Rollup merge of rust-lang#108141 - spastorino:add_rpitit_queries, r=compiler-errors

Add rpitit queries

This is part of the changes we are making to lower RPITITs as an associated type. The rest of the stuff will follow under a `-Z` flag.

I still need to add comments to the code, explain stuff and also I'd need to avoid encoding in metadata when rpitit queries return `&[]`

r? `@compiler-errors`

Author: Dylan-DPC

compiler/rustc_hir/src/definitions.rs

@@ -280,6 +280,8 @@ pub enum DefPathData {
     AnonConst,
     /// An `impl Trait` type node.
     ImplTrait,
+    /// `impl Trait` generated associated type node.
+    ImplTraitAssocTy,
 }
 
 impl Definitions {
@@ -403,7 +405,7 @@ impl DefPathData {
             TypeNs(name) | ValueNs(name) | MacroNs(name) | LifetimeNs(name) => Some(name),
 
             Impl | ForeignMod | CrateRoot | Use | GlobalAsm | ClosureExpr | Ctor | AnonConst
-            | ImplTrait => None,
+            | ImplTrait | ImplTraitAssocTy => None,
         }
     }
 
@@ -422,7 +424,7 @@ impl DefPathData {
             ClosureExpr => DefPathDataName::Anon { namespace: sym::closure },
             Ctor => DefPathDataName::Anon { namespace: sym::constructor },
             AnonConst => DefPathDataName::Anon { namespace: sym::constant },
-            ImplTrait => DefPathDataName::Anon { namespace: sym::opaque },
+            ImplTrait | ImplTraitAssocTy => DefPathDataName::Anon { namespace: sym::opaque },
         }
     }
 }

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

@@ -254,6 +254,8 @@ provide! { tcx, def_id, other, cdata,
             .process_decoded(tcx, || panic!("{def_id:?} does not have trait_impl_trait_tys")))
      }
 
+    associated_items_for_impl_trait_in_trait => { table_defaulted_array }
+
     visibility => { cdata.get_visibility(def_id.index) }
     adt_def => { cdata.get_adt_def(def_id.index, tcx) }
     adt_destructor => {

compiler/rustc_metadata/src/rmeta/encoder.rs

@@ -1129,6 +1129,11 @@ fn should_encode_trait_impl_trait_tys(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
     })
 }
 
+// Return `false` to avoid encoding impl trait in trait, while we don't use the query.
+fn should_encode_fn_impl_trait_in_trait<'tcx>(_tcx: TyCtxt<'tcx>, _def_id: DefId) -> bool {
+    false
+}
+
 impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
     fn encode_attrs(&mut self, def_id: LocalDefId) {
         let tcx = self.tcx;
@@ -1137,8 +1142,8 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
             is_doc_hidden: false,
         };
         let attr_iter = tcx
-            .hir()
-            .attrs(tcx.hir().local_def_id_to_hir_id(def_id))
+            .opt_local_def_id_to_hir_id(def_id)
+            .map_or(Default::default(), |hir_id| tcx.hir().attrs(hir_id))
             .iter()
             .filter(|attr| analyze_attr(attr, &mut state));
 
@@ -1211,6 +1216,10 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
             {
                 record!(self.tables.trait_impl_trait_tys[def_id] <- table);
             }
+            if should_encode_fn_impl_trait_in_trait(tcx, def_id) {
+                let table = tcx.associated_items_for_impl_trait_in_trait(def_id);
+                record_defaulted_array!(self.tables.associated_items_for_impl_trait_in_trait[def_id] <- table);
+            }
         }
 
         let inherent_impls = tcx.with_stable_hashing_context(|hcx| {

compiler/rustc_metadata/src/rmeta/mod.rs

@@ -354,6 +354,7 @@ define_tables! {
     explicit_item_bounds: Table<DefIndex, LazyArray<(ty::Predicate<'static>, Span)>>,
     inferred_outlives_of: Table<DefIndex, LazyArray<(ty::Clause<'static>, Span)>>,
     inherent_impls: Table<DefIndex, LazyArray<DefIndex>>,
+    associated_items_for_impl_trait_in_trait: Table<DefIndex, LazyArray<DefId>>,
 
 - optional:
     attributes: Table<DefIndex, LazyArray<ast::Attribute>>,

compiler/rustc_middle/src/hir/map/mod.rs

@@ -849,6 +849,13 @@ impl<'hir> Map<'hir> {
         }
     }
 
+    pub fn get_fn_output(self, def_id: LocalDefId) -> Option<&'hir FnRetTy<'hir>> {
+        match self.tcx.hir_owner(OwnerId { def_id }) {
+            Some(Owner { node, .. }) => node.fn_decl().map(|fn_decl| &fn_decl.output),
+            _ => None,
+        }
+    }
+
     pub fn expect_variant(self, id: HirId) -> &'hir Variant<'hir> {
         match self.find(id) {
             Some(Node::Variant(variant)) => variant,

compiler/rustc_middle/src/hir/mod.rs

@@ -121,13 +121,13 @@ pub fn provide(providers: &mut Providers) {
         let node = owner.node();
         Some(Owner { node, hash_without_bodies: owner.nodes.hash_without_bodies })
     };
-    providers.local_def_id_to_hir_id = |tcx, id| {
+    providers.opt_local_def_id_to_hir_id = |tcx, id| {
         let owner = tcx.hir_crate(()).owners[id].map(|_| ());
-        match owner {
+        Some(match owner {
             MaybeOwner::Owner(_) => HirId::make_owner(id),
             MaybeOwner::Phantom => bug!("No HirId for {:?}", id),
             MaybeOwner::NonOwner(hir_id) => hir_id,
-        }
+        })
     };
     providers.hir_owner_nodes = |tcx, id| tcx.hir_crate(()).owners[id.def_id].map(|i| &i.nodes);
     providers.hir_owner_parent = |tcx, id| {

compiler/rustc_middle/src/query/mod.rs

@@ -85,11 +85,10 @@ rustc_queries! {
         desc { |tcx| "getting HIR owner of `{}`", tcx.def_path_str(key.to_def_id()) }
     }
 
-    /// Gives access to the HIR ID for the given `LocalDefId` owner `key`.
+    /// Gives access to the HIR ID for the given `LocalDefId` owner `key` if any.
     ///
-    /// This can be conveniently accessed by methods on `tcx.hir()`.
-    /// Avoid calling this query directly.
-    query local_def_id_to_hir_id(key: LocalDefId) -> hir::HirId {
+    /// Definitions that were generated with no HIR, would be feeded to return `None`.
+    query opt_local_def_id_to_hir_id(key: LocalDefId) -> Option<hir::HirId>{
         desc { |tcx| "getting HIR ID of `{}`", tcx.def_path_str(key.to_def_id()) }
     }
 
@@ -767,6 +766,26 @@ rustc_queries! {
         desc { |tcx| "comparing impl items against trait for `{}`", tcx.def_path_str(impl_id) }
     }
 
+    /// Given `fn_def_id` of a trait or of an impl that implements a given trait:
+    /// if `fn_def_id` is the def id of a function defined inside a trait, then it creates and returns
+    /// the associated items that correspond to each impl trait in return position for that trait.
+    /// if `fn_def_id` is the def id of a function defined inside an impl that implements a trait, then it
+    /// creates and returns the associated items that correspond to each impl trait in return position
+    /// of the implemented trait.
+    query associated_items_for_impl_trait_in_trait(fn_def_id: DefId) -> &'tcx [DefId] {
+        desc { |tcx| "creating associated items for impl trait in trait returned by `{}`", tcx.def_path_str(fn_def_id) }
+        cache_on_disk_if { fn_def_id.is_local() }
+        separate_provide_extern
+    }
+
+    /// Given an impl trait in trait `opaque_ty_def_id`, create and return the corresponding
+    /// associated item.
+    query associated_item_for_impl_trait_in_trait(opaque_ty_def_id: LocalDefId) -> LocalDefId {
+        desc { |tcx| "creates the associated item corresponding to the opaque type `{}`", tcx.def_path_str(opaque_ty_def_id.to_def_id()) }
+        cache_on_disk_if { true }
+        separate_provide_extern
+    }
+
     /// Given an `impl_id`, return the trait it implements.
     /// Return `None` if this is an inherent impl.
     query impl_trait_ref(impl_id: DefId) -> Option<ty::EarlyBinder<ty::TraitRef<'tcx>>> {

compiler/rustc_middle/src/ty/context.rs

@@ -2451,6 +2451,10 @@ impl<'tcx> TyCtxt<'tcx> {
         )
     }
 
+    pub fn local_def_id_to_hir_id(self, local_def_id: LocalDefId) -> HirId {
+        self.opt_local_def_id_to_hir_id(local_def_id).unwrap()
+    }
+
     pub fn trait_solver_next(self) -> bool {
         self.sess.opts.unstable_opts.trait_solver == rustc_session::config::TraitSolver::Next
     }

compiler/rustc_symbol_mangling/src/typeid/typeid_itanium_cxx_abi.rs

@@ -396,6 +396,7 @@ fn encode_ty_name(tcx: TyCtxt<'_>, def_id: DefId) -> String {
             hir::definitions::DefPathData::CrateRoot
             | hir::definitions::DefPathData::Use
             | hir::definitions::DefPathData::GlobalAsm
+            | hir::definitions::DefPathData::ImplTraitAssocTy
             | hir::definitions::DefPathData::MacroNs(..)
             | hir::definitions::DefPathData::LifetimeNs(..) => {
                 bug!("encode_ty_name: unexpected `{:?}`", disambiguated_data.data);

compiler/rustc_symbol_mangling/src/v0.rs

@@ -791,6 +791,7 @@ impl<'tcx> Printer<'tcx> for &mut SymbolMangler<'tcx> {
             | DefPathData::Use
             | DefPathData::GlobalAsm
             | DefPathData::Impl
+            | DefPathData::ImplTraitAssocTy
             | DefPathData::MacroNs(_)
             | DefPathData::LifetimeNs(_) => {
                 bug!("symbol_names: unexpected DefPathData: {:?}", disambiguated_data.data)