Auto merge of rust-lang#138500 - oli-obk:per-item-query-define-opaque, r=<try>

Add a per-item query just for `define_opaque` attributes

follow up to rust-lang#128440 (comment)

This wasn't done in the previous PR to make sure we can gauge the perf effect independently of the other changes

Author: bors

compiler/rustc_ast_lowering/src/lib.rs

@@ -625,9 +625,9 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         let num_nodes = self.item_local_id_counter.as_usize();
         let (nodes, parenting) = index::index_hir(self.tcx, node, &bodies, num_nodes);
         let nodes = hir::OwnerNodes { opt_hash_including_bodies, nodes, bodies };
-        let attrs = hir::AttributeMap { map: attrs, opt_hash: attrs_hash, define_opaque };
+        let attrs = hir::AttributeMap { map: attrs, opt_hash: attrs_hash };
 
-        self.arena.alloc(hir::OwnerInfo { nodes, parenting, attrs, trait_map })
+        self.arena.alloc(hir::OwnerInfo { nodes, parenting, attrs, trait_map, define_opaque })
     }
 
     /// This method allocates a new `HirId` for the given `NodeId`.

compiler/rustc_hir/src/hir.rs

@@ -1307,18 +1307,13 @@ impl Attribute {
 #[derive(Debug)]
 pub struct AttributeMap<'tcx> {
     pub map: SortedMap<ItemLocalId, &'tcx [Attribute]>,
-    /// Preprocessed `#[define_opaque]` attribute.
-    pub define_opaque: Option<&'tcx [(Span, LocalDefId)]>,
     // Only present when the crate hash is needed.
     pub opt_hash: Option<Fingerprint>,
 }
 
 impl<'tcx> AttributeMap<'tcx> {
-    pub const EMPTY: &'static AttributeMap<'static> = &AttributeMap {
-        map: SortedMap::new(),
-        opt_hash: Some(Fingerprint::ZERO),
-        define_opaque: None,
-    };
+    pub const EMPTY: &'static AttributeMap<'static> =
+        &AttributeMap { map: SortedMap::new(), opt_hash: Some(Fingerprint::ZERO) };
 
     #[inline]
     pub fn get(&self, id: ItemLocalId) -> &'tcx [Attribute] {
@@ -1382,6 +1377,13 @@ pub struct OwnerInfo<'hir> {
     /// Map indicating what traits are in scope for places where this
     /// is relevant; generated by resolve.
     pub trait_map: ItemLocalMap<Box<[TraitCandidate]>>,
+    /// Preprocessed `#[define_opaque]` attribute.
+    /// `None` means there was no attribute.
+    /// `Some(&[])` means there was an attribute, but it had no entries.
+    /// This can be used to remove the opaques defined by default, e.g. on
+    /// associated methods which automatically pick up opaques in associated types
+    /// if they mention that associated type in their signature.
+    pub define_opaque: Option<&'hir [(Span, LocalDefId)]>,
 }
 
 impl<'tcx> OwnerInfo<'tcx> {

compiler/rustc_hir/src/stable_hash_impls.rs

@@ -106,7 +106,7 @@ impl<'tcx, HirCtx: crate::HashStableContext> HashStable<HirCtx> for AttributeMap
     fn hash_stable(&self, hcx: &mut HirCtx, hasher: &mut StableHasher) {
         // We ignore the `map` since it refers to information included in `opt_hash` which is
         // hashed in the collector and used for the crate hash.
-        let AttributeMap { opt_hash, define_opaque: _, map: _ } = *self;
+        let AttributeMap { opt_hash, map: _ } = *self;
         opt_hash.unwrap().hash_stable(hcx, hasher);
     }
 }

compiler/rustc_middle/src/hir/mod.rs

@@ -238,4 +238,9 @@ pub fn provide(providers: &mut Providers) {
     providers.in_scope_traits_map = |tcx, id| {
         tcx.hir_crate(()).owners[id.def_id].as_owner().map(|owner_info| &owner_info.trait_map)
     };
+    providers.explicitly_defined_opaques = |tcx, id| {
+        tcx.hir_crate(()).owners[id.def_id]
+            .as_owner()
+            .and_then(|owner_info| Some(*owner_info.define_opaque.as_ref()?))
+    };
 }

compiler/rustc_middle/src/query/mod.rs

@@ -1724,6 +1724,9 @@ rustc_queries! {
         -> Option<&'tcx ItemLocalMap<Box<[TraitCandidate]>>> {
         desc { "getting traits in scope at a block" }
     }
+    query explicitly_defined_opaques(_: hir::OwnerId) -> Option<&'tcx [(Span, LocalDefId)]> {
+        desc { "getting the explicitly defined opaque types"}
+    }
 
     /// Returns whether the impl or associated function has the `default` keyword.
     query defaultness(def_id: DefId) -> hir::Defaultness {

compiler/rustc_ty_utils/src/opaque_types.rs

@@ -184,10 +184,10 @@ impl<'tcx> OpaqueTypeCollector<'tcx> {
     #[instrument(level = "trace", skip(self))]
     fn collect_taits_from_defines_attr(&mut self) {
         let hir_id = self.tcx.local_def_id_to_hir_id(self.item);
-        if !hir_id.is_owner() {
+        let Some(owner_id) = hir_id.as_owner() else {
             return;
-        }
-        let Some(defines) = self.tcx.hir_attr_map(hir_id.owner).define_opaque else {
+        };
+        let Some(defines) = self.tcx.explicitly_defined_opaques(owner_id) else {
             return;
         };
         for &(span, define) in defines {