Auto merge of #86180 - cjgillot:defmv, r=petrochenkov

Hash DefId in rustc_span.

This is mostly just moving code around. Changes are simplifications of unneeded callbacks from rustc_span to rustc_middle.

r? `@petrochenkov`

compiler/rustc_span/src/def_id.rs

@@ -1,7 +1,7 @@
 use crate::crate_disambiguator::CrateDisambiguator;
 use crate::HashStableContext;
 use rustc_data_structures::fingerprint::Fingerprint;
-use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
+use rustc_data_structures::stable_hasher::{HashStable, StableHasher, ToStableHashKey};
 use rustc_data_structures::AtomicRef;
 use rustc_index::vec::Idx;
 use rustc_macros::HashStable_Generic;
@@ -308,13 +308,49 @@ impl<D: Decoder> Decodable<D> for LocalDefId {
 rustc_data_structures::define_id_collections!(LocalDefIdMap, LocalDefIdSet, LocalDefId);
 
 impl<CTX: HashStableContext> HashStable<CTX> for DefId {
+    #[inline]
     fn hash_stable(&self, hcx: &mut CTX, hasher: &mut StableHasher) {
-        hcx.hash_def_id(*self, hasher)
+        self.to_stable_hash_key(hcx).hash_stable(hcx, hasher);
+    }
+}
+
+impl<CTX: HashStableContext> HashStable<CTX> for LocalDefId {
+    #[inline]
+    fn hash_stable(&self, hcx: &mut CTX, hasher: &mut StableHasher) {
+        self.to_stable_hash_key(hcx).hash_stable(hcx, hasher);
     }
 }
 
 impl<CTX: HashStableContext> HashStable<CTX> for CrateNum {
+    #[inline]
     fn hash_stable(&self, hcx: &mut CTX, hasher: &mut StableHasher) {
-        hcx.hash_crate_num(*self, hasher)
+        self.to_stable_hash_key(hcx).hash_stable(hcx, hasher);
+    }
+}
+
+impl<CTX: HashStableContext> ToStableHashKey<CTX> for DefId {
+    type KeyType = DefPathHash;
+
+    #[inline]
+    fn to_stable_hash_key(&self, hcx: &CTX) -> DefPathHash {
+        hcx.def_path_hash(*self)
+    }
+}
+
+impl<CTX: HashStableContext> ToStableHashKey<CTX> for LocalDefId {
+    type KeyType = DefPathHash;
+
+    #[inline]
+    fn to_stable_hash_key(&self, hcx: &CTX) -> DefPathHash {
+        hcx.def_path_hash(self.to_def_id())
+    }
+}
+
+impl<CTX: HashStableContext> ToStableHashKey<CTX> for CrateNum {
+    type KeyType = DefPathHash;
+
+    #[inline]
+    fn to_stable_hash_key(&self, hcx: &CTX) -> DefPathHash {
+        self.as_def_id().to_stable_hash_key(hcx)
     }
 }

compiler/rustc_span/src/hygiene.rs

@@ -29,7 +29,7 @@ use crate::symbol::{kw, sym, Symbol};
 use crate::SESSION_GLOBALS;
 use crate::{BytePos, CachingSourceMapView, ExpnIdCache, SourceFile, Span, DUMMY_SP};
 
-use crate::def_id::{CrateNum, DefId, CRATE_DEF_INDEX, LOCAL_CRATE};
+use crate::def_id::{CrateNum, DefId, DefPathHash, CRATE_DEF_INDEX, LOCAL_CRATE};
 use rustc_data_structures::fingerprint::Fingerprint;
 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
@@ -1330,9 +1330,12 @@ fn update_disambiguator(expn_id: ExpnId) {
     }
 
     impl<'a> crate::HashStableContext for DummyHashStableContext<'a> {
-        fn hash_def_id(&mut self, def_id: DefId, hasher: &mut StableHasher) {
-            def_id.krate.as_u32().hash_stable(self, hasher);
-            def_id.index.as_u32().hash_stable(self, hasher);
+        #[inline]
+        fn def_path_hash(&self, def_id: DefId) -> DefPathHash {
+            DefPathHash(Fingerprint::new(
+                def_id.krate.as_u32().into(),
+                def_id.index.as_u32().into(),
+            ))
         }
 
         fn expn_id_cache() -> &'static LocalKey<ExpnIdCache> {
@@ -1345,9 +1348,6 @@ fn update_disambiguator(expn_id: ExpnId) {
             &CACHE
         }
 
-        fn hash_crate_num(&mut self, krate: CrateNum, hasher: &mut StableHasher) {
-            krate.as_u32().hash_stable(self, hasher);
-        }
         fn hash_spans(&self) -> bool {
             true
         }

compiler/rustc_span/src/lib.rs

@@ -40,7 +40,7 @@ pub use hygiene::SyntaxContext;
 use hygiene::Transparency;
 pub use hygiene::{DesugaringKind, ExpnData, ExpnId, ExpnKind, ForLoopLoc, MacroKind};
 pub mod def_id;
-use def_id::{CrateNum, DefId, LOCAL_CRATE};
+use def_id::{CrateNum, DefId, DefPathHash, LOCAL_CRATE};
 pub mod lev_distance;
 mod span_encoding;
 pub use span_encoding::{Span, DUMMY_SP};
@@ -1928,13 +1928,12 @@ fn lookup_line(lines: &[BytePos], pos: BytePos) -> isize {
 /// This is a hack to allow using the [`HashStable_Generic`] derive macro
 /// instead of implementing everything in rustc_middle.
 pub trait HashStableContext {
-    fn hash_def_id(&mut self, _: DefId, hasher: &mut StableHasher);
+    fn def_path_hash(&self, def_id: DefId) -> DefPathHash;
     /// Obtains a cache for storing the `Fingerprint` of an `ExpnId`.
     /// This method allows us to have multiple `HashStableContext` implementations
     /// that hash things in a different way, without the results of one polluting
     /// the cache of the other.
     fn expn_id_cache() -> &'static LocalKey<ExpnIdCache>;
-    fn hash_crate_num(&mut self, _: CrateNum, hasher: &mut StableHasher);
     fn hash_spans(&self) -> bool;
     fn span_data_to_lines_and_cols(
         &mut self,