Move in_trait into OpaqueTyOrigin

compiler/rustc_ast_lowering/src/item.rs

@@ -286,7 +286,6 @@ impl<'hir> LoweringContext<'_, 'hir> {
                                 parent: this.local_def_id(id),
                                 in_assoc_ty: false,
                             },
-                            fn_kind: None,
                         }),
                     },
                 );
@@ -983,7 +982,6 @@ impl<'hir> LoweringContext<'_, 'hir> {
                                     parent: this.local_def_id(i.id),
                                     in_assoc_ty: true,
                                 },
-                                fn_kind: None,
                             });
                             hir::ImplItemKind::Type(ty)
                         }

compiler/rustc_ast_lowering/src/lib.rs

@@ -288,12 +288,7 @@ enum ImplTraitContext {
     /// Example: `fn foo() -> impl Debug`, where `impl Debug` is conceptually
     /// equivalent to a new opaque type like `type T = impl Debug; fn foo() -> T`.
     ///
-    OpaqueTy {
-        origin: hir::OpaqueTyOrigin,
-        /// Only used to change the lifetime capture rules, since
-        /// RPITIT captures all in scope, RPIT does not.
-        fn_kind: Option<FnDeclKind>,
-    },
+    OpaqueTy { origin: hir::OpaqueTyOrigin },
     /// `impl Trait` is unstably accepted in this position.
     FeatureGated(ImplTraitPosition, Symbol),
     /// `impl Trait` is not accepted in this position.
@@ -1404,14 +1399,9 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
             TyKind::ImplTrait(def_node_id, bounds) => {
                 let span = t.span;
                 match itctx {
-                    ImplTraitContext::OpaqueTy { origin, fn_kind } => self.lower_opaque_impl_trait(
-                        span,
-                        origin,
-                        *def_node_id,
-                        bounds,
-                        fn_kind,
-                        itctx,
-                    ),
+                    ImplTraitContext::OpaqueTy { origin } => {
+                        self.lower_opaque_impl_trait(span, origin, *def_node_id, bounds, itctx)
+                    }
                     ImplTraitContext::Universal => {
                         if let Some(span) = bounds.iter().find_map(|bound| match *bound {
                             ast::GenericBound::Use(_, span) => Some(span),
@@ -1513,7 +1503,6 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         origin: hir::OpaqueTyOrigin,
         opaque_ty_node_id: NodeId,
         bounds: &GenericBounds,
-        fn_kind: Option<FnDeclKind>,
         itctx: ImplTraitContext,
     ) -> hir::TyKind<'hir> {
         // Make sure we know that some funky desugaring has been going on here.
@@ -1555,11 +1544,9 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                         .map(|(ident, id, _)| Lifetime { id, ident })
                         .collect()
                 }
-                hir::OpaqueTyOrigin::FnReturn { .. } => {
-                    if matches!(
-                        fn_kind.expect("expected RPITs to be lowered with a FnKind"),
-                        FnDeclKind::Impl | FnDeclKind::Trait
-                    ) || self.tcx.features().lifetime_capture_rules_2024
+                hir::OpaqueTyOrigin::FnReturn { in_trait, .. } => {
+                    if in_trait
+                        || self.tcx.features().lifetime_capture_rules_2024
                         || span.at_least_rust_2024()
                     {
                         // return-position impl trait in trait was decided to capture all
@@ -1583,30 +1570,22 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         };
         debug!(?captured_lifetimes_to_duplicate);
 
-        match fn_kind {
-            // Deny `use<>` on RPITIT in trait/trait-impl for now.
-            Some(FnDeclKind::Trait | FnDeclKind::Impl) => {
+        // Feature gate for RPITIT + use<..>
+        match origin {
+            rustc_hir::OpaqueTyOrigin::FnReturn { in_trait: true, .. } => {
                 if let Some(span) = bounds.iter().find_map(|bound| match *bound {
                     ast::GenericBound::Use(_, span) => Some(span),
                     _ => None,
                 }) {
                     self.tcx.dcx().emit_err(errors::NoPreciseCapturesOnRpitit { span });
                 }
             }
-            None
-            | Some(
-                FnDeclKind::Fn
-                | FnDeclKind::Inherent
-                | FnDeclKind::ExternFn
-                | FnDeclKind::Closure
-                | FnDeclKind::Pointer,
-            ) => {}
+            _ => {}
         }
 
         self.lower_opaque_inner(
             opaque_ty_node_id,
             origin,
-            matches!(fn_kind, Some(FnDeclKind::Trait)),
             captured_lifetimes_to_duplicate,
             span,
             opaque_ty_span,
@@ -1618,7 +1597,6 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         &mut self,
         opaque_ty_node_id: NodeId,
         origin: hir::OpaqueTyOrigin,
-        in_trait: bool,
         captured_lifetimes_to_duplicate: FxIndexSet<Lifetime>,
         span: Span,
         opaque_ty_span: Span,
@@ -1747,7 +1725,6 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                 bounds,
                 origin,
                 lifetime_mapping,
-                in_trait,
             };
 
             // Generate an `type Foo = impl Trait;` declaration.
@@ -1863,14 +1840,17 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
             None => match &decl.output {
                 FnRetTy::Ty(ty) => {
                     let itctx = match kind {
-                        FnDeclKind::Fn
-                        | FnDeclKind::Inherent
-                        | FnDeclKind::Trait
-                        | FnDeclKind::Impl => ImplTraitContext::OpaqueTy {
+                        FnDeclKind::Fn | FnDeclKind::Inherent => ImplTraitContext::OpaqueTy {
+                            origin: hir::OpaqueTyOrigin::FnReturn {
+                                parent: self.local_def_id(fn_node_id),
+                                in_trait: false,
+                            },
+                        },
+                        FnDeclKind::Trait | FnDeclKind::Impl => ImplTraitContext::OpaqueTy {
                             origin: hir::OpaqueTyOrigin::FnReturn {
                                 parent: self.local_def_id(fn_node_id),
+                                in_trait: true,
                             },
-                            fn_kind: Some(kind),
                         },
                         FnDeclKind::ExternFn => {
                             ImplTraitContext::Disallowed(ImplTraitPosition::ExternFnReturn)
@@ -1952,10 +1932,15 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
             .map(|(ident, id, _)| Lifetime { id, ident })
             .collect();
 
+        let in_trait = match fn_kind {
+            FnDeclKind::Trait | FnDeclKind::Impl => true,
+            FnDeclKind::Fn | FnDeclKind::Inherent => false,
+            FnDeclKind::ExternFn | FnDeclKind::Closure | FnDeclKind::Pointer => unreachable!(),
+        };
+
         let opaque_ty_ref = self.lower_opaque_inner(
             opaque_ty_node_id,
-            hir::OpaqueTyOrigin::AsyncFn { parent: fn_def_id },
-            matches!(fn_kind, FnDeclKind::Trait),
+            hir::OpaqueTyOrigin::AsyncFn { parent: fn_def_id, in_trait },
             captured_lifetimes,
             span,
             opaque_ty_span,
@@ -1965,8 +1950,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                     coro,
                     opaque_ty_span,
                     ImplTraitContext::OpaqueTy {
-                        origin: hir::OpaqueTyOrigin::FnReturn { parent: fn_def_id },
-                        fn_kind: Some(fn_kind),
+                        origin: hir::OpaqueTyOrigin::FnReturn { parent: fn_def_id, in_trait },
                     },
                 );
                 arena_vec![this; bound]

compiler/rustc_borrowck/src/region_infer/opaque_types.rs

@@ -503,8 +503,8 @@ impl<'tcx> LazyOpaqueTyEnv<'tcx> {
         let &Self { tcx, def_id, .. } = self;
         let origin = tcx.opaque_type_origin(def_id);
         let parent = match origin {
-            hir::OpaqueTyOrigin::FnReturn { parent }
-            | hir::OpaqueTyOrigin::AsyncFn { parent }
+            hir::OpaqueTyOrigin::FnReturn { parent, .. }
+            | hir::OpaqueTyOrigin::AsyncFn { parent, .. }
             | hir::OpaqueTyOrigin::TyAlias { parent, .. } => parent,
         };
         let param_env = tcx.param_env(parent);

compiler/rustc_hir/src/hir.rs

@@ -2762,10 +2762,6 @@ pub struct OpaqueTy<'hir> {
     /// This mapping associated a captured lifetime (first parameter) with the new
     /// early-bound lifetime that was generated for the opaque.
     pub lifetime_mapping: &'hir [(&'hir Lifetime, LocalDefId)],
-    /// Whether the opaque is a return-position impl trait (or async future)
-    /// originating from a trait method. This makes it so that the opaque is
-    /// lowered as an associated type.
-    pub in_trait: bool,
 }
 
 #[derive(Debug, Clone, Copy, HashStable_Generic)]
@@ -2809,11 +2805,15 @@ pub enum OpaqueTyOrigin {
     FnReturn {
         /// The defining function.
         parent: LocalDefId,
+        // Whether this is an RPITIT (return position impl trait in trait)
+        in_trait: bool,
     },
     /// `async fn`
     AsyncFn {
         /// The defining function.
         parent: LocalDefId,
+        // Whether this is an AFIT (async fn in trait)
+        in_trait: bool,
     },
     /// type aliases: `type Foo = impl Trait;`
     TyAlias {

compiler/rustc_hir_analysis/src/check/check.rs

@@ -336,8 +336,8 @@ fn check_opaque_meets_bounds<'tcx>(
     origin: &hir::OpaqueTyOrigin,
 ) -> Result<(), ErrorGuaranteed> {
     let defining_use_anchor = match *origin {
-        hir::OpaqueTyOrigin::FnReturn { parent }
-        | hir::OpaqueTyOrigin::AsyncFn { parent }
+        hir::OpaqueTyOrigin::FnReturn { parent, .. }
+        | hir::OpaqueTyOrigin::AsyncFn { parent, .. }
         | hir::OpaqueTyOrigin::TyAlias { parent, .. } => parent,
     };
     let param_env = tcx.param_env(defining_use_anchor);
@@ -346,8 +346,8 @@ fn check_opaque_meets_bounds<'tcx>(
     let ocx = ObligationCtxt::new_with_diagnostics(&infcx);
 
     let args = match *origin {
-        hir::OpaqueTyOrigin::FnReturn { parent }
-        | hir::OpaqueTyOrigin::AsyncFn { parent }
+        hir::OpaqueTyOrigin::FnReturn { parent, .. }
+        | hir::OpaqueTyOrigin::AsyncFn { parent, .. }
         | hir::OpaqueTyOrigin::TyAlias { parent, .. } => GenericArgs::identity_for_item(
             tcx, parent,
         )
@@ -736,8 +736,8 @@ pub(crate) fn check_item_type(tcx: TyCtxt<'_>, def_id: LocalDefId) {
             check_opaque_precise_captures(tcx, def_id);
 
             let origin = tcx.opaque_type_origin(def_id);
-            if let hir::OpaqueTyOrigin::FnReturn { parent: fn_def_id }
-            | hir::OpaqueTyOrigin::AsyncFn { parent: fn_def_id } = origin
+            if let hir::OpaqueTyOrigin::FnReturn { parent: fn_def_id, .. }
+            | hir::OpaqueTyOrigin::AsyncFn { parent: fn_def_id, .. } = origin
                 && let hir::Node::TraitItem(trait_item) = tcx.hir_node_by_def_id(fn_def_id)
                 && let (_, hir::TraitFn::Required(..)) = trait_item.expect_fn()
             {

compiler/rustc_hir_analysis/src/check/compare_impl_item/refine.rs

@@ -94,7 +94,7 @@ pub(super) fn check_refining_return_position_impl_trait_in_trait<'tcx>(
         if !tcx.hir().get_if_local(impl_opaque.def_id).is_some_and(|node| {
             matches!(
                 node.expect_item().expect_opaque_ty().origin,
-                hir::OpaqueTyOrigin::AsyncFn { parent }  | hir::OpaqueTyOrigin::FnReturn { parent }
+                hir::OpaqueTyOrigin::AsyncFn { parent, .. }  | hir::OpaqueTyOrigin::FnReturn { parent, .. }
                     if parent == impl_m.def_id.expect_local()
             )
         }) {

compiler/rustc_hir_analysis/src/collect/generics_of.rs

@@ -210,9 +210,8 @@ pub(super) fn generics_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::Generics {
         Node::Item(item) => match item.kind {
             ItemKind::OpaqueTy(&hir::OpaqueTy {
                 origin:
-                    hir::OpaqueTyOrigin::FnReturn { parent: fn_def_id }
-                    | hir::OpaqueTyOrigin::AsyncFn { parent: fn_def_id },
-                in_trait,
+                    hir::OpaqueTyOrigin::FnReturn { parent: fn_def_id, in_trait }
+                    | hir::OpaqueTyOrigin::AsyncFn { parent: fn_def_id, in_trait },
                 ..
             }) => {
                 if in_trait {

compiler/rustc_hir_analysis/src/collect/item_bounds.rs

@@ -370,39 +370,35 @@ pub(super) fn explicit_item_bounds_with_filter(
             ..
         }) => associated_type_bounds(tcx, def_id, bounds, *span, filter),
         hir::Node::Item(hir::Item {
-            kind: hir::ItemKind::OpaqueTy(hir::OpaqueTy { bounds, in_trait: false, .. }),
+            kind: hir::ItemKind::OpaqueTy(hir::OpaqueTy { bounds, origin, .. }),
             span,
             ..
-        }) => {
-            let args = GenericArgs::identity_for_item(tcx, def_id);
-            let item_ty = Ty::new_opaque(tcx, def_id.to_def_id(), args);
-            let bounds = opaque_type_bounds(tcx, def_id, bounds, item_ty, *span, filter);
-            assert_only_contains_predicates_from(filter, bounds, item_ty);
-            bounds
-        }
-        // Since RPITITs are lowered as projections in `<dyn HirTyLowerer>::lower_ty`, when we're
-        // asking for the item bounds of the *opaques* in a trait's default method signature, we
-        // need to map these projections back to opaques.
-        hir::Node::Item(hir::Item {
-            kind: hir::ItemKind::OpaqueTy(hir::OpaqueTy { bounds, in_trait: true, origin, .. }),
-            span,
-            ..
-        }) => {
-            let (hir::OpaqueTyOrigin::FnReturn { parent: fn_def_id }
-            | hir::OpaqueTyOrigin::AsyncFn { parent: fn_def_id }) = *origin
-            else {
-                span_bug!(*span, "RPITIT cannot be a TAIT, but got origin {origin:?}");
-            };
-            let args = GenericArgs::identity_for_item(tcx, def_id);
-            let item_ty = Ty::new_opaque(tcx, def_id.to_def_id(), args);
-            let bounds = &*tcx.arena.alloc_slice(
-                &opaque_type_bounds(tcx, def_id, bounds, item_ty, *span, filter)
-                    .to_vec()
-                    .fold_with(&mut AssocTyToOpaque { tcx, fn_def_id: fn_def_id.to_def_id() }),
-            );
-            assert_only_contains_predicates_from(filter, bounds, item_ty);
-            bounds
-        }
+        }) => match origin {
+            // Since RPITITs are lowered as projections in `<dyn HirTyLowerer>::lower_ty`,
+            // when we're asking for the item bounds of the *opaques* in a trait's default
+            // method signature, we need to map these projections back to opaques.
+            rustc_hir::OpaqueTyOrigin::FnReturn { parent, in_trait: true }
+            | rustc_hir::OpaqueTyOrigin::AsyncFn { parent, in_trait: true } => {
+                let args = GenericArgs::identity_for_item(tcx, def_id);
+                let item_ty = Ty::new_opaque(tcx, def_id.to_def_id(), args);
+                let bounds = &*tcx.arena.alloc_slice(
+                    &opaque_type_bounds(tcx, def_id, bounds, item_ty, *span, filter)
+                        .to_vec()
+                        .fold_with(&mut AssocTyToOpaque { tcx, fn_def_id: parent.to_def_id() }),
+                );
+                assert_only_contains_predicates_from(filter, bounds, item_ty);
+                bounds
+            }
+            rustc_hir::OpaqueTyOrigin::FnReturn { parent: _, in_trait: false }
+            | rustc_hir::OpaqueTyOrigin::AsyncFn { parent: _, in_trait: false }
+            | rustc_hir::OpaqueTyOrigin::TyAlias { parent: _, .. } => {
+                let args = GenericArgs::identity_for_item(tcx, def_id);
+                let item_ty = Ty::new_opaque(tcx, def_id.to_def_id(), args);
+                let bounds = opaque_type_bounds(tcx, def_id, bounds, item_ty, *span, filter);
+                assert_only_contains_predicates_from(filter, bounds, item_ty);
+                bounds
+            }
+        },
         hir::Node::Item(hir::Item { kind: hir::ItemKind::TyAlias(..), .. }) => &[],
         _ => bug!("item_bounds called on {:?}", def_id),
     };

compiler/rustc_hir_analysis/src/collect/resolve_bound_vars.rs

@@ -515,8 +515,8 @@ impl<'a, 'tcx> Visitor<'tcx> for BoundVarContext<'a, 'tcx> {
             }
             hir::ItemKind::OpaqueTy(&hir::OpaqueTy {
                 origin:
-                    hir::OpaqueTyOrigin::FnReturn { parent }
-                    | hir::OpaqueTyOrigin::AsyncFn { parent }
+                    hir::OpaqueTyOrigin::FnReturn { parent, .. }
+                    | hir::OpaqueTyOrigin::AsyncFn { parent, .. }
                     | hir::OpaqueTyOrigin::TyAlias { parent, .. },
                 generics,
                 ..

compiler/rustc_hir_analysis/src/collect/type_of.rs

@@ -618,9 +618,8 @@ pub(super) fn type_of_opaque(
                 // Opaque types desugared from `impl Trait`.
                 ItemKind::OpaqueTy(&OpaqueTy {
                     origin:
-                        hir::OpaqueTyOrigin::FnReturn { parent: owner }
-                        | hir::OpaqueTyOrigin::AsyncFn { parent: owner },
-                    in_trait,
+                        hir::OpaqueTyOrigin::FnReturn { parent: owner, in_trait }
+                        | hir::OpaqueTyOrigin::AsyncFn { parent: owner, in_trait },
                     ..
                 }) => {
                     if in_trait && !tcx.defaultness(owner).has_value() {

compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs

@@ -2091,17 +2091,26 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
                 let opaque_ty = tcx.hir().item(item_id);
 
                 match opaque_ty.kind {
-                    hir::ItemKind::OpaqueTy(&hir::OpaqueTy { in_trait, .. }) => {
+                    hir::ItemKind::OpaqueTy(&hir::OpaqueTy { origin, .. }) => {
                         let local_def_id = item_id.owner_id.def_id;
                         // If this is an RPITIT and we are using the new RPITIT lowering scheme, we
                         // generate the def_id of an associated type for the trait and return as
                         // type a projection.
-                        let def_id = if in_trait {
-                            tcx.associated_type_for_impl_trait_in_trait(local_def_id).to_def_id()
-                        } else {
-                            local_def_id.to_def_id()
-                        };
-                        self.lower_opaque_ty(def_id, lifetimes, in_trait)
+                        match origin {
+                            hir::OpaqueTyOrigin::FnReturn { in_trait: true, .. }
+                            | hir::OpaqueTyOrigin::AsyncFn { in_trait: true, .. } => self
+                                .lower_opaque_ty(
+                                    tcx.associated_type_for_impl_trait_in_trait(local_def_id)
+                                        .to_def_id(),
+                                    lifetimes,
+                                    true,
+                                ),
+                            hir::OpaqueTyOrigin::FnReturn { in_trait: false, .. }
+                            | hir::OpaqueTyOrigin::AsyncFn { in_trait: false, .. }
+                            | hir::OpaqueTyOrigin::TyAlias { .. } => {
+                                self.lower_opaque_ty(local_def_id.to_def_id(), lifetimes, false)
+                            }
+                        }
                     }
                     ref i => bug!("`impl Trait` pointed to non-opaque type?? {:#?}", i),
                 }

compiler/rustc_hir_typeck/src/_match.rs

@@ -602,7 +602,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 .map(|(k, _)| (k.def_id, k.args))?,
             _ => return None,
         };
-        let hir::OpaqueTyOrigin::FnReturn { parent: parent_def_id } =
+        let hir::OpaqueTyOrigin::FnReturn { parent: parent_def_id, .. } =
             self.tcx.opaque_type_origin(def_id)
         else {
             return None;