fix non_blanket_impls iteration order

Author: lcnr

compiler/rustc_middle/src/ich/hcx.rs

@@ -3,7 +3,7 @@ use crate::middle::cstore::CrateStore;
 use crate::ty::{fast_reject, 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;
@@ -15,7 +15,7 @@ use rustc_span::symbol::Symbol;
 use rustc_span::{BytePos, CachingSourceMapView, SourceFile, SpanData};
 
 use smallvec::SmallVec;
-use std::cmp::Ord;
+use std::collections::BTreeMap;
 
 fn compute_ignored_attr_names() -> FxHashSet<Symbol> {
     debug_assert!(!ich::IGNORED_ATTRIBUTES.is_empty());
@@ -243,7 +243,7 @@ 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>>,
+    non_blanket_impls: &BTreeMap<fast_reject::StableSimplifiedType, Vec<DefId>>,
 ) {
     {
         let mut blanket_impls: SmallVec<[_; 8]> =
@@ -257,14 +257,11 @@ pub fn hash_stable_trait_impls<'a>(
     }
 
     {
-        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);
+        non_blanket_impls.len().hash_stable(hcx, hasher);
+        for (key, impls) in non_blanket_impls.iter() {
+            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();
+                impls.iter().map(|&impl_id| hcx.def_path_hash(impl_id)).collect();
 
             if impls.len() > 1 {
                 impls.sort_unstable();

compiler/rustc_middle/src/traits/specialization_graph.rs

@@ -1,12 +1,12 @@
 use crate::ich::{self, StableHashingContext};
-use crate::ty::fast_reject::SimplifiedType;
+use crate::ty::fast_reject::StableSimplifiedType;
 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_errors::ErrorReported;
 use rustc_hir::def_id::{DefId, DefIdMap};
 use rustc_span::symbol::Ident;
+use std::collections::BTreeMap;
 
 /// A per-trait graph of impls in specialization order. At the moment, this
 /// graph forms a tree rooted with the trait itself, with all other nodes
@@ -62,7 +62,7 @@ pub struct Children {
     // together *all* the impls for a trait, and are populated prior to building
     // the specialization graph.
     /// Impls of the trait.
-    pub nonblanket_impls: FxHashMap<SimplifiedType, Vec<DefId>>,
+    pub nonblanket_impls: BTreeMap<StableSimplifiedType, Vec<DefId>>,
 
     /// Blanket impls associated with the trait.
     pub blanket_impls: Vec<DefId>,

compiler/rustc_middle/src/ty/fast_reject.rs

@@ -1,14 +1,15 @@
 use crate::ich::StableHashingContext;
 use crate::ty::{self, Ty, TyCtxt};
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
-use rustc_hir::def_id::DefId;
+use rustc_hir::def_id::{DefId, DefPathHash};
 use std::fmt::Debug;
 use std::hash::Hash;
 use std::mem;
 
 use self::SimplifiedTypeGen::*;
 
 pub type SimplifiedType = SimplifiedTypeGen<DefId>;
+pub type StableSimplifiedType = SimplifiedTypeGen<DefPathHash>;
 
 /// See `simplify_type`
 ///
@@ -107,6 +108,12 @@ pub fn simplify_type(
     }
 }
 
+impl SimplifiedType {
+    pub fn to_stable(self, tcx: TyCtxt<'tcx>) -> StableSimplifiedType {
+        self.map_def(|def_id| tcx.def_path_hash(def_id))
+    }
+}
+
 impl<D: Copy + Debug + Ord + Eq> SimplifiedTypeGen<D> {
     pub fn map_def<U, F>(self, map: F) -> SimplifiedTypeGen<U>
     where

compiler/rustc_middle/src/ty/trait_def.rs

@@ -3,14 +3,13 @@ use crate::traits::specialization_graph;
 use crate::ty::fast_reject;
 use crate::ty::fold::TypeFoldable;
 use crate::ty::{Ty, TyCtxt};
+use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
+use rustc_errors::ErrorReported;
 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_errors::ErrorReported;
 use rustc_macros::HashStable;
+use std::collections::BTreeMap;
 
 /// A trait's definition with type information.
 #[derive(HashStable)]
@@ -70,7 +69,7 @@ pub enum TraitSpecializationKind {
 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: BTreeMap<fast_reject::StableSimplifiedType, Vec<DefId>>,
 }
 
 impl TraitImpls {
@@ -182,7 +181,7 @@ impl<'tcx> TyCtxt<'tcx> {
         //
         // I think we'll cross that bridge when we get to it.
         if let Some(simp) = fast_reject::simplify_type(self, self_ty, true) {
-            if let Some(impls) = impls.non_blanket_impls.get(&simp) {
+            if let Some(impls) = impls.non_blanket_impls.get(&simp.to_stable(self)) {
                 for &impl_def_id in impls {
                     if let result @ Some(_) = f(impl_def_id) {
                         return result;
@@ -222,7 +221,7 @@ pub(super) fn trait_impls_of_provider(tcx: TyCtxt<'_>, trait_id: DefId) -> Trait
                 if let Some(simplified_self_ty) = simplified_self_ty {
                     impls
                         .non_blanket_impls
-                        .entry(simplified_self_ty)
+                        .entry(simplified_self_ty.to_stable(tcx))
                         .or_default()
                         .push(impl_def_id);
                 } else {
@@ -241,7 +240,11 @@ pub(super) fn trait_impls_of_provider(tcx: TyCtxt<'_>, trait_id: DefId) -> Trait
         }
 
         if let Some(simplified_self_ty) = fast_reject::simplify_type(tcx, impl_self_ty, false) {
-            impls.non_blanket_impls.entry(simplified_self_ty).or_default().push(impl_def_id);
+            impls
+                .non_blanket_impls
+                .entry(simplified_self_ty.to_stable(tcx))
+                .or_default()
+                .push(impl_def_id);
         } else {
             impls.blanket_impls.push(impl_def_id);
         }

compiler/rustc_trait_selection/src/traits/specialize/specialization_graph.rs

@@ -2,7 +2,7 @@ use super::OverlapError;
 
 use crate::traits;
 use rustc_hir::def_id::DefId;
-use rustc_middle::ty::fast_reject::{self, SimplifiedType};
+use rustc_middle::ty::fast_reject::{self, StableSimplifiedType};
 use rustc_middle::ty::print::with_no_trimmed_paths;
 use rustc_middle::ty::{self, TyCtxt, TypeFoldable};
 
@@ -40,7 +40,7 @@ trait ChildrenExt {
         &mut self,
         tcx: TyCtxt<'tcx>,
         impl_def_id: DefId,
-        simplified_self: Option<SimplifiedType>,
+        simplified_self: Option<StableSimplifiedType>,
     ) -> Result<Inserted, OverlapError>;
 }
 
@@ -50,7 +50,7 @@ impl ChildrenExt for Children {
         let trait_ref = tcx.impl_trait_ref(impl_def_id).unwrap();
         if let Some(st) = fast_reject::simplify_type(tcx, trait_ref.self_ty(), false) {
             debug!("insert_blindly: impl_def_id={:?} st={:?}", impl_def_id, st);
-            self.nonblanket_impls.entry(st).or_default().push(impl_def_id)
+            self.nonblanket_impls.entry(st.to_stable(tcx)).or_default().push(impl_def_id)
         } else {
             debug!("insert_blindly: impl_def_id={:?} st=None", impl_def_id);
             self.blanket_impls.push(impl_def_id)
@@ -65,7 +65,7 @@ impl ChildrenExt for Children {
         let vec: &mut Vec<DefId>;
         if let Some(st) = fast_reject::simplify_type(tcx, trait_ref.self_ty(), false) {
             debug!("remove_existing: impl_def_id={:?} st={:?}", impl_def_id, st);
-            vec = self.nonblanket_impls.get_mut(&st).unwrap();
+            vec = self.nonblanket_impls.get_mut(&st.to_stable(tcx)).unwrap();
         } else {
             debug!("remove_existing: impl_def_id={:?} st=None", impl_def_id);
             vec = &mut self.blanket_impls;
@@ -81,7 +81,7 @@ impl ChildrenExt for Children {
         &mut self,
         tcx: TyCtxt<'tcx>,
         impl_def_id: DefId,
-        simplified_self: Option<SimplifiedType>,
+        simplified_self: Option<StableSimplifiedType>,
     ) -> Result<Inserted, OverlapError> {
         let mut last_lint = None;
         let mut replace_children = Vec::new();
@@ -222,7 +222,7 @@ fn iter_children(children: &mut Children) -> impl Iterator<Item = DefId> + '_ {
 
 fn filtered_children(
     children: &mut Children,
-    st: SimplifiedType,
+    st: StableSimplifiedType,
 ) -> impl Iterator<Item = DefId> + '_ {
     let nonblanket = children.nonblanket_impls.entry(st).or_default().iter();
     children.blanket_impls.iter().chain(nonblanket).cloned()
@@ -304,7 +304,8 @@ impl GraphExt for Graph {
 
         let mut parent = trait_def_id;
         let mut last_lint = None;
-        let simplified = fast_reject::simplify_type(tcx, trait_ref.self_ty(), false);
+        let simplified =
+            fast_reject::simplify_type(tcx, trait_ref.self_ty(), false).map(|st| st.to_stable(tcx));
 
         // Descend the specialization tree, where `parent` is the current parent node.
         loop {