Auto merge of #143845 - cjgillot:stability-query, r=jieyouxu

Split-up stability_index query

This PR aims to move deprecation and stability processing away from the monolithic `stability_index` query, and directly implement `lookup_{deprecation,stability,body_stability,const_stability}` queries.

The basic idea is to:
- move per-attribute sanity checks into `check_attr.rs`;
- move attribute compatibility checks into the `MissingStabilityAnnotations` visitor;
- progressively dismantle the `Annotator` visitor and the `stability_index` query.

The first commit contains functional change, and now warns when `#[automatically_derived]` is applied on a non-trait impl block. The other commits should not change visible behaviour.

Perf in https://github.com/rust-lang/rust/pull/143845#issuecomment-3066308630 shows small but consistent improvement, except for unused-warnings case. That case being a stress test, I'm leaning towards accepting the regression.

This PR changes `check_attr`, so has a high conflict rate on that file. This should not cause issues for review.

3 files changed, 15 insertions, 55 deletions

diff --git a/compiler/rustc_middle/src/middle/stability.rs b/compiler/rustc_middle/src/middle/stability.rs
index 99faba7b2c0..dc9311188e8 100644
--- a/compiler/rustc_middle/src/middle/stability.rs
+++ b/compiler/rustc_middle/src/middle/stability.rs
@@ -7,10 +7,9 @@ use rustc_ast::NodeId;
 use rustc_attr_data_structures::{
     self as attrs, ConstStability, DefaultBodyStability, DeprecatedSince, Deprecation, Stability,
 };
-use rustc_data_structures::unord::UnordMap;
 use rustc_errors::{Applicability, Diag, EmissionGuarantee};
 use rustc_feature::GateIssue;
-use rustc_hir::def_id::{DefId, LocalDefId, LocalDefIdMap};
+use rustc_hir::def_id::{DefId, LocalDefId};
 use rustc_hir::{self as hir, HirId};
 use rustc_macros::{Decodable, Encodable, HashStable, Subdiagnostic};
 use rustc_session::Session;
@@ -65,48 +64,6 @@ impl DeprecationEntry {
     }
 }
 
-/// A stability index, giving the stability level for items and methods.
-#[derive(HashStable, Debug)]
-pub struct Index {
-    /// This is mostly a cache, except the stabilities of local items
-    /// are filled by the annotator.
-    pub stab_map: LocalDefIdMap<Stability>,
-    pub const_stab_map: LocalDefIdMap<ConstStability>,
-    pub default_body_stab_map: LocalDefIdMap<DefaultBodyStability>,
-    pub depr_map: LocalDefIdMap<DeprecationEntry>,
-    /// Mapping from feature name to feature name based on the `implied_by` field of `#[unstable]`
-    /// attributes. If a `#[unstable(feature = "implier", implied_by = "impliee")]` attribute
-    /// exists, then this map will have a `impliee -> implier` entry.
-    ///
-    /// This mapping is necessary unless both the `#[stable]` and `#[unstable]` attributes should
-    /// specify their implications (both `implies` and `implied_by`). If only one of the two
-    /// attributes do (as in the current implementation, `implied_by` in `#[unstable]`), then this
-    /// mapping is necessary for diagnostics. When a "unnecessary feature attribute" error is
-    /// reported, only the `#[stable]` attribute information is available, so the map is necessary
-    /// to know that the feature implies another feature. If it were reversed, and the `#[stable]`
-    /// attribute had an `implies` meta item, then a map would be necessary when avoiding a "use of
-    /// unstable feature" error for a feature that was implied.
-    pub implications: UnordMap<Symbol, Symbol>,
-}
-
-impl Index {
-    pub fn local_stability(&self, def_id: LocalDefId) -> Option<Stability> {
-        self.stab_map.get(&def_id).copied()
-    }
-
-    pub fn local_const_stability(&self, def_id: LocalDefId) -> Option<ConstStability> {
-        self.const_stab_map.get(&def_id).copied()
-    }
-
-    pub fn local_default_body_stability(&self, def_id: LocalDefId) -> Option<DefaultBodyStability> {
-        self.default_body_stab_map.get(&def_id).copied()
-    }
-
-    pub fn local_deprecation_entry(&self, def_id: LocalDefId) -> Option<DeprecationEntry> {
-        self.depr_map.get(&def_id).cloned()
-    }
-}
-
 pub fn report_unstable(
     sess: &Session,
     feature: Symbol,
diff --git a/compiler/rustc_middle/src/query/mod.rs b/compiler/rustc_middle/src/query/mod.rs
index d5c2b6de4ae..ae8c8259be4 100644
--- a/compiler/rustc_middle/src/query/mod.rs
+++ b/compiler/rustc_middle/src/query/mod.rs
@@ -112,7 +112,7 @@ use crate::middle::exported_symbols::{ExportedSymbol, SymbolExportInfo};
 use crate::middle::lib_features::LibFeatures;
 use crate::middle::privacy::EffectiveVisibilities;
 use crate::middle::resolve_bound_vars::{ObjectLifetimeDefault, ResolveBoundVars, ResolvedArg};
-use crate::middle::stability::{self, DeprecationEntry};
+use crate::middle::stability::DeprecationEntry;
 use crate::mir::interpret::{
     EvalStaticInitializerRawResult, EvalToAllocationRawResult, EvalToConstValueResult,
     EvalToValTreeResult, GlobalId, LitToConstInput,
@@ -2171,6 +2171,18 @@ rustc_queries! {
         separate_provide_extern
         arena_cache
     }
+    /// Mapping from feature name to feature name based on the `implied_by` field of `#[unstable]`
+    /// attributes. If a `#[unstable(feature = "implier", implied_by = "impliee")]` attribute
+    /// exists, then this map will have a `impliee -> implier` entry.
+    ///
+    /// This mapping is necessary unless both the `#[stable]` and `#[unstable]` attributes should
+    /// specify their implications (both `implies` and `implied_by`). If only one of the two
+    /// attributes do (as in the current implementation, `implied_by` in `#[unstable]`), then this
+    /// mapping is necessary for diagnostics. When a "unnecessary feature attribute" error is
+    /// reported, only the `#[stable]` attribute information is available, so the map is necessary
+    /// to know that the feature implies another feature. If it were reversed, and the `#[stable]`
+    /// attribute had an `implies` meta item, then a map would be necessary when avoiding a "use of
+    /// unstable feature" error for a feature that was implied.
     query stability_implications(_: CrateNum) -> &'tcx UnordMap<Symbol, Symbol> {
         arena_cache
         desc { "calculating the implications between `#[unstable]` features defined in a crate" }
@@ -2277,11 +2289,6 @@ rustc_queries! {
         desc { "fetching potentially unused trait imports" }
     }
 
-    query stability_index(_: ()) -> &'tcx stability::Index {
-        arena_cache
-        eval_always
-        desc { "calculating the stability index for the local crate" }
-    }
     /// All available crates in the graph, including those that should not be user-facing
     /// (such as private crates).
     query crates(_: ()) -> &'tcx [CrateNum] {
diff --git a/compiler/rustc_middle/src/ty/context.rs b/compiler/rustc_middle/src/ty/context.rs
index 81c13e55dd8..7e6bcfee025 100644
--- a/compiler/rustc_middle/src/ty/context.rs
+++ b/compiler/rustc_middle/src/ty/context.rs
@@ -65,7 +65,7 @@ use crate::infer::canonical::{CanonicalParamEnvCache, CanonicalVarKind, Canonica
 use crate::lint::lint_level;
 use crate::metadata::ModChild;
 use crate::middle::codegen_fn_attrs::{CodegenFnAttrs, TargetFeature};
-use crate::middle::{resolve_bound_vars, stability};
+use crate::middle::resolve_bound_vars;
 use crate::mir::interpret::{self, Allocation, ConstAllocation};
 use crate::mir::{Body, Local, Place, PlaceElem, ProjectionKind, Promoted};
 use crate::query::plumbing::QuerySystem;
@@ -1807,10 +1807,6 @@ impl<'tcx> TyCtxt<'tcx> {
         )
     }
 
-    pub fn stability(self) -> &'tcx stability::Index {
-        self.stability_index(())
-    }
-
     pub fn features(self) -> &'tcx rustc_feature::Features {
         self.features_query(())
     }