Rollup of 8 pull requests

compiler/rustc_borrowck/src/diagnostics/bound_region_errors.rs

@@ -3,12 +3,16 @@ use std::rc::Rc;
 
 use rustc_errors::Diag;
 use rustc_hir::def_id::LocalDefId;
-use rustc_infer::infer::canonical::Canonical;
+use rustc_infer::infer::canonical::CanonicalQueryInput;
 use rustc_infer::infer::region_constraints::{Constraint, RegionConstraintData};
 use rustc_infer::infer::{
     InferCtxt, RegionResolutionError, RegionVariableOrigin, SubregionOrigin, TyCtxtInferExt as _,
 };
 use rustc_infer::traits::ObligationCause;
+use rustc_infer::traits::query::{
+    CanonicalTypeOpAscribeUserTypeGoal, CanonicalTypeOpNormalizeGoal,
+    CanonicalTypeOpProvePredicateGoal,
+};
 use rustc_middle::ty::error::TypeError;
 use rustc_middle::ty::{
     self, RePlaceholder, Region, RegionVid, Ty, TyCtxt, TypeFoldable, UniverseIndex,
@@ -95,9 +99,7 @@ impl<'tcx> ToUniverseInfo<'tcx> for crate::type_check::InstantiateOpaqueType<'tc
     }
 }
 
-impl<'tcx> ToUniverseInfo<'tcx>
-    for Canonical<'tcx, ty::ParamEnvAnd<'tcx, type_op::prove_predicate::ProvePredicate<'tcx>>>
-{
+impl<'tcx> ToUniverseInfo<'tcx> for CanonicalTypeOpProvePredicateGoal<'tcx> {
     fn to_universe_info(self, base_universe: ty::UniverseIndex) -> UniverseInfo<'tcx> {
         UniverseInfo(UniverseInfoInner::TypeOp(Rc::new(PredicateQuery {
             canonical_query: self,
@@ -107,7 +109,7 @@ impl<'tcx> ToUniverseInfo<'tcx>
 }
 
 impl<'tcx, T: Copy + fmt::Display + TypeFoldable<TyCtxt<'tcx>> + 'tcx> ToUniverseInfo<'tcx>
-    for Canonical<'tcx, ty::ParamEnvAnd<'tcx, type_op::Normalize<T>>>
+    for CanonicalTypeOpNormalizeGoal<'tcx, T>
 {
     fn to_universe_info(self, base_universe: ty::UniverseIndex) -> UniverseInfo<'tcx> {
         UniverseInfo(UniverseInfoInner::TypeOp(Rc::new(NormalizeQuery {
@@ -117,9 +119,7 @@ impl<'tcx, T: Copy + fmt::Display + TypeFoldable<TyCtxt<'tcx>> + 'tcx> ToUnivers
     }
 }
 
-impl<'tcx> ToUniverseInfo<'tcx>
-    for Canonical<'tcx, ty::ParamEnvAnd<'tcx, type_op::AscribeUserType<'tcx>>>
-{
+impl<'tcx> ToUniverseInfo<'tcx> for CanonicalTypeOpAscribeUserTypeGoal<'tcx> {
     fn to_universe_info(self, base_universe: ty::UniverseIndex) -> UniverseInfo<'tcx> {
         UniverseInfo(UniverseInfoInner::TypeOp(Rc::new(AscribeUserTypeQuery {
             canonical_query: self,
@@ -128,7 +128,7 @@ impl<'tcx> ToUniverseInfo<'tcx>
     }
 }
 
-impl<'tcx, F> ToUniverseInfo<'tcx> for Canonical<'tcx, type_op::custom::CustomTypeOp<F>> {
+impl<'tcx, F> ToUniverseInfo<'tcx> for CanonicalQueryInput<'tcx, type_op::custom::CustomTypeOp<F>> {
     fn to_universe_info(self, _base_universe: ty::UniverseIndex) -> UniverseInfo<'tcx> {
         // We can't rerun custom type ops.
         UniverseInfo::other()
@@ -211,16 +211,15 @@ trait TypeOpInfo<'tcx> {
 }
 
 struct PredicateQuery<'tcx> {
-    canonical_query:
-        Canonical<'tcx, ty::ParamEnvAnd<'tcx, type_op::prove_predicate::ProvePredicate<'tcx>>>,
+    canonical_query: CanonicalTypeOpProvePredicateGoal<'tcx>,
     base_universe: ty::UniverseIndex,
 }
 
 impl<'tcx> TypeOpInfo<'tcx> for PredicateQuery<'tcx> {
     fn fallback_error(&self, tcx: TyCtxt<'tcx>, span: Span) -> Diag<'tcx> {
         tcx.dcx().create_err(HigherRankedLifetimeError {
             cause: Some(HigherRankedErrorCause::CouldNotProve {
-                predicate: self.canonical_query.value.value.predicate.to_string(),
+                predicate: self.canonical_query.canonical.value.value.predicate.to_string(),
             }),
             span,
         })
@@ -253,7 +252,7 @@ impl<'tcx> TypeOpInfo<'tcx> for PredicateQuery<'tcx> {
 }
 
 struct NormalizeQuery<'tcx, T> {
-    canonical_query: Canonical<'tcx, ty::ParamEnvAnd<'tcx, type_op::Normalize<T>>>,
+    canonical_query: CanonicalTypeOpNormalizeGoal<'tcx, T>,
     base_universe: ty::UniverseIndex,
 }
 
@@ -264,7 +263,7 @@ where
     fn fallback_error(&self, tcx: TyCtxt<'tcx>, span: Span) -> Diag<'tcx> {
         tcx.dcx().create_err(HigherRankedLifetimeError {
             cause: Some(HigherRankedErrorCause::CouldNotNormalize {
-                value: self.canonical_query.value.value.value.to_string(),
+                value: self.canonical_query.canonical.value.value.value.to_string(),
             }),
             span,
         })
@@ -306,7 +305,7 @@ where
 }
 
 struct AscribeUserTypeQuery<'tcx> {
-    canonical_query: Canonical<'tcx, ty::ParamEnvAnd<'tcx, type_op::AscribeUserType<'tcx>>>,
+    canonical_query: CanonicalTypeOpAscribeUserTypeGoal<'tcx>,
     base_universe: ty::UniverseIndex,
 }
 

compiler/rustc_borrowck/src/type_check/canonical.rs

@@ -137,7 +137,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
         let _: Result<_, ErrorGuaranteed> = self.fully_perform_op(
             locations,
             category,
-            param_env.and(type_op::prove_predicate::ProvePredicate::new(predicate)),
+            param_env.and(type_op::prove_predicate::ProvePredicate { predicate }),
         );
     }
 
@@ -162,7 +162,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
         let result: Result<_, ErrorGuaranteed> = self.fully_perform_op(
             location.to_locations(),
             category,
-            param_env.and(type_op::normalize::Normalize::new(value)),
+            param_env.and(type_op::normalize::Normalize { value }),
         );
         result.unwrap_or(value)
     }
@@ -223,7 +223,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
         let _: Result<_, ErrorGuaranteed> = self.fully_perform_op(
             Locations::All(span),
             ConstraintCategory::Boring,
-            self.param_env.and(type_op::ascribe_user_type::AscribeUserType::new(mir_ty, user_ty)),
+            self.param_env.and(type_op::ascribe_user_type::AscribeUserType { mir_ty, user_ty }),
         );
     }
 

compiler/rustc_borrowck/src/type_check/free_region_relations.rs

@@ -280,7 +280,7 @@ impl<'tcx> UniversalRegionRelationsBuilder<'_, 'tcx> {
             }
             let TypeOpOutput { output: norm_ty, constraints: constraints_normalize, .. } = self
                 .param_env
-                .and(type_op::normalize::Normalize::new(ty))
+                .and(type_op::normalize::Normalize { value: ty })
                 .fully_perform(self.infcx, span)
                 .unwrap_or_else(|guar| TypeOpOutput {
                     output: Ty::new_error(self.infcx.tcx, guar),
@@ -318,7 +318,7 @@ impl<'tcx> UniversalRegionRelationsBuilder<'_, 'tcx> {
             for &(ty, _) in tcx.assumed_wf_types(tcx.local_parent(defining_ty_def_id)) {
                 let result: Result<_, ErrorGuaranteed> = self
                     .param_env
-                    .and(type_op::normalize::Normalize::new(ty))
+                    .and(type_op::normalize::Normalize { value: ty })
                     .fully_perform(self.infcx, span);
                 let Ok(TypeOpOutput { output: norm_ty, constraints: c, .. }) = result else {
                     continue;
@@ -373,7 +373,7 @@ impl<'tcx> UniversalRegionRelationsBuilder<'_, 'tcx> {
     ) -> Option<&'tcx QueryRegionConstraints<'tcx>> {
         let TypeOpOutput { output: bounds, constraints, .. } = self
             .param_env
-            .and(type_op::implied_outlives_bounds::ImpliedOutlivesBounds { ty })
+            .and(type_op::ImpliedOutlivesBounds { ty })
             .fully_perform(self.infcx, span)
             .map_err(|_: ErrorGuaranteed| debug!("failed to compute implied bounds {:?}", ty))
             .ok()?;

compiler/rustc_borrowck/src/type_check/liveness/trace.rs

@@ -11,8 +11,7 @@ use rustc_mir_dataflow::impls::MaybeInitializedPlaces;
 use rustc_mir_dataflow::move_paths::{HasMoveData, MoveData, MovePathIndex};
 use rustc_mir_dataflow::points::{DenseLocationMap, PointIndex};
 use rustc_span::DUMMY_SP;
-use rustc_trait_selection::traits::query::type_op::outlives::DropckOutlives;
-use rustc_trait_selection::traits::query::type_op::{TypeOp, TypeOpOutput};
+use rustc_trait_selection::traits::query::type_op::{DropckOutlives, TypeOp, TypeOpOutput};
 use tracing::debug;
 
 use crate::location::RichLocation;
@@ -632,7 +631,7 @@ impl<'tcx> LivenessContext<'_, '_, '_, 'tcx> {
 
         match typeck
             .param_env
-            .and(DropckOutlives::new(dropped_ty))
+            .and(DropckOutlives { dropped_ty })
             .fully_perform(typeck.infcx, DUMMY_SP)
         {
             Ok(TypeOpOutput { output, constraints, .. }) => {

compiler/rustc_hir_analysis/src/check/wfcheck.rs

@@ -1875,24 +1875,15 @@ fn check_variances_for_type_defn<'tcx>(
     item: &'tcx hir::Item<'tcx>,
     hir_generics: &hir::Generics<'tcx>,
 ) {
-    let identity_args = ty::GenericArgs::identity_for_item(tcx, item.owner_id);
-
     match item.kind {
         ItemKind::Enum(..) | ItemKind::Struct(..) | ItemKind::Union(..) => {
-            for field in tcx.adt_def(item.owner_id).all_fields() {
-                if field.ty(tcx, identity_args).references_error() {
-                    return;
-                }
-            }
+            // Ok
         }
         ItemKind::TyAlias(..) => {
             assert!(
                 tcx.type_alias_is_lazy(item.owner_id),
                 "should not be computing variance of non-weak type alias"
             );
-            if tcx.type_of(item.owner_id).skip_binder().references_error() {
-                return;
-            }
         }
         kind => span_bug!(item.span, "cannot compute the variances of {kind:?}"),
     }
@@ -1955,6 +1946,15 @@ fn check_variances_for_type_defn<'tcx>(
             continue;
         }
 
+        // Look for `ErrorGuaranteed` deeply within this type.
+        if let ControlFlow::Break(ErrorGuaranteed { .. }) = tcx
+            .type_of(item.owner_id)
+            .instantiate_identity()
+            .visit_with(&mut HasErrorDeep { tcx, seen: Default::default() })
+        {
+            continue;
+        }
+
         match hir_param.name {
             hir::ParamName::Error => {}
             _ => {
@@ -1965,6 +1965,46 @@ fn check_variances_for_type_defn<'tcx>(
     }
 }
 
+/// Look for `ErrorGuaranteed` deeply within structs' (unsubstituted) fields.
+struct HasErrorDeep<'tcx> {
+    tcx: TyCtxt<'tcx>,
+    seen: FxHashSet<DefId>,
+}
+impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for HasErrorDeep<'tcx> {
+    type Result = ControlFlow<ErrorGuaranteed>;
+
+    fn visit_ty(&mut self, ty: Ty<'tcx>) -> Self::Result {
+        match *ty.kind() {
+            ty::Adt(def, _) => {
+                if self.seen.insert(def.did()) {
+                    for field in def.all_fields() {
+                        self.tcx.type_of(field.did).instantiate_identity().visit_with(self)?;
+                    }
+                }
+            }
+            ty::Error(guar) => return ControlFlow::Break(guar),
+            _ => {}
+        }
+        ty.super_visit_with(self)
+    }
+
+    fn visit_region(&mut self, r: ty::Region<'tcx>) -> Self::Result {
+        if let Err(guar) = r.error_reported() {
+            ControlFlow::Break(guar)
+        } else {
+            ControlFlow::Continue(())
+        }
+    }
+
+    fn visit_const(&mut self, c: ty::Const<'tcx>) -> Self::Result {
+        if let Err(guar) = c.error_reported() {
+            ControlFlow::Break(guar)
+        } else {
+            ControlFlow::Continue(())
+        }
+    }
+}
+
 fn report_bivariance<'tcx>(
     tcx: TyCtxt<'tcx>,
     param: &'tcx hir::GenericParam<'tcx>,

compiler/rustc_hir_typeck/src/_match.rs

@@ -235,8 +235,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             Some(ret_coercion) => {
                 let ret_ty = ret_coercion.borrow().expected_ty();
                 let ret_ty = self.infcx.shallow_resolve(ret_ty);
-                self.can_coerce(arm_ty, ret_ty)
-                    && prior_arm.is_none_or(|(_, ty, _)| self.can_coerce(ty, ret_ty))
+                self.may_coerce(arm_ty, ret_ty)
+                    && prior_arm.is_none_or(|(_, ty, _)| self.may_coerce(ty, ret_ty))
                     // The match arms need to unify for the case of `impl Trait`.
                     && !matches!(ret_ty.kind(), ty::Alias(ty::Opaque, ..))
             }

compiler/rustc_hir_typeck/src/cast.rs

@@ -409,7 +409,7 @@ impl<'a, 'tcx> CastCheck<'tcx> {
                 let mut sugg_mutref = false;
                 if let ty::Ref(reg, cast_ty, mutbl) = *self.cast_ty.kind() {
                     if let ty::RawPtr(expr_ty, _) = *self.expr_ty.kind()
-                        && fcx.can_coerce(
+                        && fcx.may_coerce(
                             Ty::new_ref(fcx.tcx, fcx.tcx.lifetimes.re_erased, expr_ty, mutbl),
                             self.cast_ty,
                         )
@@ -418,22 +418,22 @@ impl<'a, 'tcx> CastCheck<'tcx> {
                     } else if let ty::Ref(expr_reg, expr_ty, expr_mutbl) = *self.expr_ty.kind()
                         && expr_mutbl == Mutability::Not
                         && mutbl == Mutability::Mut
-                        && fcx.can_coerce(Ty::new_mut_ref(fcx.tcx, expr_reg, expr_ty), self.cast_ty)
+                        && fcx.may_coerce(Ty::new_mut_ref(fcx.tcx, expr_reg, expr_ty), self.cast_ty)
                     {
                         sugg_mutref = true;
                     }
 
                     if !sugg_mutref
                         && sugg == None
-                        && fcx.can_coerce(
+                        && fcx.may_coerce(
                             Ty::new_ref(fcx.tcx, reg, self.expr_ty, mutbl),
                             self.cast_ty,
                         )
                     {
                         sugg = Some((format!("&{}", mutbl.prefix_str()), false));
                     }
                 } else if let ty::RawPtr(_, mutbl) = *self.cast_ty.kind()
-                    && fcx.can_coerce(
+                    && fcx.may_coerce(
                         Ty::new_ref(fcx.tcx, fcx.tcx.lifetimes.re_erased, self.expr_ty, mutbl),
                         self.cast_ty,
                     )

compiler/rustc_hir_typeck/src/coercion.rs

@@ -1083,24 +1083,42 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         })
     }
 
-    /// Same as `coerce()`, but without side-effects.
+    /// Probe whether `expr_ty` can be coerced to `target_ty`. This has no side-effects,
+    /// and may return false positives if types are not yet fully constrained by inference.
     ///
-    /// Returns false if the coercion creates any obligations that result in
-    /// errors.
-    pub(crate) fn can_coerce(&self, expr_ty: Ty<'tcx>, target: Ty<'tcx>) -> bool {
-        // FIXME(-Znext-solver): We need to structurally resolve both types here.
-        let source = self.resolve_vars_with_obligations(expr_ty);
-        debug!("coercion::can_with_predicates({:?} -> {:?})", source, target);
-
+    /// Returns false if the coercion is not possible, or if the coercion creates any
+    /// sub-obligations that result in errors.
+    ///
+    /// This should only be used for diagnostics.
+    pub(crate) fn may_coerce(&self, expr_ty: Ty<'tcx>, target_ty: Ty<'tcx>) -> bool {
         let cause = self.cause(DUMMY_SP, ObligationCauseCode::ExprAssignable);
         // We don't ever need two-phase here since we throw out the result of the coercion.
         // We also just always set `coerce_never` to true, since this is a heuristic.
-        let coerce = Coerce::new(self, cause, AllowTwoPhase::No, true);
+        let coerce = Coerce::new(self, cause.clone(), AllowTwoPhase::No, true);
         self.probe(|_| {
-            let Ok(ok) = coerce.coerce(source, target) else {
+            // Make sure to structurally resolve the types, since we use
+            // the `TyKind`s heavily in coercion.
+            let ocx = ObligationCtxt::new(self);
+            let structurally_resolve = |ty| {
+                let ty = self.shallow_resolve(ty);
+                if self.next_trait_solver()
+                    && let ty::Alias(..) = ty.kind()
+                {
+                    ocx.structurally_normalize(&cause, self.param_env, ty)
+                } else {
+                    Ok(ty)
+                }
+            };
+            let Ok(expr_ty) = structurally_resolve(expr_ty) else {
+                return false;
+            };
+            let Ok(target_ty) = structurally_resolve(target_ty) else {
+                return false;
+            };
+
+            let Ok(ok) = coerce.coerce(expr_ty, target_ty) else {
                 return false;
             };
-            let ocx = ObligationCtxt::new(self);
             ocx.register_obligations(ok.obligations);
             ocx.select_where_possible().is_empty()
         })
@@ -1369,7 +1387,7 @@ pub fn can_coerce<'tcx>(
 ) -> bool {
     let root_ctxt = crate::typeck_root_ctxt::TypeckRootCtxt::new(tcx, body_id);
     let fn_ctxt = FnCtxt::new(&root_ctxt, param_env, body_id);
-    fn_ctxt.can_coerce(ty, output_ty)
+    fn_ctxt.may_coerce(ty, output_ty)
 }
 
 /// CoerceMany encapsulates the pattern you should use when you have