22 files changed, 352 insertions, 304 deletions

diff --git a/src/librustc/dep_graph/dep_node.rs b/src/librustc/dep_graph/dep_node.rs
index 6824c015eab..7d8709a82f4 100644
--- a/src/librustc/dep_graph/dep_node.rs
+++ b/src/librustc/dep_graph/dep_node.rs
@@ -661,7 +661,7 @@ trait DepNodeParams<'a, 'gcx: 'tcx + 'a, 'tcx: 'a> : fmt::Debug {
 }
 
 impl<'a, 'gcx: 'tcx + 'a, 'tcx: 'a, T> DepNodeParams<'a, 'gcx, 'tcx> for T
-    where T: HashStable<StableHashingContext<'gcx>> + fmt::Debug
+    where T: HashStable<StableHashingContext<'a>> + fmt::Debug
 {
     default const CAN_RECONSTRUCT_QUERY_KEY: bool = false;
 
diff --git a/src/librustc/hir/map/collector.rs b/src/librustc/hir/map/collector.rs
index 9bbda9d7447..3c523f5633e 100644
--- a/src/librustc/hir/map/collector.rs
+++ b/src/librustc/hir/map/collector.rs
@@ -529,7 +529,7 @@ struct HirItemLike<T> {
     hash_bodies: bool,
 }
 
-impl<'hir, T> HashStable<StableHashingContext<'hir>> for HirItemLike<T>
+impl<'a, 'hir, T> HashStable<StableHashingContext<'hir>> for HirItemLike<T>
     where T: HashStable<StableHashingContext<'hir>>
 {
     fn hash_stable<W: StableHasherResult>(&self,
diff --git a/src/librustc/ich/hcx.rs b/src/librustc/ich/hcx.rs
index 4dcab6a04ee..6ae588b2a07 100644
--- a/src/librustc/ich/hcx.rs
+++ b/src/librustc/ich/hcx.rs
@@ -46,19 +46,19 @@ pub fn compute_ignored_attr_names() -> FxHashSet<Symbol> {
 /// a reference to the TyCtxt) and it holds a few caches for speeding up various
 /// things (e.g. each DefId/DefPath is only hashed once).
 #[derive(Clone)]
-pub struct StableHashingContext<'gcx> {
-    sess: &'gcx Session,
-    definitions: &'gcx Definitions,
-    cstore: &'gcx dyn CrateStore,
-    body_resolver: BodyResolver<'gcx>,
+pub struct StableHashingContext<'a> {
+    sess: &'a Session,
+    definitions: &'a Definitions,
+    cstore: &'a dyn CrateStore,
+    body_resolver: BodyResolver<'a>,
     hash_spans: bool,
     hash_bodies: bool,
     node_id_hashing_mode: NodeIdHashingMode,
 
     // Very often, we are hashing something that does not need the
     // CachingCodemapView, so we initialize it lazily.
-    raw_codemap: &'gcx CodeMap,
-    caching_codemap: Option<CachingCodemapView<'gcx>>,
+    raw_codemap: &'a CodeMap,
+    caching_codemap: Option<CachingCodemapView<'a>>,
 }
 
 #[derive(PartialEq, Eq, Clone, Copy)]
@@ -81,14 +81,14 @@ impl<'gcx> BodyResolver<'gcx> {
     }
 }
 
-impl<'gcx> StableHashingContext<'gcx> {
+impl<'a> StableHashingContext<'a> {
     // The `krate` here is only used for mapping BodyIds to Bodies.
     // Don't use it for anything else or you'll run the risk of
     // leaking data out of the tracking system.
-    pub fn new(sess: &'gcx Session,
-               krate: &'gcx hir::Crate,
-               definitions: &'gcx Definitions,
-               cstore: &'gcx dyn CrateStore)
+    pub fn new(sess: &'a Session,
+               krate: &'a hir::Crate,
+               definitions: &'a Definitions,
+               cstore: &'a dyn CrateStore)
                -> Self {
         let hash_spans_initial = !sess.opts.debugging_opts.incremental_ignore_spans;
 
@@ -106,7 +106,7 @@ impl<'gcx> StableHashingContext<'gcx> {
     }
 
     #[inline]
-    pub fn sess(&self) -> &'gcx Session {
+    pub fn sess(&self) -> &'a Session {
         self.sess
     }
 
@@ -165,7 +165,7 @@ impl<'gcx> StableHashingContext<'gcx> {
     }
 
     #[inline]
-    pub fn codemap(&mut self) -> &mut CachingCodemapView<'gcx> {
+    pub fn codemap(&mut self) -> &mut CachingCodemapView<'a> {
         match self.caching_codemap {
             Some(ref mut cm) => {
                 cm
@@ -193,27 +193,27 @@ impl<'gcx> StableHashingContext<'gcx> {
 }
 
 impl<'a, 'gcx, 'lcx> StableHashingContextProvider for TyCtxt<'a, 'gcx, 'lcx> {
-    type ContextType = StableHashingContext<'gcx>;
+    type ContextType = StableHashingContext<'a>;
     fn create_stable_hashing_context(&self) -> Self::ContextType {
         (*self).create_stable_hashing_context()
     }
 }
 
 
-impl<'gcx> StableHashingContextProvider for StableHashingContext<'gcx> {
-    type ContextType = StableHashingContext<'gcx>;
+impl<'a> StableHashingContextProvider for StableHashingContext<'a> {
+    type ContextType = StableHashingContext<'a>;
     fn create_stable_hashing_context(&self) -> Self::ContextType {
         self.clone()
     }
 }
 
-impl<'gcx> ::dep_graph::DepGraphSafe for StableHashingContext<'gcx> {
+impl<'a> ::dep_graph::DepGraphSafe for StableHashingContext<'a> {
 }
 
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>> for hir::BodyId {
+impl<'a> HashStable<StableHashingContext<'a>> for hir::BodyId {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         if hcx.hash_bodies() {
             hcx.body_resolver.body(*self).hash_stable(hcx, hasher);
@@ -221,10 +221,10 @@ impl<'gcx> HashStable<StableHashingContext<'gcx>> for hir::BodyId {
     }
 }
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>> for hir::HirId {
+impl<'a> HashStable<StableHashingContext<'a>> for hir::HirId {
     #[inline]
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         match hcx.node_id_hashing_mode {
             NodeIdHashingMode::Ignore => {
@@ -243,21 +243,21 @@ impl<'gcx> HashStable<StableHashingContext<'gcx>> for hir::HirId {
     }
 }
 
-impl<'gcx> ToStableHashKey<StableHashingContext<'gcx>> for hir::HirId {
+impl<'a> ToStableHashKey<StableHashingContext<'a>> for hir::HirId {
     type KeyType = (DefPathHash, hir::ItemLocalId);
 
     #[inline]
     fn to_stable_hash_key(&self,
-                          hcx: &StableHashingContext<'gcx>)
+                          hcx: &StableHashingContext<'a>)
                           -> (DefPathHash, hir::ItemLocalId) {
         let def_path_hash = hcx.local_def_path_hash(self.owner);
         (def_path_hash, self.local_id)
     }
 }
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>> for ast::NodeId {
+impl<'a> HashStable<StableHashingContext<'a>> for ast::NodeId {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         match hcx.node_id_hashing_mode {
             NodeIdHashingMode::Ignore => {
@@ -270,18 +270,18 @@ impl<'gcx> HashStable<StableHashingContext<'gcx>> for ast::NodeId {
     }
 }
 
-impl<'gcx> ToStableHashKey<StableHashingContext<'gcx>> for ast::NodeId {
+impl<'a> ToStableHashKey<StableHashingContext<'a>> for ast::NodeId {
     type KeyType = (DefPathHash, hir::ItemLocalId);
 
     #[inline]
     fn to_stable_hash_key(&self,
-                          hcx: &StableHashingContext<'gcx>)
+                          hcx: &StableHashingContext<'a>)
                           -> (DefPathHash, hir::ItemLocalId) {
         hcx.definitions.node_to_hir_id(*self).to_stable_hash_key(hcx)
     }
 }
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>> for Span {
+impl<'a> HashStable<StableHashingContext<'a>> for Span {
 
     // Hash a span in a stable way. We can't directly hash the span's BytePos
     // fields (that would be similar to hashing pointers, since those are just
@@ -293,7 +293,7 @@ impl<'gcx> HashStable<StableHashingContext<'gcx>> for Span {
     // Also, hashing filenames is expensive so we avoid doing it twice when the
     // span starts and ends in the same file, which is almost always the case.
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         const TAG_VALID_SPAN: u8 = 0;
         const TAG_INVALID_SPAN: u8 = 1;
@@ -373,8 +373,8 @@ impl<'gcx> HashStable<StableHashingContext<'gcx>> for Span {
     }
 }
 
-pub fn hash_stable_trait_impls<'gcx, W, R>(
-    hcx: &mut StableHashingContext<'gcx>,
+pub fn hash_stable_trait_impls<'a, 'gcx, W, R>(
+    hcx: &mut StableHashingContext<'a>,
     hasher: &mut StableHasher<W>,
     blanket_impls: &Vec<DefId>,
     non_blanket_impls: &HashMap<fast_reject::SimplifiedType, Vec<DefId>, R>)
diff --git a/src/librustc/ich/impls_hir.rs b/src/librustc/ich/impls_hir.rs
index faad3f35631..c085b803085 100644
--- a/src/librustc/ich/impls_hir.rs
+++ b/src/librustc/ich/impls_hir.rs
@@ -21,46 +21,46 @@ use std::mem;
 use syntax::ast;
 use syntax::attr;
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>> for DefId {
+impl<'a> HashStable<StableHashingContext<'a>> for DefId {
     #[inline]
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         hcx.def_path_hash(*self).hash_stable(hcx, hasher);
     }
 }
 
-impl<'gcx> ToStableHashKey<StableHashingContext<'gcx>> for DefId {
+impl<'a> ToStableHashKey<StableHashingContext<'a>> for DefId {
     type KeyType = DefPathHash;
 
     #[inline]
-    fn to_stable_hash_key(&self, hcx: &StableHashingContext<'gcx>) -> DefPathHash {
+    fn to_stable_hash_key(&self, hcx: &StableHashingContext<'a>) -> DefPathHash {
         hcx.def_path_hash(*self)
     }
 }
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>> for LocalDefId {
+impl<'a> HashStable<StableHashingContext<'a>> for LocalDefId {
     #[inline]
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         hcx.def_path_hash(self.to_def_id()).hash_stable(hcx, hasher);
     }
 }
 
-impl<'gcx> ToStableHashKey<StableHashingContext<'gcx>> for LocalDefId {
+impl<'a> ToStableHashKey<StableHashingContext<'a>> for LocalDefId {
     type KeyType = DefPathHash;
 
     #[inline]
-    fn to_stable_hash_key(&self, hcx: &StableHashingContext<'gcx>) -> DefPathHash {
+    fn to_stable_hash_key(&self, hcx: &StableHashingContext<'a>) -> DefPathHash {
         hcx.def_path_hash(self.to_def_id())
     }
 }
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>> for CrateNum {
+impl<'a> HashStable<StableHashingContext<'a>> for CrateNum {
     #[inline]
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         hcx.def_path_hash(DefId {
             krate: *self,
@@ -69,11 +69,11 @@ impl<'gcx> HashStable<StableHashingContext<'gcx>> for CrateNum {
     }
 }
 
-impl<'gcx> ToStableHashKey<StableHashingContext<'gcx>> for CrateNum {
+impl<'a> ToStableHashKey<StableHashingContext<'a>> for CrateNum {
     type KeyType = DefPathHash;
 
     #[inline]
-    fn to_stable_hash_key(&self, hcx: &StableHashingContext<'gcx>) -> DefPathHash {
+    fn to_stable_hash_key(&self, hcx: &StableHashingContext<'a>) -> DefPathHash {
         let def_id = DefId { krate: *self, index: CRATE_DEF_INDEX };
         def_id.to_stable_hash_key(hcx)
     }
@@ -81,13 +81,13 @@ impl<'gcx> ToStableHashKey<StableHashingContext<'gcx>> for CrateNum {
 
 impl_stable_hash_for!(tuple_struct hir::ItemLocalId { index });
 
-impl<'gcx> ToStableHashKey<StableHashingContext<'gcx>>
+impl<'a> ToStableHashKey<StableHashingContext<'a>>
 for hir::ItemLocalId {
     type KeyType = hir::ItemLocalId;
 
     #[inline]
     fn to_stable_hash_key(&self,
-                          _: &StableHashingContext<'gcx>)
+                          _: &StableHashingContext<'a>)
                           -> hir::ItemLocalId {
         *self
     }
@@ -100,9 +100,9 @@ for hir::ItemLocalId {
 // want to pick up on a reference changing its target, so we hash the NodeIds
 // in "DefPath Mode".
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>> for hir::ItemId {
+impl<'a> HashStable<StableHashingContext<'a>> for hir::ItemId {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         let hir::ItemId {
             id
@@ -114,9 +114,9 @@ impl<'gcx> HashStable<StableHashingContext<'gcx>> for hir::ItemId {
     }
 }
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>> for hir::TraitItemId {
+impl<'a> HashStable<StableHashingContext<'a>> for hir::TraitItemId {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         let hir::TraitItemId {
             node_id
@@ -128,9 +128,9 @@ impl<'gcx> HashStable<StableHashingContext<'gcx>> for hir::TraitItemId {
     }
 }
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>> for hir::ImplItemId {
+impl<'a> HashStable<StableHashingContext<'a>> for hir::ImplItemId {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         let hir::ImplItemId {
             node_id
@@ -271,9 +271,9 @@ impl_stable_hash_for!(struct hir::TypeBinding {
     span
 });
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>> for hir::Ty {
+impl<'a> HashStable<StableHashingContext<'a>> for hir::Ty {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         hcx.while_hashing_hir_bodies(true, |hcx| {
             let hir::Ty {
@@ -339,9 +339,9 @@ impl_stable_hash_for!(enum hir::FunctionRetTy {
     Return(t)
 });
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>> for hir::TraitRef {
+impl<'a> HashStable<StableHashingContext<'a>> for hir::TraitRef {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         let hir::TraitRef {
             ref path,
@@ -376,9 +376,9 @@ impl_stable_hash_for!(struct hir::MacroDef {
 });
 
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>> for hir::Block {
+impl<'a> HashStable<StableHashingContext<'a>> for hir::Block {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         let hir::Block {
             ref stmts,
@@ -400,9 +400,9 @@ impl<'gcx> HashStable<StableHashingContext<'gcx>> for hir::Block {
     }
 }
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>> for hir::Pat {
+impl<'a> HashStable<StableHashingContext<'a>> for hir::Pat {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         let hir::Pat {
             id: _,
@@ -527,9 +527,9 @@ impl_stable_hash_for!(enum hir::UnsafeSource {
     UserProvided
 });
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>> for hir::Expr {
+impl<'a> HashStable<StableHashingContext<'a>> for hir::Expr {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         hcx.while_hashing_hir_bodies(true, |hcx| {
             let hir::Expr {
@@ -591,9 +591,9 @@ impl_stable_hash_for!(enum hir::LoopSource {
     ForLoop
 });
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>> for hir::MatchSource {
+impl<'a> HashStable<StableHashingContext<'a>> for hir::MatchSource {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         use hir::MatchSource;
 
@@ -647,9 +647,9 @@ impl_stable_hash_for!(enum hir::ScopeTarget {
     Loop(loop_id_result)
 });
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>> for ast::Ident {
+impl<'a> HashStable<StableHashingContext<'a>> for ast::Ident {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         let ast::Ident {
             ref name,
@@ -660,9 +660,9 @@ impl<'gcx> HashStable<StableHashingContext<'gcx>> for ast::Ident {
     }
 }
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>> for hir::TraitItem {
+impl<'a> HashStable<StableHashingContext<'a>> for hir::TraitItem {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         let hir::TraitItem {
             id: _,
@@ -695,9 +695,9 @@ impl_stable_hash_for!(enum hir::TraitItemKind {
     Type(bounds, rhs)
 });
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>> for hir::ImplItem {
+impl<'a> HashStable<StableHashingContext<'a>> for hir::ImplItem {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         let hir::ImplItem {
             id: _,
@@ -729,9 +729,9 @@ impl_stable_hash_for!(enum hir::ImplItemKind {
     Type(t)
 });
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>> for hir::Visibility {
+impl<'a> HashStable<StableHashingContext<'a>> for hir::Visibility {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         mem::discriminant(self).hash_stable(hcx, hasher);
         match *self {
@@ -750,9 +750,9 @@ impl<'gcx> HashStable<StableHashingContext<'gcx>> for hir::Visibility {
     }
 }
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>> for hir::Defaultness {
+impl<'a> HashStable<StableHashingContext<'a>> for hir::Defaultness {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         mem::discriminant(self).hash_stable(hcx, hasher);
         match *self {
@@ -771,9 +771,9 @@ impl_stable_hash_for!(enum hir::ImplPolarity {
     Negative
 });
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>> for hir::Mod {
+impl<'a> HashStable<StableHashingContext<'a>> for hir::Mod {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         let hir::Mod {
             inner,
@@ -826,9 +826,9 @@ impl_stable_hash_for!(enum hir::VariantData {
     Unit(id)
 });
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>> for hir::Item {
+impl<'a> HashStable<StableHashingContext<'a>> for hir::Item {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         let hir::Item {
             name,
@@ -885,10 +885,10 @@ impl_stable_hash_for!(struct hir::ImplItemRef {
     defaultness
 });
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>>
+impl<'a> HashStable<StableHashingContext<'a>>
 for hir::AssociatedItemKind {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         mem::discriminant(self).hash_stable(hcx, hasher);
         match *self {
@@ -930,9 +930,9 @@ impl_stable_hash_for!(struct hir::Arg {
     hir_id
 });
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>> for hir::Body {
+impl<'a> HashStable<StableHashingContext<'a>> for hir::Body {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         let hir::Body {
             ref arguments,
@@ -948,12 +948,12 @@ impl<'gcx> HashStable<StableHashingContext<'gcx>> for hir::Body {
     }
 }
 
-impl<'gcx> ToStableHashKey<StableHashingContext<'gcx>> for hir::BodyId {
+impl<'a> ToStableHashKey<StableHashingContext<'a>> for hir::BodyId {
     type KeyType = (DefPathHash, hir::ItemLocalId);
 
     #[inline]
     fn to_stable_hash_key(&self,
-                          hcx: &StableHashingContext<'gcx>)
+                          hcx: &StableHashingContext<'a>)
                           -> (DefPathHash, hir::ItemLocalId) {
         let hir::BodyId { node_id } = *self;
         node_id.to_stable_hash_key(hcx)
@@ -966,9 +966,9 @@ impl_stable_hash_for!(struct hir::InlineAsmOutput {
     is_indirect
 });
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>> for hir::GlobalAsm {
+impl<'a> HashStable<StableHashingContext<'a>> for hir::GlobalAsm {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         let hir::GlobalAsm {
             asm,
@@ -979,9 +979,9 @@ impl<'gcx> HashStable<StableHashingContext<'gcx>> for hir::GlobalAsm {
     }
 }
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>> for hir::InlineAsm {
+impl<'a> HashStable<StableHashingContext<'a>> for hir::InlineAsm {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         let hir::InlineAsm {
             asm,
@@ -1062,22 +1062,22 @@ impl_stable_hash_for!(enum hir::Constness {
     NotConst
 });
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>>
+impl<'a> HashStable<StableHashingContext<'a>>
 for hir::def_id::DefIndex {
 
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         hcx.local_def_path_hash(*self).hash_stable(hcx, hasher);
     }
 }
 
-impl<'gcx> ToStableHashKey<StableHashingContext<'gcx>>
+impl<'a> ToStableHashKey<StableHashingContext<'a>>
 for hir::def_id::DefIndex {
     type KeyType = DefPathHash;
 
     #[inline]
-    fn to_stable_hash_key(&self, hcx: &StableHashingContext<'gcx>) -> DefPathHash {
+    fn to_stable_hash_key(&self, hcx: &StableHashingContext<'a>) -> DefPathHash {
          hcx.local_def_path_hash(*self)
     }
 }
@@ -1090,10 +1090,10 @@ impl_stable_hash_for!(struct hir::def::Export {
     is_import
 });
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>>
+impl<'a> HashStable<StableHashingContext<'a>>
 for ::middle::lang_items::LangItem {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          _: &mut StableHashingContext<'gcx>,
+                                          _: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         ::std::hash::Hash::hash(self, hasher);
     }
@@ -1104,10 +1104,10 @@ impl_stable_hash_for!(struct ::middle::lang_items::LanguageItems {
     missing
 });
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>>
+impl<'a> HashStable<StableHashingContext<'a>>
 for hir::TraitCandidate {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         hcx.with_node_id_hashing_mode(NodeIdHashingMode::HashDefPath, |hcx| {
             let hir::TraitCandidate {
@@ -1121,11 +1121,11 @@ for hir::TraitCandidate {
     }
 }
 
-impl<'gcx> ToStableHashKey<StableHashingContext<'gcx>> for hir::TraitCandidate {
+impl<'a> ToStableHashKey<StableHashingContext<'a>> for hir::TraitCandidate {
     type KeyType = (DefPathHash, Option<(DefPathHash, hir::ItemLocalId)>);
 
     fn to_stable_hash_key(&self,
-                          hcx: &StableHashingContext<'gcx>)
+                          hcx: &StableHashingContext<'a>)
                           -> Self::KeyType {
         let hir::TraitCandidate {
             def_id,
diff --git a/src/librustc/ich/impls_mir.rs b/src/librustc/ich/impls_mir.rs
index 40204943bb5..1e6dadae363 100644
--- a/src/librustc/ich/impls_mir.rs
+++ b/src/librustc/ich/impls_mir.rs
@@ -35,11 +35,11 @@ impl_stable_hash_for!(struct mir::BasicBlockData<'tcx> { statements, terminator,
 impl_stable_hash_for!(struct mir::UnsafetyViolation { source_info, description, kind });
 impl_stable_hash_for!(struct mir::UnsafetyCheckResult { violations, unsafe_blocks });
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>>
+impl<'a> HashStable<StableHashingContext<'a>>
 for mir::BorrowKind {
     #[inline]
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         mem::discriminant(self).hash_stable(hcx, hasher);
 
@@ -54,11 +54,11 @@ for mir::BorrowKind {
 }
 
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>>
+impl<'a> HashStable<StableHashingContext<'a>>
 for mir::UnsafetyViolationKind {
     #[inline]
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
 
         mem::discriminant(self).hash_stable(hcx, hasher);
@@ -79,12 +79,12 @@ impl_stable_hash_for!(struct mir::Terminator<'tcx> {
     source_info
 });
 
-impl<'gcx, T> HashStable<StableHashingContext<'gcx>> for mir::ClearCrossCrate<T>
-    where T: HashStable<StableHashingContext<'gcx>>
+impl<'a, 'gcx, T> HashStable<StableHashingContext<'a>> for mir::ClearCrossCrate<T>
+    where T: HashStable<StableHashingContext<'a>>
 {
     #[inline]
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         mem::discriminant(self).hash_stable(hcx, hasher);
         match *self {
@@ -96,61 +96,61 @@ impl<'gcx, T> HashStable<StableHashingContext<'gcx>> for mir::ClearCrossCrate<T>
     }
 }
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>> for mir::Local {
+impl<'a> HashStable<StableHashingContext<'a>> for mir::Local {
     #[inline]
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         use rustc_data_structures::indexed_vec::Idx;
         self.index().hash_stable(hcx, hasher);
     }
 }
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>> for mir::BasicBlock {
+impl<'a> HashStable<StableHashingContext<'a>> for mir::BasicBlock {
     #[inline]
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         use rustc_data_structures::indexed_vec::Idx;
         self.index().hash_stable(hcx, hasher);
     }
 }
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>> for mir::Field {
+impl<'a> HashStable<StableHashingContext<'a>> for mir::Field {
     #[inline]
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         use rustc_data_structures::indexed_vec::Idx;
         self.index().hash_stable(hcx, hasher);
     }
 }
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>>
+impl<'a> HashStable<StableHashingContext<'a>>
 for mir::VisibilityScope {
     #[inline]
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         use rustc_data_structures::indexed_vec::Idx;
         self.index().hash_stable(hcx, hasher);
     }
 }
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>> for mir::Promoted {
+impl<'a> HashStable<StableHashingContext<'a>> for mir::Promoted {
     #[inline]
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         use rustc_data_structures::indexed_vec::Idx;
         self.index().hash_stable(hcx, hasher);
     }
 }
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>>
+impl<'a, 'gcx> HashStable<StableHashingContext<'a>>
 for mir::TerminatorKind<'gcx> {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         mem::discriminant(self).hash_stable(hcx, hasher);
 
@@ -227,10 +227,10 @@ for mir::TerminatorKind<'gcx> {
     }
 }
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>>
+impl<'a, 'gcx> HashStable<StableHashingContext<'a>>
 for mir::AssertMessage<'gcx> {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         mem::discriminant(self).hash_stable(hcx, hasher);
 
@@ -250,10 +250,10 @@ for mir::AssertMessage<'gcx> {
 
 impl_stable_hash_for!(struct mir::Statement<'tcx> { source_info, kind });
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>>
+impl<'a, 'gcx> HashStable<StableHashingContext<'a>>
 for mir::StatementKind<'gcx> {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         mem::discriminant(self).hash_stable(hcx, hasher);
 
@@ -287,12 +287,12 @@ for mir::StatementKind<'gcx> {
     }
 }
 
-impl<'gcx, T> HashStable<StableHashingContext<'gcx>>
+impl<'a, 'gcx, T> HashStable<StableHashingContext<'a>>
     for mir::ValidationOperand<'gcx, T>
-    where T: HashStable<StableHashingContext<'gcx>>
+    where T: HashStable<StableHashingContext<'a>>
 {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>)
     {
         self.place.hash_stable(hcx, hasher);
@@ -304,9 +304,9 @@ impl<'gcx, T> HashStable<StableHashingContext<'gcx>>
 
 impl_stable_hash_for!(enum mir::ValidationOp { Acquire, Release, Suspend(region_scope) });
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>> for mir::Place<'gcx> {
+impl<'a, 'gcx> HashStable<StableHashingContext<'a>> for mir::Place<'gcx> {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         mem::discriminant(self).hash_stable(hcx, hasher);
         match *self {
@@ -323,14 +323,14 @@ impl<'gcx> HashStable<StableHashingContext<'gcx>> for mir::Place<'gcx> {
     }
 }
 
-impl<'gcx, B, V, T> HashStable<StableHashingContext<'gcx>>
+impl<'a, 'gcx, B, V, T> HashStable<StableHashingContext<'a>>
 for mir::Projection<'gcx, B, V, T>
-    where B: HashStable<StableHashingContext<'gcx>>,
-          V: HashStable<StableHashingContext<'gcx>>,
-          T: HashStable<StableHashingContext<'gcx>>
+    where B: HashStable<StableHashingContext<'a>>,
+          V: HashStable<StableHashingContext<'a>>,
+          T: HashStable<StableHashingContext<'a>>
 {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         let mir::Projection {
             ref base,
@@ -342,13 +342,13 @@ for mir::Projection<'gcx, B, V, T>
     }
 }
 
-impl<'gcx, V, T> HashStable<StableHashingContext<'gcx>>
+impl<'a, 'gcx, V, T> HashStable<StableHashingContext<'a>>
 for mir::ProjectionElem<'gcx, V, T>
-    where V: HashStable<StableHashingContext<'gcx>>,
-          T: HashStable<StableHashingContext<'gcx>>
+    where V: HashStable<StableHashingContext<'a>>,
+          T: HashStable<StableHashingContext<'a>>
 {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         mem::discriminant(self).hash_stable(hcx, hasher);
         match *self {
@@ -382,9 +382,9 @@ impl_stable_hash_for!(struct mir::VisibilityScopeInfo {
     lint_root, safety
 });
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>> for mir::Safety {
+impl<'a> HashStable<StableHashingContext<'a>> for mir::Safety {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         mem::discriminant(self).hash_stable(hcx, hasher);
 
@@ -399,9 +399,9 @@ impl<'gcx> HashStable<StableHashingContext<'gcx>> for mir::Safety {
     }
 }
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>> for mir::Operand<'gcx> {
+impl<'a, 'gcx> HashStable<StableHashingContext<'a>> for mir::Operand<'gcx> {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         mem::discriminant(self).hash_stable(hcx, hasher);
 
@@ -419,9 +419,9 @@ impl<'gcx> HashStable<StableHashingContext<'gcx>> for mir::Operand<'gcx> {
     }
 }
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>> for mir::Rvalue<'gcx> {
+impl<'a, 'gcx> HashStable<StableHashingContext<'a>> for mir::Rvalue<'gcx> {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         mem::discriminant(self).hash_stable(hcx, hasher);
 
@@ -479,10 +479,10 @@ impl_stable_hash_for!(enum mir::CastKind {
     Unsize
 });
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>>
+impl<'a, 'gcx> HashStable<StableHashingContext<'a>>
 for mir::AggregateKind<'gcx> {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         mem::discriminant(self).hash_stable(hcx, hasher);
         match *self {
@@ -541,9 +541,9 @@ impl_stable_hash_for!(enum mir::NullOp {
 
 impl_stable_hash_for!(struct mir::Constant<'tcx> { span, ty, literal });
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>> for mir::Literal<'gcx> {
+impl<'a, 'gcx> HashStable<StableHashingContext<'a>> for mir::Literal<'gcx> {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         mem::discriminant(self).hash_stable(hcx, hasher);
         match *self {
@@ -570,9 +570,9 @@ impl_stable_hash_for!(struct mir::ClosureOutlivesRequirement<'tcx> {
     blame_span
 });
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>> for mir::ClosureOutlivesSubject<'gcx> {
+impl<'a, 'gcx> HashStable<StableHashingContext<'a>> for mir::ClosureOutlivesSubject<'gcx> {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         mem::discriminant(self).hash_stable(hcx, hasher);
         match *self {
diff --git a/src/librustc/ich/impls_syntax.rs b/src/librustc/ich/impls_syntax.rs
index f935cbfcde9..52f43fbed7b 100644
--- a/src/librustc/ich/impls_syntax.rs
+++ b/src/librustc/ich/impls_syntax.rs
@@ -29,42 +29,42 @@ use rustc_data_structures::stable_hasher::{HashStable, ToStableHashKey,
                                            StableHasher, StableHasherResult};
 use rustc_data_structures::accumulate_vec::AccumulateVec;
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>> for InternedString {
+impl<'a> HashStable<StableHashingContext<'a>> for InternedString {
     #[inline]
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         let s: &str = &**self;
         s.hash_stable(hcx, hasher);
     }
 }
 
-impl<'gcx> ToStableHashKey<StableHashingContext<'gcx>> for InternedString {
+impl<'a> ToStableHashKey<StableHashingContext<'a>> for InternedString {
     type KeyType = InternedString;
 
     #[inline]
     fn to_stable_hash_key(&self,
-                          _: &StableHashingContext<'gcx>)
+                          _: &StableHashingContext<'a>)
                           -> InternedString {
         self.clone()
     }
 }
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>> for ast::Name {
+impl<'a> HashStable<StableHashingContext<'a>> for ast::Name {
     #[inline]
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         self.as_str().hash_stable(hcx, hasher);
     }
 }
 
-impl<'gcx> ToStableHashKey<StableHashingContext<'gcx>> for ast::Name {
+impl<'a> ToStableHashKey<StableHashingContext<'a>> for ast::Name {
     type KeyType = InternedString;
 
     #[inline]
     fn to_stable_hash_key(&self,
-                          _: &StableHashingContext<'gcx>)
+                          _: &StableHashingContext<'a>)
                           -> InternedString {
         self.as_str()
     }
@@ -111,10 +111,10 @@ impl_stable_hash_for!(struct ::syntax::attr::Stability {
     rustc_const_unstable
 });
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>>
+impl<'a> HashStable<StableHashingContext<'a>>
 for ::syntax::attr::StabilityLevel {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         mem::discriminant(self).hash_stable(hcx, hasher);
         match *self {
@@ -166,9 +166,9 @@ impl_stable_hash_for!(struct ::syntax::ast::Lifetime { id, span, ident });
 impl_stable_hash_for!(enum ::syntax::ast::StrStyle { Cooked, Raw(pounds) });
 impl_stable_hash_for!(enum ::syntax::ast::AttrStyle { Outer, Inner });
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>> for [ast::Attribute] {
+impl<'a> HashStable<StableHashingContext<'a>> for [ast::Attribute] {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         if self.len() == 0 {
             self.len().hash_stable(hcx, hasher);
@@ -191,9 +191,9 @@ impl<'gcx> HashStable<StableHashingContext<'gcx>> for [ast::Attribute] {
     }
 }
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>> for ast::Attribute {
+impl<'a> HashStable<StableHashingContext<'a>> for ast::Attribute {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         // Make sure that these have been filtered out.
         debug_assert!(self.name().map(|name| !hcx.is_ignored_attr(name)).unwrap_or(true));
@@ -220,10 +220,10 @@ impl<'gcx> HashStable<StableHashingContext<'gcx>> for ast::Attribute {
     }
 }
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>>
+impl<'a> HashStable<StableHashingContext<'a>>
 for tokenstream::TokenTree {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         mem::discriminant(self).hash_stable(hcx, hasher);
         match *self {
@@ -242,10 +242,10 @@ for tokenstream::TokenTree {
     }
 }
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>>
+impl<'a> HashStable<StableHashingContext<'a>>
 for tokenstream::TokenStream {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         for sub_tt in self.trees() {
             sub_tt.hash_stable(hcx, hasher);
@@ -253,9 +253,11 @@ for tokenstream::TokenStream {
     }
 }
 
-fn hash_token<'gcx, W: StableHasherResult>(token: &token::Token,
-                                           hcx: &mut StableHashingContext<'gcx>,
-                                           hasher: &mut StableHasher<W>) {
+fn hash_token<'a, 'gcx, W: StableHasherResult>(
+    token: &token::Token,
+    hcx: &mut StableHashingContext<'a>,
+    hasher: &mut StableHasher<W>,
+) {
     mem::discriminant(token).hash_stable(hcx, hasher);
     match *token {
         token::Token::Eq |
@@ -383,9 +385,9 @@ impl_stable_hash_for!(enum ::syntax_pos::FileName {
     Custom(s)
 });
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>> for FileMap {
+impl<'a> HashStable<StableHashingContext<'a>> for FileMap {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         let FileMap {
             name: _, // We hash the smaller name_hash instead of this
diff --git a/src/librustc/ich/impls_ty.rs b/src/librustc/ich/impls_ty.rs
index a25741c95aa..a92d9b16612 100644
--- a/src/librustc/ich/impls_ty.rs
+++ b/src/librustc/ich/impls_ty.rs
@@ -23,11 +23,11 @@ use traits;
 use ty;
 use mir;
 
-impl<'gcx, T> HashStable<StableHashingContext<'gcx>>
+impl<'a, 'gcx, T> HashStable<StableHashingContext<'a>>
 for &'gcx ty::Slice<T>
-    where T: HashStable<StableHashingContext<'gcx>> {
+    where T: HashStable<StableHashingContext<'a>> {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         thread_local! {
             static CACHE: RefCell<FxHashMap<(usize, usize), Fingerprint>> =
@@ -52,10 +52,10 @@ for &'gcx ty::Slice<T>
     }
 }
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>>
+impl<'a, 'gcx> HashStable<StableHashingContext<'a>>
 for ty::subst::Kind<'gcx> {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         self.unpack().hash_stable(hcx, hasher);
     }
@@ -73,10 +73,10 @@ for ty::subst::UnpackedKind<'gcx> {
     }
 }
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>>
+impl<'a> HashStable<StableHashingContext<'a>>
 for ty::RegionKind {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         mem::discriminant(self).hash_stable(hcx, hasher);
         match *self {
@@ -120,20 +120,20 @@ for ty::RegionKind {
     }
 }
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>> for ty::RegionVid {
+impl<'a> HashStable<StableHashingContext<'a>> for ty::RegionVid {
     #[inline]
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         use rustc_data_structures::indexed_vec::Idx;
         self.index().hash_stable(hcx, hasher);
     }
 }
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>>
+impl<'a, 'gcx> HashStable<StableHashingContext<'a>>
 for ty::adjustment::AutoBorrow<'gcx> {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         mem::discriminant(self).hash_stable(hcx, hasher);
         match *self {
@@ -148,10 +148,10 @@ for ty::adjustment::AutoBorrow<'gcx> {
     }
 }
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>>
+impl<'a, 'gcx> HashStable<StableHashingContext<'a>>
 for ty::adjustment::Adjust<'gcx> {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         mem::discriminant(self).hash_stable(hcx, hasher);
         match *self {
@@ -197,10 +197,10 @@ impl_stable_hash_for!(enum ty::BorrowKind {
     MutBorrow
 });
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>>
+impl<'a, 'gcx> HashStable<StableHashingContext<'a>>
 for ty::UpvarCapture<'gcx> {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         mem::discriminant(self).hash_stable(hcx, hasher);
         match *self {
@@ -224,11 +224,11 @@ impl_stable_hash_for!(struct ty::FnSig<'tcx> {
     abi
 });
 
-impl<'gcx, T> HashStable<StableHashingContext<'gcx>> for ty::Binder<T>
-    where T: HashStable<StableHashingContext<'gcx>>
+impl<'a, 'gcx, T> HashStable<StableHashingContext<'a>> for ty::Binder<T>
+    where T: HashStable<StableHashingContext<'a>>
 {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         let ty::Binder(ref inner) = *self;
         inner.hash_stable(hcx, hasher);
@@ -247,13 +247,13 @@ impl_stable_hash_for!(struct ty::TraitRef<'tcx> { def_id, substs });
 impl_stable_hash_for!(struct ty::TraitPredicate<'tcx> { trait_ref });
 impl_stable_hash_for!(struct ty::SubtypePredicate<'tcx> { a_is_expected, a, b });
 
-impl<'gcx, A, B> HashStable<StableHashingContext<'gcx>>
+impl<'a, 'gcx, A, B> HashStable<StableHashingContext<'a>>
 for ty::OutlivesPredicate<A, B>
-    where A: HashStable<StableHashingContext<'gcx>>,
-          B: HashStable<StableHashingContext<'gcx>>,
+    where A: HashStable<StableHashingContext<'a>>,
+          B: HashStable<StableHashingContext<'a>>,
 {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         let ty::OutlivesPredicate(ref a, ref b) = *self;
         a.hash_stable(hcx, hasher);
@@ -265,9 +265,9 @@ impl_stable_hash_for!(struct ty::ProjectionPredicate<'tcx> { projection_ty, ty }
 impl_stable_hash_for!(struct ty::ProjectionTy<'tcx> { substs, item_def_id });
 
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>> for ty::Predicate<'gcx> {
+impl<'a, 'gcx> HashStable<StableHashingContext<'a>> for ty::Predicate<'gcx> {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         mem::discriminant(self).hash_stable(hcx, hasher);
         match *self {
@@ -305,9 +305,9 @@ impl<'gcx> HashStable<StableHashingContext<'gcx>> for ty::Predicate<'gcx> {
     }
 }
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>> for ty::AdtFlags {
+impl<'a> HashStable<StableHashingContext<'a>> for ty::AdtFlags {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          _: &mut StableHashingContext<'gcx>,
+                                          _: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         std_hash::Hash::hash(self, hasher);
     }
@@ -332,10 +332,10 @@ impl_stable_hash_for!(struct ty::FieldDef {
     vis
 });
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>>
+impl<'a, 'gcx> HashStable<StableHashingContext<'a>>
 for ::middle::const_val::ConstVal<'gcx> {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         use middle::const_val::ConstVal::*;
 
@@ -368,7 +368,51 @@ impl_stable_hash_for!(struct mir::interpret::MemoryPointer {
     offset
 });
 
-impl_stable_hash_for!(tuple_struct mir::interpret::AllocId{id});
+impl<'a> HashStable<StableHashingContext<'a>> for mir::interpret::AllocId {
+    fn hash_stable<W: StableHasherResult>(
+        &self,
+        hcx: &mut StableHashingContext<'a>,
+        hasher: &mut StableHasher<W>,
+    ) {
+        ty::tls::with_opt(|tcx| {
+            let tcx = tcx.expect("can't hash AllocIds during hir lowering");
+            let interner = tcx
+                .interpret_interner
+                .borrow();
+            if let Some(def_id) = interner.get_corresponding_static_def_id(*self) {
+                0.hash_stable(hcx, hasher);
+                // statics are unique via their DefId
+                def_id.hash_stable(hcx, hasher);
+            } else if let Some(alloc) = interner.get_alloc(*self) {
+                // not a static, can't be recursive, hash the allocation
+                1.hash_stable(hcx, hasher);
+                alloc.hash_stable(hcx, hasher);
+            } else if let Some(inst) = interner.get_fn(*self) {
+                2.hash_stable(hcx, hasher);
+                inst.hash_stable(hcx, hasher);
+            } else {
+                bug!("no allocation for {}", self);
+            }
+        });
+    }
+}
+
+impl<'a> HashStable<StableHashingContext<'a>> for mir::interpret::Allocation {
+    fn hash_stable<W: StableHasherResult>(
+        &self,
+        hcx: &mut StableHashingContext<'a>,
+        hasher: &mut StableHasher<W>,
+    ) {
+        self.bytes.hash_stable(hcx, hasher);
+        for reloc in self.relocations.iter() {
+            reloc.hash_stable(hcx, hasher);
+        }
+        self.undef_mask.hash_stable(hcx, hasher);
+        self.align.hash_stable(hcx, hasher);
+        self.mutable.hash_stable(hcx, hasher);
+    }
+}
+
 impl_stable_hash_for!(struct mir::interpret::Pointer{primval});
 
 impl_stable_hash_for!(enum mir::interpret::PrimVal {
@@ -387,10 +431,10 @@ impl_stable_hash_for!(struct ::middle::const_val::ConstEvalErr<'tcx> {
     kind
 });
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>>
+impl<'a, 'gcx> HashStable<StableHashingContext<'a>>
 for ::middle::const_val::ErrKind<'gcx> {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         use middle::const_val::ErrKind::*;
 
@@ -441,10 +485,10 @@ impl_stable_hash_for!(struct ty::GenericPredicates<'tcx> {
     predicates
 });
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>>
+impl<'a, 'gcx> HashStable<StableHashingContext<'a>>
 for ::mir::interpret::EvalError<'gcx> {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         use mir::interpret::EvalErrorKind::*;
 
@@ -621,9 +665,9 @@ impl_stable_hash_for!(enum ty::adjustment::CustomCoerceUnsized {
     Struct(index)
 });
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>> for ty::Generics {
+impl<'a> HashStable<StableHashingContext<'a>> for ty::Generics {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         let ty::Generics {
             parent,
@@ -649,10 +693,10 @@ impl<'gcx> HashStable<StableHashingContext<'gcx>> for ty::Generics {
     }
 }
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>>
+impl<'a> HashStable<StableHashingContext<'a>>
 for ty::RegionParameterDef {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         let ty::RegionParameterDef {
             name,
@@ -678,12 +722,12 @@ impl_stable_hash_for!(struct ty::TypeParameterDef {
     synthetic
 });
 
-impl<'gcx, T> HashStable<StableHashingContext<'gcx>>
+impl<'a, 'gcx, T> HashStable<StableHashingContext<'a>>
 for ::middle::resolve_lifetime::Set1<T>
-    where T: HashStable<StableHashingContext<'gcx>>
+    where T: HashStable<StableHashingContext<'a>>
 {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         use middle::resolve_lifetime::Set1;
 
@@ -734,11 +778,11 @@ impl_stable_hash_for!(enum ty::cast::CastKind {
 impl_stable_hash_for!(tuple_struct ::middle::region::FirstStatementIndex { idx });
 impl_stable_hash_for!(struct ::middle::region::Scope { id, code });
 
-impl<'gcx> ToStableHashKey<StableHashingContext<'gcx>> for region::Scope {
+impl<'a> ToStableHashKey<StableHashingContext<'a>> for region::Scope {
     type KeyType = region::Scope;
 
     #[inline]
-    fn to_stable_hash_key(&self, _: &StableHashingContext<'gcx>) -> region::Scope {
+    fn to_stable_hash_key(&self, _: &StableHashingContext<'a>) -> region::Scope {
         *self
     }
 }
@@ -764,11 +808,11 @@ impl_stable_hash_for!(enum ty::BoundRegion {
     BrEnv
 });
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>>
+impl<'a, 'gcx> HashStable<StableHashingContext<'a>>
 for ty::TypeVariants<'gcx>
 {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         use ty::TypeVariants::*;
 
@@ -865,11 +909,11 @@ impl_stable_hash_for!(struct ty::TypeAndMut<'tcx> {
     mutbl
 });
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>>
+impl<'a, 'gcx> HashStable<StableHashingContext<'a>>
 for ty::ExistentialPredicate<'gcx>
 {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         mem::discriminant(self).hash_stable(hcx, hasher);
         match *self {
@@ -902,9 +946,9 @@ impl_stable_hash_for!(struct ty::Instance<'tcx> {
     substs
 });
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>> for ty::InstanceDef<'gcx> {
+impl<'a, 'gcx> HashStable<StableHashingContext<'a>> for ty::InstanceDef<'gcx> {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         mem::discriminant(self).hash_stable(hcx, hasher);
 
@@ -938,9 +982,9 @@ impl<'gcx> HashStable<StableHashingContext<'gcx>> for ty::InstanceDef<'gcx> {
     }
 }
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>> for ty::TraitDef {
+impl<'a> HashStable<StableHashingContext<'a>> for ty::TraitDef {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         let ty::TraitDef {
             // We already have the def_path_hash below, no need to hash it twice
@@ -968,9 +1012,9 @@ impl_stable_hash_for!(struct ty::DtorckConstraint<'tcx> {
 });
 
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>> for ty::CrateVariancesMap {
+impl<'a> HashStable<StableHashingContext<'a>> for ty::CrateVariancesMap {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         let ty::CrateVariancesMap {
             ref variances,
@@ -1004,12 +1048,12 @@ impl_stable_hash_for!(enum ty::AssociatedItemContainer {
 });
 
 
-impl<'gcx, T> HashStable<StableHashingContext<'gcx>>
+impl<'a, 'gcx, T> HashStable<StableHashingContext<'a>>
 for ty::steal::Steal<T>
-    where T: HashStable<StableHashingContext<'gcx>>
+    where T: HashStable<StableHashingContext<'a>>
 {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         self.borrow().hash_stable(hcx, hasher);
     }
@@ -1032,10 +1076,10 @@ impl_stable_hash_for!(enum ::middle::privacy::AccessLevel {
     Public
 });
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>>
+impl<'a> HashStable<StableHashingContext<'a>>
 for ::middle::privacy::AccessLevels {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         hcx.with_node_id_hashing_mode(NodeIdHashingMode::HashDefPath, |hcx| {
             let ::middle::privacy::AccessLevels {
@@ -1062,10 +1106,10 @@ impl_stable_hash_for!(tuple_struct ::middle::reachable::ReachableSet {
     reachable_set
 });
 
-impl<'gcx, N> HashStable<StableHashingContext<'gcx>>
-for traits::Vtable<'gcx, N> where N: HashStable<StableHashingContext<'gcx>> {
+impl<'a, 'gcx, N> HashStable<StableHashingContext<'a>>
+for traits::Vtable<'gcx, N> where N: HashStable<StableHashingContext<'a>> {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         use traits::Vtable::*;
 
@@ -1084,10 +1128,10 @@ for traits::Vtable<'gcx, N> where N: HashStable<StableHashingContext<'gcx>> {
     }
 }
 
-impl<'gcx, N> HashStable<StableHashingContext<'gcx>>
-for traits::VtableImplData<'gcx, N> where N: HashStable<StableHashingContext<'gcx>> {
+impl<'a, 'gcx, N> HashStable<StableHashingContext<'a>>
+for traits::VtableImplData<'gcx, N> where N: HashStable<StableHashingContext<'a>> {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         let traits::VtableImplData {
             impl_def_id,
@@ -1100,10 +1144,10 @@ for traits::VtableImplData<'gcx, N> where N: HashStable<StableHashingContext<'gc
     }
 }
 
-impl<'gcx, N> HashStable<StableHashingContext<'gcx>>
-for traits::VtableAutoImplData<N> where N: HashStable<StableHashingContext<'gcx>> {
+impl<'a, 'gcx, N> HashStable<StableHashingContext<'a>>
+for traits::VtableAutoImplData<N> where N: HashStable<StableHashingContext<'a>> {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         let traits::VtableAutoImplData {
             trait_def_id,
@@ -1114,10 +1158,10 @@ for traits::VtableAutoImplData<N> where N: HashStable<StableHashingContext<'gcx>
     }
 }
 
-impl<'gcx, N> HashStable<StableHashingContext<'gcx>>
-for traits::VtableObjectData<'gcx, N> where N: HashStable<StableHashingContext<'gcx>> {
+impl<'a, 'gcx, N> HashStable<StableHashingContext<'a>>
+for traits::VtableObjectData<'gcx, N> where N: HashStable<StableHashingContext<'a>> {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         let traits::VtableObjectData {
             upcast_trait_ref,
@@ -1130,10 +1174,10 @@ for traits::VtableObjectData<'gcx, N> where N: HashStable<StableHashingContext<'
     }
 }
 
-impl<'gcx, N> HashStable<StableHashingContext<'gcx>>
-for traits::VtableBuiltinData<N> where N: HashStable<StableHashingContext<'gcx>> {
+impl<'a, 'gcx, N> HashStable<StableHashingContext<'a>>
+for traits::VtableBuiltinData<N> where N: HashStable<StableHashingContext<'a>> {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         let traits::VtableBuiltinData {
             ref nested,
@@ -1142,10 +1186,10 @@ for traits::VtableBuiltinData<N> where N: HashStable<StableHashingContext<'gcx>>
     }
 }
 
-impl<'gcx, N> HashStable<StableHashingContext<'gcx>>
-for traits::VtableClosureData<'gcx, N> where N: HashStable<StableHashingContext<'gcx>> {
+impl<'a, 'gcx, N> HashStable<StableHashingContext<'a>>
+for traits::VtableClosureData<'gcx, N> where N: HashStable<StableHashingContext<'a>> {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         let traits::VtableClosureData {
             closure_def_id,
@@ -1158,10 +1202,10 @@ for traits::VtableClosureData<'gcx, N> where N: HashStable<StableHashingContext<
     }
 }
 
-impl<'gcx, N> HashStable<StableHashingContext<'gcx>>
-for traits::VtableFnPointerData<'gcx, N> where N: HashStable<StableHashingContext<'gcx>> {
+impl<'a, 'gcx, N> HashStable<StableHashingContext<'a>>
+for traits::VtableFnPointerData<'gcx, N> where N: HashStable<StableHashingContext<'a>> {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         let traits::VtableFnPointerData {
             fn_ty,
@@ -1172,10 +1216,10 @@ for traits::VtableFnPointerData<'gcx, N> where N: HashStable<StableHashingContex
     }
 }
 
-impl<'gcx, N> HashStable<StableHashingContext<'gcx>>
-for traits::VtableGeneratorData<'gcx, N> where N: HashStable<StableHashingContext<'gcx>> {
+impl<'a, 'gcx, N> HashStable<StableHashingContext<'a>>
+for traits::VtableGeneratorData<'gcx, N> where N: HashStable<StableHashingContext<'a>> {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         let traits::VtableGeneratorData {
             closure_def_id,
diff --git a/src/librustc/lint/levels.rs b/src/librustc/lint/levels.rs
index 909904b4fc3..8a899a35ecb 100644
--- a/src/librustc/lint/levels.rs
+++ b/src/librustc/lint/levels.rs
@@ -394,10 +394,10 @@ impl LintLevelMap {
     }
 }
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>> for LintLevelMap {
+impl<'a> HashStable<StableHashingContext<'a>> for LintLevelMap {
     #[inline]
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         let LintLevelMap {
             ref sets,
diff --git a/src/librustc/macros.rs b/src/librustc/macros.rs
index f0285d6a937..9a394e52481 100644
--- a/src/librustc/macros.rs
+++ b/src/librustc/macros.rs
@@ -73,10 +73,10 @@ macro_rules! __impl_stable_hash_field {
 #[macro_export]
 macro_rules! impl_stable_hash_for {
     (enum $enum_name:path { $( $variant:ident $( ( $($arg:ident),* ) )* ),* }) => {
-        impl<'tcx> ::rustc_data_structures::stable_hasher::HashStable<$crate::ich::StableHashingContext<'tcx>> for $enum_name {
+        impl<'a, 'tcx> ::rustc_data_structures::stable_hasher::HashStable<$crate::ich::StableHashingContext<'a>> for $enum_name {
             #[inline]
             fn hash_stable<W: ::rustc_data_structures::stable_hasher::StableHasherResult>(&self,
-                                                  __ctx: &mut $crate::ich::StableHashingContext<'tcx>,
+                                                  __ctx: &mut $crate::ich::StableHashingContext<'a>,
                                                   __hasher: &mut ::rustc_data_structures::stable_hasher::StableHasher<W>) {
                 use $enum_name::*;
                 ::std::mem::discriminant(self).hash_stable(__ctx, __hasher);
@@ -92,10 +92,10 @@ macro_rules! impl_stable_hash_for {
         }
     };
     (struct $struct_name:path { $($field:ident),* }) => {
-        impl<'tcx> ::rustc_data_structures::stable_hasher::HashStable<$crate::ich::StableHashingContext<'tcx>> for $struct_name {
+        impl<'a, 'tcx> ::rustc_data_structures::stable_hasher::HashStable<$crate::ich::StableHashingContext<'a>> for $struct_name {
             #[inline]
             fn hash_stable<W: ::rustc_data_structures::stable_hasher::StableHasherResult>(&self,
-                                                  __ctx: &mut $crate::ich::StableHashingContext<'tcx>,
+                                                  __ctx: &mut $crate::ich::StableHashingContext<'a>,
                                                   __hasher: &mut ::rustc_data_structures::stable_hasher::StableHasher<W>) {
                 let $struct_name {
                     $(ref $field),*
@@ -106,10 +106,10 @@ macro_rules! impl_stable_hash_for {
         }
     };
     (tuple_struct $struct_name:path { $($field:ident),* }) => {
-        impl<'tcx> ::rustc_data_structures::stable_hasher::HashStable<$crate::ich::StableHashingContext<'tcx>> for $struct_name {
+        impl<'a, 'tcx> ::rustc_data_structures::stable_hasher::HashStable<$crate::ich::StableHashingContext<'a>> for $struct_name {
             #[inline]
             fn hash_stable<W: ::rustc_data_structures::stable_hasher::StableHasherResult>(&self,
-                                                  __ctx: &mut $crate::ich::StableHashingContext<'tcx>,
+                                                  __ctx: &mut $crate::ich::StableHashingContext<'a>,
                                                   __hasher: &mut ::rustc_data_structures::stable_hasher::StableHasher<W>) {
                 let $struct_name (
                     $(ref $field),*
@@ -125,11 +125,11 @@ macro_rules! impl_stable_hash_for {
 macro_rules! impl_stable_hash_for_spanned {
     ($T:path) => (
 
-        impl<'tcx> HashStable<StableHashingContext<'tcx>> for ::syntax::codemap::Spanned<$T>
+        impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for ::syntax::codemap::Spanned<$T>
         {
             #[inline]
             fn hash_stable<W: StableHasherResult>(&self,
-                                                  hcx: &mut StableHashingContext<'tcx>,
+                                                  hcx: &mut StableHashingContext<'a>,
                                                   hasher: &mut StableHasher<W>) {
                 self.node.hash_stable(hcx, hasher);
                 self.span.hash_stable(hcx, hasher);
diff --git a/src/librustc/middle/borrowck.rs b/src/librustc/middle/borrowck.rs
index 380f79361e2..6f5791ed5d7 100644
--- a/src/librustc/middle/borrowck.rs
+++ b/src/librustc/middle/borrowck.rs
@@ -20,9 +20,9 @@ pub struct BorrowCheckResult {
     pub used_mut_nodes: FxHashSet<HirId>,
 }
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>> for BorrowCheckResult {
+impl<'a> HashStable<StableHashingContext<'a>> for BorrowCheckResult {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         let BorrowCheckResult {
             ref used_mut_nodes,
diff --git a/src/librustc/middle/region.rs b/src/librustc/middle/region.rs
index 812ee0dc72f..c73930553cd 100644
--- a/src/librustc/middle/region.rs
+++ b/src/librustc/middle/region.rs
@@ -1488,9 +1488,9 @@ pub fn provide(providers: &mut Providers) {
     };
 }
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>> for ScopeTree {
+impl<'a> HashStable<StableHashingContext<'a>> for ScopeTree {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         let ScopeTree {
             root_body,
diff --git a/src/librustc/mir/cache.rs b/src/librustc/mir/cache.rs
index efc2f647cfd..45cb70d0070 100644
--- a/src/librustc/mir/cache.rs
+++ b/src/librustc/mir/cache.rs
@@ -35,9 +35,9 @@ impl serialize::Decodable for Cache {
     }
 }
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>> for Cache {
+impl<'a> HashStable<StableHashingContext<'a>> for Cache {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          _: &mut StableHashingContext<'gcx>,
+                                          _: &mut StableHashingContext<'a>,
                                           _: &mut StableHasher<W>) {
         // do nothing
     }
diff --git a/src/librustc/mir/interpret/mod.rs b/src/librustc/mir/interpret/mod.rs
index 394b3d96a4f..c395be549a3 100644
--- a/src/librustc/mir/interpret/mod.rs
+++ b/src/librustc/mir/interpret/mod.rs
@@ -200,6 +200,8 @@ pub struct UndefMask {
     len: u64,
 }
 
+impl_stable_hash_for!(struct mir::interpret::UndefMask{blocks, len});
+
 impl UndefMask {
     pub fn new(size: u64) -> Self {
         let mut m = UndefMask {
diff --git a/src/librustc/mir/mod.rs b/src/librustc/mir/mod.rs
index 9e9ba516203..8da3a125d3f 100644
--- a/src/librustc/mir/mod.rs
+++ b/src/librustc/mir/mod.rs
@@ -1877,7 +1877,7 @@ fn fmt_const_val<W: Write>(fmt: &mut W, const_val: &ty::Const) -> fmt::Result {
     }
 }
 
-fn print_miri_value<W: Write>(value: Value, ty: Ty, f: &mut W) -> fmt::Result {
+pub fn print_miri_value<W: Write>(value: Value, ty: Ty, f: &mut W) -> fmt::Result {
     use ty::TypeVariants::*;
     use rustc_const_math::ConstFloat;
     match (value, &ty.sty) {
diff --git a/src/librustc/mir/mono.rs b/src/librustc/mir/mono.rs
index d8eac2b4159..d01059a3e01 100644
--- a/src/librustc/mir/mono.rs
+++ b/src/librustc/mir/mono.rs
@@ -41,9 +41,9 @@ impl<'tcx> MonoItem<'tcx> {
     }
 }
 
-impl<'tcx> HashStable<StableHashingContext<'tcx>> for MonoItem<'tcx> {
+impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for MonoItem<'tcx> {
     fn hash_stable<W: StableHasherResult>(&self,
-                                           hcx: &mut StableHashingContext<'tcx>,
+                                           hcx: &mut StableHashingContext<'a>,
                                            hasher: &mut StableHasher<W>) {
         ::std::mem::discriminant(self).hash_stable(hcx, hasher);
 
@@ -171,9 +171,9 @@ impl<'tcx> CodegenUnit<'tcx> {
     }
 }
 
-impl<'tcx> HashStable<StableHashingContext<'tcx>> for CodegenUnit<'tcx> {
+impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for CodegenUnit<'tcx> {
     fn hash_stable<W: StableHasherResult>(&self,
-                                           hcx: &mut StableHashingContext<'tcx>,
+                                           hcx: &mut StableHashingContext<'a>,
                                            hasher: &mut StableHasher<W>) {
         let CodegenUnit {
             ref items,
diff --git a/src/librustc/session/config.rs b/src/librustc/session/config.rs
index 157614f847a..437369400ed 100644
--- a/src/librustc/session/config.rs
+++ b/src/librustc/session/config.rs
@@ -179,10 +179,10 @@ impl_stable_hash_for!(enum self::OutputType {
     DepInfo
 });
 
-impl<'tcx> ToStableHashKey<StableHashingContext<'tcx>> for OutputType {
+impl<'a, 'tcx> ToStableHashKey<StableHashingContext<'a>> for OutputType {
     type KeyType = OutputType;
     #[inline]
-    fn to_stable_hash_key(&self, _: &StableHashingContext<'tcx>) -> Self::KeyType {
+    fn to_stable_hash_key(&self, _: &StableHashingContext<'a>) -> Self::KeyType {
         *self
     }
 }
diff --git a/src/librustc/traits/specialize/specialization_graph.rs b/src/librustc/traits/specialize/specialization_graph.rs
index dbf15ad1707..f8b895177f3 100644
--- a/src/librustc/traits/specialize/specialization_graph.rs
+++ b/src/librustc/traits/specialize/specialization_graph.rs
@@ -391,9 +391,9 @@ pub fn ancestors(tcx: TyCtxt,
     }
 }
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>> for Children {
+impl<'a> HashStable<StableHashingContext<'a>> for Children {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         let Children {
             ref nonblanket_impls,
diff --git a/src/librustc/ty/context.rs b/src/librustc/ty/context.rs
index bf75afcfa1a..3ec3f665db9 100644
--- a/src/librustc/ty/context.rs
+++ b/src/librustc/ty/context.rs
@@ -676,9 +676,9 @@ impl<'tcx> TypeckTables<'tcx> {
     }
 }
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>> for TypeckTables<'gcx> {
+impl<'a, 'gcx> HashStable<StableHashingContext<'a>> for TypeckTables<'gcx> {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         let ty::TypeckTables {
             local_id_root,
@@ -1366,7 +1366,7 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
         self.cstore.crate_data_as_rc_any(cnum)
     }
 
-    pub fn create_stable_hashing_context(self) -> StableHashingContext<'gcx> {
+    pub fn create_stable_hashing_context(self) -> StableHashingContext<'a> {
         let krate = self.dep_graph.with_ignore(|| self.gcx.hir.krate());
 
         StableHashingContext::new(self.sess,
diff --git a/src/librustc/ty/fast_reject.rs b/src/librustc/ty/fast_reject.rs
index 97c259e6bf3..93d8a4d979d 100644
--- a/src/librustc/ty/fast_reject.rs
+++ b/src/librustc/ty/fast_reject.rs
@@ -154,12 +154,12 @@ impl<D: Copy + Debug + Ord + Eq + Hash> SimplifiedTypeGen<D> {
     }
 }
 
-impl<'gcx, D> HashStable<StableHashingContext<'gcx>> for SimplifiedTypeGen<D>
+impl<'a, 'gcx, D> HashStable<StableHashingContext<'a>> for SimplifiedTypeGen<D>
     where D: Copy + Debug + Ord + Eq + Hash +
-             HashStable<StableHashingContext<'gcx>>,
+             HashStable<StableHashingContext<'a>>,
 {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         mem::discriminant(self).hash_stable(hcx, hasher);
         match *self {
diff --git a/src/librustc/ty/layout.rs b/src/librustc/ty/layout.rs
index 35d8fb2a67a..79f01a32cd9 100644
--- a/src/librustc/ty/layout.rs
+++ b/src/librustc/ty/layout.rs
@@ -2369,9 +2369,9 @@ impl<'a, 'tcx> TyLayout<'tcx> {
     }
 }
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>> for Variants {
+impl<'a> HashStable<StableHashingContext<'a>> for Variants {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         use ty::layout::Variants::*;
         mem::discriminant(self).hash_stable(hcx, hasher);
@@ -2405,9 +2405,9 @@ impl<'gcx> HashStable<StableHashingContext<'gcx>> for Variants {
     }
 }
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>> for FieldPlacement {
+impl<'a> HashStable<StableHashingContext<'a>> for FieldPlacement {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         use ty::layout::FieldPlacement::*;
         mem::discriminant(self).hash_stable(hcx, hasher);
@@ -2428,9 +2428,9 @@ impl<'gcx> HashStable<StableHashingContext<'gcx>> for FieldPlacement {
     }
 }
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>> for Abi {
+impl<'a> HashStable<StableHashingContext<'a>> for Abi {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         use ty::layout::Abi::*;
         mem::discriminant(self).hash_stable(hcx, hasher);
@@ -2455,9 +2455,9 @@ impl<'gcx> HashStable<StableHashingContext<'gcx>> for Abi {
     }
 }
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>> for Scalar {
+impl<'a> HashStable<StableHashingContext<'a>> for Scalar {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         let Scalar { value, valid_range: RangeInclusive { start, end } } = *self;
         value.hash_stable(hcx, hasher);
@@ -2498,10 +2498,10 @@ impl_stable_hash_for!(struct ::ty::layout::Size {
     raw
 });
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>> for LayoutError<'gcx>
+impl<'a, 'gcx> HashStable<StableHashingContext<'a>> for LayoutError<'gcx>
 {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         use ty::layout::LayoutError::*;
         mem::discriminant(self).hash_stable(hcx, hasher);
diff --git a/src/librustc/ty/mod.rs b/src/librustc/ty/mod.rs
index f9071cff78f..2c7ec5155a6 100644
--- a/src/librustc/ty/mod.rs
+++ b/src/librustc/ty/mod.rs
@@ -80,7 +80,7 @@ pub use self::binding::BindingMode;
 pub use self::binding::BindingMode::*;
 
 pub use self::context::{TyCtxt, GlobalArenas, AllArenas, tls, keep_local};
-pub use self::context::{Lift, TypeckTables};
+pub use self::context::{Lift, TypeckTables, InterpretInterner};
 
 pub use self::instance::{Instance, InstanceDef};
 
@@ -529,9 +529,9 @@ impl<'tcx> TyS<'tcx> {
     }
 }
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>> for ty::TyS<'gcx> {
+impl<'a, 'gcx> HashStable<StableHashingContext<'a>> for ty::TyS<'gcx> {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         let ty::TyS {
             ref sty,
@@ -1440,11 +1440,11 @@ impl<'tcx, T> ParamEnvAnd<'tcx, T> {
     }
 }
 
-impl<'gcx, T> HashStable<StableHashingContext<'gcx>> for ParamEnvAnd<'gcx, T>
-    where T: HashStable<StableHashingContext<'gcx>>
+impl<'a, 'gcx, T> HashStable<StableHashingContext<'a>> for ParamEnvAnd<'gcx, T>
+    where T: HashStable<StableHashingContext<'a>>
 {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         let ParamEnvAnd {
             ref param_env,
@@ -1545,9 +1545,9 @@ impl<'tcx> serialize::UseSpecializedEncodable for &'tcx AdtDef {
 impl<'tcx> serialize::UseSpecializedDecodable for &'tcx AdtDef {}
 
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>> for AdtDef {
+impl<'a> HashStable<StableHashingContext<'a>> for AdtDef {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         thread_local! {
             static CACHE: RefCell<FxHashMap<usize, Fingerprint>> =
diff --git a/src/librustc/ty/trait_def.rs b/src/librustc/ty/trait_def.rs
index 62d3c8dc87d..32f0d3384c4 100644
--- a/src/librustc/ty/trait_def.rs
+++ b/src/librustc/ty/trait_def.rs
@@ -186,9 +186,9 @@ pub(super) fn trait_impls_of_provider<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
     })
 }
 
-impl<'gcx> HashStable<StableHashingContext<'gcx>> for TraitImpls {
+impl<'a> HashStable<StableHashingContext<'a>> for TraitImpls {
     fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'gcx>,
+                                          hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         let TraitImpls {
             ref blanket_impls,