5 files changed, 10 insertions, 71 deletions
diff --git a/compiler/rustc_middle/src/ich/hcx.rs b/compiler/rustc_middle/src/ich/hcx.rs
index c7f58ce5b13..4b4f65a062f 100644
--- a/compiler/rustc_middle/src/ich/hcx.rs
+++ b/compiler/rustc_middle/src/ich/hcx.rs
@@ -1,9 +1,9 @@
 use crate::ich;
 use crate::middle::cstore::CrateStore;
-use crate::ty::{fast_reject, TyCtxt};
+use crate::ty::TyCtxt;
 
 use rustc_ast as ast;
-use rustc_data_structures::fx::{FxHashMap, FxHashSet};
+use rustc_data_structures::fx::FxHashSet;
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use rustc_data_structures::sync::Lrc;
 use rustc_hir as hir;
@@ -14,9 +14,6 @@ use rustc_span::source_map::SourceMap;
 use rustc_span::symbol::Symbol;
 use rustc_span::{BytePos, CachingSourceMapView, SourceFile, Span, SpanData};
 
-use smallvec::SmallVec;
-use std::cmp::Ord;
-
 fn compute_ignored_attr_names() -> FxHashSet<Symbol> {
     debug_assert!(!ich::IGNORED_ATTRIBUTES.is_empty());
     ich::IGNORED_ATTRIBUTES.iter().copied().collect()
@@ -241,39 +238,3 @@ impl<'a> rustc_span::HashStableContext for StableHashingContext<'a> {
 }
 
 impl rustc_session::HashStableContext for StableHashingContext<'a> {}
-
-pub fn hash_stable_trait_impls<'a>(
-    hcx: &mut StableHashingContext<'a>,
-    hasher: &mut StableHasher,
-    blanket_impls: &[DefId],
-    non_blanket_impls: &FxHashMap<fast_reject::SimplifiedType, Vec<DefId>>,
-) {
-    {
-        let mut blanket_impls: SmallVec<[_; 8]> =
-            blanket_impls.iter().map(|&def_id| hcx.def_path_hash(def_id)).collect();
-
-        if blanket_impls.len() > 1 {
-            blanket_impls.sort_unstable();
-        }
-
-        blanket_impls.hash_stable(hcx, hasher);
-    }
-
-    {
-        let mut keys: SmallVec<[_; 8]> =
-            non_blanket_impls.keys().map(|k| (k, k.map_def(|d| hcx.def_path_hash(d)))).collect();
-        keys.sort_unstable_by(|&(_, ref k1), &(_, ref k2)| k1.cmp(k2));
-        keys.len().hash_stable(hcx, hasher);
-        for (key, ref stable_key) in keys {
-            stable_key.hash_stable(hcx, hasher);
-            let mut impls: SmallVec<[_; 8]> =
-                non_blanket_impls[key].iter().map(|&impl_id| hcx.def_path_hash(impl_id)).collect();
-
-            if impls.len() > 1 {
-                impls.sort_unstable();
-            }
-
-            impls.hash_stable(hcx, hasher);
-        }
-    }
-}
diff --git a/compiler/rustc_middle/src/ich/mod.rs b/compiler/rustc_middle/src/ich/mod.rs
index c8fb2bf39cc..e8e5c4a2669 100644
--- a/compiler/rustc_middle/src/ich/mod.rs
+++ b/compiler/rustc_middle/src/ich/mod.rs
@@ -1,8 +1,6 @@
 //! ICH - Incremental Compilation Hash
 
-pub use self::hcx::{
-    hash_stable_trait_impls, NodeIdHashingMode, StableHashingContext, StableHashingContextProvider,
-};
+pub use self::hcx::{NodeIdHashingMode, StableHashingContext, StableHashingContextProvider};
 use rustc_span::symbol::{sym, Symbol};
 
 mod hcx;
diff --git a/compiler/rustc_middle/src/traits/specialization_graph.rs b/compiler/rustc_middle/src/traits/specialization_graph.rs
index 4c778b7bcc5..ab47c2a7636 100644
--- a/compiler/rustc_middle/src/traits/specialization_graph.rs
+++ b/compiler/rustc_middle/src/traits/specialization_graph.rs
@@ -1,9 +1,7 @@
-use crate::ich::{self, StableHashingContext};
 use crate::ty::fast_reject::SimplifiedType;
 use crate::ty::fold::TypeFoldable;
 use crate::ty::{self, TyCtxt};
-use rustc_data_structures::fx::FxHashMap;
-use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
+use rustc_data_structures::fx::FxIndexMap;
 use rustc_errors::ErrorReported;
 use rustc_hir::def_id::{DefId, DefIdMap};
 use rustc_span::symbol::Ident;
@@ -50,7 +48,7 @@ impl Graph {
 
 /// Children of a given impl, grouped into blanket/non-blanket varieties as is
 /// done in `TraitDef`.
-#[derive(Default, TyEncodable, TyDecodable, Debug)]
+#[derive(Default, TyEncodable, TyDecodable, Debug, HashStable)]
 pub struct Children {
     // Impls of a trait (or specializations of a given impl). To allow for
     // quicker lookup, the impls are indexed by a simplified version of their
@@ -62,7 +60,7 @@ pub struct Children {
     // together *all* the impls for a trait, and are populated prior to building
     // the specialization graph.
     /// Impls of the trait.
-    pub non_blanket_impls: FxHashMap<SimplifiedType, Vec<DefId>>,
+    pub non_blanket_impls: FxIndexMap<SimplifiedType, Vec<DefId>>,
 
     /// Blanket impls associated with the trait.
     pub blanket_impls: Vec<DefId>,
@@ -235,11 +233,3 @@ pub fn ancestors(
         })
     }
 }
-
-impl<'a> HashStable<StableHashingContext<'a>> for Children {
-    fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
-        let Children { ref non_blanket_impls, ref blanket_impls } = *self;
-
-        ich::hash_stable_trait_impls(hcx, hasher, blanket_impls, non_blanket_impls);
-    }
-}
diff --git a/compiler/rustc_middle/src/ty/trait_def.rs b/compiler/rustc_middle/src/ty/trait_def.rs
index ae86f51e6ac..25a310b12db 100644
--- a/compiler/rustc_middle/src/ty/trait_def.rs
+++ b/compiler/rustc_middle/src/ty/trait_def.rs
@@ -1,4 +1,3 @@
-use crate::ich::{self, StableHashingContext};
 use crate::traits::specialization_graph;
 use crate::ty::fast_reject;
 use crate::ty::fold::TypeFoldable;
@@ -7,8 +6,7 @@ use rustc_hir as hir;
 use rustc_hir::def_id::DefId;
 use rustc_hir::definitions::DefPathHash;
 
-use rustc_data_structures::fx::FxHashMap;
-use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
+use rustc_data_structures::fx::FxIndexMap;
 use rustc_errors::ErrorReported;
 use rustc_macros::HashStable;
 
@@ -66,11 +64,11 @@ pub enum TraitSpecializationKind {
     AlwaysApplicable,
 }
 
-#[derive(Default, Debug)]
+#[derive(Default, Debug, HashStable)]
 pub struct TraitImpls {
     blanket_impls: Vec<DefId>,
     /// Impls indexed by their simplified self type, for fast lookup.
-    non_blanket_impls: FxHashMap<fast_reject::SimplifiedType, Vec<DefId>>,
+    non_blanket_impls: FxIndexMap<fast_reject::SimplifiedType, Vec<DefId>>,
 }
 
 impl TraitImpls {
@@ -249,11 +247,3 @@ pub(super) fn trait_impls_of_provider(tcx: TyCtxt<'_>, trait_id: DefId) -> Trait
 
     impls
 }
-
-impl<'a> HashStable<StableHashingContext<'a>> for TraitImpls {
-    fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
-        let TraitImpls { ref blanket_impls, ref non_blanket_impls } = *self;
-
-        ich::hash_stable_trait_impls(hcx, hasher, blanket_impls, non_blanket_impls);
-    }
-}
diff --git a/compiler/rustc_trait_selection/src/traits/specialize/specialization_graph.rs b/compiler/rustc_trait_selection/src/traits/specialize/specialization_graph.rs
index c930b384120..0efc46edb06 100644
--- a/compiler/rustc_trait_selection/src/traits/specialize/specialization_graph.rs
+++ b/compiler/rustc_trait_selection/src/traits/specialize/specialization_graph.rs
@@ -216,7 +216,7 @@ impl ChildrenExt for Children {
 }
 
 fn iter_children(children: &mut Children) -> impl Iterator<Item = DefId> + '_ {
-    let nonblanket = children.non_blanket_impls.iter_mut().flat_map(|(_, v)| v.iter());
+    let nonblanket = children.non_blanket_impls.iter().flat_map(|(_, v)| v.iter());
     children.blanket_impls.iter().chain(nonblanket).cloned()
 }