Auto merge of #92455 - petrochenkov:alltraits2, r=cjgillot

rustc_metadata: Use a query for collecting all traits in encoder

Implement refactoring suggested in https://github.com/rust-lang/rust/pull/92244#discussion_r775976336
r? `@cjgillot`

compiler/rustc_metadata/src/rmeta/decoder.rs

@@ -45,7 +45,8 @@
 use std::path::Path;
 use tracing::debug;
 
-pub use cstore_impl::{provide, provide_extern};
+pub(super) use cstore_impl::provide;
+pub use cstore_impl::provide_extern;
 use rustc_span::hygiene::HygieneDecodeContext;
 
 mod cstore_impl;

compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs

@@ -4,11 +4,9 @@
 
 use rustc_ast as ast;
 use rustc_data_structures::stable_map::FxHashMap;
-use rustc_hir as hir;
 use rustc_hir::def::{CtorKind, DefKind};
 use rustc_hir::def_id::{CrateNum, DefId, DefIdMap, CRATE_DEF_INDEX, LOCAL_CRATE};
 use rustc_hir::definitions::{DefKey, DefPath, DefPathHash};
-use rustc_hir::itemlikevisit::ItemLikeVisitor;
 use rustc_middle::hir::exports::Export;
 use rustc_middle::middle::exported_symbols::ExportedSymbol;
 use rustc_middle::middle::stability::DeprecationEntry;
@@ -243,7 +241,7 @@ fn into_args(self) -> (DefId, DefId) {
     expn_that_defined => { cdata.get_expn_that_defined(def_id.index, tcx.sess) }
 }
 
-pub fn provide(providers: &mut Providers) {
+pub(in crate::rmeta) fn provide(providers: &mut Providers) {
     // FIXME(#44234) - almost all of these queries have no sub-queries and
     // therefore no actual inputs, they're just reading tables calculated in
     // resolve! Does this work? Unsure! That's what the issue is about
@@ -289,28 +287,6 @@ pub fn provide(providers: &mut Providers) {
                 foreign_modules::collect(tcx).into_iter().map(|m| (m.def_id, m)).collect();
             Lrc::new(modules)
         },
-        traits_in_crate: |tcx, cnum| {
-            assert_eq!(cnum, LOCAL_CRATE);
-
-            #[derive(Default)]
-            struct TraitsVisitor {
-                traits: Vec<DefId>,
-            }
-            impl ItemLikeVisitor<'_> for TraitsVisitor {
-                fn visit_item(&mut self, item: &hir::Item<'_>) {
-                    if let hir::ItemKind::Trait(..) | hir::ItemKind::TraitAlias(..) = item.kind {
-                        self.traits.push(item.def_id.to_def_id());
-                    }
-                }
-                fn visit_trait_item(&mut self, _trait_item: &hir::TraitItem<'_>) {}
-                fn visit_impl_item(&mut self, _impl_item: &hir::ImplItem<'_>) {}
-                fn visit_foreign_item(&mut self, _foreign_item: &hir::ForeignItem<'_>) {}
-            }
-
-            let mut visitor = TraitsVisitor::default();
-            tcx.hir().visit_all_item_likes(&mut visitor);
-            tcx.arena.alloc_slice(&visitor.traits)
-        },
 
         // Returns a map from a sufficiently visible external item (i.e., an
         // external item that is visible from at least one local module) to a

compiler/rustc_metadata/src/rmeta/encoder.rs

@@ -27,6 +27,7 @@
 use rustc_middle::traits::specialization_graph;
 use rustc_middle::ty::codec::TyEncoder;
 use rustc_middle::ty::fast_reject::{self, SimplifyParams, StripReferences};
+use rustc_middle::ty::query::Providers;
 use rustc_middle::ty::{self, SymbolName, Ty, TyCtxt};
 use rustc_serialize::{opaque, Encodable, Encoder};
 use rustc_session::config::CrateType;
@@ -612,10 +613,15 @@ fn encode_crate_root(&mut self) -> Lazy<CrateRoot<'tcx>> {
         self.encode_def_path_table();
         let def_path_table_bytes = self.position() - i;
 
+        // Encode the def IDs of traits, for rustdoc and diagnostics.
+        i = self.position();
+        let traits = self.encode_traits();
+        let traits_bytes = self.position() - i;
+
         // Encode the def IDs of impls, for coherence checking.
         i = self.position();
-        let (traits, impls) = self.encode_traits_and_impls();
-        let traits_and_impls_bytes = self.position() - i;
+        let impls = self.encode_impls();
+        let impls_bytes = self.position() - i;
 
         let tcx = self.tcx;
 
@@ -726,8 +732,8 @@ fn encode_crate_root(&mut self) -> Lazy<CrateRoot<'tcx>> {
             native_libraries,
             foreign_modules,
             source_map,
-            impls,
             traits,
+            impls,
             exported_symbols,
             interpret_alloc_index,
             tables,
@@ -754,7 +760,8 @@ fn encode_crate_root(&mut self) -> Lazy<CrateRoot<'tcx>> {
             eprintln!(" diagnostic item bytes: {}", diagnostic_item_bytes);
             eprintln!("          native bytes: {}", native_lib_bytes);
             eprintln!("      source_map bytes: {}", source_map_bytes);
-            eprintln!("traits and impls bytes: {}", traits_and_impls_bytes);
+            eprintln!("          traits bytes: {}", traits_bytes);
+            eprintln!("           impls bytes: {}", impls_bytes);
             eprintln!("    exp. symbols bytes: {}", exported_symbols_bytes);
             eprintln!("  def-path table bytes: {}", def_path_table_bytes);
             eprintln!(" def-path hashes bytes: {}", def_path_hash_map_bytes);
@@ -1791,24 +1798,22 @@ fn encode_lang_items_missing(&mut self) -> Lazy<[lang_items::LangItem]> {
         self.lazy(&tcx.lang_items().missing)
     }
 
+    fn encode_traits(&mut self) -> Lazy<[DefIndex]> {
+        empty_proc_macro!(self);
+        self.lazy(self.tcx.traits_in_crate(LOCAL_CRATE).iter().map(|def_id| def_id.index))
+    }
+
     /// Encodes an index, mapping each trait to its (local) implementations.
-    fn encode_traits_and_impls(&mut self) -> (Lazy<[DefIndex]>, Lazy<[TraitImpls]>) {
-        if self.is_proc_macro {
-            return (Lazy::empty(), Lazy::empty());
-        }
+    fn encode_impls(&mut self) -> Lazy<[TraitImpls]> {
         debug!("EncodeContext::encode_traits_and_impls()");
+        empty_proc_macro!(self);
         let tcx = self.tcx;
-        let mut visitor =
-            TraitsAndImplsVisitor { tcx, impls: FxHashMap::default(), traits: Default::default() };
+        let mut visitor = ImplsVisitor { tcx, impls: FxHashMap::default() };
         tcx.hir().visit_all_item_likes(&mut visitor);
 
-        let mut all_traits = visitor.traits;
         let mut all_impls: Vec<_> = visitor.impls.into_iter().collect();
 
         // Bring everything into deterministic order for hashing
-        all_traits.sort_by_cached_key(|&local_def_index| {
-            tcx.hir().def_path_hash(LocalDefId { local_def_index })
-        });
         all_impls.sort_by_cached_key(|&(trait_def_id, _)| tcx.def_path_hash(trait_def_id));
 
         let all_impls: Vec<_> = all_impls
@@ -1826,7 +1831,7 @@ fn encode_traits_and_impls(&mut self) -> (Lazy<[DefIndex]>, Lazy<[TraitImpls]>)
             })
             .collect();
 
-        (self.lazy(&all_traits), self.lazy(&all_impls))
+        self.lazy(&all_impls)
     }
 
     // Encodes all symbols exported from this crate into the metadata.
@@ -2048,18 +2053,14 @@ fn encode_addl_info_for_item(&mut self, item: &hir::Item<'_>) {
     }
 }
 
-struct TraitsAndImplsVisitor<'tcx> {
+struct ImplsVisitor<'tcx> {
     tcx: TyCtxt<'tcx>,
-    traits: Vec<DefIndex>,
     impls: FxHashMap<DefId, Vec<(DefIndex, Option<fast_reject::SimplifiedType>)>>,
 }
 
-impl<'tcx, 'v> ItemLikeVisitor<'v> for TraitsAndImplsVisitor<'tcx> {
+impl<'tcx, 'v> ItemLikeVisitor<'v> for ImplsVisitor<'tcx> {
     fn visit_item(&mut self, item: &hir::Item<'_>) {
         match item.kind {
-            hir::ItemKind::Trait(..) | hir::ItemKind::TraitAlias(..) => {
-                self.traits.push(item.def_id.local_def_index);
-            }
             hir::ItemKind::Impl(..) => {
                 if let Some(trait_ref) = self.tcx.impl_trait_ref(item.def_id.to_def_id()) {
                     let simplified_self_ty = fast_reject::simplify_type(
@@ -2224,3 +2225,34 @@ fn encode_metadata_impl(tcx: TyCtxt<'_>) -> EncodedMetadata {
 
     EncodedMetadata { raw_data: result }
 }
+
+pub fn provide(providers: &mut Providers) {
+    *providers = Providers {
+        traits_in_crate: |tcx, cnum| {
+            assert_eq!(cnum, LOCAL_CRATE);
+
+            #[derive(Default)]
+            struct TraitsVisitor {
+                traits: Vec<DefId>,
+            }
+            impl ItemLikeVisitor<'_> for TraitsVisitor {
+                fn visit_item(&mut self, item: &hir::Item<'_>) {
+                    if let hir::ItemKind::Trait(..) | hir::ItemKind::TraitAlias(..) = item.kind {
+                        self.traits.push(item.def_id.to_def_id());
+                    }
+                }
+                fn visit_trait_item(&mut self, _trait_item: &hir::TraitItem<'_>) {}
+                fn visit_impl_item(&mut self, _impl_item: &hir::ImplItem<'_>) {}
+                fn visit_foreign_item(&mut self, _foreign_item: &hir::ForeignItem<'_>) {}
+            }
+
+            let mut visitor = TraitsVisitor::default();
+            tcx.hir().visit_all_item_likes(&mut visitor);
+            // Bring everything into deterministic order.
+            visitor.traits.sort_by_cached_key(|&def_id| tcx.def_path_hash(def_id));
+            tcx.arena.alloc_slice(&visitor.traits)
+        },
+
+        ..*providers
+    };
+}

compiler/rustc_metadata/src/rmeta/mod.rs

@@ -16,6 +16,7 @@
 use rustc_middle::middle::exported_symbols::{ExportedSymbol, SymbolExportLevel};
 use rustc_middle::mir;
 use rustc_middle::thir;
+use rustc_middle::ty::query::Providers;
 use rustc_middle::ty::{self, ReprOptions, Ty};
 use rustc_serialize::opaque::Encoder;
 use rustc_session::config::SymbolManglingVersion;
@@ -29,8 +30,8 @@
 use std::marker::PhantomData;
 use std::num::NonZeroUsize;
 
+pub use decoder::provide_extern;
 use decoder::DecodeContext;
-pub use decoder::{provide, provide_extern};
 crate use decoder::{CrateMetadata, CrateNumMap, MetadataBlob};
 use encoder::EncodeContext;
 pub use encoder::{encode_metadata, EncodedMetadata};
@@ -454,3 +455,8 @@ struct GeneratorData<'tcx> {
 const TAG_VALID_SPAN_LOCAL: u8 = 0;
 const TAG_VALID_SPAN_FOREIGN: u8 = 1;
 const TAG_PARTIAL_SPAN: u8 = 2;
+
+pub fn provide(providers: &mut Providers) {
+    encoder::provide(providers);
+    decoder::provide(providers);
+}