Rollup merge of #112870 - compiler-errors:clause-2, r=oli-obk

Migrate `item_bounds` to `ty::Clause`

Should be simpler than the next PR that's coming up. Last three commits are the relevant ones.

r? ``@oli-obk`` or ``@lcnr``

3 files changed, 16 insertions, 21 deletions

diff --git a/src/librustdoc/clean/mod.rs b/src/librustdoc/clean/mod.rs
index 9a815694e1b..f86c32158e0 100644
--- a/src/librustdoc/clean/mod.rs
+++ b/src/librustdoc/clean/mod.rs
@@ -1361,8 +1361,10 @@ pub(crate) fn clean_middle_assoc_item<'tcx>(
             }
 
             if let ty::TraitContainer = assoc_item.container {
-                let bounds =
-                    tcx.explicit_item_bounds(assoc_item.def_id).subst_identity_iter_copied();
+                let bounds = tcx
+                    .explicit_item_bounds(assoc_item.def_id)
+                    .subst_identity_iter_copied()
+                    .map(|(c, s)| (c.as_predicate(), s));
                 let predicates = tcx.explicit_predicates_of(assoc_item.def_id).predicates;
                 let predicates =
                     tcx.arena.alloc_from_iter(bounds.chain(predicates.iter().copied()));
@@ -2117,7 +2119,7 @@ pub(crate) fn clean_middle_ty<'tcx>(
 
 fn clean_middle_opaque_bounds<'tcx>(
     cx: &mut DocContext<'tcx>,
-    bounds: Vec<ty::Predicate<'tcx>>,
+    bounds: Vec<ty::Clause<'tcx>>,
 ) -> Type {
     let mut regions = vec![];
     let mut has_sized = false;
@@ -2126,13 +2128,8 @@ fn clean_middle_opaque_bounds<'tcx>(
         .filter_map(|bound| {
             let bound_predicate = bound.kind();
             let trait_ref = match bound_predicate.skip_binder() {
-                ty::PredicateKind::Clause(ty::ClauseKind::Trait(tr)) => {
-                    bound_predicate.rebind(tr.trait_ref)
-                }
-                ty::PredicateKind::Clause(ty::ClauseKind::TypeOutlives(ty::OutlivesPredicate(
-                    _ty,
-                    reg,
-                ))) => {
+                ty::ClauseKind::Trait(tr) => bound_predicate.rebind(tr.trait_ref),
+                ty::ClauseKind::TypeOutlives(ty::OutlivesPredicate(_ty, reg)) => {
                     if let Some(r) = clean_middle_region(reg) {
                         regions.push(GenericBound::Outlives(r));
                     }
@@ -2149,9 +2146,7 @@ fn clean_middle_opaque_bounds<'tcx>(
             let bindings: ThinVec<_> = bounds
                 .iter()
                 .filter_map(|bound| {
-                    if let ty::PredicateKind::Clause(ty::ClauseKind::Projection(proj)) =
-                        bound.kind().skip_binder()
-                    {
+                    if let ty::ClauseKind::Projection(proj) = bound.kind().skip_binder() {
                         if proj.projection_ty.trait_ref(cx.tcx) == trait_ref.skip_binder() {
                             Some(TypeBinding {
                                 assoc: projection_to_path_segment(
diff --git a/src/tools/clippy/clippy_lints/src/future_not_send.rs b/src/tools/clippy/clippy_lints/src/future_not_send.rs
index a391b76910a..818ebd1134d 100644
--- a/src/tools/clippy/clippy_lints/src/future_not_send.rs
+++ b/src/tools/clippy/clippy_lints/src/future_not_send.rs
@@ -67,7 +67,7 @@ impl<'tcx> LateLintPass<'tcx> for FutureNotSend {
             let preds = cx.tcx.explicit_item_bounds(def_id);
             let mut is_future = false;
             for (p, _span) in preds.subst_iter_copied(cx.tcx, substs) {
-                if let Some(trait_pred) = p.to_opt_poly_trait_pred() {
+                if let Some(trait_pred) = p.as_trait_clause() {
                     if Some(trait_pred.skip_binder().trait_ref.def_id) == cx.tcx.lang_items().future_trait() {
                         is_future = true;
                         break;
diff --git a/src/tools/clippy/clippy_utils/src/ty.rs b/src/tools/clippy/clippy_utils/src/ty.rs
index 12f18614d71..2b185943c59 100644
--- a/src/tools/clippy/clippy_utils/src/ty.rs
+++ b/src/tools/clippy/clippy_utils/src/ty.rs
@@ -94,7 +94,7 @@ pub fn contains_ty_adt_constructor_opaque<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'
                         match predicate.kind().skip_binder() {
                             // For `impl Trait<U>`, it will register a predicate of `T: Trait<U>`, so we go through
                             // and check substitutions to find `U`.
-                            ty::PredicateKind::Clause(ty::ClauseKind::Trait(trait_predicate)) => {
+                            ty::ClauseKind::Trait(trait_predicate) => {
                                 if trait_predicate
                                     .trait_ref
                                     .substs
@@ -107,7 +107,7 @@ pub fn contains_ty_adt_constructor_opaque<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'
                             },
                             // For `impl Trait<Assoc=U>`, it will register a predicate of `<T as Trait>::Assoc = U`,
                             // so we check the term for `U`.
-                            ty::PredicateKind::Clause(ty::ClauseKind::Projection(projection_predicate)) => {
+                            ty::ClauseKind::Projection(projection_predicate) => {
                                 if let ty::TermKind::Ty(ty) = projection_predicate.term.unpack() {
                                     if contains_ty_adt_constructor_opaque_inner(cx, ty, needle, seen) {
                                         return true;
@@ -268,7 +268,7 @@ pub fn is_must_use_ty<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
         ty::Tuple(substs) => substs.iter().any(|ty| is_must_use_ty(cx, ty)),
         ty::Alias(ty::Opaque, ty::AliasTy { def_id, .. }) => {
             for (predicate, _) in cx.tcx.explicit_item_bounds(def_id).skip_binder() {
-                if let ty::PredicateKind::Clause(ty::ClauseKind::Trait(trait_predicate)) = predicate.kind().skip_binder() {
+                if let ty::ClauseKind::Trait(trait_predicate) = predicate.kind().skip_binder() {
                     if cx.tcx.has_attr(trait_predicate.trait_ref.def_id, sym::must_use) {
                         return true;
                     }
@@ -665,7 +665,7 @@ pub fn ty_sig<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> Option<ExprFnSig<'t
         ty::Alias(ty::Opaque, ty::AliasTy { def_id, substs, .. }) => sig_from_bounds(
             cx,
             ty,
-            cx.tcx.item_bounds(def_id).subst(cx.tcx, substs),
+            cx.tcx.item_bounds(def_id).subst_iter(cx.tcx, substs).map(|c| c.as_predicate()),
             cx.tcx.opt_parent(def_id),
         ),
         ty::FnPtr(sig) => Some(ExprFnSig::Sig(sig, None)),
@@ -698,7 +698,7 @@ pub fn ty_sig<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> Option<ExprFnSig<'t
 fn sig_from_bounds<'tcx>(
     cx: &LateContext<'tcx>,
     ty: Ty<'tcx>,
-    predicates: &'tcx [Predicate<'tcx>],
+    predicates: impl IntoIterator<Item = Predicate<'tcx>>,
     predicates_id: Option<DefId>,
 ) -> Option<ExprFnSig<'tcx>> {
     let mut inputs = None;
@@ -747,7 +747,7 @@ fn sig_for_projection<'tcx>(cx: &LateContext<'tcx>, ty: AliasTy<'tcx>) -> Option
         .subst_iter_copied(cx.tcx, ty.substs)
     {
         match pred.kind().skip_binder() {
-            PredicateKind::Clause(ty::ClauseKind::Trait(p))
+            ty::ClauseKind::Trait(p)
                 if (lang_items.fn_trait() == Some(p.def_id())
                     || lang_items.fn_mut_trait() == Some(p.def_id())
                     || lang_items.fn_once_trait() == Some(p.def_id())) =>
@@ -760,7 +760,7 @@ fn sig_for_projection<'tcx>(cx: &LateContext<'tcx>, ty: AliasTy<'tcx>) -> Option
                 }
                 inputs = Some(i);
             },
-            PredicateKind::Clause(ty::ClauseKind::Projection(p))
+            ty::ClauseKind::Projection(p)
                 if Some(p.projection_ty.def_id) == lang_items.fn_once_output() =>
             {
                 if output.is_some() {