Uplift complex type ops back into typeck so we can call them locally

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

@@ -3,9 +3,9 @@ use rustc_index::bit_set::HybridBitSet;
 use rustc_index::interval::IntervalSet;
 use rustc_infer::infer::canonical::QueryRegionConstraints;
 use rustc_middle::mir::{BasicBlock, Body, ConstraintCategory, Local, Location};
+use rustc_middle::traits::query::DropckOutlivesResult;
 use rustc_middle::ty::{Ty, TyCtxt, TypeVisitable, TypeVisitableExt};
 use rustc_span::DUMMY_SP;
-use rustc_trait_selection::traits::query::dropck_outlives::DropckOutlivesResult;
 use rustc_trait_selection::traits::query::type_op::outlives::DropckOutlives;
 use rustc_trait_selection::traits::query::type_op::{TypeOp, TypeOpOutput};
 use std::rc::Rc;

compiler/rustc_trait_selection/src/traits/query/dropck_outlives.rs

@@ -1,6 +1,11 @@
-use rustc_middle::ty::{self, Ty, TyCtxt};
+use crate::traits::query::normalize::QueryNormalizeExt;
+use crate::traits::query::NoSolution;
+use crate::traits::{Normalized, ObligationCause, ObligationCtxt};
 
-pub use rustc_middle::traits::query::{DropckConstraint, DropckOutlivesResult};
+use rustc_data_structures::fx::FxHashSet;
+use rustc_middle::traits::query::{DropckConstraint, DropckOutlivesResult};
+use rustc_middle::ty::{self, EarlyBinder, ParamEnvAnd, Ty, TyCtxt};
+use rustc_span::source_map::{Span, DUMMY_SP};
 
 /// This returns true if the type `ty` is "trivial" for
 /// dropck-outlives -- that is, if it doesn't require any types to
@@ -71,3 +76,263 @@ pub fn trivial_dropck_outlives<'tcx>(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> bool {
         | ty::Generator(..) => false,
     }
 }
+
+pub fn compute_dropck_outlives_inner<'tcx>(
+    ocx: &ObligationCtxt<'_, 'tcx>,
+    goal: ParamEnvAnd<'tcx, Ty<'tcx>>,
+) -> Result<DropckOutlivesResult<'tcx>, NoSolution> {
+    let tcx = ocx.infcx.tcx;
+    let ParamEnvAnd { param_env, value: for_ty } = goal;
+
+    let mut result = DropckOutlivesResult { kinds: vec![], overflows: vec![] };
+
+    // A stack of types left to process. Each round, we pop
+    // something from the stack and invoke
+    // `dtorck_constraint_for_ty_inner`. This may produce new types that
+    // have to be pushed on the stack. This continues until we have explored
+    // all the reachable types from the type `for_ty`.
+    //
+    // Example: Imagine that we have the following code:
+    //
+    // ```rust
+    // struct A {
+    //     value: B,
+    //     children: Vec<A>,
+    // }
+    //
+    // struct B {
+    //     value: u32
+    // }
+    //
+    // fn f() {
+    //   let a: A = ...;
+    //   ..
+    // } // here, `a` is dropped
+    // ```
+    //
+    // at the point where `a` is dropped, we need to figure out
+    // which types inside of `a` contain region data that may be
+    // accessed by any destructors in `a`. We begin by pushing `A`
+    // onto the stack, as that is the type of `a`. We will then
+    // invoke `dtorck_constraint_for_ty_inner` which will expand `A`
+    // into the types of its fields `(B, Vec<A>)`. These will get
+    // pushed onto the stack. Eventually, expanding `Vec<A>` will
+    // lead to us trying to push `A` a second time -- to prevent
+    // infinite recursion, we notice that `A` was already pushed
+    // once and stop.
+    let mut ty_stack = vec![(for_ty, 0)];
+
+    // Set used to detect infinite recursion.
+    let mut ty_set = FxHashSet::default();
+
+    let cause = ObligationCause::dummy();
+    let mut constraints = DropckConstraint::empty();
+    while let Some((ty, depth)) = ty_stack.pop() {
+        debug!(
+            "{} kinds, {} overflows, {} ty_stack",
+            result.kinds.len(),
+            result.overflows.len(),
+            ty_stack.len()
+        );
+        dtorck_constraint_for_ty_inner(tcx, DUMMY_SP, for_ty, depth, ty, &mut constraints)?;
+
+        // "outlives" represent types/regions that may be touched
+        // by a destructor.
+        result.kinds.append(&mut constraints.outlives);
+        result.overflows.append(&mut constraints.overflows);
+
+        // If we have even one overflow, we should stop trying to evaluate further --
+        // chances are, the subsequent overflows for this evaluation won't provide useful
+        // information and will just decrease the speed at which we can emit these errors
+        // (since we'll be printing for just that much longer for the often enormous types
+        // that result here).
+        if !result.overflows.is_empty() {
+            break;
+        }
+
+        // dtorck types are "types that will get dropped but which
+        // do not themselves define a destructor", more or less. We have
+        // to push them onto the stack to be expanded.
+        for ty in constraints.dtorck_types.drain(..) {
+            let Normalized { value: ty, obligations } =
+                ocx.infcx.at(&cause, param_env).query_normalize(ty)?;
+            ocx.register_obligations(obligations);
+
+            debug!("dropck_outlives: ty from dtorck_types = {:?}", ty);
+
+            match ty.kind() {
+                // All parameters live for the duration of the
+                // function.
+                ty::Param(..) => {}
+
+                // A projection that we couldn't resolve - it
+                // might have a destructor.
+                ty::Alias(..) => {
+                    result.kinds.push(ty.into());
+                }
+
+                _ => {
+                    if ty_set.insert(ty) {
+                        ty_stack.push((ty, depth + 1));
+                    }
+                }
+            }
+        }
+    }
+
+    debug!("dropck_outlives: result = {:#?}", result);
+    Ok(result)
+}
+
+/// Returns a set of constraints that needs to be satisfied in
+/// order for `ty` to be valid for destruction.
+pub fn dtorck_constraint_for_ty_inner<'tcx>(
+    tcx: TyCtxt<'tcx>,
+    span: Span,
+    for_ty: Ty<'tcx>,
+    depth: usize,
+    ty: Ty<'tcx>,
+    constraints: &mut DropckConstraint<'tcx>,
+) -> Result<(), NoSolution> {
+    debug!("dtorck_constraint_for_ty_inner({:?}, {:?}, {:?}, {:?})", span, for_ty, depth, ty);
+
+    if !tcx.recursion_limit().value_within_limit(depth) {
+        constraints.overflows.push(ty);
+        return Ok(());
+    }
+
+    if trivial_dropck_outlives(tcx, ty) {
+        return Ok(());
+    }
+
+    match ty.kind() {
+        ty::Bool
+        | ty::Char
+        | ty::Int(_)
+        | ty::Uint(_)
+        | ty::Float(_)
+        | ty::Str
+        | ty::Never
+        | ty::Foreign(..)
+        | ty::RawPtr(..)
+        | ty::Ref(..)
+        | ty::FnDef(..)
+        | ty::FnPtr(_)
+        | ty::GeneratorWitness(..)
+        | ty::GeneratorWitnessMIR(..) => {
+            // these types never have a destructor
+        }
+
+        ty::Array(ety, _) | ty::Slice(ety) => {
+            // single-element containers, behave like their element
+            rustc_data_structures::stack::ensure_sufficient_stack(|| {
+                dtorck_constraint_for_ty_inner(tcx, span, for_ty, depth + 1, *ety, constraints)
+            })?;
+        }
+
+        ty::Tuple(tys) => rustc_data_structures::stack::ensure_sufficient_stack(|| {
+            for ty in tys.iter() {
+                dtorck_constraint_for_ty_inner(tcx, span, for_ty, depth + 1, ty, constraints)?;
+            }
+            Ok::<_, NoSolution>(())
+        })?,
+
+        ty::Closure(_, substs) => {
+            if !substs.as_closure().is_valid() {
+                // By the time this code runs, all type variables ought to
+                // be fully resolved.
+
+                tcx.sess.delay_span_bug(
+                    span,
+                    format!("upvar_tys for closure not found. Expected capture information for closure {ty}",),
+                );
+                return Err(NoSolution);
+            }
+
+            rustc_data_structures::stack::ensure_sufficient_stack(|| {
+                for ty in substs.as_closure().upvar_tys() {
+                    dtorck_constraint_for_ty_inner(tcx, span, for_ty, depth + 1, ty, constraints)?;
+                }
+                Ok::<_, NoSolution>(())
+            })?
+        }
+
+        ty::Generator(_, substs, _movability) => {
+            // rust-lang/rust#49918: types can be constructed, stored
+            // in the interior, and sit idle when generator yields
+            // (and is subsequently dropped).
+            //
+            // It would be nice to descend into interior of a
+            // generator to determine what effects dropping it might
+            // have (by looking at any drop effects associated with
+            // its interior).
+            //
+            // However, the interior's representation uses things like
+            // GeneratorWitness that explicitly assume they are not
+            // traversed in such a manner. So instead, we will
+            // simplify things for now by treating all generators as
+            // if they were like trait objects, where its upvars must
+            // all be alive for the generator's (potential)
+            // destructor.
+            //
+            // In particular, skipping over `_interior` is safe
+            // because any side-effects from dropping `_interior` can
+            // only take place through references with lifetimes
+            // derived from lifetimes attached to the upvars and resume
+            // argument, and we *do* incorporate those here.
+
+            if !substs.as_generator().is_valid() {
+                // By the time this code runs, all type variables ought to
+                // be fully resolved.
+                tcx.sess.delay_span_bug(
+                    span,
+                    format!("upvar_tys for generator not found. Expected capture information for generator {ty}",),
+                );
+                return Err(NoSolution);
+            }
+
+            constraints.outlives.extend(
+                substs
+                    .as_generator()
+                    .upvar_tys()
+                    .map(|t| -> ty::subst::GenericArg<'tcx> { t.into() }),
+            );
+            constraints.outlives.push(substs.as_generator().resume_ty().into());
+        }
+
+        ty::Adt(def, substs) => {
+            let DropckConstraint { dtorck_types, outlives, overflows } =
+                tcx.at(span).adt_dtorck_constraint(def.did())?;
+            // FIXME: we can try to recursively `dtorck_constraint_on_ty`
+            // there, but that needs some way to handle cycles.
+            constraints
+                .dtorck_types
+                .extend(dtorck_types.iter().map(|t| EarlyBinder(*t).subst(tcx, substs)));
+            constraints
+                .outlives
+                .extend(outlives.iter().map(|t| EarlyBinder(*t).subst(tcx, substs)));
+            constraints
+                .overflows
+                .extend(overflows.iter().map(|t| EarlyBinder(*t).subst(tcx, substs)));
+        }
+
+        // Objects must be alive in order for their destructor
+        // to be called.
+        ty::Dynamic(..) => {
+            constraints.outlives.push(ty.into());
+        }
+
+        // Types that can't be resolved. Pass them forward.
+        ty::Alias(..) | ty::Param(..) => {
+            constraints.dtorck_types.push(ty);
+        }
+
+        ty::Placeholder(..) | ty::Bound(..) | ty::Infer(..) | ty::Error(_) => {
+            // By the time this code runs, all type variables ought to
+            // be fully resolved.
+            return Err(NoSolution);
+        }
+    }
+
+    Ok(())
+}

compiler/rustc_trait_selection/src/traits/query/type_op/ascribe_user_type.rs

@@ -1,9 +1,13 @@
 use crate::infer::canonical::{Canonical, CanonicalQueryResponse};
 use crate::traits::ObligationCtxt;
+use rustc_hir::def_id::{DefId, CRATE_DEF_ID};
+use rustc_infer::traits::Obligation;
 use rustc_middle::traits::query::NoSolution;
-use rustc_middle::ty::{ParamEnvAnd, TyCtxt};
+use rustc_middle::traits::{ObligationCause, ObligationCauseCode};
+use rustc_middle::ty::{self, ParamEnvAnd, Ty, TyCtxt, UserSelfTy, UserSubsts, UserType};
 
 pub use rustc_middle::traits::query::type_op::AscribeUserType;
+use rustc_span::{Span, DUMMY_SP};
 
 impl<'tcx> super::QueryTypeOp<'tcx> for AscribeUserType<'tcx> {
     type QueryResponse = ();
@@ -23,9 +27,114 @@ impl<'tcx> super::QueryTypeOp<'tcx> for AscribeUserType<'tcx> {
     }
 
     fn perform_locally_in_new_solver(
-        _ocx: &ObligationCtxt<'_, 'tcx>,
+        ocx: &ObligationCtxt<'_, 'tcx>,
-        _key: ParamEnvAnd<'tcx, Self>,
+        key: ParamEnvAnd<'tcx, Self>,
     ) -> Result<Self::QueryResponse, NoSolution> {
-        todo!()
+        type_op_ascribe_user_type_with_span(ocx, key, None)
     }
 }
+
+/// The core of the `type_op_ascribe_user_type` query: for diagnostics purposes in NLL HRTB errors,
+/// this query can be re-run to better track the span of the obligation cause, and improve the error
+/// message. Do not call directly unless you're in that very specific context.
+pub fn type_op_ascribe_user_type_with_span<'tcx>(
+    ocx: &ObligationCtxt<'_, 'tcx>,
+    key: ParamEnvAnd<'tcx, AscribeUserType<'tcx>>,
+    span: Option<Span>,
+) -> Result<(), NoSolution> {
+    let (param_env, AscribeUserType { mir_ty, user_ty }) = key.into_parts();
+    debug!("type_op_ascribe_user_type: mir_ty={:?} user_ty={:?}", mir_ty, user_ty);
+    let span = span.unwrap_or(DUMMY_SP);
+    match user_ty {
+        UserType::Ty(user_ty) => relate_mir_and_user_ty(ocx, param_env, span, mir_ty, user_ty)?,
+        UserType::TypeOf(def_id, user_substs) => {
+            relate_mir_and_user_substs(ocx, param_env, span, mir_ty, def_id, user_substs)?
+        }
+    };
+    Ok(())
+}
+
+#[instrument(level = "debug", skip(ocx, param_env, span))]
+fn relate_mir_and_user_ty<'tcx>(
+    ocx: &ObligationCtxt<'_, 'tcx>,
+    param_env: ty::ParamEnv<'tcx>,
+    span: Span,
+    mir_ty: Ty<'tcx>,
+    user_ty: Ty<'tcx>,
+) -> Result<(), NoSolution> {
+    let cause = ObligationCause::dummy_with_span(span);
+    let user_ty = ocx.normalize(&cause, param_env, user_ty);
+    ocx.eq(&cause, param_env, mir_ty, user_ty)?;
+
+    // FIXME(#104764): We should check well-formedness before normalization.
+    let predicate = ty::Binder::dummy(ty::PredicateKind::WellFormed(user_ty.into()));
+    ocx.register_obligation(Obligation::new(ocx.infcx.tcx, cause, param_env, predicate));
+    Ok(())
+}
+
+#[instrument(level = "debug", skip(ocx, param_env, span))]
+fn relate_mir_and_user_substs<'tcx>(
+    ocx: &ObligationCtxt<'_, 'tcx>,
+    param_env: ty::ParamEnv<'tcx>,
+    span: Span,
+    mir_ty: Ty<'tcx>,
+    def_id: DefId,
+    user_substs: UserSubsts<'tcx>,
+) -> Result<(), NoSolution> {
+    let param_env = param_env.without_const();
+    let UserSubsts { user_self_ty, substs } = user_substs;
+    let tcx = ocx.infcx.tcx;
+    let cause = ObligationCause::dummy_with_span(span);
+
+    let ty = tcx.type_of(def_id).subst(tcx, substs);
+    let ty = ocx.normalize(&cause, param_env, ty);
+    debug!("relate_type_and_user_type: ty of def-id is {:?}", ty);
+
+    ocx.eq(&cause, param_env, mir_ty, ty)?;
+
+    // Prove the predicates coming along with `def_id`.
+    //
+    // Also, normalize the `instantiated_predicates`
+    // because otherwise we wind up with duplicate "type
+    // outlives" error messages.
+    let instantiated_predicates = tcx.predicates_of(def_id).instantiate(tcx, substs);
+
+    debug!(?instantiated_predicates);
+    for (instantiated_predicate, predicate_span) in instantiated_predicates {
+        let span = if span == DUMMY_SP { predicate_span } else { span };
+        let cause = ObligationCause::new(
+            span,
+            CRATE_DEF_ID,
+            ObligationCauseCode::AscribeUserTypeProvePredicate(predicate_span),
+        );
+        let instantiated_predicate =
+            ocx.normalize(&cause.clone(), param_env, instantiated_predicate);
+
+        ocx.register_obligation(Obligation::new(tcx, cause, param_env, instantiated_predicate));
+    }
+
+    if let Some(UserSelfTy { impl_def_id, self_ty }) = user_self_ty {
+        let self_ty = ocx.normalize(&cause, param_env, self_ty);
+        let impl_self_ty = tcx.type_of(impl_def_id).subst(tcx, substs);
+        let impl_self_ty = ocx.normalize(&cause, param_env, impl_self_ty);
+
+        ocx.eq(&cause, param_env, self_ty, impl_self_ty)?;
+        let predicate = ty::Binder::dummy(ty::PredicateKind::WellFormed(impl_self_ty.into()));
+        ocx.register_obligation(Obligation::new(tcx, cause.clone(), param_env, predicate));
+    }
+
+    // In addition to proving the predicates, we have to
+    // prove that `ty` is well-formed -- this is because
+    // the WF of `ty` is predicated on the substs being
+    // well-formed, and we haven't proven *that*. We don't
+    // want to prove the WF of types from  `substs` directly because they
+    // haven't been normalized.
+    //
+    // FIXME(nmatsakis): Well, perhaps we should normalize
+    // them?  This would only be relevant if some input
+    // type were ill-formed but did not appear in `ty`,
+    // which...could happen with normalization...
+    let predicate = ty::Binder::dummy(ty::PredicateKind::WellFormed(ty.into()));
+    ocx.register_obligation(Obligation::new(tcx, cause, param_env, predicate));
+    Ok(())
+}

compiler/rustc_trait_selection/src/traits/query/type_op/implied_outlives_bounds.rs

@@ -1,8 +1,15 @@
-use crate::infer::canonical::{Canonical, CanonicalQueryResponse};
+use crate::traits::query::NoSolution;
+use crate::traits::wf;
 use crate::traits::ObligationCtxt;
+
+use rustc_infer::infer::canonical::Canonical;
+use rustc_infer::infer::outlives::components::{push_outlives_components, Component};
 use rustc_infer::traits::query::OutlivesBound;
-use rustc_middle::traits::query::NoSolution;
+use rustc_middle::infer::canonical::CanonicalQueryResponse;
-use rustc_middle::ty::{self, ParamEnvAnd, Ty, TyCtxt};
+use rustc_middle::ty::{self, ParamEnvAnd, Ty, TyCtxt, TypeVisitableExt};
+use rustc_span::def_id::CRATE_DEF_ID;
+use rustc_span::source_map::DUMMY_SP;
+use smallvec::{smallvec, SmallVec};
 
 #[derive(Copy, Clone, Debug, HashStable, TypeFoldable, TypeVisitable, Lift)]
 pub struct ImpliedOutlivesBounds<'tcx> {
@@ -42,9 +49,167 @@ impl<'tcx> super::QueryTypeOp<'tcx> for ImpliedOutlivesBounds<'tcx> {
     }
 
     fn perform_locally_in_new_solver(
-        _ocx: &ObligationCtxt<'_, 'tcx>,
+        ocx: &ObligationCtxt<'_, 'tcx>,
-        _key: ParamEnvAnd<'tcx, Self>,
+        key: ParamEnvAnd<'tcx, Self>,
     ) -> Result<Self::QueryResponse, NoSolution> {
-        todo!()
+        compute_implied_outlives_bounds_inner(ocx, key.param_env, key.value.ty)
     }
 }
+
+pub fn compute_implied_outlives_bounds_inner<'tcx>(
+    ocx: &ObligationCtxt<'_, 'tcx>,
+    param_env: ty::ParamEnv<'tcx>,
+    ty: Ty<'tcx>,
+) -> Result<Vec<OutlivesBound<'tcx>>, NoSolution> {
+    let tcx = ocx.infcx.tcx;
+
+    // Sometimes when we ask what it takes for T: WF, we get back that
+    // U: WF is required; in that case, we push U onto this stack and
+    // process it next. Because the resulting predicates aren't always
+    // guaranteed to be a subset of the original type, so we need to store the
+    // WF args we've computed in a set.
+    let mut checked_wf_args = rustc_data_structures::fx::FxHashSet::default();
+    let mut wf_args = vec![ty.into()];
+
+    let mut outlives_bounds: Vec<ty::OutlivesPredicate<ty::GenericArg<'tcx>, ty::Region<'tcx>>> =
+        vec![];
+
+    while let Some(arg) = wf_args.pop() {
+        if !checked_wf_args.insert(arg) {
+            continue;
+        }
+
+        // Compute the obligations for `arg` to be well-formed. If `arg` is
+        // an unresolved inference variable, just substituted an empty set
+        // -- because the return type here is going to be things we *add*
+        // to the environment, it's always ok for this set to be smaller
+        // than the ultimate set. (Note: normally there won't be
+        // unresolved inference variables here anyway, but there might be
+        // during typeck under some circumstances.)
+        //
+        // FIXME(@lcnr): It's not really "always fine", having fewer implied
+        // bounds can be backward incompatible, e.g. #101951 was caused by
+        // us not dealing with inference vars in `TypeOutlives` predicates.
+        let obligations = wf::obligations(ocx.infcx, param_env, CRATE_DEF_ID, 0, arg, DUMMY_SP)
+            .unwrap_or_default();
+
+        for obligation in obligations {
+            debug!(?obligation);
+            assert!(!obligation.has_escaping_bound_vars());
+
+            // While these predicates should all be implied by other parts of
+            // the program, they are still relevant as they may constrain
+            // inference variables, which is necessary to add the correct
+            // implied bounds in some cases, mostly when dealing with projections.
+            //
+            // Another important point here: we only register `Projection`
+            // predicates, since otherwise we might register outlives
+            // predicates containing inference variables, and we don't
+            // learn anything new from those.
+            if obligation.predicate.has_non_region_infer() {
+                match obligation.predicate.kind().skip_binder() {
+                    ty::PredicateKind::Clause(ty::Clause::Projection(..))
+                    | ty::PredicateKind::AliasRelate(..) => {
+                        ocx.register_obligation(obligation.clone());
+                    }
+                    _ => {}
+                }
+            }
+
+            let pred = match obligation.predicate.kind().no_bound_vars() {
+                None => continue,
+                Some(pred) => pred,
+            };
+            match pred {
+                ty::PredicateKind::Clause(ty::Clause::Trait(..))
+                // FIXME(const_generics): Make sure that `<'a, 'b, const N: &'a &'b u32>` is sound
+                // if we ever support that
+                | ty::PredicateKind::Clause(ty::Clause::ConstArgHasType(..))
+                | ty::PredicateKind::Subtype(..)
+                | ty::PredicateKind::Coerce(..)
+                | ty::PredicateKind::Clause(ty::Clause::Projection(..))
+                | ty::PredicateKind::ClosureKind(..)
+                | ty::PredicateKind::ObjectSafe(..)
+                | ty::PredicateKind::ConstEvaluatable(..)
+                | ty::PredicateKind::ConstEquate(..)
+                | ty::PredicateKind::Ambiguous
+                | ty::PredicateKind::AliasRelate(..)
+                | ty::PredicateKind::TypeWellFormedFromEnv(..) => {}
+
+                // We need to search through *all* WellFormed predicates
+                ty::PredicateKind::WellFormed(arg) => {
+                    wf_args.push(arg);
+                }
+
+                // We need to register region relationships
+                ty::PredicateKind::Clause(ty::Clause::RegionOutlives(ty::OutlivesPredicate(
+                    r_a,
+                    r_b,
+                ))) => outlives_bounds.push(ty::OutlivesPredicate(r_a.into(), r_b)),
+
+                ty::PredicateKind::Clause(ty::Clause::TypeOutlives(ty::OutlivesPredicate(
+                    ty_a,
+                    r_b,
+                ))) => outlives_bounds.push(ty::OutlivesPredicate(ty_a.into(), r_b)),
+            }
+        }
+    }
+
+    // This call to `select_all_or_error` is necessary to constrain inference variables, which we
+    // use further down when computing the implied bounds.
+    match ocx.select_all_or_error().as_slice() {
+        [] => (),
+        _ => return Err(NoSolution),
+    }
+
+    // We lazily compute the outlives components as
+    // `select_all_or_error` constrains inference variables.
+    let implied_bounds = outlives_bounds
+        .into_iter()
+        .flat_map(|ty::OutlivesPredicate(a, r_b)| match a.unpack() {
+            ty::GenericArgKind::Lifetime(r_a) => vec![OutlivesBound::RegionSubRegion(r_b, r_a)],
+            ty::GenericArgKind::Type(ty_a) => {
+                let ty_a = ocx.infcx.resolve_vars_if_possible(ty_a);
+                let mut components = smallvec![];
+                push_outlives_components(tcx, ty_a, &mut components);
+                implied_bounds_from_components(r_b, components)
+            }
+            ty::GenericArgKind::Const(_) => unreachable!(),
+        })
+        .collect();
+
+    Ok(implied_bounds)
+}
+
+/// When we have an implied bound that `T: 'a`, we can further break
+/// this down to determine what relationships would have to hold for
+/// `T: 'a` to hold. We get to assume that the caller has validated
+/// those relationships.
+fn implied_bounds_from_components<'tcx>(
+    sub_region: ty::Region<'tcx>,
+    sup_components: SmallVec<[Component<'tcx>; 4]>,
+) -> Vec<OutlivesBound<'tcx>> {
+    sup_components
+        .into_iter()
+        .filter_map(|component| {
+            match component {
+                Component::Region(r) => Some(OutlivesBound::RegionSubRegion(sub_region, r)),
+                Component::Param(p) => Some(OutlivesBound::RegionSubParam(sub_region, p)),
+                Component::Alias(p) => Some(OutlivesBound::RegionSubAlias(sub_region, p)),
+                Component::EscapingAlias(_) =>
+                // If the projection has escaping regions, don't
+                // try to infer any implied bounds even for its
+                // free components. This is conservative, because
+                // the caller will still have to prove that those
+                // free components outlive `sub_region`. But the
+                // idea is that the WAY that the caller proves
+                // that may change in the future and we want to
+                // give ourselves room to get smarter here.
+                {
+                    None
+                }
+                Component::UnresolvedInferenceVariable(..) => None,
+            }
+        })
+        .collect()
+}

compiler/rustc_trait_selection/src/traits/query/type_op/outlives.rs

@@ -1,7 +1,9 @@
 use crate::infer::canonical::{Canonical, CanonicalQueryResponse};
-use crate::traits::query::dropck_outlives::{trivial_dropck_outlives, DropckOutlivesResult};
+use crate::traits::query::dropck_outlives::{
+    compute_dropck_outlives_inner, trivial_dropck_outlives,
+};
 use crate::traits::ObligationCtxt;
-use rustc_middle::traits::query::NoSolution;
+use rustc_middle::traits::query::{DropckOutlivesResult, NoSolution};
 use rustc_middle::ty::{ParamEnvAnd, Ty, TyCtxt};
 
 #[derive(Copy, Clone, Debug, HashStable, TypeFoldable, TypeVisitable, Lift)]
@@ -51,9 +53,9 @@ impl<'tcx> super::QueryTypeOp<'tcx> for DropckOutlives<'tcx> {
     }
 
     fn perform_locally_in_new_solver(
-        _ocx: &ObligationCtxt<'_, 'tcx>,
+        ocx: &ObligationCtxt<'_, 'tcx>,
-        _key: ParamEnvAnd<'tcx, Self>,
+        key: ParamEnvAnd<'tcx, Self>,
     ) -> Result<Self::QueryResponse, NoSolution> {
-        todo!()
+        compute_dropck_outlives_inner(ocx, key.param_env.and(key.value.dropped_ty))
     }
 }

compiler/rustc_traits/src/dropck_outlives.rs

@@ -3,17 +3,14 @@ use rustc_hir::def_id::DefId;
 use rustc_infer::infer::canonical::{Canonical, QueryResponse};
 use rustc_infer::infer::TyCtxtInferExt;
 use rustc_middle::query::Providers;
+use rustc_middle::traits::query::{DropckConstraint, DropckOutlivesResult};
 use rustc_middle::ty::InternalSubsts;
-use rustc_middle::ty::{self, EarlyBinder, ParamEnvAnd, Ty, TyCtxt};
+use rustc_middle::ty::TyCtxt;
-use rustc_span::source_map::{Span, DUMMY_SP};
 use rustc_trait_selection::infer::InferCtxtBuilderExt;
-use rustc_trait_selection::traits::query::dropck_outlives::trivial_dropck_outlives;
 use rustc_trait_selection::traits::query::dropck_outlives::{
-    DropckConstraint, DropckOutlivesResult,
+    compute_dropck_outlives_inner, dtorck_constraint_for_ty_inner,
 };
-use rustc_trait_selection::traits::query::normalize::QueryNormalizeExt;
 use rustc_trait_selection::traits::query::{CanonicalTyGoal, NoSolution};
-use rustc_trait_selection::traits::{Normalized, ObligationCause};
 
 pub(crate) fn provide(p: &mut Providers) {
     *p = Providers { dropck_outlives, adt_dtorck_constraint, ..*p };
@@ -26,263 +23,10 @@ fn dropck_outlives<'tcx>(
     debug!("dropck_outlives(goal={:#?})", canonical_goal);
 
     tcx.infer_ctxt().enter_canonical_trait_query(&canonical_goal, |ocx, goal| {
-        let tcx = ocx.infcx.tcx;
+        compute_dropck_outlives_inner(ocx, goal)
-        let ParamEnvAnd { param_env, value: for_ty } = goal;
-
-        let mut result = DropckOutlivesResult { kinds: vec![], overflows: vec![] };
-
-        // A stack of types left to process. Each round, we pop
-        // something from the stack and invoke
-        // `dtorck_constraint_for_ty`. This may produce new types that
-        // have to be pushed on the stack. This continues until we have explored
-        // all the reachable types from the type `for_ty`.
-        //
-        // Example: Imagine that we have the following code:
-        //
-        // ```rust
-        // struct A {
-        //     value: B,
-        //     children: Vec<A>,
-        // }
-        //
-        // struct B {
-        //     value: u32
-        // }
-        //
-        // fn f() {
-        //   let a: A = ...;
-        //   ..
-        // } // here, `a` is dropped
-        // ```
-        //
-        // at the point where `a` is dropped, we need to figure out
-        // which types inside of `a` contain region data that may be
-        // accessed by any destructors in `a`. We begin by pushing `A`
-        // onto the stack, as that is the type of `a`. We will then
-        // invoke `dtorck_constraint_for_ty` which will expand `A`
-        // into the types of its fields `(B, Vec<A>)`. These will get
-        // pushed onto the stack. Eventually, expanding `Vec<A>` will
-        // lead to us trying to push `A` a second time -- to prevent
-        // infinite recursion, we notice that `A` was already pushed
-        // once and stop.
-        let mut ty_stack = vec![(for_ty, 0)];
-
-        // Set used to detect infinite recursion.
-        let mut ty_set = FxHashSet::default();
-
-        let cause = ObligationCause::dummy();
-        let mut constraints = DropckConstraint::empty();
-        while let Some((ty, depth)) = ty_stack.pop() {
-            debug!(
-                "{} kinds, {} overflows, {} ty_stack",
-                result.kinds.len(),
-                result.overflows.len(),
-                ty_stack.len()
-            );
-            dtorck_constraint_for_ty(tcx, DUMMY_SP, for_ty, depth, ty, &mut constraints)?;
-
-            // "outlives" represent types/regions that may be touched
-            // by a destructor.
-            result.kinds.append(&mut constraints.outlives);
-            result.overflows.append(&mut constraints.overflows);
-
-            // If we have even one overflow, we should stop trying to evaluate further --
-            // chances are, the subsequent overflows for this evaluation won't provide useful
-            // information and will just decrease the speed at which we can emit these errors
-            // (since we'll be printing for just that much longer for the often enormous types
-            // that result here).
-            if !result.overflows.is_empty() {
-                break;
-            }
-
-            // dtorck types are "types that will get dropped but which
-            // do not themselves define a destructor", more or less. We have
-            // to push them onto the stack to be expanded.
-            for ty in constraints.dtorck_types.drain(..) {
-                let Normalized { value: ty, obligations } =
-                    ocx.infcx.at(&cause, param_env).query_normalize(ty)?;
-                ocx.register_obligations(obligations);
-
-                debug!("dropck_outlives: ty from dtorck_types = {:?}", ty);
-
-                match ty.kind() {
-                    // All parameters live for the duration of the
-                    // function.
-                    ty::Param(..) => {}
-
-                    // A projection that we couldn't resolve - it
-                    // might have a destructor.
-                    ty::Alias(..) => {
-                        result.kinds.push(ty.into());
-                    }
-
-                    _ => {
-                        if ty_set.insert(ty) {
-                            ty_stack.push((ty, depth + 1));
-                        }
-                    }
-                }
-            }
-        }
-
-        debug!("dropck_outlives: result = {:#?}", result);
-        Ok(result)
     })
 }
 
-/// Returns a set of constraints that needs to be satisfied in
-/// order for `ty` to be valid for destruction.
-fn dtorck_constraint_for_ty<'tcx>(
-    tcx: TyCtxt<'tcx>,
-    span: Span,
-    for_ty: Ty<'tcx>,
-    depth: usize,
-    ty: Ty<'tcx>,
-    constraints: &mut DropckConstraint<'tcx>,
-) -> Result<(), NoSolution> {
-    debug!("dtorck_constraint_for_ty({:?}, {:?}, {:?}, {:?})", span, for_ty, depth, ty);
-
-    if !tcx.recursion_limit().value_within_limit(depth) {
-        constraints.overflows.push(ty);
-        return Ok(());
-    }
-
-    if trivial_dropck_outlives(tcx, ty) {
-        return Ok(());
-    }
-
-    match ty.kind() {
-        ty::Bool
-        | ty::Char
-        | ty::Int(_)
-        | ty::Uint(_)
-        | ty::Float(_)
-        | ty::Str
-        | ty::Never
-        | ty::Foreign(..)
-        | ty::RawPtr(..)
-        | ty::Ref(..)
-        | ty::FnDef(..)
-        | ty::FnPtr(_)
-        | ty::GeneratorWitness(..)
-        | ty::GeneratorWitnessMIR(..) => {
-            // these types never have a destructor
-        }
-
-        ty::Array(ety, _) | ty::Slice(ety) => {
-            // single-element containers, behave like their element
-            rustc_data_structures::stack::ensure_sufficient_stack(|| {
-                dtorck_constraint_for_ty(tcx, span, for_ty, depth + 1, *ety, constraints)
-            })?;
-        }
-
-        ty::Tuple(tys) => rustc_data_structures::stack::ensure_sufficient_stack(|| {
-            for ty in tys.iter() {
-                dtorck_constraint_for_ty(tcx, span, for_ty, depth + 1, ty, constraints)?;
-            }
-            Ok::<_, NoSolution>(())
-        })?,
-
-        ty::Closure(_, substs) => {
-            if !substs.as_closure().is_valid() {
-                // By the time this code runs, all type variables ought to
-                // be fully resolved.
-
-                tcx.sess.delay_span_bug(
-                    span,
-                    format!("upvar_tys for closure not found. Expected capture information for closure {ty}",),
-                );
-                return Err(NoSolution);
-            }
-
-            rustc_data_structures::stack::ensure_sufficient_stack(|| {
-                for ty in substs.as_closure().upvar_tys() {
-                    dtorck_constraint_for_ty(tcx, span, for_ty, depth + 1, ty, constraints)?;
-                }
-                Ok::<_, NoSolution>(())
-            })?
-        }
-
-        ty::Generator(_, substs, _movability) => {
-            // rust-lang/rust#49918: types can be constructed, stored
-            // in the interior, and sit idle when generator yields
-            // (and is subsequently dropped).
-            //
-            // It would be nice to descend into interior of a
-            // generator to determine what effects dropping it might
-            // have (by looking at any drop effects associated with
-            // its interior).
-            //
-            // However, the interior's representation uses things like
-            // GeneratorWitness that explicitly assume they are not
-            // traversed in such a manner. So instead, we will
-            // simplify things for now by treating all generators as
-            // if they were like trait objects, where its upvars must
-            // all be alive for the generator's (potential)
-            // destructor.
-            //
-            // In particular, skipping over `_interior` is safe
-            // because any side-effects from dropping `_interior` can
-            // only take place through references with lifetimes
-            // derived from lifetimes attached to the upvars and resume
-            // argument, and we *do* incorporate those here.
-
-            if !substs.as_generator().is_valid() {
-                // By the time this code runs, all type variables ought to
-                // be fully resolved.
-                tcx.sess.delay_span_bug(
-                    span,
-                    format!("upvar_tys for generator not found. Expected capture information for generator {ty}",),
-                );
-                return Err(NoSolution);
-            }
-
-            constraints.outlives.extend(
-                substs
-                    .as_generator()
-                    .upvar_tys()
-                    .map(|t| -> ty::subst::GenericArg<'tcx> { t.into() }),
-            );
-            constraints.outlives.push(substs.as_generator().resume_ty().into());
-        }
-
-        ty::Adt(def, substs) => {
-            let DropckConstraint { dtorck_types, outlives, overflows } =
-                tcx.at(span).adt_dtorck_constraint(def.did())?;
-            // FIXME: we can try to recursively `dtorck_constraint_on_ty`
-            // there, but that needs some way to handle cycles.
-            constraints
-                .dtorck_types
-                .extend(dtorck_types.iter().map(|t| EarlyBinder(*t).subst(tcx, substs)));
-            constraints
-                .outlives
-                .extend(outlives.iter().map(|t| EarlyBinder(*t).subst(tcx, substs)));
-            constraints
-                .overflows
-                .extend(overflows.iter().map(|t| EarlyBinder(*t).subst(tcx, substs)));
-        }
-
-        // Objects must be alive in order for their destructor
-        // to be called.
-        ty::Dynamic(..) => {
-            constraints.outlives.push(ty.into());
-        }
-
-        // Types that can't be resolved. Pass them forward.
-        ty::Alias(..) | ty::Param(..) => {
-            constraints.dtorck_types.push(ty);
-        }
-
-        ty::Placeholder(..) | ty::Bound(..) | ty::Infer(..) | ty::Error(_) => {
-            // By the time this code runs, all type variables ought to
-            // be fully resolved.
-            return Err(NoSolution);
-        }
-    }
-
-    Ok(())
-}
-
 /// Calculates the dtorck constraint for a type.
 pub(crate) fn adt_dtorck_constraint(
     tcx: TyCtxt<'_>,
@@ -311,7 +55,7 @@ pub(crate) fn adt_dtorck_constraint(
     let mut result = DropckConstraint::empty();
     for field in def.all_fields() {
         let fty = tcx.type_of(field.did).subst_identity();
-        dtorck_constraint_for_ty(tcx, span, fty, 0, fty, &mut result)?;
+        dtorck_constraint_for_ty_inner(tcx, span, fty, 0, fty, &mut result)?;
     }
     result.outlives.extend(tcx.destructor_constraints(def));
     dedup_dtorck_constraint(&mut result);

compiler/rustc_traits/src/implied_outlives_bounds.rs

@@ -3,18 +3,13 @@
 //! [`rustc_trait_selection::traits::query::type_op::implied_outlives_bounds`].
 
 use rustc_infer::infer::canonical::{self, Canonical};
-use rustc_infer::infer::outlives::components::{push_outlives_components, Component};
 use rustc_infer::infer::TyCtxtInferExt;
 use rustc_infer::traits::query::OutlivesBound;
 use rustc_middle::query::Providers;
-use rustc_middle::ty::{self, Ty, TyCtxt, TypeVisitableExt};
+use rustc_middle::ty::TyCtxt;
-use rustc_span::def_id::CRATE_DEF_ID;
-use rustc_span::source_map::DUMMY_SP;
 use rustc_trait_selection::infer::InferCtxtBuilderExt;
+use rustc_trait_selection::traits::query::type_op::implied_outlives_bounds::compute_implied_outlives_bounds_inner;
 use rustc_trait_selection::traits::query::{CanonicalTyGoal, NoSolution};
-use rustc_trait_selection::traits::wf;
-use rustc_trait_selection::traits::ObligationCtxt;
-use smallvec::{smallvec, SmallVec};
 
 pub(crate) fn provide(p: &mut Providers) {
     *p = Providers { implied_outlives_bounds, ..*p };
@@ -29,164 +24,6 @@ fn implied_outlives_bounds<'tcx>(
 > {
     tcx.infer_ctxt().enter_canonical_trait_query(&goal, |ocx, key| {
         let (param_env, ty) = key.into_parts();
-        compute_implied_outlives_bounds(ocx, param_env, ty)
+        compute_implied_outlives_bounds_inner(ocx, param_env, ty)
     })
 }
-
-fn compute_implied_outlives_bounds<'tcx>(
-    ocx: &ObligationCtxt<'_, 'tcx>,
-    param_env: ty::ParamEnv<'tcx>,
-    ty: Ty<'tcx>,
-) -> Result<Vec<OutlivesBound<'tcx>>, NoSolution> {
-    let tcx = ocx.infcx.tcx;
-
-    // Sometimes when we ask what it takes for T: WF, we get back that
-    // U: WF is required; in that case, we push U onto this stack and
-    // process it next. Because the resulting predicates aren't always
-    // guaranteed to be a subset of the original type, so we need to store the
-    // WF args we've computed in a set.
-    let mut checked_wf_args = rustc_data_structures::fx::FxHashSet::default();
-    let mut wf_args = vec![ty.into()];
-
-    let mut outlives_bounds: Vec<ty::OutlivesPredicate<ty::GenericArg<'tcx>, ty::Region<'tcx>>> =
-        vec![];
-
-    while let Some(arg) = wf_args.pop() {
-        if !checked_wf_args.insert(arg) {
-            continue;
-        }
-
-        // Compute the obligations for `arg` to be well-formed. If `arg` is
-        // an unresolved inference variable, just substituted an empty set
-        // -- because the return type here is going to be things we *add*
-        // to the environment, it's always ok for this set to be smaller
-        // than the ultimate set. (Note: normally there won't be
-        // unresolved inference variables here anyway, but there might be
-        // during typeck under some circumstances.)
-        //
-        // FIXME(@lcnr): It's not really "always fine", having fewer implied
-        // bounds can be backward incompatible, e.g. #101951 was caused by
-        // us not dealing with inference vars in `TypeOutlives` predicates.
-        let obligations = wf::obligations(ocx.infcx, param_env, CRATE_DEF_ID, 0, arg, DUMMY_SP)
-            .unwrap_or_default();
-
-        for obligation in obligations {
-            debug!(?obligation);
-            assert!(!obligation.has_escaping_bound_vars());
-
-            // While these predicates should all be implied by other parts of
-            // the program, they are still relevant as they may constrain
-            // inference variables, which is necessary to add the correct
-            // implied bounds in some cases, mostly when dealing with projections.
-            //
-            // Another important point here: we only register `Projection`
-            // predicates, since otherwise we might register outlives
-            // predicates containing inference variables, and we don't
-            // learn anything new from those.
-            if obligation.predicate.has_non_region_infer() {
-                match obligation.predicate.kind().skip_binder() {
-                    ty::PredicateKind::Clause(ty::Clause::Projection(..))
-                    | ty::PredicateKind::AliasRelate(..) => {
-                        ocx.register_obligation(obligation.clone());
-                    }
-                    _ => {}
-                }
-            }
-
-            let pred = match obligation.predicate.kind().no_bound_vars() {
-                None => continue,
-                Some(pred) => pred,
-            };
-            match pred {
-                ty::PredicateKind::Clause(ty::Clause::Trait(..))
-                // FIXME(const_generics): Make sure that `<'a, 'b, const N: &'a &'b u32>` is sound
-                // if we ever support that
-                | ty::PredicateKind::Clause(ty::Clause::ConstArgHasType(..))
-                | ty::PredicateKind::Subtype(..)
-                | ty::PredicateKind::Coerce(..)
-                | ty::PredicateKind::Clause(ty::Clause::Projection(..))
-                | ty::PredicateKind::ClosureKind(..)
-                | ty::PredicateKind::ObjectSafe(..)
-                | ty::PredicateKind::ConstEvaluatable(..)
-                | ty::PredicateKind::ConstEquate(..)
-                | ty::PredicateKind::Ambiguous
-                | ty::PredicateKind::AliasRelate(..)
-                | ty::PredicateKind::TypeWellFormedFromEnv(..) => {}
-
-                // We need to search through *all* WellFormed predicates
-                ty::PredicateKind::WellFormed(arg) => {
-                    wf_args.push(arg);
-                }
-
-                // We need to register region relationships
-                ty::PredicateKind::Clause(ty::Clause::RegionOutlives(ty::OutlivesPredicate(
-                    r_a,
-                    r_b,
-                ))) => outlives_bounds.push(ty::OutlivesPredicate(r_a.into(), r_b)),
-
-                ty::PredicateKind::Clause(ty::Clause::TypeOutlives(ty::OutlivesPredicate(
-                    ty_a,
-                    r_b,
-                ))) => outlives_bounds.push(ty::OutlivesPredicate(ty_a.into(), r_b)),
-            }
-        }
-    }
-
-    // This call to `select_all_or_error` is necessary to constrain inference variables, which we
-    // use further down when computing the implied bounds.
-    match ocx.select_all_or_error().as_slice() {
-        [] => (),
-        _ => return Err(NoSolution),
-    }
-
-    // We lazily compute the outlives components as
-    // `select_all_or_error` constrains inference variables.
-    let implied_bounds = outlives_bounds
-        .into_iter()
-        .flat_map(|ty::OutlivesPredicate(a, r_b)| match a.unpack() {
-            ty::GenericArgKind::Lifetime(r_a) => vec![OutlivesBound::RegionSubRegion(r_b, r_a)],
-            ty::GenericArgKind::Type(ty_a) => {
-                let ty_a = ocx.infcx.resolve_vars_if_possible(ty_a);
-                let mut components = smallvec![];
-                push_outlives_components(tcx, ty_a, &mut components);
-                implied_bounds_from_components(r_b, components)
-            }
-            ty::GenericArgKind::Const(_) => unreachable!(),
-        })
-        .collect();
-
-    Ok(implied_bounds)
-}
-
-/// When we have an implied bound that `T: 'a`, we can further break
-/// this down to determine what relationships would have to hold for
-/// `T: 'a` to hold. We get to assume that the caller has validated
-/// those relationships.
-fn implied_bounds_from_components<'tcx>(
-    sub_region: ty::Region<'tcx>,
-    sup_components: SmallVec<[Component<'tcx>; 4]>,
-) -> Vec<OutlivesBound<'tcx>> {
-    sup_components
-        .into_iter()
-        .filter_map(|component| {
-            match component {
-                Component::Region(r) => Some(OutlivesBound::RegionSubRegion(sub_region, r)),
-                Component::Param(p) => Some(OutlivesBound::RegionSubParam(sub_region, p)),
-                Component::Alias(p) => Some(OutlivesBound::RegionSubAlias(sub_region, p)),
-                Component::EscapingAlias(_) =>
-                // If the projection has escaping regions, don't
-                // try to infer any implied bounds even for its
-                // free components. This is conservative, because
-                // the caller will still have to prove that those
-                // free components outlive `sub_region`. But the
-                // idea is that the WAY that the caller proves
-                // that may change in the future and we want to
-                // give ourselves room to get smarter here.
-                {
-                    None
-                }
-                Component::UnresolvedInferenceVariable(..) => None,
-            }
-        })
-        .collect()
-}

compiler/rustc_traits/src/lib.rs

@@ -21,7 +21,8 @@ mod normalize_erasing_regions;
 mod normalize_projection_ty;
 mod type_op;
 
-pub use type_op::{type_op_ascribe_user_type_with_span, type_op_prove_predicate_with_cause};
+pub use rustc_trait_selection::traits::query::type_op::ascribe_user_type::type_op_ascribe_user_type_with_span;
+pub use type_op::type_op_prove_predicate_with_cause;
 
 use rustc_middle::query::Providers;
 

compiler/rustc_traits/src/type_op.rs

@@ -1,17 +1,15 @@
-use rustc_hir as hir;
 use rustc_infer::infer::canonical::{Canonical, QueryResponse};
 use rustc_infer::infer::TyCtxtInferExt;
 use rustc_middle::query::Providers;
 use rustc_middle::traits::query::NoSolution;
-use rustc_middle::traits::{DefiningAnchor, ObligationCauseCode};
+use rustc_middle::traits::DefiningAnchor;
-use rustc_middle::ty::{self, FnSig, Lift, PolyFnSig, Ty, TyCtxt, TypeFoldable};
+use rustc_middle::ty::{FnSig, Lift, PolyFnSig, Ty, TyCtxt, TypeFoldable};
 use rustc_middle::ty::{ParamEnvAnd, Predicate};
-use rustc_middle::ty::{UserSelfTy, UserSubsts, UserType};
-use rustc_span::def_id::CRATE_DEF_ID;
-use rustc_span::{Span, DUMMY_SP};
 use rustc_trait_selection::infer::InferCtxtBuilderExt;
 use rustc_trait_selection::traits::query::normalize::QueryNormalizeExt;
-use rustc_trait_selection::traits::query::type_op::ascribe_user_type::AscribeUserType;
+use rustc_trait_selection::traits::query::type_op::ascribe_user_type::{
+    type_op_ascribe_user_type_with_span, AscribeUserType,
+};
 use rustc_trait_selection::traits::query::type_op::eq::Eq;
 use rustc_trait_selection::traits::query::type_op::normalize::Normalize;
 use rustc_trait_selection::traits::query::type_op::prove_predicate::ProvePredicate;
@@ -42,111 +40,6 @@ fn type_op_ascribe_user_type<'tcx>(
     })
 }
 
-/// The core of the `type_op_ascribe_user_type` query: for diagnostics purposes in NLL HRTB errors,
-/// this query can be re-run to better track the span of the obligation cause, and improve the error
-/// message. Do not call directly unless you're in that very specific context.
-pub fn type_op_ascribe_user_type_with_span<'tcx>(
-    ocx: &ObligationCtxt<'_, 'tcx>,
-    key: ParamEnvAnd<'tcx, AscribeUserType<'tcx>>,
-    span: Option<Span>,
-) -> Result<(), NoSolution> {
-    let (param_env, AscribeUserType { mir_ty, user_ty }) = key.into_parts();
-    debug!("type_op_ascribe_user_type: mir_ty={:?} user_ty={:?}", mir_ty, user_ty);
-    let span = span.unwrap_or(DUMMY_SP);
-    match user_ty {
-        UserType::Ty(user_ty) => relate_mir_and_user_ty(ocx, param_env, span, mir_ty, user_ty)?,
-        UserType::TypeOf(def_id, user_substs) => {
-            relate_mir_and_user_substs(ocx, param_env, span, mir_ty, def_id, user_substs)?
-        }
-    };
-    Ok(())
-}
-
-#[instrument(level = "debug", skip(ocx, param_env, span))]
-fn relate_mir_and_user_ty<'tcx>(
-    ocx: &ObligationCtxt<'_, 'tcx>,
-    param_env: ty::ParamEnv<'tcx>,
-    span: Span,
-    mir_ty: Ty<'tcx>,
-    user_ty: Ty<'tcx>,
-) -> Result<(), NoSolution> {
-    let cause = ObligationCause::dummy_with_span(span);
-    let user_ty = ocx.normalize(&cause, param_env, user_ty);
-    ocx.eq(&cause, param_env, mir_ty, user_ty)?;
-
-    // FIXME(#104764): We should check well-formedness before normalization.
-    let predicate = ty::Binder::dummy(ty::PredicateKind::WellFormed(user_ty.into()));
-    ocx.register_obligation(Obligation::new(ocx.infcx.tcx, cause, param_env, predicate));
-    Ok(())
-}
-
-#[instrument(level = "debug", skip(ocx, param_env, span))]
-fn relate_mir_and_user_substs<'tcx>(
-    ocx: &ObligationCtxt<'_, 'tcx>,
-    param_env: ty::ParamEnv<'tcx>,
-    span: Span,
-    mir_ty: Ty<'tcx>,
-    def_id: hir::def_id::DefId,
-    user_substs: UserSubsts<'tcx>,
-) -> Result<(), NoSolution> {
-    let param_env = param_env.without_const();
-    let UserSubsts { user_self_ty, substs } = user_substs;
-    let tcx = ocx.infcx.tcx;
-    let cause = ObligationCause::dummy_with_span(span);
-
-    let ty = tcx.type_of(def_id).subst(tcx, substs);
-    let ty = ocx.normalize(&cause, param_env, ty);
-    debug!("relate_type_and_user_type: ty of def-id is {:?}", ty);
-
-    ocx.eq(&cause, param_env, mir_ty, ty)?;
-
-    // Prove the predicates coming along with `def_id`.
-    //
-    // Also, normalize the `instantiated_predicates`
-    // because otherwise we wind up with duplicate "type
-    // outlives" error messages.
-    let instantiated_predicates = tcx.predicates_of(def_id).instantiate(tcx, substs);
-
-    debug!(?instantiated_predicates);
-    for (instantiated_predicate, predicate_span) in instantiated_predicates {
-        let span = if span == DUMMY_SP { predicate_span } else { span };
-        let cause = ObligationCause::new(
-            span,
-            CRATE_DEF_ID,
-            ObligationCauseCode::AscribeUserTypeProvePredicate(predicate_span),
-        );
-        let instantiated_predicate =
-            ocx.normalize(&cause.clone(), param_env, instantiated_predicate);
-
-        ocx.register_obligation(Obligation::new(tcx, cause, param_env, instantiated_predicate));
-    }
-
-    if let Some(UserSelfTy { impl_def_id, self_ty }) = user_self_ty {
-        let self_ty = ocx.normalize(&cause, param_env, self_ty);
-        let impl_self_ty = tcx.type_of(impl_def_id).subst(tcx, substs);
-        let impl_self_ty = ocx.normalize(&cause, param_env, impl_self_ty);
-
-        ocx.eq(&cause, param_env, self_ty, impl_self_ty)?;
-        let predicate = ty::Binder::dummy(ty::PredicateKind::WellFormed(impl_self_ty.into()));
-        ocx.register_obligation(Obligation::new(tcx, cause.clone(), param_env, predicate));
-    }
-
-    // In addition to proving the predicates, we have to
-    // prove that `ty` is well-formed -- this is because
-    // the WF of `ty` is predicated on the substs being
-    // well-formed, and we haven't proven *that*. We don't
-    // want to prove the WF of types from  `substs` directly because they
-    // haven't been normalized.
-    //
-    // FIXME(nmatsakis): Well, perhaps we should normalize
-    // them?  This would only be relevant if some input
-    // type were ill-formed but did not appear in `ty`,
-    // which...could happen with normalization...
-    let predicate = ty::Binder::dummy(ty::PredicateKind::WellFormed(ty.into()));
-    ocx.register_obligation(Obligation::new(tcx, cause, param_env, predicate));
-    Ok(())
-}
-
 fn type_op_eq<'tcx>(
     tcx: TyCtxt<'tcx>,
     canonicalized: Canonical<'tcx, ParamEnvAnd<'tcx, Eq<'tcx>>>,