Add new effects desugaring

fee1-dead · fee1-dead · commit 7e1eb87de68a · 2024-02-26T00:15:31.000Z
diff --git a/compiler/rustc_ast_lowering/src/item.rs b/compiler/rustc_ast_lowering/src/item.rs
@@ -338,13 +338,11 @@ impl<'hir> LoweringContext<'_, 'hir> {
                 // lifetime to be added, but rather a reference to a
                 // parent lifetime.
                 let itctx = ImplTraitContext::Universal;
+                // TODO we need to rip apart this infrastructure
                 let (generics, (trait_ref, lowered_ty)) =
-                    self.lower_generics(ast_generics, *constness, id, itctx, |this| {
+                    self.lower_generics(ast_generics, Const::No, id, itctx, |this| {
                         let modifiers = TraitBoundModifiers {
-                            constness: match *constness {
-                                Const::Yes(span) => BoundConstness::Maybe(span),
-                                Const::No => BoundConstness::Never,
-                            },
+                            constness: BoundConstness::Never,
                             asyncness: BoundAsyncness::Normal,
                             // we don't use this in bound lowering
                             polarity: BoundPolarity::Positive,
@@ -379,6 +377,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                     ImplPolarity::Negative(s) => ImplPolarity::Negative(self.lower_span(*s)),
                 };
                 hir::ItemKind::Impl(self.arena.alloc(hir::Impl {
+                    constness: self.lower_constness(*constness),
                     unsafety: self.lower_unsafety(*unsafety),
                     polarity,
                     defaultness,
@@ -390,15 +389,9 @@ impl<'hir> LoweringContext<'_, 'hir> {
                 }))
             }
             ItemKind::Trait(box Trait { is_auto, unsafety, generics, bounds, items }) => {
-                // FIXME(const_trait_impl, effects, fee1-dead) this should be simplified if possible
-                let constness = attrs
-                    .unwrap_or(&[])
-                    .iter()
-                    .find(|x| x.has_name(sym::const_trait))
-                    .map_or(Const::No, |x| Const::Yes(x.span));
                 let (generics, (unsafety, items, bounds)) = self.lower_generics(
                     generics,
-                    constness,
+                    Const::No,
                     id,
                     ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
                     |this| {
diff --git a/compiler/rustc_hir/src/hir.rs b/compiler/rustc_hir/src/hir.rs
@@ -3168,6 +3168,7 @@ pub enum ItemKind<'hir> {
 
 #[derive(Debug, Clone, Copy, HashStable_Generic)]
 pub struct Impl<'hir> {
+    pub constness: Constness,
     pub unsafety: Unsafety,
     pub polarity: ImplPolarity,
     pub defaultness: Defaultness,
diff --git a/compiler/rustc_hir/src/intravisit.rs b/compiler/rustc_hir/src/intravisit.rs
@@ -533,6 +533,7 @@ pub fn walk_item<'v, V: Visitor<'v>>(visitor: &mut V, item: &'v Item<'v>) -> V::
             try_visit!(visitor.visit_enum_def(enum_definition, item.hir_id()));
         }
         ItemKind::Impl(Impl {
+            constness: _,
             unsafety: _,
             defaultness: _,
             polarity: _,
diff --git a/compiler/rustc_hir/src/lang_items.rs b/compiler/rustc_hir/src/lang_items.rs
@@ -342,6 +342,11 @@ language_item_table! {
 
     String,                  sym::String,              string,                     Target::Struct,         GenericRequirement::None;
     CStr,                    sym::CStr,                c_str,                      Target::Struct,         GenericRequirement::None;
+
+    EffectsRuntime,          sym::EffectsRuntime,      effects_runtime,            Target::Struct,         GenericRequirement::None;
+    EffectsNoRuntime,        sym::EffectsNoRuntime,    effects_no_runtime,         Target::Struct,         GenericRequirement::None;
+    EffectsMaybe,            sym::EffectsMaybe,        effects_maybe,              Target::Struct,         GenericRequirement::None;
+    EffectsCompat,           sym::EffectsCompat,       effects_compat,             Target::Trait,          GenericRequirement::Exact(1);
 }
 
 pub enum GenericRequirement {
diff --git a/compiler/rustc_hir_analysis/src/check/compare_impl_item.rs b/compiler/rustc_hir_analysis/src/check/compare_impl_item.rs
@@ -1987,10 +1987,10 @@ pub(super) fn check_type_bounds<'tcx>(
     let infcx = tcx.infer_ctxt().build();
     let ocx = ObligationCtxt::new(&infcx);
 
-    // A synthetic impl Trait for RPITIT desugaring has no HIR, which we currently use to get the
-    // span for an impl's associated type. Instead, for these, use the def_span for the synthesized
-    // associated type.
-    let impl_ty_span = if impl_ty.is_impl_trait_in_trait() {
+    // A synthetic impl Trait for RPITIT desugaring or assoc type for effects desugaring has no HIR,
+    // which we currently use to get the span for an impl's associated type. Instead, for these,
+    // use the def_span for the synthesized  associated type.
+    let impl_ty_span = if impl_ty.is_impl_trait_in_trait() || impl_ty.is_effects_desugaring {
         tcx.def_span(impl_ty_def_id)
     } else {
         match tcx.hir_node_by_def_id(impl_ty_def_id) {
diff --git a/compiler/rustc_hir_analysis/src/collect/item_bounds.rs b/compiler/rustc_hir_analysis/src/collect/item_bounds.rs
@@ -104,6 +104,11 @@ pub(super) fn explicit_item_bounds(
         None => {}
     }
 
+    // effects desugared associated types have no bounds.
+    if tcx.is_effects_desugared_assoc_ty(def_id.to_def_id()) {
+        return ty::EarlyBinder::bind(&[]);
+    }
+
     let bounds = match tcx.hir_node_by_def_id(def_id) {
         hir::Node::TraitItem(hir::TraitItem {
             kind: hir::TraitItemKind::Type(bounds, _),
diff --git a/compiler/rustc_hir_analysis/src/collect/predicates_of.rs b/compiler/rustc_hir_analysis/src/collect/predicates_of.rs
@@ -108,6 +108,22 @@ fn gather_explicit_predicates_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::Gen
         None => {}
     }
 
+    if tcx.is_effects_desugared_assoc_ty(def_id.to_def_id()) {
+        let mut predicates = Vec::new();
+
+        // Inherit predicates of parent (impl or trait)
+        // TODO do we need to distinguish impl or trait?
+        let parent = tcx.local_parent(def_id);
+
+        let identity_args = ty::GenericArgs::identity_for_item(tcx, def_id);
+        predicates
+            .extend(tcx.explicit_predicates_of(parent).instantiate_own(tcx, identity_args));
+        return ty::GenericPredicates {
+            parent: Some(parent.to_def_id()),
+            predicates: tcx.arena.alloc_from_iter(predicates),
+        };
+    }
+
     let hir_id = tcx.local_def_id_to_hir_id(def_id);
     let node = tcx.hir_node(hir_id);
 
diff --git a/compiler/rustc_hir_pretty/src/lib.rs b/compiler/rustc_hir_pretty/src/lib.rs
@@ -574,6 +574,7 @@ impl<'a> State<'a> {
                 self.print_struct(struct_def, generics, item.ident.name, item.span, true);
             }
             hir::ItemKind::Impl(&hir::Impl {
+                constness,
                 unsafety,
                 polarity,
                 defaultness,
@@ -588,6 +589,10 @@ impl<'a> State<'a> {
                 self.print_unsafety(unsafety);
                 self.word_nbsp("impl");
 
+                if let hir::Constness::Const = constness {
+                    self.word_nbsp("const");
+                }
+
                 if !generics.params.is_empty() {
                     self.print_generic_params(generics.params);
                     self.space();
diff --git a/compiler/rustc_hir_typeck/src/method/probe.rs b/compiler/rustc_hir_typeck/src/method/probe.rs
@@ -1359,6 +1359,7 @@ impl<'tcx> Pick<'tcx> {
                     trait_item_def_id: _,
                     fn_has_self_parameter: _,
                     opt_rpitit_info: _,
+                    is_effects_desugaring: _,
                 },
             kind: _,
             import_ids: _,
diff --git a/compiler/rustc_metadata/src/rmeta/decoder.rs b/compiler/rustc_metadata/src/rmeta/decoder.rs
@@ -1293,7 +1293,7 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {
     }
 
     fn get_associated_item(self, id: DefIndex, sess: &'a Session) -> ty::AssocItem {
-        let name = if self.root.tables.opt_rpitit_info.get(self, id).is_some() {
+        let name = if self.root.tables.opt_rpitit_info.get(self, id).is_some() || self.root.tables.is_effects_desugaring.get(self, id) {
             kw::Empty
         } else {
             self.item_name(id)
@@ -1316,6 +1316,7 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {
             container,
             fn_has_self_parameter: has_self,
             opt_rpitit_info,
+            is_effects_desugaring: self.root.tables.is_effects_desugaring.get(self, id),
         }
     }
 
diff --git a/compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs b/compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs
@@ -288,6 +288,9 @@ provide! { tcx, def_id, other, cdata,
             })
     }
 
+    associated_type_for_effects => {
+        table
+    }
     associated_types_for_impl_traits_in_associated_fn => { table_defaulted_array }
 
     visibility => { cdata.get_visibility(def_id.index) }
diff --git a/compiler/rustc_metadata/src/rmeta/encoder.rs b/compiler/rustc_metadata/src/rmeta/encoder.rs
@@ -1441,6 +1441,9 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
                 for &def_id in associated_item_def_ids {
                     self.encode_info_for_assoc_item(def_id);
                 }
+                if let Some(assoc_def_id) = self.tcx.associated_type_for_effects(def_id) {
+                    record!(self.tables.associated_type_for_effects[def_id] <- assoc_def_id);
+                }
             }
             if def_kind == DefKind::Closure
                 && let Some(coroutine_kind) = self.tcx.coroutine_kind(def_id)
@@ -1613,6 +1616,9 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
                 );
             }
         }
+        if item.is_effects_desugaring {
+            self.tables.is_effects_desugaring.set(def_id.index, true);
+        }
     }
 
     fn encode_mir(&mut self) {
diff --git a/compiler/rustc_metadata/src/rmeta/mod.rs b/compiler/rustc_metadata/src/rmeta/mod.rs
@@ -390,7 +390,9 @@ define_tables! {
     inferred_outlives_of: Table<DefIndex, LazyArray<(ty::Clause<'static>, Span)>>,
     inherent_impls: Table<DefIndex, LazyArray<DefIndex>>,
     associated_types_for_impl_traits_in_associated_fn: Table<DefIndex, LazyArray<DefId>>,
+    associated_type_for_effects: Table<DefIndex, Option<LazyValue<DefId>>>,
     opt_rpitit_info: Table<DefIndex, Option<LazyValue<ty::ImplTraitInTraitData>>>,
+    is_effects_desugaring: Table<DefIndex, bool>,
     unused_generic_params: Table<DefIndex, UnusedGenericParams>,
     // Reexported names are not associated with individual `DefId`s,
     // e.g. a glob import can introduce a lot of names, all with the same `DefId`.
diff --git a/compiler/rustc_middle/src/query/mod.rs b/compiler/rustc_middle/src/query/mod.rs
@@ -840,6 +840,12 @@ rustc_queries! {
         separate_provide_extern
     }
 
+    query associated_type_for_effects(def_id: DefId) -> Option<DefId> {
+        desc { |tcx| "creating associated items for effects in `{}`", tcx.def_path_str(def_id) }
+        cache_on_disk_if { 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_type_for_impl_trait_in_trait(opaque_ty_def_id: LocalDefId) -> LocalDefId {
diff --git a/compiler/rustc_middle/src/ty/assoc.rs b/compiler/rustc_middle/src/ty/assoc.rs
@@ -33,6 +33,9 @@ pub struct AssocItem {
     /// return-position `impl Trait` in trait desugaring. The `ImplTraitInTraitData`
     /// provides additional information about its source.
     pub opt_rpitit_info: Option<ty::ImplTraitInTraitData>,
+
+    // TODO: is this necessary
+    pub is_effects_desugaring: bool,
 }
 
 impl AssocItem {
diff --git a/compiler/rustc_middle/src/ty/context.rs b/compiler/rustc_middle/src/ty/context.rs
@@ -2288,9 +2288,9 @@ impl<'tcx> TyCtxt<'tcx> {
         matches!(
             node,
             hir::Node::Item(hir::Item {
-                kind: hir::ItemKind::Impl(hir::Impl { generics, .. }),
+                kind: hir::ItemKind::Impl(hir::Impl { constness, .. }),
                 ..
-            }) if generics.params.iter().any(|p| matches!(p.kind, hir::GenericParamKind::Const { is_host_effect: true, .. }))
+            }) if matches!(constness, hir::Constness::Const)
         )
     }
 
diff --git a/compiler/rustc_middle/src/ty/mod.rs b/compiler/rustc_middle/src/ty/mod.rs
@@ -1595,7 +1595,7 @@ impl<'tcx> TyCtxt<'tcx> {
         }
     }
 
-    /// If the def-id is an associated type that was desugared from a
+    /// If the `def_id`` is an associated type that was desugared from a
     /// return-position `impl Trait` from a trait, then provide the source info
     /// about where that RPITIT came from.
     pub fn opt_rpitit_info(self, def_id: DefId) -> Option<ImplTraitInTraitData> {
@@ -1606,6 +1606,16 @@ impl<'tcx> TyCtxt<'tcx> {
         }
     }
 
+    /// Whether the `def_id` is an associated type that was desugared from a
+    /// `#[const_trait]` or `impl_const`.
+    pub fn is_effects_desugared_assoc_ty(self, def_id: DefId) -> bool {
+        if let DefKind::AssocTy = self.def_kind(def_id) {
+            self.associated_item(def_id).is_effects_desugaring
+        } else {
+            false
+        }
+    }
+
     pub fn find_field_index(self, ident: Ident, variant: &VariantDef) -> Option<FieldIdx> {
         variant.fields.iter_enumerated().find_map(|(i, field)| {
             self.hygienic_eq(ident, field.ident(self), variant.def_id).then_some(i)
diff --git a/compiler/rustc_span/src/symbol.rs b/compiler/rustc_span/src/symbol.rs
@@ -192,6 +192,11 @@ symbols! {
         Display,
         DoubleEndedIterator,
         Duration,
+        EffectsCompat,
+        EffectsMaybe,
+        EffectsNoRuntime,
+        EffectsRuntime,
+        Effects__,
         Encodable,
         Encoder,
         Eq,
diff --git a/compiler/rustc_ty_utils/src/assoc.rs b/compiler/rustc_ty_utils/src/assoc.rs
diff --git a/library/core/src/marker.rs b/library/core/src/marker.rs

Original file line number	Diff line number	Diff line change
`@@ -533,6 +533,7 @@ pub fn walk_item<'v, V: Visitor<'v>>(visitor: &mut V, item: &'v Item<'v>) -> V::`
`533`	`533`	`try_visit!(visitor.visit_enum_def(enum_definition, item.hir_id()));`
`534`	`534`	`}`
`535`	`535`	`ItemKind::Impl(Impl {`
	`536`	`+ constness: _,`
`536`	`537`	`unsafety: _,`
`537`	`538`	`defaultness: _,`
`538`	`539`	`polarity: _,`
Original file line number	Diff line number	Diff line change
`@@ -1293,7 +1293,7 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {`
`1293`	`1293`	`}`
`1294`	`1294`
`1295`	`1295`	`fn get_associated_item(self, id: DefIndex, sess: &'a Session) -> ty::AssocItem {`
`1296`		`- let name = if self.root.tables.opt_rpitit_info.get(self, id).is_some() {`
	`1296`	`+ let name = if self.root.tables.opt_rpitit_info.get(self, id).is_some() \|\| self.root.tables.is_effects_desugaring.get(self, id) {`
`1297`	`1297`	`kw::Empty`
`1298`	`1298`	`} else {`
`1299`	`1299`	`self.item_name(id)`
`@@ -1316,6 +1316,7 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {`
`1316`	`1316`	`container,`
`1317`	`1317`	`fn_has_self_parameter: has_self,`
`1318`	`1318`	`opt_rpitit_info,`
	`1319`	`+ is_effects_desugaring: self.root.tables.is_effects_desugaring.get(self, id),`
`1319`	`1320`	`}`
`1320`	`1321`	`}`
`1321`	`1322`