Auto merge of #121796 - oli-obk:eager_opaque_checks3, r=<try>

Make `DefiningAnchor::Bind` only store the opaque types that may be constrained, instead of the current infcx root item.

This makes `Bind` almost always be empty, so we can start forwarding it to queries, allowing us to remove `Bubble` entirely (not done in this PR)

The only behaviour change is in diagnostics.

r? `@lcnr` `@compiler-errors`

Author: bors

compiler/rustc_borrowck/src/consumers.rs

@@ -106,7 +106,7 @@ pub fn get_body_with_borrowck_facts(
     options: ConsumerOptions,
 ) -> BodyWithBorrowckFacts<'_> {
     let (input_body, promoted) = tcx.mir_promoted(def);
-    let infcx = tcx.infer_ctxt().with_opaque_type_inference(DefiningAnchor::Bind(def)).build();
+    let infcx = tcx.infer_ctxt().with_opaque_type_inference(DefiningAnchor::bind(tcx, def)).build();
     let input_body: &Body<'_> = &input_body.borrow();
     let promoted: &IndexSlice<_, _> = &promoted.borrow();
     *super::do_mir_borrowck(&infcx, input_body, promoted, Some(options)).1.unwrap()

compiler/rustc_borrowck/src/lib.rs

@@ -127,8 +127,10 @@ fn mir_borrowck(tcx: TyCtxt<'_>, def: LocalDefId) -> &BorrowCheckResult<'_> {
 
     let hir_owner = tcx.local_def_id_to_hir_id(def).owner;
 
-    let infcx =
-        tcx.infer_ctxt().with_opaque_type_inference(DefiningAnchor::Bind(hir_owner.def_id)).build();
+    let infcx = tcx
+        .infer_ctxt()
+        .with_opaque_type_inference(DefiningAnchor::bind(tcx, hir_owner.def_id))
+        .build();
     let promoted: &IndexSlice<_, _> = &promoted.borrow();
     let opt_closure_req = do_mir_borrowck(&infcx, input_body, promoted, None).0;
     debug!("mir_borrowck done");

compiler/rustc_borrowck/src/region_infer/opaque_types.rs

@@ -317,7 +317,7 @@ fn check_opaque_type_well_formed<'tcx>(
     let infcx = tcx
         .infer_ctxt()
         .with_next_trait_solver(next_trait_solver)
-        .with_opaque_type_inference(DefiningAnchor::Bind(parent_def_id))
+        .with_opaque_type_inference(DefiningAnchor::bind(tcx, parent_def_id))
         .build();
     let ocx = ObligationCtxt::new(&infcx);
     let identity_args = GenericArgs::identity_for_item(tcx, def_id);

compiler/rustc_hir_analysis/src/check/check.rs

@@ -346,7 +346,7 @@ fn check_opaque_meets_bounds<'tcx>(
 
     let infcx = tcx
         .infer_ctxt()
-        .with_opaque_type_inference(DefiningAnchor::Bind(defining_use_anchor))
+        .with_opaque_type_inference(DefiningAnchor::bind(tcx, defining_use_anchor))
         .build();
     let ocx = ObligationCtxt::new(&infcx);
 
@@ -1569,7 +1569,7 @@ pub(super) fn check_coroutine_obligations(
         .ignoring_regions()
         // Bind opaque types to type checking root, as they should have been checked by borrowck,
         // but may show up in some cases, like when (root) obligations are stalled in the new solver.
-        .with_opaque_type_inference(DefiningAnchor::Bind(typeck.hir_owner.def_id))
+        .with_opaque_type_inference(DefiningAnchor::bind(tcx, typeck.hir_owner.def_id))
         .build();
 
     let mut fulfillment_cx = <dyn TraitEngine<'_>>::new(&infcx);

compiler/rustc_hir_analysis/src/collect/type_of/opaque.rs

@@ -46,9 +46,7 @@ pub(super) fn find_opaque_ty_constraints_for_impl_trait_in_assoc_type(
     for &assoc_id in tcx.associated_item_def_ids(impl_def_id) {
         let assoc = tcx.associated_item(assoc_id);
         match assoc.kind {
-            ty::AssocKind::Const | ty::AssocKind::Fn => {
-                locator.check(assoc_id.expect_local(), ImplTraitSource::AssocTy)
-            }
+            ty::AssocKind::Const | ty::AssocKind::Fn => locator.check(assoc_id.expect_local()),
             // Associated types don't have bodies, so they can't constrain hidden types
             ty::AssocKind::Type => {}
         }
@@ -182,15 +180,9 @@ struct TaitConstraintLocator<'tcx> {
     typeck_types: Vec<ty::OpaqueHiddenType<'tcx>>,
 }
 
-#[derive(Debug)]
-enum ImplTraitSource {
-    AssocTy,
-    TyAlias,
-}
-
 impl TaitConstraintLocator<'_> {
     #[instrument(skip(self), level = "debug")]
-    fn check(&mut self, item_def_id: LocalDefId, source: ImplTraitSource) {
+    fn check(&mut self, item_def_id: LocalDefId) {
         // Don't try to check items that cannot possibly constrain the type.
         if !self.tcx.has_typeck_results(item_def_id) {
             debug!("no constraint: no typeck results");
@@ -242,12 +234,8 @@ impl TaitConstraintLocator<'_> {
                 continue;
             }
             constrained = true;
-            let opaque_types_defined_by = match source {
-                ImplTraitSource::AssocTy => {
-                    self.tcx.impl_trait_in_assoc_types_defined_by(item_def_id)
-                }
-                ImplTraitSource::TyAlias => self.tcx.opaque_types_defined_by(item_def_id),
-            };
+            let opaque_types_defined_by = self.tcx.opaque_types_defined_by(item_def_id);
+
             if !opaque_types_defined_by.contains(&self.def_id) {
                 self.tcx.dcx().emit_err(TaitForwardCompat {
                     span: hidden_type.span,
@@ -308,29 +296,29 @@ impl<'tcx> intravisit::Visitor<'tcx> for TaitConstraintLocator<'tcx> {
     }
     fn visit_expr(&mut self, ex: &'tcx Expr<'tcx>) {
         if let hir::ExprKind::Closure(closure) = ex.kind {
-            self.check(closure.def_id, ImplTraitSource::TyAlias);
+            self.check(closure.def_id);
         }
         intravisit::walk_expr(self, ex);
     }
     fn visit_item(&mut self, it: &'tcx Item<'tcx>) {
         trace!(?it.owner_id);
         // The opaque type itself or its children are not within its reveal scope.
         if it.owner_id.def_id != self.def_id {
-            self.check(it.owner_id.def_id, ImplTraitSource::TyAlias);
+            self.check(it.owner_id.def_id);
             intravisit::walk_item(self, it);
         }
     }
     fn visit_impl_item(&mut self, it: &'tcx ImplItem<'tcx>) {
         trace!(?it.owner_id);
         // The opaque type itself or its children are not within its reveal scope.
         if it.owner_id.def_id != self.def_id {
-            self.check(it.owner_id.def_id, ImplTraitSource::TyAlias);
+            self.check(it.owner_id.def_id);
             intravisit::walk_impl_item(self, it);
         }
     }
     fn visit_trait_item(&mut self, it: &'tcx TraitItem<'tcx>) {
         trace!(?it.owner_id);
-        self.check(it.owner_id.def_id, ImplTraitSource::TyAlias);
+        self.check(it.owner_id.def_id);
         intravisit::walk_trait_item(self, it);
     }
     fn visit_foreign_item(&mut self, it: &'tcx hir::ForeignItem<'tcx>) {

compiler/rustc_hir_typeck/src/inherited.rs

@@ -79,7 +79,7 @@ impl<'tcx> Inherited<'tcx> {
         let infcx = tcx
             .infer_ctxt()
             .ignoring_regions()
-            .with_opaque_type_inference(DefiningAnchor::Bind(def_id))
+            .with_opaque_type_inference(DefiningAnchor::bind(tcx, def_id))
             .build();
         let typeck_results = RefCell::new(ty::TypeckResults::new(hir_owner));
 

compiler/rustc_infer/src/infer/mod.rs

@@ -252,7 +252,7 @@ pub struct InferCtxt<'tcx> {
     ///
     /// Its default value is `DefiningAnchor::Error`, this way it is easier to catch errors that
     /// might come up during inference or typeck.
-    pub defining_use_anchor: DefiningAnchor,
+    pub defining_use_anchor: DefiningAnchor<'tcx>,
 
     /// Whether this inference context should care about region obligations in
     /// the root universe. Most notably, this is used during hir typeck as region
@@ -613,7 +613,7 @@ impl fmt::Display for FixupError {
 /// Used to configure inference contexts before their creation.
 pub struct InferCtxtBuilder<'tcx> {
     tcx: TyCtxt<'tcx>,
-    defining_use_anchor: DefiningAnchor,
+    defining_use_anchor: DefiningAnchor<'tcx>,
     considering_regions: bool,
     skip_leak_check: bool,
     /// Whether we are in coherence mode.
@@ -644,7 +644,7 @@ impl<'tcx> InferCtxtBuilder<'tcx> {
     /// It is only meant to be called in two places, for typeck
     /// (via `Inherited::build`) and for the inference context used
     /// in mir borrowck.
-    pub fn with_opaque_type_inference(mut self, defining_use_anchor: DefiningAnchor) -> Self {
+    pub fn with_opaque_type_inference(mut self, defining_use_anchor: DefiningAnchor<'tcx>) -> Self {
         self.defining_use_anchor = defining_use_anchor;
         self
     }

compiler/rustc_infer/src/infer/opaque_types.rs

@@ -368,28 +368,14 @@ impl<'tcx> InferCtxt<'tcx> {
     /// in its defining scope.
     #[instrument(skip(self), level = "trace", ret)]
     pub fn opaque_type_origin(&self, def_id: LocalDefId) -> Option<OpaqueTyOrigin> {
-        let opaque_hir_id = self.tcx.local_def_id_to_hir_id(def_id);
-        let parent_def_id = match self.defining_use_anchor {
+        let defined_opaque_types = match self.defining_use_anchor {
             DefiningAnchor::Bubble | DefiningAnchor::Error => return None,
             DefiningAnchor::Bind(bind) => bind,
         };
 
         let origin = self.tcx.opaque_type_origin(def_id);
-        let in_definition_scope = match origin {
-            // Async `impl Trait`
-            hir::OpaqueTyOrigin::AsyncFn(parent) => parent == parent_def_id,
-            // Anonymous `impl Trait`
-            hir::OpaqueTyOrigin::FnReturn(parent) => parent == parent_def_id,
-            // Named `type Foo = impl Bar;`
-            hir::OpaqueTyOrigin::TyAlias { in_assoc_ty } => {
-                if in_assoc_ty {
-                    self.tcx.opaque_types_defined_by(parent_def_id).contains(&def_id)
-                } else {
-                    may_define_opaque_type(self.tcx, parent_def_id, opaque_hir_id)
-                }
-            }
-        };
-        in_definition_scope.then_some(origin)
+
+        defined_opaque_types.contains(&def_id).then_some(origin)
     }
 }
 
@@ -638,43 +624,3 @@ impl<'tcx> InferCtxt<'tcx> {
         }
     }
 }
-
-/// Returns `true` if `opaque_hir_id` is a sibling or a child of a sibling of `def_id`.
-///
-/// Example:
-/// ```ignore UNSOLVED (is this a bug?)
-/// # #![feature(type_alias_impl_trait)]
-/// pub mod foo {
-///     pub mod bar {
-///         pub trait Bar { /* ... */ }
-///         pub type Baz = impl Bar;
-///
-///         # impl Bar for () {}
-///         fn f1() -> Baz { /* ... */ }
-///     }
-///     fn f2() -> bar::Baz { /* ... */ }
-/// }
-/// ```
-///
-/// Here, `def_id` is the `LocalDefId` of the defining use of the opaque type (e.g., `f1` or `f2`),
-/// and `opaque_hir_id` is the `HirId` of the definition of the opaque type `Baz`.
-/// For the above example, this function returns `true` for `f1` and `false` for `f2`.
-fn may_define_opaque_type(tcx: TyCtxt<'_>, def_id: LocalDefId, opaque_hir_id: hir::HirId) -> bool {
-    let mut hir_id = tcx.local_def_id_to_hir_id(def_id);
-
-    // Named opaque types can be defined by any siblings or children of siblings.
-    let scope = tcx.hir().get_defining_scope(opaque_hir_id);
-    // We walk up the node tree until we hit the root or the scope of the opaque type.
-    while hir_id != scope && hir_id != hir::CRATE_HIR_ID {
-        hir_id = tcx.hir().get_parent_item(hir_id).into();
-    }
-    // Syntactically, we are allowed to define the concrete type if:
-    let res = hir_id == scope;
-    trace!(
-        "may_define_opaque_type(def={:?}, opaque_node={:?}) = {}",
-        tcx.hir_node(hir_id),
-        tcx.hir_node(opaque_hir_id),
-        res
-    );
-    res
-}

compiler/rustc_middle/src/mir/type_foldable.rs

@@ -1,6 +1,7 @@
 //! `TypeFoldable` implementations for MIR types
 
 use rustc_ast::InlineAsmTemplatePiece;
+use rustc_hir::def_id::LocalDefId;
 
 use super::*;
 
@@ -44,6 +45,15 @@ impl<'tcx> TypeFoldable<TyCtxt<'tcx>> for &'tcx [Span] {
     }
 }
 
+impl<'tcx> TypeFoldable<TyCtxt<'tcx>> for &'tcx [LocalDefId] {
+    fn try_fold_with<F: FallibleTypeFolder<TyCtxt<'tcx>>>(
+        self,
+        _folder: &mut F,
+    ) -> Result<Self, F::Error> {
+        Ok(self)
+    }
+}
+
 impl<'tcx> TypeFoldable<TyCtxt<'tcx>> for &'tcx ty::List<PlaceElem<'tcx>> {
     fn try_fold_with<F: FallibleTypeFolder<TyCtxt<'tcx>>>(
         self,

compiler/rustc_middle/src/query/mod.rs

@@ -344,15 +344,6 @@ rustc_queries! {
         }
     }
 
-    query impl_trait_in_assoc_types_defined_by(
-        key: LocalDefId
-    ) -> &'tcx ty::List<LocalDefId> {
-        desc {
-            |tcx| "computing the opaque types defined by `{}`",
-            tcx.def_path_str(key.to_def_id())
-        }
-    }
-
     /// Returns the list of bounds that can be used for
     /// `SelectionCandidate::ProjectionCandidate(_)` and
     /// `ProjectionTyCandidate::TraitDef`.