5 files changed, 26 insertions, 32 deletions

diff --git a/crates/hir/src/lib.rs b/crates/hir/src/lib.rs
index d7065ff2b..7e8a5bca3 100644
--- a/crates/hir/src/lib.rs
+++ b/crates/hir/src/lib.rs
@@ -53,7 +53,7 @@ use hir_def::{
 use hir_expand::{diagnostics::DiagnosticSink, name::name, MacroDefKind};
 use hir_ty::{
     autoderef,
-    consteval::ConstExtension,
+    consteval::ConstExt,
     could_unify,
     method_resolution::{self, def_crates, TyFingerprint},
     primitive::UintTy,
diff --git a/crates/hir_def/src/type_ref.rs b/crates/hir_def/src/type_ref.rs
index 6a3259b27..9e44547cb 100644
--- a/crates/hir_def/src/type_ref.rs
+++ b/crates/hir_def/src/type_ref.rs
@@ -336,6 +336,14 @@ impl std::fmt::Display for ConstScalar {
 }
 
 impl ConstScalar {
+    /// Gets a target usize out of the ConstScalar
+    pub fn as_usize(&self) -> Option<u64> {
+        match self {
+            &ConstScalar::Usize(us) => Some(us),
+            _ => None,
+        }
+    }
+
     // FIXME: as per the comments on `TypeRef::Array`, this evaluation should not happen at this
     // parse stage.
     fn usize_from_literal_expr(expr: ast::Expr) -> ConstScalar {
diff --git a/crates/hir_ty/src/consteval.rs b/crates/hir_ty/src/consteval.rs
index a4a430f30..e3ceb3d62 100644
--- a/crates/hir_ty/src/consteval.rs
+++ b/crates/hir_ty/src/consteval.rs
@@ -11,12 +11,12 @@ use hir_def::{
 use crate::{Const, ConstData, ConstValue, Interner, TyKind};
 
 /// Extension trait for [`Const`]
-pub trait ConstExtension {
+pub trait ConstExt {
     /// Is a [`Const`] unknown?
     fn is_unknown(&self) -> bool;
 }
 
-impl ConstExtension for Const {
+impl ConstExt for Const {
     fn is_unknown(&self) -> bool {
         match self.data(&Interner).value {
             // interned Unknown
@@ -35,20 +35,12 @@ impl ConstExtension for Const {
     }
 }
 
-/// Extension trait for [`Expr`]
-pub trait ExprEval {
-    /// Attempts to evaluate the expression as a target usize.
-    fn eval_usize(&self) -> Option<u64>;
-}
-
-impl ExprEval for Expr {
-    // FIXME: support more than just evaluating literals
-    fn eval_usize(&self) -> Option<u64> {
-        match self {
-            Expr::Literal(Literal::Uint(v, None))
-            | Expr::Literal(Literal::Uint(v, Some(BuiltinUint::Usize))) => (*v).try_into().ok(),
-            _ => None,
-        }
+// FIXME: support more than just evaluating literals
+pub fn eval_usize(expr: &Expr) -> Option<u64> {
+    match expr {
+        Expr::Literal(Literal::Uint(v, None))
+        | Expr::Literal(Literal::Uint(v, Some(BuiltinUint::Usize))) => (*v).try_into().ok(),
+        _ => None,
     }
 }
 
diff --git a/crates/hir_ty/src/infer/expr.rs b/crates/hir_ty/src/infer/expr.rs
index 04fc2f12b..b6b5a1b75 100644
--- a/crates/hir_ty/src/infer/expr.rs
+++ b/crates/hir_ty/src/infer/expr.rs
@@ -15,8 +15,7 @@ use stdx::always;
 use syntax::ast::RangeOp;
 
 use crate::{
-    autoderef,
-    consteval::{self, ExprEval},
+    autoderef, consteval,
     lower::lower_to_chalk_mutability,
     mapping::from_chalk,
     method_resolution, op,
@@ -738,7 +737,7 @@ impl<'a> InferenceContext<'a> {
                         );
 
                         let repeat_expr = &self.body.exprs[*repeat];
-                        repeat_expr.eval_usize()
+                        consteval::eval_usize(repeat_expr)
                     }
                 };
 
diff --git a/crates/hir_ty/src/lower.rs b/crates/hir_ty/src/lower.rs
index f7015e5ff..bd8bb6028 100644
--- a/crates/hir_ty/src/lower.rs
+++ b/crates/hir_ty/src/lower.rs
@@ -9,9 +9,7 @@ use std::cell::{Cell, RefCell};
 use std::{iter, sync::Arc};
 
 use base_db::CrateId;
-use chalk_ir::{
-    cast::Cast, fold::Shift, interner::HasInterner, Mutability, Safety, Scalar, UintTy,
-};
+use chalk_ir::{cast::Cast, fold::Shift, interner::HasInterner, Mutability, Safety};
 use hir_def::{
     adt::StructKind,
     body::{Expander, LowerCtx},
@@ -31,16 +29,17 @@ use stdx::impl_from;
 use syntax::ast;
 
 use crate::{
+    consteval,
     db::HirDatabase,
     mapping::ToChalk,
     static_lifetime, to_assoc_type_id, to_chalk_trait_id, to_placeholder_idx,
     utils::{
         all_super_trait_refs, associated_type_by_name_including_super_traits, generics, Generics,
     },
-    AliasEq, AliasTy, Binders, BoundVar, CallableSig, ConstData, ConstValue, DebruijnIndex, DynTy,
-    FnPointer, FnSig, FnSubst, ImplTraitId, Interner, OpaqueTy, PolyFnSig, ProjectionTy,
-    QuantifiedWhereClause, QuantifiedWhereClauses, ReturnTypeImplTrait, ReturnTypeImplTraits,
-    Substitution, TraitEnvironment, TraitRef, TraitRefExt, Ty, TyBuilder, TyKind, WhereClause,
+    AliasEq, AliasTy, Binders, BoundVar, CallableSig, DebruijnIndex, DynTy, FnPointer, FnSig,
+    FnSubst, ImplTraitId, Interner, OpaqueTy, PolyFnSig, ProjectionTy, QuantifiedWhereClause,
+    QuantifiedWhereClauses, ReturnTypeImplTrait, ReturnTypeImplTraits, Substitution,
+    TraitEnvironment, TraitRef, TraitRefExt, Ty, TyBuilder, TyKind, WhereClause,
 };
 
 #[derive(Debug)]
@@ -176,11 +175,7 @@ impl<'a> TyLoweringContext<'a> {
             TypeRef::Array(inner, len) => {
                 let inner_ty = self.lower_ty(inner);
 
-                let const_len = ConstData {
-                    ty: TyKind::Scalar(Scalar::Uint(UintTy::Usize)).intern(&Interner),
-                    value: ConstValue::Concrete(chalk_ir::ConcreteConst { interned: *len }),
-                }
-                .intern(&Interner);
+                let const_len = consteval::usize_const(len.as_usize());
 
                 TyKind::Array(inner_ty, const_len).intern(&Interner)
             }