Rollup merge of #144822 - Zalathar:hash-owner-nodes, r=compiler-errors

Return a struct with named fields from `hash_owner_nodes`

While looking through this code for other reasons, I noticed a nice opportunity to return a struct with named fields instead of a tuple. The first patch also introduces an early-return to flatten the rest of `hash_owner_nodes`.

There are further changes that could potentially be made here (renaming things, `Option<Hashes>` instead of optional fields), but I'm not deeply familiar with this code so I didn't want to disturb the calling code too much.

compiler/rustc_ast_lowering/src/lib.rs

@@ -675,7 +675,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         let bodies = SortedMap::from_presorted_elements(bodies);
 
         // Don't hash unless necessary, because it's expensive.
-        let (opt_hash_including_bodies, attrs_hash, delayed_lints_hash) =
+        let rustc_middle::hir::Hashes { opt_hash_including_bodies, attrs_hash, delayed_lints_hash } =
             self.tcx.hash_owner_nodes(node, &bodies, &attrs, &delayed_lints, define_opaque);
         let num_nodes = self.item_local_id_counter.as_usize();
         let (nodes, parenting) = index::index_hir(self.tcx, node, &bodies, num_nodes);

compiler/rustc_middle/src/hir/mod.rs

@@ -174,8 +174,15 @@ impl<'tcx> TyCtxt<'tcx> {
         attrs: &SortedMap<ItemLocalId, &[Attribute]>,
         delayed_lints: &[DelayedLint],
         define_opaque: Option<&[(Span, LocalDefId)]>,
-    ) -> (Option<Fingerprint>, Option<Fingerprint>, Option<Fingerprint>) {
+    ) -> Hashes {
-        if self.needs_crate_hash() {
+        if !self.needs_crate_hash() {
+            return Hashes {
+                opt_hash_including_bodies: None,
+                attrs_hash: None,
+                delayed_lints_hash: None,
+            };
+        }
+
         self.with_stable_hashing_context(|mut hcx| {
             let mut stable_hasher = StableHasher::new();
             node.hash_stable(&mut hcx, &mut stable_hasher);
@@ -196,12 +203,21 @@ impl<'tcx> TyCtxt<'tcx> {
             delayed_lints.hash_stable(&mut hcx, &mut stable_hasher);
             let h3 = stable_hasher.finish();
 
-                (Some(h1), Some(h2), Some(h3))
+            Hashes {
+                opt_hash_including_bodies: Some(h1),
+                attrs_hash: Some(h2),
+                delayed_lints_hash: Some(h3),
+            }
         })
-        } else {
-            (None, None, None)
     }
 }
+
+/// Hashes computed by [`TyCtxt::hash_owner_nodes`] if necessary.
+#[derive(Clone, Copy, Debug)]
+pub struct Hashes {
+    pub opt_hash_including_bodies: Option<Fingerprint>,
+    pub attrs_hash: Option<Fingerprint>,
+    pub delayed_lints_hash: Option<Fingerprint>,
 }
 
 pub fn provide(providers: &mut Providers) {

compiler/rustc_middle/src/ty/context.rs

@@ -1381,7 +1381,7 @@ impl<'tcx> TyCtxtFeed<'tcx, LocalDefId> {
         let bodies = Default::default();
         let attrs = hir::AttributeMap::EMPTY;
 
-        let (opt_hash_including_bodies, _, _) =
+        let rustc_middle::hir::Hashes { opt_hash_including_bodies, .. } =
             self.tcx.hash_owner_nodes(node, &bodies, &attrs.map, &[], attrs.define_opaque);
         let node = node.into();
         self.opt_hir_owner_nodes(Some(self.tcx.arena.alloc(hir::OwnerNodes {