Auto merge of rust-lang#93511 - cjgillot:query-copy, r=oli-obk

Ensure that queries only return Copy types.

This should pervent the perf footgun of returning a result with an expensive `Clone` impl (like a `Vec` of a hash map).

I went for the stupid solution of allocating on an arena everything that was not `Copy`. Some query results could be made Copy easily, but I did not really investigate.

compiler/rustc_attr/src/builtin.rs

@@ -604,7 +604,7 @@ pub fn eval_condition(
     }
 }
 
-#[derive(Debug, Encodable, Decodable, Clone, HashStable_Generic)]
+#[derive(Copy, Debug, Encodable, Decodable, Clone, HashStable_Generic)]
 pub struct Deprecation {
     pub since: Option<Symbol>,
     /// The note to issue a reason.

compiler/rustc_codegen_ssa/src/back/write.rs

@@ -477,7 +477,7 @@ pub fn start_async_codegen<B: ExtraBackendMethods>(
         codegen_worker_receive,
         shared_emitter_main,
         future: coordinator_thread,
-        output_filenames: tcx.output_filenames(()),
+        output_filenames: tcx.output_filenames(()).clone(),
     }
 }
 
@@ -1050,7 +1050,7 @@ fn start_executing_work<B: ExtraBackendMethods>(
         cgu_reuse_tracker: sess.cgu_reuse_tracker.clone(),
         coordinator_send,
         diag_emitter: shared_emitter.clone(),
-        output_filenames: tcx.output_filenames(()),
+        output_filenames: tcx.output_filenames(()).clone(),
         regular_module_config: regular_config,
         metadata_module_config: metadata_config,
         allocator_module_config: allocator_config,

compiler/rustc_codegen_ssa/src/base.rs

@@ -843,7 +843,7 @@ impl CrateInfo {
             used_crate_source: Default::default(),
             lang_item_to_crate: Default::default(),
             missing_lang_items: Default::default(),
-            dependency_formats: tcx.dependency_formats(()),
+            dependency_formats: tcx.dependency_formats(()).clone(),
             windows_subsystem,
         };
         let lang_items = tcx.lang_items();
@@ -860,7 +860,7 @@ impl CrateInfo {
             info.native_libraries
                 .insert(cnum, tcx.native_libraries(cnum).iter().map(Into::into).collect());
             info.crate_name.insert(cnum, tcx.crate_name(cnum).to_string());
-            info.used_crate_source.insert(cnum, tcx.used_crate_source(cnum));
+            info.used_crate_source.insert(cnum, tcx.used_crate_source(cnum).clone());
             if tcx.is_compiler_builtins(cnum) {
                 info.compiler_builtins = Some(cnum);
             }

compiler/rustc_interface/src/passes.rs

@@ -658,13 +658,13 @@ fn write_out_deps(
             boxed_resolver.borrow_mut().access(|resolver| {
                 for cnum in resolver.cstore().crates_untracked() {
                     let source = resolver.cstore().crate_source_untracked(cnum);
-                    if let Some((path, _)) = source.dylib {
+                    if let Some((path, _)) = &source.dylib {
                         files.push(escape_dep_filename(&path.display().to_string()));
                     }
-                    if let Some((path, _)) = source.rlib {
+                    if let Some((path, _)) = &source.rlib {
                         files.push(escape_dep_filename(&path.display().to_string()));
                     }
-                    if let Some((path, _)) = source.rmeta {
+                    if let Some((path, _)) = &source.rmeta {
                         files.push(escape_dep_filename(&path.display().to_string()));
                     }
                 }

compiler/rustc_metadata/src/rmeta/decoder.rs

@@ -120,7 +120,7 @@ crate struct CrateMetadata {
     /// How to link (or not link) this crate to the currently compiled crate.
     dep_kind: Lock<CrateDepKind>,
     /// Filesystem location of this crate.
-    source: CrateSource,
+    source: Lrc<CrateSource>,
     /// Whether or not this crate should be consider a private dependency
     /// for purposes of the 'exported_private_dependencies' lint
     private_dep: bool,
@@ -1875,7 +1875,7 @@ impl CrateMetadata {
             cnum_map,
             dependencies,
             dep_kind: Lock::new(dep_kind),
-            source,
+            source: Lrc::new(source),
             private_dep,
             host_hash,
             extern_crate: Lock::new(None),
@@ -1903,7 +1903,7 @@ impl CrateMetadata {
     }
 
     crate fn source(&self) -> &CrateSource {
-        &self.source
+        &*self.source
     }
 
     crate fn dep_kind(&self) -> CrateDepKind {

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

@@ -3,7 +3,6 @@ use crate::foreign_modules;
 use crate::native_libs;
 
 use rustc_ast as ast;
-use rustc_data_structures::stable_map::FxHashMap;
 use rustc_hir::def::{CtorKind, DefKind, Res};
 use rustc_hir::def_id::{CrateNum, DefId, DefIdMap, CRATE_DEF_INDEX, LOCAL_CRATE};
 use rustc_hir::definitions::{DefKey, DefPath, DefPathHash};
@@ -13,7 +12,7 @@ use rustc_middle::middle::stability::DeprecationEntry;
 use rustc_middle::ty::fast_reject::SimplifiedType;
 use rustc_middle::ty::query::{ExternProviders, Providers};
 use rustc_middle::ty::{self, TyCtxt, Visibility};
-use rustc_session::cstore::{CrateSource, CrateStore, ForeignModule};
+use rustc_session::cstore::{CrateSource, CrateStore};
 use rustc_session::utils::NativeLibKind;
 use rustc_session::{Session, StableCrateId};
 use rustc_span::hygiene::{ExpnHash, ExpnId};
@@ -179,10 +178,8 @@ provide! { <'tcx> tcx, def_id, other, cdata,
 
         reachable_non_generics
     }
-    native_libraries => { Lrc::new(cdata.get_native_libraries(tcx.sess).collect()) }
-    foreign_modules => {
-        Lrc::new(cdata.get_foreign_modules(tcx.sess).map(|m| (m.def_id, m)).collect())
-    }
+    native_libraries => { cdata.get_native_libraries(tcx.sess).collect() }
+    foreign_modules => { cdata.get_foreign_modules(tcx.sess).map(|m| (m.def_id, m)).collect() }
     crate_hash => { cdata.root.hash }
     crate_host_hash => { cdata.host_hash }
     crate_name => { cdata.root.name }
@@ -212,7 +209,7 @@ provide! { <'tcx> tcx, def_id, other, cdata,
         r
     }
 
-    used_crate_source => { Lrc::new(cdata.source.clone()) }
+    used_crate_source => { Lrc::clone(&cdata.source) }
 
     exported_symbols => {
         let syms = cdata.exported_symbols(tcx);
@@ -266,13 +263,11 @@ pub(in crate::rmeta) fn provide(providers: &mut Providers) {
         },
         native_libraries: |tcx, cnum| {
             assert_eq!(cnum, LOCAL_CRATE);
-            Lrc::new(native_libs::collect(tcx))
+            native_libs::collect(tcx)
         },
         foreign_modules: |tcx, cnum| {
             assert_eq!(cnum, LOCAL_CRATE);
-            let modules: FxHashMap<DefId, ForeignModule> =
-                foreign_modules::collect(tcx).into_iter().map(|m| (m.def_id, m)).collect();
-            Lrc::new(modules)
+            foreign_modules::collect(tcx).into_iter().map(|m| (m.def_id, m)).collect()
         },
 
         // Returns a map from a sufficiently visible external item (i.e., an
@@ -354,7 +349,7 @@ pub(in crate::rmeta) fn provide(providers: &mut Providers) {
                 visible_parent_map.entry(child).or_insert(parent);
             }
 
-            Lrc::new(visible_parent_map)
+            visible_parent_map
         },
 
         dependency_formats: |tcx, ()| Lrc::new(crate::dependency_format::calculate(tcx)),
@@ -438,7 +433,7 @@ impl CStore {
         self.get_crate_data(def.krate).get_fn_has_self_parameter(def.index)
     }
 
-    pub fn crate_source_untracked(&self, cnum: CrateNum) -> CrateSource {
+    pub fn crate_source_untracked(&self, cnum: CrateNum) -> Lrc<CrateSource> {
         self.get_crate_data(cnum).source.clone()
     }
 

compiler/rustc_metadata/src/rmeta/encoder.rs

@@ -1742,7 +1742,7 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
                     hash: self.tcx.crate_hash(cnum),
                     host_hash: self.tcx.crate_host_hash(cnum),
                     kind: self.tcx.dep_kind(cnum),
-                    extra_filename: self.tcx.extra_filename(cnum),
+                    extra_filename: self.tcx.extra_filename(cnum).clone(),
                 };
                 (cnum, dep)
             })

compiler/rustc_middle/src/arena.rs

@@ -52,6 +52,9 @@ macro_rules! arena_types {
                         Vec<rustc_middle::traits::query::OutlivesBound<'tcx>>
                     >
                 >,
+            [] dtorck_constraint: rustc_middle::traits::query::DtorckConstraint<'tcx>,
+            [] candidate_step: rustc_middle::traits::query::CandidateStep<'tcx>,
+            [] autoderef_bad_ty: rustc_middle::traits::query::MethodAutoderefBadTy<'tcx>,
             [] type_op_subtype:
                 rustc_middle::infer::canonical::Canonical<'tcx,
                     rustc_middle::infer::canonical::QueryResponse<'tcx, ()>
@@ -95,6 +98,7 @@ macro_rules! arena_types {
             // This is used to decode the &'tcx [Span] for InlineAsm's line_spans.
             [decode] span: rustc_span::Span,
             [decode] used_trait_imports: rustc_data_structures::fx::FxHashSet<rustc_hir::def_id::LocalDefId>,
+            [decode] impl_source: rustc_middle::traits::ImplSource<'tcx, ()>,
 
             [] dep_kind: rustc_middle::dep_graph::DepKindStruct,
         ]);

compiler/rustc_middle/src/middle/stability.rs

@@ -29,7 +29,7 @@ pub enum StabilityLevel {
 }
 
 /// An entry in the `depr_map`.
-#[derive(Clone, HashStable, Debug)]
+#[derive(Copy, Clone, HashStable, Debug)]
 pub struct DeprecationEntry {
     /// The metadata of the attribute associated with this entry.
     pub attr: Deprecation,

compiler/rustc_middle/src/query/mod.rs

@@ -215,7 +215,8 @@ rustc_queries! {
         desc { |tcx| "elaborating item bounds for `{}`", tcx.def_path_str(key) }
     }
 
-    query native_libraries(_: CrateNum) -> Lrc<Vec<NativeLib>> {
+    query native_libraries(_: CrateNum) -> Vec<NativeLib> {
+        storage(ArenaCacheSelector<'tcx>)
         desc { "looking up the native libraries of a linked crate" }
         separate_provide_extern
     }
@@ -254,6 +255,7 @@ rustc_queries! {
     /// Create a THIR tree for debugging.
     query thir_tree(key: ty::WithOptConstParam<LocalDefId>) -> String {
         no_hash
+        storage(ArenaCacheSelector<'tcx>)
         desc { |tcx| "constructing THIR tree for `{}`", tcx.def_path_str(key.did.to_def_id()) }
     }
 
@@ -368,6 +370,7 @@ rustc_queries! {
     query symbols_for_closure_captures(
         key: (LocalDefId, DefId)
     ) -> Vec<rustc_span::Symbol> {
+        storage(ArenaCacheSelector<'tcx>)
         desc {
             |tcx| "symbols for captures of closure `{}` in `{}`",
             tcx.def_path_str(key.1),
@@ -538,7 +541,7 @@ rustc_queries! {
 
     query adt_dtorck_constraint(
         key: DefId
-    ) -> Result<DtorckConstraint<'tcx>, NoSolution> {
+    ) -> Result<&'tcx DtorckConstraint<'tcx>, NoSolution> {
         desc { |tcx| "computing drop-check constraints for `{}`", tcx.def_path_str(key) }
     }
 
@@ -646,8 +649,8 @@ rustc_queries! {
     /// The map returned for `tcx.impl_item_implementor_ids(impl_id)` would be
     ///`{ trait_f: impl_f, trait_g: impl_g }`
     query impl_item_implementor_ids(impl_id: DefId) -> FxHashMap<DefId, DefId> {
-        desc { |tcx| "comparing impl items against trait for {}", tcx.def_path_str(impl_id) }
         storage(ArenaCacheSelector<'tcx>)
+        desc { |tcx| "comparing impl items against trait for {}", tcx.def_path_str(impl_id) }
     }
 
     /// Given an `impl_id`, return the trait it implements.
@@ -1042,6 +1045,7 @@ rustc_queries! {
     /// Gets the rendered value of the specified constant or associated constant.
     /// Used by rustdoc.
     query rendered_const(def_id: DefId) -> String {
+        storage(ArenaCacheSelector<'tcx>)
         desc { |tcx| "rendering constant intializer of `{}`", tcx.def_path_str(def_id) }
         separate_provide_extern
     }
@@ -1091,7 +1095,7 @@ rustc_queries! {
 
     query codegen_fulfill_obligation(
         key: (ty::ParamEnv<'tcx>, ty::PolyTraitRef<'tcx>)
-    ) -> Result<ImplSource<'tcx, ()>, ErrorReported> {
+    ) -> Result<&'tcx ImplSource<'tcx, ()>, ErrorReported> {
         cache_on_disk_if { true }
         desc { |tcx|
             "checking if `{}` fulfills its obligations",
@@ -1237,6 +1241,7 @@ rustc_queries! {
     }
 
     query dependency_formats(_: ()) -> Lrc<crate::middle::dependency_format::Dependencies> {
+        storage(ArenaCacheSelector<'tcx>)
         desc { "get the linkage format of all dependencies" }
     }
 
@@ -1369,13 +1374,15 @@ rustc_queries! {
     /// You likely want to call `Instance::upstream_monomorphization()`
     /// instead of invoking this query directly.
     query upstream_monomorphizations_for(def_id: DefId)
-        -> Option<&'tcx FxHashMap<SubstsRef<'tcx>, CrateNum>> {
-            desc { |tcx|
-                "collecting available upstream monomorphizations for `{}`",
-                tcx.def_path_str(def_id),
-            }
-            separate_provide_extern
+        -> Option<&'tcx FxHashMap<SubstsRef<'tcx>, CrateNum>>
+    {
+        storage(ArenaCacheSelector<'tcx>)
+        desc { |tcx|
+            "collecting available upstream monomorphizations for `{}`",
+            tcx.def_path_str(def_id),
         }
+        separate_provide_extern
+    }
 
     /// Returns the upstream crate that exports drop-glue for the given
     /// type (`substs` is expected to be a single-item list containing the
@@ -1396,7 +1403,8 @@ rustc_queries! {
         desc { "available upstream drop-glue for `{:?}`", substs }
     }
 
-    query foreign_modules(_: CrateNum) -> Lrc<FxHashMap<DefId, ForeignModule>> {
+    query foreign_modules(_: CrateNum) -> FxHashMap<DefId, ForeignModule> {
+        storage(ArenaCacheSelector<'tcx>)
         desc { "looking up the foreign modules of a linked crate" }
         separate_provide_extern
     }
@@ -1422,11 +1430,13 @@ rustc_queries! {
         separate_provide_extern
     }
     query extra_filename(_: CrateNum) -> String {
+        storage(ArenaCacheSelector<'tcx>)
         eval_always
         desc { "looking up the extra filename for a crate" }
         separate_provide_extern
     }
     query crate_extern_paths(_: CrateNum) -> Vec<PathBuf> {
+        storage(ArenaCacheSelector<'tcx>)
         eval_always
         desc { "looking up the paths for extern crates" }
         separate_provide_extern
@@ -1478,8 +1488,7 @@ rustc_queries! {
     /// for each parameter if a trait object were to be passed for that parameter.
     /// For example, for `struct Foo<'a, T, U>`, this would be `['static, 'static]`.
     /// For `struct Foo<'a, T: 'a, U>`, this would instead be `['a, 'static]`.
-    query object_lifetime_defaults_map(_: LocalDefId)
-        -> Option<Vec<ObjectLifetimeDefault>> {
+    query object_lifetime_defaults(_: LocalDefId) -> Option<&'tcx [ObjectLifetimeDefault]> {
         desc { "looking up lifetime defaults for a region on an item" }
     }
     query late_bound_vars_map(_: LocalDefId)
@@ -1488,6 +1497,7 @@ rustc_queries! {
     }
 
     query lifetime_scope_map(_: LocalDefId) -> Option<FxHashMap<ItemLocalId, LifetimeScopeForPath>> {
+        storage(ArenaCacheSelector<'tcx>)
         desc { "finds the lifetime scope for an HirId of a PathSegment" }
     }
 
@@ -1501,7 +1511,7 @@ rustc_queries! {
     /// check whether the forest is empty.
     query type_uninhabited_from(
         key: ty::ParamEnvAnd<'tcx, Ty<'tcx>>
-    ) -> ty::inhabitedness::DefIdForest {
+    ) -> ty::inhabitedness::DefIdForest<'tcx> {
         desc { "computing the inhabitedness of `{:?}`", key }
         remap_env_constness
     }
@@ -1566,7 +1576,8 @@ rustc_queries! {
         desc { "calculating the missing lang items in a crate" }
         separate_provide_extern
     }
-    query visible_parent_map(_: ()) -> Lrc<DefIdMap<DefId>> {
+    query visible_parent_map(_: ()) -> DefIdMap<DefId> {
+        storage(ArenaCacheSelector<'tcx>)
         desc { "calculating the visible parent map" }
     }
     query trimmed_def_paths(_: ()) -> FxHashMap<DefId, Symbol> {
@@ -1579,6 +1590,7 @@ rustc_queries! {
         separate_provide_extern
     }
     query used_crate_source(_: CrateNum) -> Lrc<CrateSource> {
+        storage(ArenaCacheSelector<'tcx>)
         eval_always
         desc { "looking at the source for a crate" }
         separate_provide_extern
@@ -1669,7 +1681,11 @@ rustc_queries! {
         desc { "optimization level used by backend" }
     }
 
-    query output_filenames(_: ()) -> Arc<OutputFilenames> {
+    /// Return the filenames where output artefacts shall be stored.
+    ///
+    /// This query returns an `&Arc` because codegen backends need the value even after the `TyCtxt`
+    /// has been destroyed.
+    query output_filenames(_: ()) -> &'tcx Arc<OutputFilenames> {
         eval_always
         desc { "output_filenames" }
     }
@@ -1911,6 +1927,7 @@ rustc_queries! {
     /// all of the cases that the normal `ty::Ty`-based wfcheck does. This is fine,
     /// because the `ty::Ty`-based wfcheck is always run.
     query diagnostic_hir_wf_check(key: (ty::Predicate<'tcx>, traits::WellFormedLoc)) -> Option<traits::ObligationCause<'tcx>> {
+        storage(ArenaCacheSelector<'tcx>)
         eval_always
         no_hash
         desc { "performing HIR wf-checking for predicate {:?} at item {:?}", key.0, key.1 }