Make iteration order of crate_inherent_impls query result stable.

Author: michaelwoerister

compiler/rustc_metadata/src/rmeta/encoder.rs

@@ -2,10 +2,8 @@ use crate::errors::{FailCreateFileEncoder, FailWriteFile};
 use crate::rmeta::*;
 
 use rustc_ast::Attribute;
-use rustc_data_structures::fingerprint::Fingerprint;
 use rustc_data_structures::fx::FxIndexSet;
 use rustc_data_structures::memmap::{Mmap, MmapMut};
-use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use rustc_data_structures::sync::{join, par_for_each_in, Lrc};
 use rustc_data_structures::temp_dir::MaybeTempDir;
 use rustc_hir as hir;
@@ -2034,14 +2032,10 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
     fn encode_incoherent_impls(&mut self) -> LazyArray<IncoherentImpls> {
         empty_proc_macro!(self);
         let tcx = self.tcx;
-        let mut all_impls: Vec<_> = tcx.crate_inherent_impls(()).incoherent_impls.iter().collect();
-        tcx.with_stable_hashing_context(|mut ctx| {
-            all_impls.sort_by_cached_key(|&(&simp, _)| {
-                let mut hasher = StableHasher::new();
-                simp.hash_stable(&mut ctx, &mut hasher);
-                hasher.finish::<Fingerprint>()
-            })
+        let all_impls = tcx.with_stable_hashing_context(|hcx| {
+            tcx.crate_inherent_impls(()).incoherent_impls.to_sorted(&hcx, true)
         });
+
         let all_impls: Vec<_> = all_impls
             .into_iter()
             .map(|(&simp, impls)| {

compiler/rustc_middle/src/ty/mod.rs

@@ -38,6 +38,7 @@ use rustc_data_structures::intern::Interned;
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use rustc_data_structures::steal::Steal;
 use rustc_data_structures::tagged_ptr::CopyTaggedPtr;
+use rustc_data_structures::unord::UnordMap;
 use rustc_errors::{DiagnosticBuilder, ErrorGuaranteed, StashKey};
 use rustc_hir as hir;
 use rustc_hir::def::{CtorKind, CtorOf, DefKind, DocLinkResMap, LifetimeRes, Res};
@@ -2658,7 +2659,7 @@ pub fn provide(providers: &mut Providers) {
 #[derive(Clone, Debug, Default, HashStable)]
 pub struct CrateInherentImpls {
     pub inherent_impls: LocalDefIdMap<Vec<DefId>>,
-    pub incoherent_impls: FxHashMap<SimplifiedType, Vec<LocalDefId>>,
+    pub incoherent_impls: UnordMap<SimplifiedType, Vec<LocalDefId>>,
 }
 
 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, HashStable)]