout(tcx, param_env)?;
                 let element_size = element.size(dl);
-                let count = count.as_u64();
+                let count = count.val.to_const_int().unwrap().to_u64().unwrap();
                 if element_size.checked_mul(count, dl).is_none() {
                     return Err(LayoutError::SizeOverflow(ty));
                 }

src/librustc/ty/relate.rs

@@ -428,10 +428,14 @@ pub fn super_relate_tys<'a, 'gcx, 'tcx, R>(relation: &mut R,
         (&ty::TyArray(a_t, sz_a), &ty::TyArray(b_t, sz_b)) =>
         {
             let t = relation.relate(&a_t, &b_t)?;
-            if sz_a == sz_b {
-                Ok(tcx.mk_array(t, sz_a.as_u64()))
+            assert_eq!(sz_a.ty, tcx.types.usize);
+            assert_eq!(sz_b.ty, tcx.types.usize);
+            let sz_a_u64 = sz_a.val.to_const_int().unwrap().to_u64().unwrap();
+            let sz_b_u64 = sz_b.val.to_const_int().unwrap().to_u64().unwrap();
+            if sz_a_u64 == sz_b_u64 {
+                Ok(tcx.mk_ty(ty::TyArray(t, sz_a)))
             } else {
-                Err(TypeError::FixedArraySize(expected_found(relation, &sz_a, &sz_b)))
+                Err(TypeError::FixedArraySize(expected_found(relation, &sz_a_u64, &sz_b_u64)))
             }
         }
 

src/librustc/ty/structural_impls.rs

@@ -552,7 +552,7 @@ impl<'tcx> TypeFoldable<'tcx> for Ty<'tcx> {
     fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
         let sty = match self.sty {
             ty::TyRawPtr(tm) => ty::TyRawPtr(tm.fold_with(folder)),
-            ty::TyArray(typ, sz) => ty::TyArray(typ.fold_with(folder), sz),
+            ty::TyArray(typ, sz) => ty::TyArray(typ.fold_with(folder), sz.fold_with(folder)),
             ty::TySlice(typ) => ty::TySlice(typ.fold_with(folder)),
             ty::TyAdt(tid, substs) => ty::TyAdt(tid, substs.fold_with(folder)),
             ty::TyDynamic(ref trait_ty, ref region) =>
@@ -590,7 +590,7 @@ impl<'tcx> TypeFoldable<'tcx> for Ty<'tcx> {
     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
         match self.sty {
             ty::TyRawPtr(ref tm) => tm.visit_with(visitor),
-            ty::TyArray(typ, _sz) => typ.visit_with(visitor),
+            ty::TyArray(typ, sz) => typ.visit_with(visitor) || sz.visit_with(visitor),
             ty::TySlice(typ) => typ.visit_with(visitor),
             ty::TyAdt(_, substs) => substs.visit_with(visitor),
             ty::TyDynamic(ref trait_ty, ref reg) =>

src/librustc/ty/sty.rs

@@ -27,8 +27,6 @@ use syntax::ast::{self, Name};
 use syntax::symbol::keywords;
 use util::nodemap::FxHashMap;
 
-use rustc_const_math::ConstUsize;
-
 use serialize;
 
 use hir;
@@ -112,7 +110,7 @@ pub enum TypeVariants<'tcx> {
     TyStr,
 
     /// An array with the given length. Written as `[T; n]`.
-    TyArray(Ty<'tcx>, ConstUsize),
+    TyArray(Ty<'tcx>, &'tcx ty::Const<'tcx>),
 
     /// The pointee of an array slice.  Written as `[T]`.
     TySlice(Ty<'tcx>),

src/librustc/ty/util.rs

@@ -697,7 +697,9 @@ impl<'a, 'gcx, 'tcx, W> TypeVisitor<'tcx> for TypeIdHasher<'a, 'gcx, 'tcx, W>
             TyInt(i) => self.hash(i),
             TyUint(u) => self.hash(u),
             TyFloat(f) => self.hash(f),
-            TyArray(_, n) => self.hash(n),
+            TyArray(_, n) => {
+                self.hash(n.val.to_const_int().unwrap().to_u64().unwrap())
+            }
             TyRawPtr(m) |
             TyRef(_, m) => self.hash(m.mutbl),
             TyClosure(def_id, _) |

src/librustc/ty/walk.rs

@@ -11,6 +11,7 @@
 //! An iterator over the type substructure.
 //! WARNING: this does not keep track of the region depth.
 
+use middle::const_val::{ConstVal, ConstAggregate};
 use ty::{self, Ty};
 use rustc_data_structures::small_vec::SmallVec;
 use rustc_data_structures::accumulate_vec::IntoIter as AccIntoIter;
@@ -83,7 +84,11 @@ fn push_subtypes<'tcx>(stack: &mut TypeWalkerStack<'tcx>, parent_ty: Ty<'tcx>) {
         ty::TyBool | ty::TyChar | ty::TyInt(_) | ty::TyUint(_) | ty::TyFloat(_) |
         ty::TyStr | ty::TyInfer(_) | ty::TyParam(_) | ty::TyNever | ty::TyError => {
         }
-        ty::TyArray(ty, _) | ty::TySlice(ty) => {
+        ty::TyArray(ty, len) => {
+            push_const(stack, len);
+            stack.push(ty);
+        }
+        ty::TySlice(ty) => {
             stack.push(ty);
         }
         ty::TyRawPtr(ref mt) | ty::TyRef(_, ref mt) => {
@@ -122,13 +127,39 @@ fn push_subtypes<'tcx>(stack: &mut TypeWalkerStack<'tcx>, parent_ty: Ty<'tcx>) {
         ty::TyFnDef(_, substs) => {
             stack.extend(substs.types().rev());
         }
-        ty::TyFnPtr(ft) => {
-            push_sig_subtypes(stack, ft);
+        ty::TyFnPtr(sig) => {
+            stack.push(sig.skip_binder().output());
+            stack.extend(sig.skip_binder().inputs().iter().cloned().rev());
         }
     }
 }
 
-fn push_sig_subtypes<'tcx>(stack: &mut TypeWalkerStack<'tcx>, sig: ty::PolyFnSig<'tcx>) {
-    stack.push(sig.skip_binder().output());
-    stack.extend(sig.skip_binder().inputs().iter().cloned().rev());
+fn push_const<'tcx>(stack: &mut TypeWalkerStack<'tcx>, constant: &'tcx ty::Const<'tcx>) {
+    match constant.val {
+        ConstVal::Integral(_) |
+        ConstVal::Float(_) |
+        ConstVal::Str(_) |
+        ConstVal::ByteStr(_) |
+        ConstVal::Bool(_) |
+        ConstVal::Char(_) |
+        ConstVal::Variant(_) => {}
+        ConstVal::Function(_, substs) => {
+            stack.extend(substs.types().rev());
+        }
+        ConstVal::Aggregate(ConstAggregate::Struct(fields)) => {
+            for &(_, v) in fields.iter().rev() {
+                push_const(stack, v);
+            }
+        }
+        ConstVal::Aggregate(ConstAggregate::Tuple(fields)) |
+        ConstVal::Aggregate(ConstAggregate::Array(fields)) => {
+            for v in fields.iter().rev() {
+                push_const(stack, v);
+            }
+        }
+        ConstVal::Aggregate(ConstAggregate::Repeat(v, _)) => {
+            push_const(stack, v);
+        }
+    }
+    stack.push(constant.ty);
 }

src/librustc/ty/wf.rs

@@ -207,6 +207,10 @@ impl<'a, 'gcx, 'tcx> WfPredicates<'a, 'gcx, 'tcx> {
         }
     }
 
+    /// Pushes the obligations required for a constant value to be WF
+    /// into `self.out`.
+    fn compute_const(&mut self, _constant: &'tcx ty::Const<'tcx>) {}
+
     fn require_sized(&mut self, subty: Ty<'tcx>, cause: traits::ObligationCauseCode<'tcx>) {
         if !subty.has_escaping_regions() {
             let cause = self.cause(cause);
@@ -239,9 +243,14 @@ impl<'a, 'gcx, 'tcx> WfPredicates<'a, 'gcx, 'tcx> {
                     // WfScalar, WfParameter, etc
                 }
 
-                ty::TySlice(subty) |
-                ty::TyArray(subty, _) => {
+                ty::TySlice(subty) => {
+                    self.require_sized(subty, traits::SliceOrArrayElem);
+                }
+
+                ty::TyArray(subty, len) => {
                     self.require_sized(subty, traits::SliceOrArrayElem);
+                    assert_eq!(len.ty, self.infcx.tcx.types.usize);
+                    self.compute_const(len);
                 }
 
                 ty::TyTuple(ref tys, _) => {