Revert PR "Rework some predicates_of/{Generic,Instantiated}Predicates code"

Revert "Remove bound_{explicit,}_item_bounds"

This reverts commit 90df86f.

Revert "drive-by: assert when iterating through InstantiatedPredicates"

This reverts commit e1533a2.

Revert "Make InstantiatedPredicates impl IntoIterator"

This reverts commit 9b28edb.

Revert "instantiate_own doesn't need to return a pair of vectors"

This reverts commit 91fd862.

Author: compiler-errors

compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs

@@ -673,34 +673,40 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
         let tcx = self.infcx.tcx;
 
         // Find out if the predicates show that the type is a Fn or FnMut
-        let find_fn_kind_from_did = |(pred, _): (ty::Predicate<'tcx>, _)| {
-            if let ty::PredicateKind::Clause(ty::Clause::Trait(pred)) = pred.kind().skip_binder()
-                && pred.self_ty() == ty
-            {
-                if Some(pred.def_id()) == tcx.lang_items().fn_trait() {
-                    return Some(hir::Mutability::Not);
-                } else if Some(pred.def_id()) == tcx.lang_items().fn_mut_trait() {
-                    return Some(hir::Mutability::Mut);
+        let find_fn_kind_from_did = |predicates: ty::EarlyBinder<
+            &[(ty::Predicate<'tcx>, Span)],
+        >,
+                                     substs| {
+            predicates.0.iter().find_map(|(pred, _)| {
+                    let pred = if let Some(substs) = substs {
+                        predicates.rebind(*pred).subst(tcx, substs).kind().skip_binder()
+                    } else {
+                        pred.kind().skip_binder()
+                    };
+                    if let ty::PredicateKind::Clause(ty::Clause::Trait(pred)) = pred && pred.self_ty() == ty {
+                    if Some(pred.def_id()) == tcx.lang_items().fn_trait() {
+                        return Some(hir::Mutability::Not);
+                    } else if Some(pred.def_id()) == tcx.lang_items().fn_mut_trait() {
+                        return Some(hir::Mutability::Mut);
+                    }
                 }
-            }
-            None
+                    None
+                })
         };
 
         // If the type is opaque/param/closure, and it is Fn or FnMut, let's suggest (mutably)
         // borrowing the type, since `&mut F: FnMut` iff `F: FnMut` and similarly for `Fn`.
         // These types seem reasonably opaque enough that they could be substituted with their
         // borrowed variants in a function body when we see a move error.
-        let borrow_level = match *ty.kind() {
-            ty::Param(_) => tcx
-                .explicit_predicates_of(self.mir_def_id().to_def_id())
-                .predicates
-                .iter()
-                .copied()
-                .find_map(find_fn_kind_from_did),
-            ty::Alias(ty::Opaque, ty::AliasTy { def_id, substs, .. }) => tcx
-                .bound_explicit_item_bounds(def_id)
-                .subst_iter_copied(tcx, substs)
-                .find_map(find_fn_kind_from_did),
+        let borrow_level = match ty.kind() {
+            ty::Param(_) => find_fn_kind_from_did(
+                tcx.bound_explicit_predicates_of(self.mir_def_id().to_def_id())
+                    .map_bound(|p| p.predicates),
+                None,
+            ),
+            ty::Alias(ty::Opaque, ty::AliasTy { def_id, substs, .. }) => {
+                find_fn_kind_from_did(tcx.bound_explicit_item_bounds(*def_id), Some(*substs))
+            }
             ty::Closure(_, substs) => match substs.as_closure().kind() {
                 ty::ClosureKind::Fn => Some(hir::Mutability::Not),
                 ty::ClosureKind::FnMut => Some(hir::Mutability::Mut),

compiler/rustc_borrowck/src/type_check/canonical.rs

@@ -107,7 +107,11 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
         instantiated_predicates: ty::InstantiatedPredicates<'tcx>,
         locations: Locations,
     ) {
-        for (predicate, span) in instantiated_predicates {
+        for (predicate, span) in instantiated_predicates
+            .predicates
+            .into_iter()
+            .zip(instantiated_predicates.spans.into_iter())
+        {
             debug!(?predicate);
             let category = ConstraintCategory::Predicate(span);
             let predicate = self.normalize_with_category(predicate, locations, category);

compiler/rustc_hir_analysis/src/check/compare_impl_item.rs

@@ -209,11 +209,9 @@ fn compare_method_predicate_entailment<'tcx>(
     //
     // We then register the obligations from the impl_m and check to see
     // if all constraints hold.
-    hybrid_preds.predicates.extend(
-        trait_m_predicates
-            .instantiate_own(tcx, trait_to_placeholder_substs)
-            .map(|(predicate, _)| predicate),
-    );
+    hybrid_preds
+        .predicates
+        .extend(trait_m_predicates.instantiate_own(tcx, trait_to_placeholder_substs).predicates);
 
     // Construct trait parameter environment and then shift it into the placeholder viewpoint.
     // The key step here is to update the caller_bounds's predicates to be
@@ -232,7 +230,7 @@ fn compare_method_predicate_entailment<'tcx>(
     debug!("compare_impl_method: caller_bounds={:?}", param_env.caller_bounds());
 
     let impl_m_own_bounds = impl_m_predicates.instantiate_own(tcx, impl_to_placeholder_substs);
-    for (predicate, span) in impl_m_own_bounds {
+    for (predicate, span) in iter::zip(impl_m_own_bounds.predicates, impl_m_own_bounds.spans) {
         let normalize_cause = traits::ObligationCause::misc(span, impl_m_hir_id);
         let predicate = ocx.normalize(&normalize_cause, param_env, predicate);
 
@@ -1830,7 +1828,8 @@ fn compare_type_predicate_entailment<'tcx>(
     check_region_bounds_on_impl_item(tcx, impl_ty, trait_ty, false)?;
 
     let impl_ty_own_bounds = impl_ty_predicates.instantiate_own(tcx, impl_substs);
-    if impl_ty_own_bounds.len() == 0 {
+
+    if impl_ty_own_bounds.is_empty() {
         // Nothing to check.
         return Ok(());
     }
@@ -1845,11 +1844,9 @@ fn compare_type_predicate_entailment<'tcx>(
     // associated type in the trait are assumed.
     let impl_predicates = tcx.predicates_of(impl_ty_predicates.parent.unwrap());
     let mut hybrid_preds = impl_predicates.instantiate_identity(tcx);
-    hybrid_preds.predicates.extend(
-        trait_ty_predicates
-            .instantiate_own(tcx, trait_to_impl_substs)
-            .map(|(predicate, _)| predicate),
-    );
+    hybrid_preds
+        .predicates
+        .extend(trait_ty_predicates.instantiate_own(tcx, trait_to_impl_substs).predicates);
 
     debug!("compare_type_predicate_entailment: bounds={:?}", hybrid_preds);
 
@@ -1865,7 +1862,9 @@ fn compare_type_predicate_entailment<'tcx>(
 
     debug!("compare_type_predicate_entailment: caller_bounds={:?}", param_env.caller_bounds());
 
-    for (predicate, span) in impl_ty_own_bounds {
+    assert_eq!(impl_ty_own_bounds.predicates.len(), impl_ty_own_bounds.spans.len());
+    for (span, predicate) in std::iter::zip(impl_ty_own_bounds.spans, impl_ty_own_bounds.predicates)
+    {
         let cause = ObligationCause::misc(span, impl_ty_hir_id);
         let predicate = ocx.normalize(&cause, param_env, predicate);
 

compiler/rustc_hir_analysis/src/check/wfcheck.rs

@@ -32,6 +32,7 @@ use rustc_trait_selection::traits::{
 };
 
 use std::cell::LazyCell;
+use std::iter;
 use std::ops::{ControlFlow, Deref};
 
 pub(super) struct WfCheckingCtxt<'a, 'tcx> {
@@ -1309,7 +1310,7 @@ fn check_where_clauses<'tcx>(wfcx: &WfCheckingCtxt<'_, 'tcx>, span: Span, def_id
     let infcx = wfcx.infcx;
     let tcx = wfcx.tcx();
 
-    let predicates = tcx.predicates_of(def_id.to_def_id());
+    let predicates = tcx.bound_predicates_of(def_id.to_def_id());
     let generics = tcx.generics_of(def_id);
 
     let is_our_default = |def: &ty::GenericParamDef| match def.kind {
@@ -1410,6 +1411,7 @@ fn check_where_clauses<'tcx>(wfcx: &WfCheckingCtxt<'_, 'tcx>, span: Span, def_id
 
     // Now we build the substituted predicates.
     let default_obligations = predicates
+        .0
         .predicates
         .iter()
         .flat_map(|&(pred, sp)| {
@@ -1440,13 +1442,13 @@ fn check_where_clauses<'tcx>(wfcx: &WfCheckingCtxt<'_, 'tcx>, span: Span, def_id
             }
             let mut param_count = CountParams::default();
             let has_region = pred.visit_with(&mut param_count).is_break();
-            let substituted_pred = ty::EarlyBinder(pred).subst(tcx, substs);
+            let substituted_pred = predicates.rebind(pred).subst(tcx, substs);
             // Don't check non-defaulted params, dependent defaults (including lifetimes)
             // or preds with multiple params.
             if substituted_pred.has_non_region_param() || param_count.params.len() > 1 || has_region
             {
                 None
-            } else if predicates.predicates.iter().any(|&(p, _)| p == substituted_pred) {
+            } else if predicates.0.predicates.iter().any(|&(p, _)| p == substituted_pred) {
                 // Avoid duplication of predicates that contain no parameters, for example.
                 None
             } else {
@@ -1472,21 +1474,22 @@ fn check_where_clauses<'tcx>(wfcx: &WfCheckingCtxt<'_, 'tcx>, span: Span, def_id
             traits::Obligation::new(tcx, cause, wfcx.param_env, pred)
         });
 
-    let predicates = predicates.instantiate_identity(tcx);
+    let predicates = predicates.0.instantiate_identity(tcx);
 
     let predicates = wfcx.normalize(span, None, predicates);
 
     debug!(?predicates.predicates);
     assert_eq!(predicates.predicates.len(), predicates.spans.len());
-    let wf_obligations = predicates.into_iter().flat_map(|(p, sp)| {
-        traits::wf::predicate_obligations(
-            infcx,
-            wfcx.param_env.without_const(),
-            wfcx.body_id,
-            p,
-            sp,
-        )
-    });
+    let wf_obligations =
+        iter::zip(&predicates.predicates, &predicates.spans).flat_map(|(&p, &sp)| {
+            traits::wf::predicate_obligations(
+                infcx,
+                wfcx.param_env.without_const(),
+                wfcx.body_id,
+                p,
+                sp,
+            )
+        });
 
     let obligations: Vec<_> = wf_obligations.chain(default_obligations).collect();
     wfcx.register_obligations(obligations);

compiler/rustc_hir_typeck/src/callee.rs

@@ -375,12 +375,14 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 if self.tcx.has_attr(def_id, sym::rustc_evaluate_where_clauses) {
                     let predicates = self.tcx.predicates_of(def_id);
                     let predicates = predicates.instantiate(self.tcx, subst);
-                    for (predicate, predicate_span) in predicates {
+                    for (predicate, predicate_span) in
+                        predicates.predicates.iter().zip(&predicates.spans)
+                    {
                         let obligation = Obligation::new(
                             self.tcx,
                             ObligationCause::dummy_with_span(callee_expr.span),
                             self.param_env,
-                            predicate,
+                            *predicate,
                         );
                         let result = self.evaluate_obligation(&obligation);
                         self.tcx
@@ -389,7 +391,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                                 callee_expr.span,
                                 &format!("evaluate({:?}) = {:?}", predicate, result),
                             )
-                            .span_label(predicate_span, "predicate")
+                            .span_label(*predicate_span, "predicate")
                             .emit();
                     }
                 }

compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs

@@ -2140,7 +2140,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                         // FIXME(compiler-errors): This could be problematic if something has two
                         // fn-like predicates with different args, but callable types really never
                         // do that, so it's OK.
-                        for (predicate, span) in instantiated
+                        for (predicate, span) in
+                            std::iter::zip(instantiated.predicates, instantiated.spans)
                         {
                             if let ty::PredicateKind::Clause(ty::Clause::Trait(pred)) = predicate.kind().skip_binder()
                                 && pred.self_ty().peel_refs() == callee_ty

compiler/rustc_hir_typeck/src/method/confirm.rs

@@ -19,6 +19,7 @@ use rustc_middle::ty::{InternalSubsts, UserSubsts, UserType};
 use rustc_span::{Span, DUMMY_SP};
 use rustc_trait_selection::traits;
 
+use std::iter;
 use std::ops::Deref;
 
 struct ConfirmContext<'a, 'tcx> {
@@ -100,7 +101,7 @@ impl<'a, 'tcx> ConfirmContext<'a, 'tcx> {
         let filler_substs = rcvr_substs
             .extend_to(self.tcx, pick.item.def_id, |def, _| self.tcx.mk_param_from_def(def));
         let illegal_sized_bound = self.predicates_require_illegal_sized_bound(
-            self.tcx.predicates_of(pick.item.def_id).instantiate(self.tcx, filler_substs),
+            &self.tcx.predicates_of(pick.item.def_id).instantiate(self.tcx, filler_substs),
         );
 
         // Unify the (adjusted) self type with what the method expects.
@@ -564,7 +565,7 @@ impl<'a, 'tcx> ConfirmContext<'a, 'tcx> {
 
     fn predicates_require_illegal_sized_bound(
         &self,
-        predicates: ty::InstantiatedPredicates<'tcx>,
+        predicates: &ty::InstantiatedPredicates<'tcx>,
     ) -> Option<Span> {
         let sized_def_id = self.tcx.lang_items().sized_trait()?;
 
@@ -574,11 +575,10 @@ impl<'a, 'tcx> ConfirmContext<'a, 'tcx> {
                 ty::PredicateKind::Clause(ty::Clause::Trait(trait_pred))
                     if trait_pred.def_id() == sized_def_id =>
                 {
-                    let span = predicates
-                        .iter()
+                    let span = iter::zip(&predicates.predicates, &predicates.spans)
                         .find_map(
                             |(p, span)| {
-                                if p == obligation.predicate { Some(span) } else { None }
+                                if *p == obligation.predicate { Some(*span) } else { None }
                             },
                         )
                         .unwrap_or(rustc_span::DUMMY_SP);

compiler/rustc_infer/src/infer/error_reporting/note.rs

@@ -330,8 +330,9 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
 
         let Ok(trait_predicates) = self
             .tcx
-            .explicit_predicates_of(trait_item_def_id)
-            .instantiate_own(self.tcx, trait_item_substs)
+            .bound_explicit_predicates_of(trait_item_def_id)
+            .map_bound(|p| p.predicates)
+            .subst_iter_copied(self.tcx, trait_item_substs)
             .map(|(pred, _)| {
                 if pred.is_suggestable(self.tcx, false) {
                     Ok(pred.to_string())

compiler/rustc_middle/src/ty/generics.rs

@@ -341,9 +341,15 @@ impl<'tcx> GenericPredicates<'tcx> {
         &self,
         tcx: TyCtxt<'tcx>,
         substs: SubstsRef<'tcx>,
-    ) -> impl Iterator<Item = (Predicate<'tcx>, Span)> + DoubleEndedIterator + ExactSizeIterator
-    {
-        EarlyBinder(self.predicates).subst_iter_copied(tcx, substs)
+    ) -> InstantiatedPredicates<'tcx> {
+        InstantiatedPredicates {
+            predicates: self
+                .predicates
+                .iter()
+                .map(|(p, _)| EarlyBinder(*p).subst(tcx, substs))
+                .collect(),
+            spans: self.predicates.iter().map(|(_, sp)| *sp).collect(),
+        }
     }
 
     #[instrument(level = "debug", skip(self, tcx))]

compiler/rustc_middle/src/ty/mod.rs

@@ -1252,35 +1252,6 @@ impl<'tcx> InstantiatedPredicates<'tcx> {
     pub fn is_empty(&self) -> bool {
         self.predicates.is_empty()
     }
-
-    pub fn iter(&self) -> <&Self as IntoIterator>::IntoIter {
-        (&self).into_iter()
-    }
-}
-
-impl<'tcx> IntoIterator for InstantiatedPredicates<'tcx> {
-    type Item = (Predicate<'tcx>, Span);
-
-    type IntoIter = std::iter::Zip<std::vec::IntoIter<Predicate<'tcx>>, std::vec::IntoIter<Span>>;
-
-    fn into_iter(self) -> Self::IntoIter {
-        debug_assert_eq!(self.predicates.len(), self.spans.len());
-        std::iter::zip(self.predicates, self.spans)
-    }
-}
-
-impl<'a, 'tcx> IntoIterator for &'a InstantiatedPredicates<'tcx> {
-    type Item = (Predicate<'tcx>, Span);
-
-    type IntoIter = std::iter::Zip<
-        std::iter::Copied<std::slice::Iter<'a, Predicate<'tcx>>>,
-        std::iter::Copied<std::slice::Iter<'a, Span>>,
-    >;
-
-    fn into_iter(self) -> Self::IntoIter {
-        debug_assert_eq!(self.predicates.len(), self.spans.len());
-        std::iter::zip(self.predicates.iter().copied(), self.spans.iter().copied())
-    }
 }
 
 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, HashStable, TyEncodable, TyDecodable, Lift)]

compiler/rustc_middle/src/ty/subst.rs

@@ -639,13 +639,6 @@ where
     }
 }
 
-impl<'tcx, I: IntoIterator> ExactSizeIterator for SubstIter<'_, 'tcx, I>
-where
-    I::IntoIter: ExactSizeIterator,
-    I::Item: TypeFoldable<'tcx>,
-{
-}
-
 impl<'tcx, 's, I: IntoIterator> EarlyBinder<I>
 where
     I::Item: Deref,
@@ -693,14 +686,6 @@ where
     }
 }
 
-impl<'tcx, I: IntoIterator> ExactSizeIterator for SubstIterCopied<'_, 'tcx, I>
-where
-    I::IntoIter: ExactSizeIterator,
-    I::Item: Deref,
-    <I::Item as Deref>::Target: Copy + TypeFoldable<'tcx>,
-{
-}
-
 pub struct EarlyBinderIter<T> {
     t: T,
 }