Replace RPITIT current impl with new strategy that lowers as a GAT

5 files changed, 7 insertions, 48 deletions

diff --git a/compiler/rustc_hir_analysis/src/astconv/mod.rs b/compiler/rustc_hir_analysis/src/astconv/mod.rs
index 3d698462840..db3d41ed247 100644
--- a/compiler/rustc_hir_analysis/src/astconv/mod.rs
+++ b/compiler/rustc_hir_analysis/src/astconv/mod.rs
@@ -2128,7 +2128,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
 
         let span = path.span;
         match path.res {
-            Res::Def(DefKind::OpaqueTy | DefKind::ImplTraitPlaceholder, did) => {
+            Res::Def(DefKind::OpaqueTy, did) => {
                 // Check for desugared `impl Trait`.
                 assert!(tcx.is_type_alias_impl_trait(did));
                 let item_segment = path.segments.split_last().unwrap();
@@ -2439,7 +2439,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
                         // 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.lower_impl_trait_in_trait_to_assoc_ty() {
+                        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()
diff --git a/compiler/rustc_hir_analysis/src/check/check.rs b/compiler/rustc_hir_analysis/src/check/check.rs
index 120545c8e5d..91c33b09082 100644
--- a/compiler/rustc_hir_analysis/src/check/check.rs
+++ b/compiler/rustc_hir_analysis/src/check/check.rs
@@ -302,16 +302,11 @@ pub(super) fn check_opaque_for_inheriting_lifetimes(
 
     if let ItemKind::OpaqueTy(&hir::OpaqueTy {
         origin: hir::OpaqueTyOrigin::AsyncFn(..) | hir::OpaqueTyOrigin::FnReturn(..),
-        in_trait,
         ..
     }) = item.kind
     {
         let substs = InternalSubsts::identity_for_item(tcx, def_id);
-        let opaque_identity_ty = if in_trait && !tcx.lower_impl_trait_in_trait_to_assoc_ty() {
-            Ty::new_projection(tcx, def_id.to_def_id(), substs)
-        } else {
-            Ty::new_opaque(tcx, def_id.to_def_id(), substs)
-        };
+        let opaque_identity_ty = Ty::new_opaque(tcx, def_id.to_def_id(), substs);
         let mut visitor = ProhibitOpaqueVisitor {
             opaque_identity_ty,
             parent_count: tcx.generics_of(def_id).parent_count as u32,
@@ -576,17 +571,6 @@ fn check_item_type(tcx: TyCtxt<'_>, id: hir::ItemId) {
                 check_opaque(tcx, id);
             }
         }
-        DefKind::ImplTraitPlaceholder => {
-            let parent = tcx.impl_trait_in_trait_parent_fn(id.owner_id.to_def_id());
-            // Only check the validity of this opaque type if the function has a default body
-            if let hir::Node::TraitItem(hir::TraitItem {
-                kind: hir::TraitItemKind::Fn(_, hir::TraitFn::Provided(_)),
-                ..
-            }) = tcx.hir().get_by_def_id(parent.expect_local())
-            {
-                check_opaque(tcx, id);
-            }
-        }
         DefKind::TyAlias => {
             let pty_ty = tcx.type_of(id.owner_id).subst_identity();
             let generics = tcx.generics_of(id.owner_id);
diff --git a/compiler/rustc_hir_analysis/src/collect/item_bounds.rs b/compiler/rustc_hir_analysis/src/collect/item_bounds.rs
index 57f74172ed0..d6f33869a03 100644
--- a/compiler/rustc_hir_analysis/src/collect/item_bounds.rs
+++ b/compiler/rustc_hir_analysis/src/collect/item_bounds.rs
@@ -113,16 +113,12 @@ pub(super) fn explicit_item_bounds(
             ..
         }) => associated_type_bounds(tcx, def_id, bounds, *span),
         hir::Node::Item(hir::Item {
-            kind: hir::ItemKind::OpaqueTy(hir::OpaqueTy { bounds, in_trait, .. }),
+            kind: hir::ItemKind::OpaqueTy(hir::OpaqueTy { bounds, .. }),
             span,
             ..
         }) => {
             let substs = InternalSubsts::identity_for_item(tcx, def_id);
-            let item_ty = if *in_trait && !tcx.lower_impl_trait_in_trait_to_assoc_ty() {
-                Ty::new_projection(tcx, def_id.to_def_id(), substs)
-            } else {
-                Ty::new_opaque(tcx, def_id.to_def_id(), substs)
-            };
+            let item_ty = Ty::new_opaque(tcx, def_id.to_def_id(), substs);
             opaque_type_bounds(tcx, def_id, bounds, item_ty, *span)
         }
         hir::Node::Item(hir::Item { kind: hir::ItemKind::TyAlias(..), .. }) => &[],
diff --git a/compiler/rustc_hir_analysis/src/impl_wf_check.rs b/compiler/rustc_hir_analysis/src/impl_wf_check.rs
index 5526dd4b007..d654b0be620 100644
--- a/compiler/rustc_hir_analysis/src/impl_wf_check.rs
+++ b/compiler/rustc_hir_analysis/src/impl_wf_check.rs
@@ -109,20 +109,7 @@ fn enforce_impl_params_are_constrained(tcx: TyCtxt<'_>, impl_def_id: LocalDefId)
                         vec![]
                     }
                 }
-                ty::AssocKind::Fn => {
-                    if !tcx.lower_impl_trait_in_trait_to_assoc_ty()
-                        && item.defaultness(tcx).has_value()
-                        && tcx.impl_method_has_trait_impl_trait_tys(item.def_id)
-                        && let Ok(table) = tcx.collect_return_position_impl_trait_in_trait_tys(def_id)
-                    {
-                        table.values().copied().flat_map(|ty| {
-                            cgp::parameters_for(&ty.subst_identity(), true)
-                        }).collect()
-                    } else {
-                        vec![]
-                    }
-                }
-                ty::AssocKind::Const => vec![],
+                ty::AssocKind::Fn | ty::AssocKind::Const => vec![],
             }
         })
         .collect();
diff --git a/compiler/rustc_hir_analysis/src/variance/mod.rs b/compiler/rustc_hir_analysis/src/variance/mod.rs
index 066e7449189..c703cb03515 100644
--- a/compiler/rustc_hir_analysis/src/variance/mod.rs
+++ b/compiler/rustc_hir_analysis/src/variance/mod.rs
@@ -56,7 +56,7 @@ fn variances_of(tcx: TyCtxt<'_>, item_def_id: LocalDefId) -> &[ty::Variance] {
             let crate_map = tcx.crate_variances(());
             return crate_map.variances.get(&item_def_id.to_def_id()).copied().unwrap_or(&[]);
         }
-        DefKind::OpaqueTy | DefKind::ImplTraitPlaceholder => {
+        DefKind::OpaqueTy => {
             return variance_of_opaque(tcx, item_def_id);
         }
         _ => {}
@@ -115,14 +115,6 @@ fn variance_of_opaque(tcx: TyCtxt<'_>, item_def_id: LocalDefId) -> &[ty::Varianc
                 {
                     self.visit_opaque(*def_id, substs)
                 }
-                // FIXME(-Zlower-impl-trait-in-trait-to-assoc-ty) check whether this is necessary
-                // at all for RPITITs.
-                ty::Alias(_, ty::AliasTy { def_id, substs, .. })
-                    if self.tcx.is_impl_trait_in_trait(*def_id)
-                        && !self.tcx.lower_impl_trait_in_trait_to_assoc_ty() =>
-                {
-                    self.visit_opaque(*def_id, substs)
-                }
                 _ => t.super_visit_with(self),
             }
         }