Rollup merge of #119869 - oli-obk:track_errors2, r=matthewjasper

replace `track_errors` usages with bubbling up `ErrorGuaranteed`

more of the same as https://github.com/rust-lang/rust/pull/117449 (removing `track_errors`)

compiler/rustc_hir_analysis/src/astconv/mod.rs

@@ -1446,7 +1446,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
         }
 
         let candidates: Vec<_> = tcx
-            .inherent_impls(adt_did)
+            .inherent_impls(adt_did)?
             .iter()
             .filter_map(|&impl_| Some((impl_, self.lookup_assoc_ty_unchecked(name, block, impl_)?)))
             .collect();

compiler/rustc_hir_analysis/src/coherence/inherent_impls.rs

@@ -13,32 +13,41 @@ use rustc_hir::def_id::{DefId, LocalDefId};
 use rustc_middle::ty::fast_reject::{simplify_type, SimplifiedType, TreatParams};
 use rustc_middle::ty::{self, CrateInherentImpls, Ty, TyCtxt};
 use rustc_span::symbol::sym;
+use rustc_span::ErrorGuaranteed;
 
 use crate::errors;
 
 /// On-demand query: yields a map containing all types mapped to their inherent impls.
-pub fn crate_inherent_impls(tcx: TyCtxt<'_>, (): ()) -> CrateInherentImpls {
+pub fn crate_inherent_impls(
+    tcx: TyCtxt<'_>,
+    (): (),
+) -> Result<&'_ CrateInherentImpls, ErrorGuaranteed> {
     let mut collect = InherentCollect { tcx, impls_map: Default::default() };
+    let mut res = Ok(());
     for id in tcx.hir().items() {
-        collect.check_item(id);
+        res = res.and(collect.check_item(id));
     }
-    collect.impls_map
+    res?;
+    Ok(tcx.arena.alloc(collect.impls_map))
 }
 
-pub fn crate_incoherent_impls(tcx: TyCtxt<'_>, simp: SimplifiedType) -> &[DefId] {
+pub fn crate_incoherent_impls(
-    let crate_map = tcx.crate_inherent_impls(());
+    tcx: TyCtxt<'_>,
-    tcx.arena.alloc_from_iter(
+    simp: SimplifiedType,
+) -> Result<&[DefId], ErrorGuaranteed> {
+    let crate_map = tcx.crate_inherent_impls(())?;
+    Ok(tcx.arena.alloc_from_iter(
         crate_map.incoherent_impls.get(&simp).unwrap_or(&Vec::new()).iter().map(|d| d.to_def_id()),
-    )
+    ))
 }
 
 /// On-demand query: yields a vector of the inherent impls for a specific type.
-pub fn inherent_impls(tcx: TyCtxt<'_>, ty_def_id: LocalDefId) -> &[DefId] {
+pub fn inherent_impls(tcx: TyCtxt<'_>, ty_def_id: LocalDefId) -> Result<&[DefId], ErrorGuaranteed> {
-    let crate_map = tcx.crate_inherent_impls(());
+    let crate_map = tcx.crate_inherent_impls(())?;
-    match crate_map.inherent_impls.get(&ty_def_id) {
+    Ok(match crate_map.inherent_impls.get(&ty_def_id) {
         Some(v) => &v[..],
         None => &[],
-    }
+    })
 }
 
 struct InherentCollect<'tcx> {
@@ -47,14 +56,19 @@ struct InherentCollect<'tcx> {
 }
 
 impl<'tcx> InherentCollect<'tcx> {
-    fn check_def_id(&mut self, impl_def_id: LocalDefId, self_ty: Ty<'tcx>, ty_def_id: DefId) {
+    fn check_def_id(
+        &mut self,
+        impl_def_id: LocalDefId,
+        self_ty: Ty<'tcx>,
+        ty_def_id: DefId,
+    ) -> Result<(), ErrorGuaranteed> {
         if let Some(ty_def_id) = ty_def_id.as_local() {
             // Add the implementation to the mapping from implementation to base
             // type def ID, if there is a base type for this implementation and
             // the implementation does not have any associated traits.
             let vec = self.impls_map.inherent_impls.entry(ty_def_id).or_default();
             vec.push(impl_def_id.to_def_id());
-            return;
+            return Ok(());
         }
 
         if self.tcx.features().rustc_attrs {
@@ -62,18 +76,16 @@ impl<'tcx> InherentCollect<'tcx> {
 
             if !self.tcx.has_attr(ty_def_id, sym::rustc_has_incoherent_inherent_impls) {
                 let impl_span = self.tcx.def_span(impl_def_id);
-                self.tcx.dcx().emit_err(errors::InherentTyOutside { span: impl_span });
+                return Err(self.tcx.dcx().emit_err(errors::InherentTyOutside { span: impl_span }));
-                return;
             }
 
             for &impl_item in items {
                 if !self.tcx.has_attr(impl_item, sym::rustc_allow_incoherent_impl) {
                     let impl_span = self.tcx.def_span(impl_def_id);
-                    self.tcx.dcx().emit_err(errors::InherentTyOutsideRelevant {
+                    return Err(self.tcx.dcx().emit_err(errors::InherentTyOutsideRelevant {
                         span: impl_span,
                         help_span: self.tcx.def_span(impl_item),
-                    });
+                    }));
-                    return;
                 }
             }
 
@@ -82,24 +94,28 @@ impl<'tcx> InherentCollect<'tcx> {
             } else {
                 bug!("unexpected self type: {:?}", self_ty);
             }
+            Ok(())
         } else {
             let impl_span = self.tcx.def_span(impl_def_id);
-            self.tcx.dcx().emit_err(errors::InherentTyOutsideNew { span: impl_span });
+            Err(self.tcx.dcx().emit_err(errors::InherentTyOutsideNew { span: impl_span }))
         }
     }
 
-    fn check_primitive_impl(&mut self, impl_def_id: LocalDefId, ty: Ty<'tcx>) {
+    fn check_primitive_impl(
+        &mut self,
+        impl_def_id: LocalDefId,
+        ty: Ty<'tcx>,
+    ) -> Result<(), ErrorGuaranteed> {
         let items = self.tcx.associated_item_def_ids(impl_def_id);
         if !self.tcx.hir().rustc_coherence_is_core() {
             if self.tcx.features().rustc_attrs {
                 for &impl_item in items {
                     if !self.tcx.has_attr(impl_item, sym::rustc_allow_incoherent_impl) {
                         let span = self.tcx.def_span(impl_def_id);
-                        self.tcx.dcx().emit_err(errors::InherentTyOutsidePrimitive {
+                        return Err(self.tcx.dcx().emit_err(errors::InherentTyOutsidePrimitive {
                             span,
                             help_span: self.tcx.def_span(impl_item),
-                        });
+                        }));
-                        return;
                     }
                 }
             } else {
@@ -108,8 +124,7 @@ impl<'tcx> InherentCollect<'tcx> {
                 if let ty::Ref(_, subty, _) = ty.kind() {
                     note = Some(errors::InherentPrimitiveTyNote { subty: *subty });
                 }
-                self.tcx.dcx().emit_err(errors::InherentPrimitiveTy { span, note });
+                return Err(self.tcx.dcx().emit_err(errors::InherentPrimitiveTy { span, note }));
-                return;
             }
         }
 
@@ -118,11 +133,12 @@ impl<'tcx> InherentCollect<'tcx> {
         } else {
             bug!("unexpected primitive type: {:?}", ty);
         }
+        Ok(())
     }
 
-    fn check_item(&mut self, id: hir::ItemId) {
+    fn check_item(&mut self, id: hir::ItemId) -> Result<(), ErrorGuaranteed> {
         if !matches!(self.tcx.def_kind(id.owner_id), DefKind::Impl { of_trait: false }) {
-            return;
+            return Ok(());
         }
 
         let id = id.owner_id.def_id;
@@ -132,10 +148,10 @@ impl<'tcx> InherentCollect<'tcx> {
             ty::Adt(def, _) => self.check_def_id(id, self_ty, def.did()),
             ty::Foreign(did) => self.check_def_id(id, self_ty, did),
             ty::Dynamic(data, ..) if data.principal_def_id().is_some() => {
-                self.check_def_id(id, self_ty, data.principal_def_id().unwrap());
+                self.check_def_id(id, self_ty, data.principal_def_id().unwrap())
             }
             ty::Dynamic(..) => {
-                self.tcx.dcx().emit_err(errors::InherentDyn { span: item_span });
+                Err(self.tcx.dcx().emit_err(errors::InherentDyn { span: item_span }))
             }
             ty::Bool
             | ty::Char
@@ -151,7 +167,7 @@ impl<'tcx> InherentCollect<'tcx> {
             | ty::FnPtr(_)
             | ty::Tuple(..) => self.check_primitive_impl(id, self_ty),
             ty::Alias(..) | ty::Param(_) => {
-                self.tcx.dcx().emit_err(errors::InherentNominal { span: item_span });
+                Err(self.tcx.dcx().emit_err(errors::InherentNominal { span: item_span }))
             }
             ty::FnDef(..)
             | ty::Closure(..)
@@ -162,7 +178,8 @@ impl<'tcx> InherentCollect<'tcx> {
             | ty::Infer(_) => {
                 bug!("unexpected impl self type of impl: {:?} {:?}", id, self_ty);
             }
-            ty::Error(_) => {}
+            // We could bail out here, but that will silence other useful errors.
+            ty::Error(_) => Ok(()),
         }
     }
 }

compiler/rustc_hir_analysis/src/coherence/inherent_impls_overlap.rs

@@ -6,16 +6,18 @@ use rustc_hir::def_id::DefId;
 use rustc_index::IndexVec;
 use rustc_middle::traits::specialization_graph::OverlapMode;
 use rustc_middle::ty::{self, TyCtxt};
-use rustc_span::Symbol;
+use rustc_span::{ErrorGuaranteed, Symbol};
 use rustc_trait_selection::traits::{self, SkipLeakCheck};
 use smallvec::SmallVec;
 use std::collections::hash_map::Entry;
 
-pub fn crate_inherent_impls_overlap_check(tcx: TyCtxt<'_>, (): ()) {
+pub fn crate_inherent_impls_overlap_check(tcx: TyCtxt<'_>, (): ()) -> Result<(), ErrorGuaranteed> {
     let mut inherent_overlap_checker = InherentOverlapChecker { tcx };
+    let mut res = Ok(());
     for id in tcx.hir().items() {
-        inherent_overlap_checker.check_item(id);
+        res = res.and(inherent_overlap_checker.check_item(id));
     }
+    res
 }
 
 struct InherentOverlapChecker<'tcx> {
@@ -58,10 +60,11 @@ impl<'tcx> InherentOverlapChecker<'tcx> {
                 == item2.ident(self.tcx).normalize_to_macros_2_0()
     }
 
-    fn check_for_duplicate_items_in_impl(&self, impl_: DefId) {
+    fn check_for_duplicate_items_in_impl(&self, impl_: DefId) -> Result<(), ErrorGuaranteed> {
         let impl_items = self.tcx.associated_items(impl_);
 
         let mut seen_items = FxHashMap::default();
+        let mut res = Ok(());
         for impl_item in impl_items.in_definition_order() {
             let span = self.tcx.def_span(impl_item.def_id);
             let ident = impl_item.ident(self.tcx);
@@ -70,7 +73,7 @@ impl<'tcx> InherentOverlapChecker<'tcx> {
             match seen_items.entry(norm_ident) {
                 Entry::Occupied(entry) => {
                     let former = entry.get();
-                    struct_span_code_err!(
+                    res = Err(struct_span_code_err!(
                         self.tcx.dcx(),
                         span,
                         E0592,
@@ -79,13 +82,14 @@ impl<'tcx> InherentOverlapChecker<'tcx> {
                     )
                     .with_span_label(span, format!("duplicate definitions for `{ident}`"))
                     .with_span_label(*former, format!("other definition for `{ident}`"))
-                    .emit();
+                    .emit());
                 }
                 Entry::Vacant(entry) => {
                     entry.insert(span);
                 }
             }
         }
+        res
     }
 
     fn check_for_common_items_in_impls(
@@ -93,10 +97,11 @@ impl<'tcx> InherentOverlapChecker<'tcx> {
         impl1: DefId,
         impl2: DefId,
         overlap: traits::OverlapResult<'_>,
-    ) {
+    ) -> Result<(), ErrorGuaranteed> {
         let impl_items1 = self.tcx.associated_items(impl1);
         let impl_items2 = self.tcx.associated_items(impl2);
 
+        let mut res = Ok(());
         for &item1 in impl_items1.in_definition_order() {
             let collision = impl_items2
                 .filter_by_name_unhygienic(item1.name)
@@ -128,9 +133,10 @@ impl<'tcx> InherentOverlapChecker<'tcx> {
                     traits::add_placeholder_note(&mut err);
                 }
 
-                err.emit();
+                res = Err(err.emit());
             }
         }
+        res
     }
 
     fn check_for_overlapping_inherent_impls(
@@ -138,7 +144,7 @@ impl<'tcx> InherentOverlapChecker<'tcx> {
         overlap_mode: OverlapMode,
         impl1_def_id: DefId,
         impl2_def_id: DefId,
-    ) {
+    ) -> Result<(), ErrorGuaranteed> {
         let maybe_overlap = traits::overlapping_impls(
             self.tcx,
             impl1_def_id,
@@ -150,17 +156,19 @@ impl<'tcx> InherentOverlapChecker<'tcx> {
         );
 
         if let Some(overlap) = maybe_overlap {
-            self.check_for_common_items_in_impls(impl1_def_id, impl2_def_id, overlap);
+            self.check_for_common_items_in_impls(impl1_def_id, impl2_def_id, overlap)
+        } else {
+            Ok(())
         }
     }
 
-    fn check_item(&mut self, id: hir::ItemId) {
+    fn check_item(&mut self, id: hir::ItemId) -> Result<(), ErrorGuaranteed> {
         let def_kind = self.tcx.def_kind(id.owner_id);
         if !matches!(def_kind, DefKind::Enum | DefKind::Struct | DefKind::Trait | DefKind::Union) {
-            return;
+            return Ok(());
         }
 
-        let impls = self.tcx.inherent_impls(id.owner_id);
+        let impls = self.tcx.inherent_impls(id.owner_id)?;
 
         let overlap_mode = OverlapMode::get(self.tcx, id.owner_id.to_def_id());
 
@@ -173,17 +181,18 @@ impl<'tcx> InherentOverlapChecker<'tcx> {
         // otherwise switch to an allocating algorithm with
         // faster asymptotic runtime.
         const ALLOCATING_ALGO_THRESHOLD: usize = 500;
+        let mut res = Ok(());
         if impls.len() < ALLOCATING_ALGO_THRESHOLD {
             for (i, &(&impl1_def_id, impl_items1)) in impls_items.iter().enumerate() {
-                self.check_for_duplicate_items_in_impl(impl1_def_id);
+                res = res.and(self.check_for_duplicate_items_in_impl(impl1_def_id));
 
                 for &(&impl2_def_id, impl_items2) in &impls_items[(i + 1)..] {
                     if self.impls_have_common_items(impl_items1, impl_items2) {
-                        self.check_for_overlapping_inherent_impls(
+                        res = res.and(self.check_for_overlapping_inherent_impls(
                             overlap_mode,
                             impl1_def_id,
                             impl2_def_id,
-                        );
+                        ));
                     }
                 }
             }
@@ -315,20 +324,21 @@ impl<'tcx> InherentOverlapChecker<'tcx> {
                 impl_blocks.sort_unstable();
                 for (i, &impl1_items_idx) in impl_blocks.iter().enumerate() {
                     let &(&impl1_def_id, impl_items1) = &impls_items[impl1_items_idx];
-                    self.check_for_duplicate_items_in_impl(impl1_def_id);
+                    res = res.and(self.check_for_duplicate_items_in_impl(impl1_def_id));
 
                     for &impl2_items_idx in impl_blocks[(i + 1)..].iter() {
                         let &(&impl2_def_id, impl_items2) = &impls_items[impl2_items_idx];
                         if self.impls_have_common_items(impl_items1, impl_items2) {
-                            self.check_for_overlapping_inherent_impls(
+                            res = res.and(self.check_for_overlapping_inherent_impls(
                                 overlap_mode,
                                 impl1_def_id,
                                 impl2_def_id,
-                            );
+                            ));
                         }
                     }
                 }
             }
         }
+        res
     }
 }

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

@@ -5,20 +5,22 @@ use rustc_hir::intravisit::{self, Visitor};
 use rustc_hir::{self as hir, def, Expr, ImplItem, Item, Node, TraitItem};
 use rustc_middle::hir::nested_filter;
 use rustc_middle::ty::{self, Ty, TyCtxt, TypeVisitableExt};
-use rustc_span::{sym, DUMMY_SP};
+use rustc_span::{sym, ErrorGuaranteed, DUMMY_SP};
 
 use crate::errors::{TaitForwardCompat, TypeOf, UnconstrainedOpaqueType};
 
-pub fn test_opaque_hidden_types(tcx: TyCtxt<'_>) {
+pub fn test_opaque_hidden_types(tcx: TyCtxt<'_>) -> Result<(), ErrorGuaranteed> {
+    let mut res = Ok(());
     if tcx.has_attr(CRATE_DEF_ID, sym::rustc_hidden_type_of_opaques) {
         for id in tcx.hir().items() {
             if matches!(tcx.def_kind(id.owner_id), DefKind::OpaqueTy) {
                 let type_of = tcx.type_of(id.owner_id).instantiate_identity();
 
-                tcx.dcx().emit_err(TypeOf { span: tcx.def_span(id.owner_id), type_of });
+                res = Err(tcx.dcx().emit_err(TypeOf { span: tcx.def_span(id.owner_id), type_of }));
             }
         }
     }
+    res
 }
 
 /// Checks "defining uses" of opaque `impl Trait` types to ensure that they meet the restrictions

compiler/rustc_hir_analysis/src/impl_wf_check.rs

@@ -17,7 +17,7 @@ use rustc_hir::def::DefKind;
 use rustc_hir::def_id::{LocalDefId, LocalModDefId};
 use rustc_middle::query::Providers;
 use rustc_middle::ty::{self, TyCtxt, TypeVisitableExt};
-use rustc_span::{Span, Symbol};
+use rustc_span::{ErrorGuaranteed, Span, Symbol};
 
 mod min_specialization;
 
@@ -51,24 +51,29 @@ mod min_specialization;
 /// impl<'a> Trait<Foo> for Bar { type X = &'a i32; }
 /// //   ^ 'a is unused and appears in assoc type, error
 /// ```
-fn check_mod_impl_wf(tcx: TyCtxt<'_>, module_def_id: LocalModDefId) {
+fn check_mod_impl_wf(tcx: TyCtxt<'_>, module_def_id: LocalModDefId) -> Result<(), ErrorGuaranteed> {
     let min_specialization = tcx.features().min_specialization;
     let module = tcx.hir_module_items(module_def_id);
+    let mut res = Ok(());
     for id in module.items() {
         if matches!(tcx.def_kind(id.owner_id), DefKind::Impl { .. }) {
-            enforce_impl_params_are_constrained(tcx, id.owner_id.def_id);
+            res = res.and(enforce_impl_params_are_constrained(tcx, id.owner_id.def_id));
             if min_specialization {
-                check_min_specialization(tcx, id.owner_id.def_id);
+                res = res.and(check_min_specialization(tcx, id.owner_id.def_id));
             }
         }
     }
+    res
 }
 
 pub fn provide(providers: &mut Providers) {
     *providers = Providers { check_mod_impl_wf, ..*providers };
 }
 
-fn enforce_impl_params_are_constrained(tcx: TyCtxt<'_>, impl_def_id: LocalDefId) {
+fn enforce_impl_params_are_constrained(
+    tcx: TyCtxt<'_>,
+    impl_def_id: LocalDefId,
+) -> Result<(), ErrorGuaranteed> {
     // Every lifetime used in an associated type must be constrained.
     let impl_self_ty = tcx.type_of(impl_def_id).instantiate_identity();
     if impl_self_ty.references_error() {
@@ -80,7 +85,10 @@ fn enforce_impl_params_are_constrained(tcx: TyCtxt<'_>, impl_def_id: LocalDefId)
                 "potentially unconstrained type parameters weren't evaluated: {impl_self_ty:?}",
             ),
         );
-        return;
+        // This is super fishy, but our current `rustc_hir_analysis::check_crate` pipeline depends on
+        // `type_of` having been called much earlier, and thus this value being read from cache.
+        // Compilation must continue in order for other important diagnostics to keep showing up.
+        return Ok(());
     }
     let impl_generics = tcx.generics_of(impl_def_id);
     let impl_predicates = tcx.predicates_of(impl_def_id);
@@ -113,13 +121,19 @@ fn enforce_impl_params_are_constrained(tcx: TyCtxt<'_>, impl_def_id: LocalDefId)
         })
         .collect();
 
+    let mut res = Ok(());
     for param in &impl_generics.params {
         match param.kind {
             // Disallow ANY unconstrained type parameters.
             ty::GenericParamDefKind::Type { .. } => {
                 let param_ty = ty::ParamTy::for_def(param);
                 if !input_parameters.contains(&cgp::Parameter::from(param_ty)) {
-                    report_unused_parameter(tcx, tcx.def_span(param.def_id), "type", param_ty.name);
+                    res = Err(report_unused_parameter(
+                        tcx,
+                        tcx.def_span(param.def_id),
+                        "type",
+                        param_ty.name,
+                    ));
                 }
             }
             ty::GenericParamDefKind::Lifetime => {
@@ -127,27 +141,28 @@ fn enforce_impl_params_are_constrained(tcx: TyCtxt<'_>, impl_def_id: LocalDefId)
                 if lifetimes_in_associated_types.contains(&param_lt) && // (*)
                     !input_parameters.contains(&param_lt)
                 {
-                    report_unused_parameter(
+                    res = Err(report_unused_parameter(
                         tcx,
                         tcx.def_span(param.def_id),
                         "lifetime",
                         param.name,
-                    );
+                    ));
                 }
             }
             ty::GenericParamDefKind::Const { .. } => {
                 let param_ct = ty::ParamConst::for_def(param);
                 if !input_parameters.contains(&cgp::Parameter::from(param_ct)) {
-                    report_unused_parameter(
+                    res = Err(report_unused_parameter(
                         tcx,
                         tcx.def_span(param.def_id),
                         "const",
                         param_ct.name,
-                    );
+                    ));
                 }
             }
         }
     }
+    res
 
     // (*) This is a horrible concession to reality. I think it'd be
     // better to just ban unconstrained lifetimes outright, but in
@@ -169,7 +184,12 @@ fn enforce_impl_params_are_constrained(tcx: TyCtxt<'_>, impl_def_id: LocalDefId)
     // used elsewhere are not projected back out.
 }
 
-fn report_unused_parameter(tcx: TyCtxt<'_>, span: Span, kind: &str, name: Symbol) {
+fn report_unused_parameter(
+    tcx: TyCtxt<'_>,
+    span: Span,
+    kind: &str,
+    name: Symbol,
+) -> ErrorGuaranteed {
     let mut err = struct_span_code_err!(
         tcx.dcx(),
         span,
@@ -188,5 +208,5 @@ fn report_unused_parameter(tcx: TyCtxt<'_>, span: Span, kind: &str, name: Symbol
             "proving the result of expressions other than the parameter are unique is not supported",
         );
     }
-    err.emit();
+    err.emit()
 }

compiler/rustc_hir_analysis/src/impl_wf_check/min_specialization.rs

@@ -82,10 +82,14 @@ use rustc_trait_selection::traits::error_reporting::TypeErrCtxtExt;
 use rustc_trait_selection::traits::outlives_bounds::InferCtxtExt as _;
 use rustc_trait_selection::traits::{self, translate_args_with_cause, wf, ObligationCtxt};
 
-pub(super) fn check_min_specialization(tcx: TyCtxt<'_>, impl_def_id: LocalDefId) {
+pub(super) fn check_min_specialization(
+    tcx: TyCtxt<'_>,
+    impl_def_id: LocalDefId,
+) -> Result<(), ErrorGuaranteed> {
     if let Some(node) = parent_specialization_node(tcx, impl_def_id) {
-        check_always_applicable(tcx, impl_def_id, node);
+        check_always_applicable(tcx, impl_def_id, node)?;
     }
+    Ok(())
 }
 
 fn parent_specialization_node(tcx: TyCtxt<'_>, impl1_def_id: LocalDefId) -> Option<Node> {
@@ -109,42 +113,58 @@ fn parent_specialization_node(tcx: TyCtxt<'_>, impl1_def_id: LocalDefId) -> Opti
 
 /// Check that `impl1` is a sound specialization
 #[instrument(level = "debug", skip(tcx))]
-fn check_always_applicable(tcx: TyCtxt<'_>, impl1_def_id: LocalDefId, impl2_node: Node) {
+fn check_always_applicable(
+    tcx: TyCtxt<'_>,
+    impl1_def_id: LocalDefId,
+    impl2_node: Node,
+) -> Result<(), ErrorGuaranteed> {
     let span = tcx.def_span(impl1_def_id);
-    check_has_items(tcx, impl1_def_id, impl2_node, span);
+    let mut res = check_has_items(tcx, impl1_def_id, impl2_node, span);
 
-    if let Ok((impl1_args, impl2_args)) = get_impl_args(tcx, impl1_def_id, impl2_node) {
+    let (impl1_args, impl2_args) = get_impl_args(tcx, impl1_def_id, impl2_node)?;
-        let impl2_def_id = impl2_node.def_id();
+    let impl2_def_id = impl2_node.def_id();
-        debug!(?impl2_def_id, ?impl2_args);
+    debug!(?impl2_def_id, ?impl2_args);
 
-        let parent_args = if impl2_node.is_from_trait() {
+    let parent_args = if impl2_node.is_from_trait() {
-            impl2_args.to_vec()
+        impl2_args.to_vec()
-        } else {
+    } else {
-            unconstrained_parent_impl_args(tcx, impl2_def_id, impl2_args)
+        unconstrained_parent_impl_args(tcx, impl2_def_id, impl2_args)
-        };
+    };
 
-        check_constness(tcx, impl1_def_id, impl2_node, span);
+    res = res.and(check_constness(tcx, impl1_def_id, impl2_node, span));
-        check_static_lifetimes(tcx, &parent_args, span);
+    res = res.and(check_static_lifetimes(tcx, &parent_args, span));
-        check_duplicate_params(tcx, impl1_args, &parent_args, span);
+    res = res.and(check_duplicate_params(tcx, impl1_args, &parent_args, span));
-        check_predicates(tcx, impl1_def_id, impl1_args, impl2_node, impl2_args, span);
+    res = res.and(check_predicates(tcx, impl1_def_id, impl1_args, impl2_node, impl2_args, span));
-    }
+
+    res
 }
 
-fn check_has_items(tcx: TyCtxt<'_>, impl1_def_id: LocalDefId, impl2_node: Node, span: Span) {
+fn check_has_items(
+    tcx: TyCtxt<'_>,
+    impl1_def_id: LocalDefId,
+    impl2_node: Node,
+    span: Span,
+) -> Result<(), ErrorGuaranteed> {
     if let Node::Impl(impl2_id) = impl2_node
         && tcx.associated_item_def_ids(impl1_def_id).is_empty()
     {
         let base_impl_span = tcx.def_span(impl2_id);
-        tcx.dcx().emit_err(errors::EmptySpecialization { span, base_impl_span });
+        return Err(tcx.dcx().emit_err(errors::EmptySpecialization { span, base_impl_span }));
     }
+    Ok(())
 }
 
 /// Check that the specializing impl `impl1` is at least as const as the base
 /// impl `impl2`
-fn check_constness(tcx: TyCtxt<'_>, impl1_def_id: LocalDefId, impl2_node: Node, span: Span) {
+fn check_constness(
+    tcx: TyCtxt<'_>,
+    impl1_def_id: LocalDefId,
+    impl2_node: Node,
+    span: Span,
+) -> Result<(), ErrorGuaranteed> {
     if impl2_node.is_from_trait() {
         // This isn't a specialization
-        return;
+        return Ok(());
     }
 
     let impl1_constness = tcx.constness(impl1_def_id.to_def_id());
@@ -152,9 +172,10 @@ fn check_constness(tcx: TyCtxt<'_>, impl1_def_id: LocalDefId, impl2_node: Node,
 
     if let hir::Constness::Const = impl2_constness {
         if let hir::Constness::NotConst = impl1_constness {
-            tcx.dcx().emit_err(errors::ConstSpecialize { span });
+            return Err(tcx.dcx().emit_err(errors::ConstSpecialize { span }));
         }
     }
+    Ok(())
 }
 
 /// Given a specializing impl `impl1`, and the base impl `impl2`, returns two
@@ -290,15 +311,17 @@ fn check_duplicate_params<'tcx>(
     impl1_args: GenericArgsRef<'tcx>,
     parent_args: &Vec<GenericArg<'tcx>>,
     span: Span,
-) {
+) -> Result<(), ErrorGuaranteed> {
     let mut base_params = cgp::parameters_for(parent_args, true);
     base_params.sort_by_key(|param| param.0);
     if let (_, [duplicate, ..]) = base_params.partition_dedup() {
         let param = impl1_args[duplicate.0 as usize];
-        tcx.dcx()
+        return Err(tcx
+            .dcx()
             .struct_span_err(span, format!("specializing impl repeats parameter `{param}`"))
-            .emit();
+            .emit());
     }
+    Ok(())
 }
 
 /// Check that `'static` lifetimes are not introduced by the specializing impl.
@@ -313,10 +336,11 @@ fn check_static_lifetimes<'tcx>(
     tcx: TyCtxt<'tcx>,
     parent_args: &Vec<GenericArg<'tcx>>,
     span: Span,
-) {
+) -> Result<(), ErrorGuaranteed> {
     if tcx.any_free_region_meets(parent_args, |r| r.is_static()) {
-        tcx.dcx().emit_err(errors::StaticSpecialize { span });
+        return Err(tcx.dcx().emit_err(errors::StaticSpecialize { span }));
     }
+    Ok(())
 }
 
 /// Check whether predicates on the specializing impl (`impl1`) are allowed.
@@ -337,7 +361,7 @@ fn check_predicates<'tcx>(
     impl2_node: Node,
     impl2_args: GenericArgsRef<'tcx>,
     span: Span,
-) {
+) -> Result<(), ErrorGuaranteed> {
     let impl1_predicates: Vec<_> = traits::elaborate(
         tcx,
         tcx.predicates_of(impl1_def_id).instantiate(tcx, impl1_args).into_iter(),
@@ -399,14 +423,16 @@ fn check_predicates<'tcx>(
     }
     impl2_predicates.extend(traits::elaborate(tcx, always_applicable_traits));
 
+    let mut res = Ok(());
     for (clause, span) in impl1_predicates {
         if !impl2_predicates
             .iter()
             .any(|pred2| trait_predicates_eq(tcx, clause.as_predicate(), *pred2, span))
         {
-            check_specialization_on(tcx, clause, span)
+            res = res.and(check_specialization_on(tcx, clause, span))
         }
     }
+    res
 }
 
 /// Checks if some predicate on the specializing impl (`predicate1`) is the same
@@ -443,19 +469,26 @@ fn trait_predicates_eq<'tcx>(
 }
 
 #[instrument(level = "debug", skip(tcx))]
-fn check_specialization_on<'tcx>(tcx: TyCtxt<'tcx>, clause: ty::Clause<'tcx>, span: Span) {
+fn check_specialization_on<'tcx>(
+    tcx: TyCtxt<'tcx>,
+    clause: ty::Clause<'tcx>,
+    span: Span,
+) -> Result<(), ErrorGuaranteed> {
     match clause.kind().skip_binder() {
         // Global predicates are either always true or always false, so we
         // are fine to specialize on.
-        _ if clause.is_global() => (),
+        _ if clause.is_global() => Ok(()),
         // We allow specializing on explicitly marked traits with no associated
         // items.
         ty::ClauseKind::Trait(ty::TraitPredicate { trait_ref, polarity: _ }) => {
-            if !matches!(
+            if matches!(
                 trait_specialization_kind(tcx, clause),
                 Some(TraitSpecializationKind::Marker)
             ) {
-                tcx.dcx()
+                Ok(())
+            } else {
+                Err(tcx
+                    .dcx()
                     .struct_span_err(
                         span,
                         format!(
@@ -463,17 +496,16 @@ fn check_specialization_on<'tcx>(tcx: TyCtxt<'tcx>, clause: ty::Clause<'tcx>, sp
                             tcx.def_path_str(trait_ref.def_id),
                         ),
                     )
-                    .emit();
+                    .emit())
             }
         }
-        ty::ClauseKind::Projection(ty::ProjectionPredicate { projection_ty, term }) => {
+        ty::ClauseKind::Projection(ty::ProjectionPredicate { projection_ty, term }) => Err(tcx
-            tcx.dcx()
+            .dcx()
-                .struct_span_err(
+            .struct_span_err(
-                    span,
+                span,
-                    format!("cannot specialize on associated type `{projection_ty} == {term}`",),
+                format!("cannot specialize on associated type `{projection_ty} == {term}`",),
-                )
+            )
-                .emit();
+            .emit()),
-        }
         ty::ClauseKind::ConstArgHasType(..) => {
             // FIXME(min_specialization), FIXME(const_generics):
             // It probably isn't right to allow _every_ `ConstArgHasType` but I am somewhat unsure
@@ -483,12 +515,12 @@ fn check_specialization_on<'tcx>(tcx: TyCtxt<'tcx>, clause: ty::Clause<'tcx>, sp
             // While we do not support constructs like `<T, const N: T>` there is probably no risk of
             // soundness bugs, but when we support generic const parameter types this will need to be
             // revisited.
+            Ok(())
         }
-        _ => {
+        _ => Err(tcx
-            tcx.dcx()
+            .dcx()
-                .struct_span_err(span, format!("cannot specialize on predicate `{clause}`"))
+            .struct_span_err(span, format!("cannot specialize on predicate `{clause}`"))
-                .emit();
+            .emit()),
-        }
     }
 }
 

compiler/rustc_hir_analysis/src/lib.rs

@@ -166,33 +166,29 @@ pub fn check_crate(tcx: TyCtxt<'_>) -> Result<(), ErrorGuaranteed> {
         tcx.hir().for_each_module(|module| tcx.ensure().collect_mod_item_types(module))
     });
 
-    // FIXME(matthewjasper) We shouldn't need to use `track_errors` anywhere in this function
-    // or the compiler in general.
     if tcx.features().rustc_attrs {
-        tcx.sess.track_errors(|| {
+        tcx.sess.time("outlives_testing", || outlives::test::test_inferred_outlives(tcx))?;
-            tcx.sess.time("outlives_testing", || outlives::test::test_inferred_outlives(tcx));
-        })?;
     }
 
-    tcx.sess.track_errors(|| {
+    tcx.sess.time("coherence_checking", || {
-        tcx.sess.time("coherence_checking", || {
+        // Check impls constrain their parameters
-            // Check impls constrain their parameters
+        let res =
-            tcx.hir().for_each_module(|module| tcx.ensure().check_mod_impl_wf(module));
+            tcx.hir().try_par_for_each_module(|module| tcx.ensure().check_mod_impl_wf(module));
 
+        // FIXME(matthewjasper) We shouldn't need to use `track_errors` anywhere in this function
+        // or the compiler in general.
+        res.and(tcx.sess.track_errors(|| {
             for &trait_def_id in tcx.all_local_trait_impls(()).keys() {
                 tcx.ensure().coherent_trait(trait_def_id);
             }
-
+        }))
-            // these queries are executed for side-effects (error reporting):
+        // these queries are executed for side-effects (error reporting):
-            tcx.ensure().crate_inherent_impls(());
+        .and(tcx.ensure().crate_inherent_impls(()))
-            tcx.ensure().crate_inherent_impls_overlap_check(());
+        .and(tcx.ensure().crate_inherent_impls_overlap_check(()))
-        });
     })?;
 
     if tcx.features().rustc_attrs {
-        tcx.sess.track_errors(|| {
+        tcx.sess.time("variance_testing", || variance::test::test_variance(tcx))?;
-            tcx.sess.time("variance_testing", || variance::test::test_variance(tcx));
-        })?;
     }
 
     tcx.sess.time("wf_checking", || {
@@ -200,7 +196,7 @@ pub fn check_crate(tcx: TyCtxt<'_>) -> Result<(), ErrorGuaranteed> {
     })?;
 
     if tcx.features().rustc_attrs {
-        tcx.sess.track_errors(|| collect::test_opaque_hidden_types(tcx))?;
+        collect::test_opaque_hidden_types(tcx)?;
     }
 
     // Freeze definitions as we don't add new ones at this point. This improves performance by

compiler/rustc_hir_analysis/src/outlives/test.rs

@@ -1,7 +1,8 @@
 use rustc_middle::ty::{self, TyCtxt};
-use rustc_span::symbol::sym;
+use rustc_span::{symbol::sym, ErrorGuaranteed};
 
-pub fn test_inferred_outlives(tcx: TyCtxt<'_>) {
+pub fn test_inferred_outlives(tcx: TyCtxt<'_>) -> Result<(), ErrorGuaranteed> {
+    let mut res = Ok(());
     for id in tcx.hir().items() {
         // For unit testing: check for a special "rustc_outlives"
         // attribute and report an error with various results if found.
@@ -22,7 +23,8 @@ pub fn test_inferred_outlives(tcx: TyCtxt<'_>) {
             for p in pred {
                 err.note(p);
             }
-            err.emit();
+            res = Err(err.emit());
         }
     }
+    res
 }

compiler/rustc_hir_analysis/src/variance/test.rs

@@ -2,19 +2,21 @@ use rustc_hir::def::DefKind;
 use rustc_hir::def_id::CRATE_DEF_ID;
 use rustc_middle::ty::TyCtxt;
 use rustc_span::symbol::sym;
+use rustc_span::ErrorGuaranteed;
 
 use crate::errors;
 
-pub fn test_variance(tcx: TyCtxt<'_>) {
+pub fn test_variance(tcx: TyCtxt<'_>) -> Result<(), ErrorGuaranteed> {
+    let mut res = Ok(());
     if tcx.has_attr(CRATE_DEF_ID, sym::rustc_variance_of_opaques) {
         for id in tcx.hir().items() {
             if matches!(tcx.def_kind(id.owner_id), DefKind::OpaqueTy) {
                 let variances_of = tcx.variances_of(id.owner_id);
 
-                tcx.dcx().emit_err(errors::VariancesOf {
+                res = Err(tcx.dcx().emit_err(errors::VariancesOf {
                     span: tcx.def_span(id.owner_id),
                     variances_of: format!("{variances_of:?}"),
-                });
+                }));
             }
         }
     }
@@ -25,10 +27,11 @@ pub fn test_variance(tcx: TyCtxt<'_>) {
         if tcx.has_attr(id.owner_id, sym::rustc_variance) {
             let variances_of = tcx.variances_of(id.owner_id);
 
-            tcx.dcx().emit_err(errors::VariancesOf {
+            res = Err(tcx.dcx().emit_err(errors::VariancesOf {
                 span: tcx.def_span(id.owner_id),
                 variances_of: format!("{variances_of:?}"),
-            });
+            }));
         }
     }
+    res
 }

compiler/rustc_hir_typeck/src/expr.rs

@@ -2102,7 +2102,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             let mut items = self
                 .tcx
                 .inherent_impls(def_id)
-                .iter()
+                .into_iter()
+                .flatten()
                 .flat_map(|i| self.tcx.associated_items(i).in_definition_order())
                 // Only assoc fn with no receivers.
                 .filter(|item| {

compiler/rustc_hir_typeck/src/method/probe.rs

@@ -711,14 +711,14 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
         let Some(simp) = simplify_type(self.tcx, self_ty, TreatParams::AsCandidateKey) else {
             bug!("unexpected incoherent type: {:?}", self_ty)
         };
-        for &impl_def_id in self.tcx.incoherent_impls(simp) {
+        for &impl_def_id in self.tcx.incoherent_impls(simp).into_iter().flatten() {
             self.assemble_inherent_impl_probe(impl_def_id);
         }
     }
 
     fn assemble_inherent_impl_candidates_for_type(&mut self, def_id: DefId) {
-        let impl_def_ids = self.tcx.at(self.span).inherent_impls(def_id);
+        let impl_def_ids = self.tcx.at(self.span).inherent_impls(def_id).into_iter().flatten();
-        for &impl_def_id in impl_def_ids.iter() {
+        for &impl_def_id in impl_def_ids {
             self.assemble_inherent_impl_probe(impl_def_id);
         }
     }

compiler/rustc_hir_typeck/src/method/suggest.rs

@@ -359,7 +359,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     if let ty::Adt(adt_def, _) = ty.kind() {
                         self.tcx
                             .inherent_impls(adt_def.did())
-                            .iter()
+                            .into_iter()
+                            .flatten()
                             .any(|def_id| self.associated_value(*def_id, item_name).is_some())
                     } else {
                         false
@@ -1048,7 +1049,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     let mut inherent_impls_candidate = self
                         .tcx
                         .inherent_impls(adt.did())
-                        .iter()
+                        .into_iter()
+                        .flatten()
                         .copied()
                         .filter(|def_id| {
                             if let Some(assoc) = self.associated_value(*def_id, item_name) {
@@ -1103,7 +1105,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                             "the {item_kind} was found for\n{type_candidates}{additional_types}"
                         ));
                     } else {
-                        'outer: for inherent_impl_did in self.tcx.inherent_impls(adt.did()) {
+                        'outer: for inherent_impl_did in
+                            self.tcx.inherent_impls(adt.did()).into_iter().flatten()
+                        {
                             for inherent_method in
                                 self.tcx.associated_items(inherent_impl_did).in_definition_order()
                             {
@@ -1457,9 +1461,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         let ty::Adt(adt_def, _) = rcvr_ty.kind() else {
             return;
         };
-        let mut items = self
+        // FIXME(oli-obk): try out bubbling this error up one level and cancelling the other error in that case.
-            .tcx
+        let Ok(impls) = self.tcx.inherent_impls(adt_def.did()) else { return };
-            .inherent_impls(adt_def.did())
+        let mut items = impls
             .iter()
             .flat_map(|i| self.tcx.associated_items(i).in_definition_order())
             // Only assoc fn with no receivers.
@@ -1823,7 +1827,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             simplify_type(tcx, ty, TreatParams::AsCandidateKey)
                 .and_then(|simp| {
                     tcx.incoherent_impls(simp)
-                        .iter()
+                        .into_iter()
+                        .flatten()
                         .find_map(|&id| self.associated_value(id, item_name))
                 })
                 .is_some()

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

@@ -283,7 +283,7 @@ provide! { tcx, def_id, other, cdata,
         tcx.arena.alloc_from_iter(cdata.get_associated_item_or_field_def_ids(def_id.index))
     }
     associated_item => { cdata.get_associated_item(def_id.index, tcx.sess) }
-    inherent_impls => { cdata.get_inherent_implementations_for_type(tcx, def_id.index) }
+    inherent_impls => { Ok(cdata.get_inherent_implementations_for_type(tcx, def_id.index)) }
     item_attrs => { tcx.arena.alloc_from_iter(cdata.get_item_attrs(def_id.index, tcx.sess)) }
     is_mir_available => { cdata.is_item_mir_available(def_id.index) }
     is_ctfe_mir_available => { cdata.is_ctfe_mir_available(def_id.index) }
@@ -328,7 +328,7 @@ provide! { tcx, def_id, other, cdata,
     traits => { tcx.arena.alloc_from_iter(cdata.get_traits()) }
     trait_impls_in_crate => { tcx.arena.alloc_from_iter(cdata.get_trait_impls()) }
     implementations_of_trait => { cdata.get_implementations_of_trait(tcx, other) }
-    crate_incoherent_impls => { cdata.get_incoherent_impls(tcx, other) }
+    crate_incoherent_impls => { Ok(cdata.get_incoherent_impls(tcx, other)) }
 
     dep_kind => { cdata.dep_kind }
     module_children => {

compiler/rustc_metadata/src/rmeta/encoder.rs

@@ -1485,7 +1485,7 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
         }
 
         let inherent_impls = tcx.with_stable_hashing_context(|hcx| {
-            tcx.crate_inherent_impls(()).inherent_impls.to_sorted(&hcx, true)
+            tcx.crate_inherent_impls(()).unwrap().inherent_impls.to_sorted(&hcx, true)
         });
         for (def_id, impls) in inherent_impls {
             record_defaulted_array!(self.tables.inherent_impls[def_id.to_def_id()] <- impls.iter().map(|def_id| {
@@ -2028,7 +2028,7 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
         empty_proc_macro!(self);
         let tcx = self.tcx;
         let all_impls = tcx.with_stable_hashing_context(|hcx| {
-            tcx.crate_inherent_impls(()).incoherent_impls.to_sorted(&hcx, true)
+            tcx.crate_inherent_impls(()).unwrap().incoherent_impls.to_sorted(&hcx, true)
         });
 
         let all_impls: Vec<_> = all_impls

compiler/rustc_middle/src/arena.rs

@@ -114,6 +114,7 @@ macro_rules! arena_types {
             [] mod_child: rustc_middle::metadata::ModChild,
             [] features: rustc_feature::Features,
             [decode] specialization_graph: rustc_middle::traits::specialization_graph::Graph,
+            [] crate_inherent_impls: rustc_middle::ty::CrateInherentImpls,
         ]);
     )
 }

compiler/rustc_middle/src/query/erase.rs

@@ -82,6 +82,10 @@ impl<T> EraseType for Result<&'_ T, rustc_errors::ErrorGuaranteed> {
     type Result = [u8; size_of::<Result<&'static (), rustc_errors::ErrorGuaranteed>>()];
 }
 
+impl<T> EraseType for Result<&'_ [T], rustc_errors::ErrorGuaranteed> {
+    type Result = [u8; size_of::<Result<&'static [()], rustc_errors::ErrorGuaranteed>>()];
+}
+
 impl<T> EraseType for Result<&'_ T, traits::CodegenObligationError> {
     type Result = [u8; size_of::<Result<&'static (), traits::CodegenObligationError>>()];
 }

compiler/rustc_middle/src/query/mod.rs

@@ -859,13 +859,13 @@ rustc_queries! {
     /// Maps a `DefId` of a type to a list of its inherent impls.
     /// Contains implementations of methods that are inherent to a type.
     /// Methods in these implementations don't need to be exported.
-    query inherent_impls(key: DefId) -> &'tcx [DefId] {
+    query inherent_impls(key: DefId) -> Result<&'tcx [DefId], ErrorGuaranteed> {
         desc { |tcx| "collecting inherent impls for `{}`", tcx.def_path_str(key) }
         cache_on_disk_if { key.is_local() }
         separate_provide_extern
     }
 
-    query incoherent_impls(key: SimplifiedType) -> &'tcx [DefId] {
+    query incoherent_impls(key: SimplifiedType) -> Result<&'tcx [DefId], ErrorGuaranteed> {
         desc { |tcx| "collecting all inherent impls for `{:?}`", key }
     }
 
@@ -961,8 +961,9 @@ rustc_queries! {
         desc { |tcx| "checking deathness of variables in {}", describe_as_module(key, tcx) }
     }
 
-    query check_mod_impl_wf(key: LocalModDefId) -> () {
+    query check_mod_impl_wf(key: LocalModDefId) -> Result<(), ErrorGuaranteed> {
         desc { |tcx| "checking that impls are well-formed in {}", describe_as_module(key, tcx) }
+        ensure_forwards_result_if_red
     }
 
     query check_mod_type_wf(key: LocalModDefId) -> Result<(), ErrorGuaranteed> {
@@ -1011,15 +1012,16 @@ rustc_queries! {
 
     /// Gets a complete map from all types to their inherent impls.
     /// Not meant to be used directly outside of coherence.
-    query crate_inherent_impls(k: ()) -> &'tcx CrateInherentImpls {
+    query crate_inherent_impls(k: ()) -> Result<&'tcx CrateInherentImpls, ErrorGuaranteed> {
-        arena_cache
         desc { "finding all inherent impls defined in crate" }
+        ensure_forwards_result_if_red
     }
 
     /// Checks all types in the crate for overlap in their inherent impls. Reports errors.
     /// Not meant to be used directly outside of coherence.
-    query crate_inherent_impls_overlap_check(_: ()) -> () {
+    query crate_inherent_impls_overlap_check(_: ()) -> Result<(), ErrorGuaranteed> {
         desc { "check for overlap between inherent impls defined in this crate" }
+        ensure_forwards_result_if_red
     }
 
     /// Checks whether all impls in the crate pass the overlap check, returning
@@ -1645,7 +1647,7 @@ rustc_queries! {
     ///
     /// Do not call this directly, but instead use the `incoherent_impls` query.
     /// This query is only used to get the data necessary for that query.
-    query crate_incoherent_impls(key: (CrateNum, SimplifiedType)) -> &'tcx [DefId] {
+    query crate_incoherent_impls(key: (CrateNum, SimplifiedType)) -> Result<&'tcx [DefId], ErrorGuaranteed> {
         desc { |tcx| "collecting all impls for a type in a crate" }
         separate_provide_extern
     }

compiler/rustc_middle/src/query/plumbing.rs

@@ -174,7 +174,7 @@ pub fn query_ensure<'tcx, Cache>(
 }
 
 #[inline]
-pub fn query_ensure_error_guaranteed<'tcx, Cache>(
+pub fn query_ensure_error_guaranteed<'tcx, Cache, T>(
     tcx: TyCtxt<'tcx>,
     execute_query: fn(TyCtxt<'tcx>, Span, Cache::Key, QueryMode) -> Option<Cache::Value>,
     query_cache: &Cache,
@@ -182,14 +182,16 @@ pub fn query_ensure_error_guaranteed<'tcx, Cache>(
     check_cache: bool,
 ) -> Result<(), ErrorGuaranteed>
 where
-    Cache: QueryCache<Value = super::erase::Erase<Result<(), ErrorGuaranteed>>>,
+    Cache: QueryCache<Value = super::erase::Erase<Result<T, ErrorGuaranteed>>>,
+    Result<T, ErrorGuaranteed>: EraseType,
 {
     let key = key.into_query_param();
     if let Some(res) = try_get_cached(tcx, query_cache, &key) {
-        super::erase::restore(res)
+        super::erase::restore(res).map(drop)
     } else {
         execute_query(tcx, DUMMY_SP, key, QueryMode::Ensure { check_cache })
             .map(super::erase::restore)
+            .map(|res| res.map(drop))
             // Either we actually executed the query, which means we got a full `Result`,
             // or we can just assume the query succeeded, because it was green in the
             // incremental cache. If it is green, that means that the previous compilation
@@ -205,7 +207,7 @@ macro_rules! query_ensure {
         query_ensure($($args)*)
     };
     ([(ensure_forwards_result_if_red) $($rest:tt)*]$($args:tt)*) => {
-        query_ensure_error_guaranteed($($args)*)
+        query_ensure_error_guaranteed($($args)*).map(|_| ())
     };
     ([$other:tt $($modifiers:tt)*]$($args:tt)*) => {
         query_ensure!([$($modifiers)*]$($args)*)
@@ -667,5 +669,7 @@ mod sealed {
 
 pub use sealed::IntoQueryParam;
 
+use super::erase::EraseType;
+
 #[derive(Copy, Clone, Debug, HashStable)]
 pub struct CyclePlaceholder(pub ErrorGuaranteed);

compiler/rustc_middle/src/ty/trait_def.rs

@@ -254,16 +254,28 @@ pub(super) fn trait_impls_of_provider(tcx: TyCtxt<'_>, trait_id: DefId) -> Trait
 }
 
 /// Query provider for `incoherent_impls`.
-pub(super) fn incoherent_impls_provider(tcx: TyCtxt<'_>, simp: SimplifiedType) -> &[DefId] {
+pub(super) fn incoherent_impls_provider(
+    tcx: TyCtxt<'_>,
+    simp: SimplifiedType,
+) -> Result<&[DefId], ErrorGuaranteed> {
     let mut impls = Vec::new();
 
+    let mut res = Ok(());
     for cnum in iter::once(LOCAL_CRATE).chain(tcx.crates(()).iter().copied()) {
-        for &impl_def_id in tcx.crate_incoherent_impls((cnum, simp)) {
+        let incoherent_impls = match tcx.crate_incoherent_impls((cnum, simp)) {
+            Ok(impls) => impls,
+            Err(e) => {
+                res = Err(e);
+                continue;
+            }
+        };
+        for &impl_def_id in incoherent_impls {
             impls.push(impl_def_id)
         }
     }
 
     debug!(?impls);
+    res?;
 
-    tcx.arena.alloc_slice(&impls)
+    Ok(tcx.arena.alloc_slice(&impls))
 }

compiler/rustc_monomorphize/src/collector.rs

@@ -1433,7 +1433,7 @@ fn collect_alloc<'tcx>(tcx: TyCtxt<'tcx>, alloc_id: AllocId, output: &mut MonoIt
 }
 
 fn assoc_fn_of_type<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId, fn_ident: Ident) -> Option<DefId> {
-    for impl_def_id in tcx.inherent_impls(def_id) {
+    for impl_def_id in tcx.inherent_impls(def_id).ok()? {
         if let Some(new) = tcx.associated_items(impl_def_id).find_by_name_and_kind(
             tcx,
             fn_ident,

compiler/rustc_resolve/src/late/diagnostics.rs

@@ -1745,12 +1745,10 @@ impl<'a: 'ast, 'ast, 'tcx> LateResolutionVisitor<'a, '_, 'ast, 'tcx> {
             // Doing analysis on local `DefId`s would cause infinite recursion.
             return;
         }
+        let Ok(impls) = self.r.tcx.inherent_impls(def_id) else { return };
         // Look at all the associated functions without receivers in the type's
         // inherent impls to look for builders that return `Self`
-        let mut items = self
+        let mut items = impls
-            .r
-            .tcx
-            .inherent_impls(def_id)
             .iter()
             .flat_map(|i| self.r.tcx.associated_items(i).in_definition_order())
             // Only assoc fn with no receivers.

src/librustdoc/clean/inline.rs

@@ -312,7 +312,7 @@ pub(crate) fn build_impls(
     let tcx = cx.tcx;
 
     // for each implementation of an item represented by `did`, build the clean::Item for that impl
-    for &did in tcx.inherent_impls(did).iter() {
+    for &did in tcx.inherent_impls(did).into_iter().flatten() {
         build_impl(cx, did, attrs, ret);
     }
 
@@ -325,7 +325,7 @@ pub(crate) fn build_impls(
     if tcx.has_attr(did, sym::rustc_has_incoherent_inherent_impls) {
         let type_ =
             if tcx.is_trait(did) { SimplifiedType::Trait(did) } else { SimplifiedType::Adt(did) };
-        for &did in tcx.incoherent_impls(type_) {
+        for &did in tcx.incoherent_impls(type_).into_iter().flatten() {
             build_impl(cx, did, attrs, ret);
         }
     }

src/librustdoc/clean/types.rs

@@ -1862,7 +1862,7 @@ impl PrimitiveType {
             .get(self)
             .into_iter()
             .flatten()
-            .flat_map(move |&simp| tcx.incoherent_impls(simp))
+            .flat_map(move |&simp| tcx.incoherent_impls(simp).into_iter().flatten())
             .copied()
     }
 
@@ -1870,7 +1870,7 @@ impl PrimitiveType {
         Self::simplified_types()
             .values()
             .flatten()
-            .flat_map(move |&simp| tcx.incoherent_impls(simp))
+            .flat_map(move |&simp| tcx.incoherent_impls(simp).into_iter().flatten())
             .copied()
     }
 

src/librustdoc/passes/collect_intra_doc_links.rs

@@ -624,7 +624,8 @@ impl<'a, 'tcx> LinkCollector<'a, 'tcx> {
                 // Checks if item_name belongs to `impl SomeItem`
                 let mut assoc_items: Vec<_> = tcx
                     .inherent_impls(did)
-                    .iter()
+                    .into_iter()
+                    .flatten()
                     .flat_map(|&imp| {
                         filter_assoc_items_by_name_and_namespace(
                             tcx,

src/tools/clippy/clippy_lints/src/derive.rs

@@ -386,7 +386,8 @@ fn check_unsafe_derive_deserialize<'tcx>(
         && cx
             .tcx
             .inherent_impls(def.did())
-            .iter()
+            .into_iter()
+            .flatten()
             .map(|imp_did| cx.tcx.hir().expect_item(imp_did.expect_local()))
             .any(|imp| has_unsafe(cx, imp))
     {

src/tools/clippy/clippy_lints/src/inherent_impl.rs

@@ -53,9 +53,10 @@ impl<'tcx> LateLintPass<'tcx> for MultipleInherentImpl {
         // List of spans to lint. (lint_span, first_span)
         let mut lint_spans = Vec::new();
 
+        let Ok(impls) = cx.tcx.crate_inherent_impls(()) else { return };
         let inherent_impls = cx
             .tcx
-            .with_stable_hashing_context(|hcx| cx.tcx.crate_inherent_impls(()).inherent_impls.to_sorted(&hcx, true));
+            .with_stable_hashing_context(|hcx| impls.inherent_impls.to_sorted(&hcx, true));
 
         for (_, impl_ids) in inherent_impls.into_iter().filter(|(&id, impls)| {
             impls.len() > 1

src/tools/clippy/clippy_lints/src/iter_without_into_iter.rs

@@ -139,7 +139,7 @@ fn deref_chain<'cx, 'tcx>(cx: &'cx LateContext<'tcx>, ty: Ty<'tcx>) -> impl Iter
 
 fn adt_has_inherent_method(cx: &LateContext<'_>, ty: Ty<'_>, method_name: Symbol) -> bool {
     if let Some(ty_did) = ty.ty_adt_def().map(ty::AdtDef::did) {
-        cx.tcx.inherent_impls(ty_did).iter().any(|&did| {
+        cx.tcx.inherent_impls(ty_did).into_iter().flatten().any(|&did| {
             cx.tcx
                 .associated_items(did)
                 .filter_by_name_unhygienic(method_name)

src/tools/clippy/clippy_lints/src/len_zero.rs

@@ -441,7 +441,8 @@ fn check_for_is_empty(
     let is_empty = cx
         .tcx
         .inherent_impls(impl_ty)
-        .iter()
+        .into_iter()
+        .flatten()
         .flat_map(|&id| cx.tcx.associated_items(id).filter_by_name_unhygienic(is_empty))
         .find(|item| item.kind == AssocKind::Fn);
 
@@ -605,7 +606,7 @@ fn has_is_empty(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
     /// Checks the inherent impl's items for an `is_empty(self)` method.
     fn has_is_empty_impl(cx: &LateContext<'_>, id: DefId) -> bool {
         let is_empty = sym!(is_empty);
-        cx.tcx.inherent_impls(id).iter().any(|imp| {
+        cx.tcx.inherent_impls(id).into_iter().flatten().any(|imp| {
             cx.tcx
                 .associated_items(*imp)
                 .filter_by_name_unhygienic(is_empty)

src/tools/clippy/clippy_lints/src/methods/or_fun_call.rs

@@ -73,7 +73,8 @@ pub(super) fn check<'tcx>(
         let has_suggested_method = receiver_ty.ty_adt_def().is_some_and(|adt_def| {
             cx.tcx
                 .inherent_impls(adt_def.did())
-                .iter()
+                .into_iter()
+                .flatten()
                 .flat_map(|impl_id| cx.tcx.associated_items(impl_id).filter_by_name_unhygienic(sugg))
                 .any(|assoc| {
                     assoc.fn_has_self_parameter

src/tools/clippy/clippy_utils/src/lib.rs

@@ -534,10 +534,11 @@ fn find_primitive_impls<'tcx>(tcx: TyCtxt<'tcx>, name: &str) -> impl Iterator<It
         "u128" => SimplifiedType::Uint(UintTy::U128),
         "f32" => SimplifiedType::Float(FloatTy::F32),
         "f64" => SimplifiedType::Float(FloatTy::F64),
-        _ => return [].iter().copied(),
+        #[allow(trivial_casts)]
+        _ => return Result::<_, rustc_errors::ErrorGuaranteed>::Ok(&[] as &[_]).into_iter().flatten().copied(),
     };
 
-    tcx.incoherent_impls(ty).iter().copied()
+    tcx.incoherent_impls(ty).into_iter().flatten().copied()
 }
 
 fn non_local_item_children_by_name(tcx: TyCtxt<'_>, def_id: DefId, name: Symbol) -> Vec<Res> {
@@ -663,7 +664,8 @@ pub fn def_path_res(cx: &LateContext<'_>, path: &[&str]) -> Vec<Res> {
                 // `impl S { ... }`
                 let inherent_impl_children = tcx
                     .inherent_impls(def_id)
-                    .iter()
+                    .into_iter()
+                    .flatten()
                     .flat_map(|&impl_def_id| item_children_by_name(tcx, impl_def_id, segment));
 
                 let direct_children = item_children_by_name(tcx, def_id, segment);

tests/ui/impl-trait/in-trait/return-dont-satisfy-bounds.rs

@@ -7,6 +7,8 @@ struct Bar;
 impl Foo<char> for Bar {
     fn foo<F2: Foo<u8>>(self) -> impl Foo<u8> {
         //~^ ERROR: the trait bound `impl Foo<u8>: Foo<char>` is not satisfied [E0277]
+        //~| ERROR: the trait bound `Bar: Foo<u8>` is not satisfied [E0277]
+        //~| ERROR: impl has stricter requirements than trait
         self
     }
 }

tests/ui/impl-trait/in-trait/return-dont-satisfy-bounds.stderr

@@ -11,6 +11,28 @@ note: required by a bound in `Foo::{opaque#0}`
 LL |     fn foo<F2>(self) -> impl Foo<T>;
    |                              ^^^^^^ required by this bound in `Foo::{opaque#0}`
 
-error: aborting due to 1 previous error
+error[E0276]: impl has stricter requirements than trait
+  --> $DIR/return-dont-satisfy-bounds.rs:8:16
+   |
+LL |     fn foo<F2>(self) -> impl Foo<T>;
+   |     -------------------------------- definition of `foo` from trait
+...
+LL |     fn foo<F2: Foo<u8>>(self) -> impl Foo<u8> {
+   |                ^^^^^^^ impl has extra requirement `F2: Foo<u8>`
 
-For more information about this error, try `rustc --explain E0277`.
+error[E0277]: the trait bound `Bar: Foo<u8>` is not satisfied
+  --> $DIR/return-dont-satisfy-bounds.rs:8:34
+   |
+LL |     fn foo<F2: Foo<u8>>(self) -> impl Foo<u8> {
+   |                                  ^^^^^^^^^^^^ the trait `Foo<u8>` is not implemented for `Bar`
+...
+LL |         self
+   |         ---- return type was inferred to be `Bar` here
+   |
+   = help: the trait `Foo<char>` is implemented for `Bar`
+   = help: for that trait implementation, expected `char`, found `u8`
+
+error: aborting due to 3 previous errors
+
+Some errors have detailed explanations: E0276, E0277.
+For more information about an error, try `rustc --explain E0276`.

tests/ui/rfcs/rfc-2632-const-trait-impl/specializing-constness-2.stderr

@@ -7,6 +7,16 @@ LL | impl<T: Default> A for T {
 LL | impl<T: Default + ~const Sup> const A for T {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ conflicting implementation
 
-error: aborting due to 1 previous error
+error[E0308]: mismatched types
+  --> $DIR/specializing-constness-2.rs:27:5
+   |
+LL |     <T as A>::a();
+   |     ^^^^^^^^^^^^^ expected `host`, found `true`
+   |
+   = note: expected constant `host`
+              found constant `true`
 
-For more information about this error, try `rustc --explain E0119`.
+error: aborting due to 2 previous errors
+
+Some errors have detailed explanations: E0119, E0308.
+For more information about an error, try `rustc --explain E0119`.