Initial changes to librustc to support const trait fns.

src/librustc/hir/def_id.rs

@@ -220,7 +220,6 @@ impl serialize::UseSpecializedDecodable for DefId {}
 pub struct LocalDefId(DefIndex);
 
 impl LocalDefId {
-
     #[inline]
     pub fn from_def_id(def_id: DefId) -> LocalDefId {
         assert!(def_id.is_local());

src/librustc_metadata/decoder.rs

@@ -21,7 +21,7 @@
 use rustc::middle::exported_symbols::{ExportedSymbol, SymbolExportLevel};
 use rustc::hir::def::{self, Def, CtorKind};
 use rustc::hir::def_id::{CrateNum, DefId, DefIndex,
-                         CRATE_DEF_INDEX, LOCAL_CRATE};
+                         CRATE_DEF_INDEX, LOCAL_CRATE, LocalDefId};
 use rustc::ich::Fingerprint;
 use rustc::middle::lang_items;
 use rustc::mir::{self, interpret};
@@ -273,6 +273,13 @@ fn specialized_decode(&mut self) -> Result<DefIndex, Self::Error> {
     }
 }
 
+impl<'a, 'tcx> SpecializedDecoder<LocalDefId> for DecodeContext<'a, 'tcx> {
+    #[inline]
+    fn specialized_decode(&mut self) -> Result<LocalDefId, Self::Error> {
+        self.specialized_decode().map(|i| LocalDefId::from_def_id(i))
+    }
+}
+
 impl<'a, 'tcx> SpecializedDecoder<interpret::AllocId> for DecodeContext<'a, 'tcx> {
     fn specialized_decode(&mut self) -> Result<interpret::AllocId, Self::Error> {
         const MAX1: usize = usize::max_value() - 1;

src/librustc_metadata/encoder.rs

@@ -16,7 +16,7 @@
 use rustc::middle::cstore::{LinkMeta, LinkagePreference, NativeLibrary,
                             EncodedMetadata};
 use rustc::hir::def::CtorKind;
-use rustc::hir::def_id::{CrateNum, CRATE_DEF_INDEX, DefIndex, DefId, LOCAL_CRATE};
+use rustc::hir::def_id::{CrateNum, CRATE_DEF_INDEX, DefIndex, DefId, LocalDefId, LOCAL_CRATE};
 use rustc::hir::map::definitions::DefPathTable;
 use rustc::ich::Fingerprint;
 use rustc::middle::dependency_format::Linkage;
@@ -181,6 +181,13 @@ fn specialized_encode(&mut self, span: &Span) -> Result<(), Self::Error> {
     }
 }
 
+impl<'a, 'tcx> SpecializedEncoder<LocalDefId> for EncodeContext<'a, 'tcx> {
+    #[inline]
+    fn specialized_encode(&mut self, def_id: &LocalDefId) -> Result<(), Self::Error> {
+        self.specialized_encode(&def_id.to_def_id())
+    }
+}
+
 impl<'a, 'tcx> SpecializedEncoder<Ty<'tcx>> for EncodeContext<'a, 'tcx> {
     fn specialized_encode(&mut self, ty: &Ty<'tcx>) -> Result<(), Self::Error> {
         ty_codec::encode_with_shorthand(self, ty, |ecx| &mut ecx.type_shorthands)

src/librustdoc/clean/mod.rs

@@ -51,7 +51,6 @@
 use std::collections::VecDeque;
 use std::fmt;
 
-use rustc_const_math::ConstInt;
 use std::default::Default;
 use std::{mem, slice, vec};
 use std::iter::{FromIterator, once};
@@ -2507,9 +2506,7 @@ fn clean(&self, cx: &DocContext) -> Type {
                         ty: cx.tcx.types.usize
                     })
                 });
-                let n = if let ConstVal::Integral(ConstInt::Usize(n)) = n.val {
-                    n.to_string()
-                } else if let ConstVal::Unevaluated(def_id, _) = n.val {
+                let n = if let ConstVal::Unevaluated(def_id, _) = n.val {
                     if let Some(node_id) = cx.tcx.hir.as_local_node_id(def_id) {
                         print_const_expr(cx, cx.tcx.hir.body_owned_by(node_id))
                     } else {
@@ -2640,9 +2637,7 @@ fn clean(&self, cx: &DocContext) -> Type {
                         n = new_n;
                     }
                 };
-                let n = if let ConstVal::Integral(ConstInt::Usize(n)) = n.val {
-                    n.to_string()
-                } else if let ConstVal::Unevaluated(def_id, _) = n.val {
+                let n = if let ConstVal::Unevaluated(def_id, _) = n.val {
                     if let Some(node_id) = cx.tcx.hir.as_local_node_id(def_id) {
                         print_const_expr(cx, cx.tcx.hir.body_owned_by(node_id))
                     } else {