Add Display impl for ty::Const

Author: varkor

src/librustc/ty/sty.rs

@@ -1919,9 +1919,8 @@ impl<'a, 'gcx, 'tcx> TyS<'tcx> {
 /// Typed constant value.
 #[derive(Copy, Clone, Debug, Hash, RustcEncodable, RustcDecodable, Eq, PartialEq, Ord, PartialOrd)]
 pub struct Const<'tcx> {
-    pub ty: Ty<'tcx>,
-
     pub val: ConstValue<'tcx>,
+    pub ty: Ty<'tcx>,
 }
 
 impl<'tcx> Const<'tcx> {

src/librustc/ty/subst.rs

@@ -27,7 +27,7 @@ use std::mem;
 use std::num::NonZeroUsize;
 
 /// An entity in the Rust typesystem, which can be one of
-/// several kinds (only types, lifetimes, and const generics for now).
+/// several kinds (types, lifetimes, and consts).
 /// To reduce memory usage, a `Kind` is a interned pointer,
 /// with the lowest 2 bits being reserved for a tag to
 /// indicate the type (`Ty`, `Region`, or `Const`) it points to.
@@ -148,7 +148,7 @@ impl<'tcx> fmt::Display for Kind<'tcx> {
         match self.unpack() {
             UnpackedKind::Lifetime(lt) => write!(f, "{}", lt),
             UnpackedKind::Type(ty) => write!(f, "{}", ty),
-            UnpackedKind::Const(ct) => write!(f, "{:?}", ct), // TODO(const_generics): impl display for Const
+            UnpackedKind::Const(ct) => write!(f, "{}", ct),
         }
     }
 }

src/librustc/util/ppaux.rs

@@ -1283,6 +1283,26 @@ define_print! {
     }
 }
 
+define_print! {
+    ('tcx) ConstVal<'tcx>, (self, f, cx) {
+        display {
+            match self {
+                ConstVal::Value(value) => write!(f, "{:?}", value), // TODO(const_generics)
+                ConstVal::Unevaluated(..) => write!(f, "_"),
+                ConstVal::Param(ParamConst { name, .. }) => write!(f, "{}", name),
+            }
+        }
+    }
+}
+
+define_print! {
+    ('tcx) ty::Const<'tcx>, (self, f, cx) {
+        display {
+            write!(f, "{} : {}", self.val, self.ty)
+        }
+    }
+}
+
 define_print! {
     () ty::ParamTy, (self, f, cx) {
         display {

src/librustc_resolve/lib.rs

@@ -810,6 +810,7 @@ impl<'a, 'tcx, 'cl> Visitor<'tcx> for Resolver<'a, 'cl> {
         self.label_ribs.pop();
         self.ribs[ValueNS].pop();
     }
+
     fn visit_generics(&mut self, generics: &'tcx Generics) {
         // For type parameter defaults, we have to ban access
         // to following type parameters, as the Substs can only