Auto merge of #131275 - workingjubilee:rollup-4yxqio3, r=workingjubilee

Rollup of 9 pull requests

Successful merges:

 - #129517 (Compute array length from type for unconditional panic lint. )
 - #130367 (Check elaborated projections from dyn don't mention unconstrained late bound lifetimes)
 - #130403 (Stabilize `const_slice_from_raw_parts_mut`)
 - #130633 (Add support for reborrowing pinned method receivers)
 - #131105 (update `Literal`'s intro)
 - #131194 (Fix needless_lifetimes in stable_mir)
 - #131260 (rustdoc: cleaner errors on disambiguator/namespace mismatches)
 - #131267 (Stabilize `BufRead::skip_until`)
 - #131273 (Account for `impl Trait {` when `impl Trait for Type {` was intended)

r? `@ghost`
`@rustbot` modify labels: rollup

compiler/rustc_hir_analysis/src/hir_ty_lowering/dyn_compatibility.rs

@@ -13,6 +13,7 @@ use rustc_middle::ty::{
 use rustc_span::{ErrorGuaranteed, Span};
 use rustc_trait_selection::error_reporting::traits::report_dyn_incompatibility;
 use rustc_trait_selection::traits::{self, hir_ty_lowering_dyn_compatibility_violations};
+use rustc_type_ir::elaborate::ClauseWithSupertraitSpan;
 use smallvec::{SmallVec, smallvec};
 use tracing::{debug, instrument};
 
@@ -124,16 +125,19 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
             .into_iter()
             .filter(|(trait_ref, _)| !tcx.trait_is_auto(trait_ref.def_id()));
 
-        for (base_trait_ref, span) in regular_traits_refs_spans {
+        for (base_trait_ref, original_span) in regular_traits_refs_spans {
             let base_pred: ty::Predicate<'tcx> = base_trait_ref.upcast(tcx);
-            for pred in traits::elaborate(tcx, [base_pred]).filter_only_self() {
+            for ClauseWithSupertraitSpan { pred, original_span, supertrait_span } in
+                traits::elaborate(tcx, [ClauseWithSupertraitSpan::new(base_pred, original_span)])
+                    .filter_only_self()
+            {
                 debug!("observing object predicate `{pred:?}`");
 
                 let bound_predicate = pred.kind();
                 match bound_predicate.skip_binder() {
                     ty::PredicateKind::Clause(ty::ClauseKind::Trait(pred)) => {
                         let pred = bound_predicate.rebind(pred);
-                        associated_types.entry(span).or_default().extend(
+                        associated_types.entry(original_span).or_default().extend(
                             tcx.associated_items(pred.def_id())
                                 .in_definition_order()
                                 .filter(|item| item.kind == ty::AssocKind::Type)
@@ -172,8 +176,14 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
                         // the discussion in #56288 for alternatives.
                         if !references_self {
                             // Include projections defined on supertraits.
-                            projection_bounds.push((pred, span));
+                            projection_bounds.push((pred, original_span));
                         }
+
+                        self.check_elaborated_projection_mentions_input_lifetimes(
+                            pred,
+                            original_span,
+                            supertrait_span,
+                        );
                     }
                     _ => (),
                 }
@@ -360,6 +370,56 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
 
         Ty::new_dynamic(tcx, existential_predicates, region_bound, representation)
     }
+
+    /// Check that elaborating the principal of a trait ref doesn't lead to projections
+    /// that are unconstrained. This can happen because an otherwise unconstrained
+    /// *type variable* can be substituted with a type that has late-bound regions. See
+    /// `elaborated-predicates-unconstrained-late-bound.rs` for a test.
+    fn check_elaborated_projection_mentions_input_lifetimes(
+        &self,
+        pred: ty::PolyProjectionPredicate<'tcx>,
+        span: Span,
+        supertrait_span: Span,
+    ) {
+        let tcx = self.tcx();
+
+        // Find any late-bound regions declared in `ty` that are not
+        // declared in the trait-ref or assoc_item. These are not well-formed.
+        //
+        // Example:
+        //
+        //     for<'a> <T as Iterator>::Item = &'a str // <-- 'a is bad
+        //     for<'a> <T as FnMut<(&'a u32,)>>::Output = &'a str // <-- 'a is ok
+        let late_bound_in_projection_term =
+            tcx.collect_constrained_late_bound_regions(pred.map_bound(|pred| pred.projection_term));
+        let late_bound_in_term =
+            tcx.collect_referenced_late_bound_regions(pred.map_bound(|pred| pred.term));
+        debug!(?late_bound_in_projection_term);
+        debug!(?late_bound_in_term);
+
+        // FIXME: point at the type params that don't have appropriate lifetimes:
+        // struct S1<F: for<'a> Fn(&i32, &i32) -> &'a i32>(F);
+        //                         ----  ----     ^^^^^^^
+        // NOTE(associated_const_equality): This error should be impossible to trigger
+        //                                  with associated const equality constraints.
+        self.validate_late_bound_regions(
+            late_bound_in_projection_term,
+            late_bound_in_term,
+            |br_name| {
+                let item_name = tcx.item_name(pred.projection_def_id());
+                struct_span_code_err!(
+                    self.dcx(),
+                    span,
+                    E0582,
+                    "binding for associated type `{}` references {}, \
+                             which does not appear in the trait input types",
+                    item_name,
+                    br_name
+                )
+                .with_span_label(supertrait_span, "due to this supertrait")
+            },
+        );
+    }
 }
 
 fn replace_dummy_self_with_error<'tcx, T: TypeFoldable<TyCtxt<'tcx>>>(

compiler/rustc_hir_analysis/src/hir_ty_lowering/lint.rs

@@ -108,17 +108,20 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
         let tcx = self.tcx();
         let parent_id = tcx.hir().get_parent_item(self_ty.hir_id).def_id;
         if let hir::Node::Item(hir::Item {
-            kind:
+            kind: hir::ItemKind::Impl(hir::Impl { self_ty: impl_self_ty, of_trait, generics, .. }),
-                hir::ItemKind::Impl(hir::Impl {
-                    self_ty: impl_self_ty,
-                    of_trait: Some(of_trait_ref),
-                    generics,
-                    ..
-                }),
             ..
         }) = tcx.hir_node_by_def_id(parent_id)
             && self_ty.hir_id == impl_self_ty.hir_id
         {
+            let Some(of_trait_ref) = of_trait else {
+                diag.span_suggestion_verbose(
+                    impl_self_ty.span.shrink_to_hi(),
+                    "you might have intended to implement this trait for a given type",
+                    format!(" for /* Type */"),
+                    Applicability::HasPlaceholders,
+                );
+                return;
+            };
             if !of_trait_ref.trait_def_id().is_some_and(|def_id| def_id.is_local()) {
                 return;
             }

compiler/rustc_hir_typeck/src/method/confirm.rs

@@ -235,6 +235,23 @@ impl<'a, 'tcx> ConfirmContext<'a, 'tcx> {
                     target,
                 });
             }
+
+            Some(probe::AutorefOrPtrAdjustment::ReborrowPin(mutbl)) => {
+                let region = self.next_region_var(infer::Autoref(self.span));
+
+                target = match target.kind() {
+                    ty::Adt(pin, args) if self.tcx.is_lang_item(pin.did(), hir::LangItem::Pin) => {
+                        let inner_ty = match args[0].expect_ty().kind() {
+                            ty::Ref(_, ty, _) => *ty,
+                            _ => bug!("Expected a reference type for argument to Pin"),
+                        };
+                        Ty::new_pinned_ref(self.tcx, region, inner_ty, mutbl)
+                    }
+                    _ => bug!("Cannot adjust receiver type for reborrowing pin of {target:?}"),
+                };
+
+                adjustments.push(Adjustment { kind: Adjust::ReborrowPin(region, mutbl), target });
+            }
             None => {}
         }
 

compiler/rustc_hir_typeck/src/method/prelude_edition_lints.rs

@@ -121,16 +121,27 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                             mutbl.ref_prefix_str()
                         }
                         Some(probe::AutorefOrPtrAdjustment::ToConstPtr) | None => "",
+                        Some(probe::AutorefOrPtrAdjustment::ReborrowPin(mutbl)) => match mutbl {
+                            hir::Mutability::Mut => "Pin<&mut ",
+                            hir::Mutability::Not => "Pin<&",
+                        },
                     };
                     if let Ok(self_expr) = self.sess().source_map().span_to_snippet(self_expr.span)
                     {
-                        let self_adjusted = if let Some(probe::AutorefOrPtrAdjustment::ToConstPtr) =
+                        let mut self_adjusted =
+                            if let Some(probe::AutorefOrPtrAdjustment::ToConstPtr) =
+                                pick.autoref_or_ptr_adjustment
+                            {
+                                format!("{derefs}{self_expr} as *const _")
+                            } else {
+                                format!("{autoref}{derefs}{self_expr}")
+                            };
+
+                        if let Some(probe::AutorefOrPtrAdjustment::ReborrowPin(_)) =
                             pick.autoref_or_ptr_adjustment
                         {
-                            format!("{derefs}{self_expr} as *const _")
+                            self_adjusted.push('>');
-                        } else {
+                        }
-                            format!("{autoref}{derefs}{self_expr}")
-                        };
 
                         lint.span_suggestion(
                             sp,
@@ -400,6 +411,10 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         let autoref = match pick.autoref_or_ptr_adjustment {
             Some(probe::AutorefOrPtrAdjustment::Autoref { mutbl, .. }) => mutbl.ref_prefix_str(),
             Some(probe::AutorefOrPtrAdjustment::ToConstPtr) | None => "",
+            Some(probe::AutorefOrPtrAdjustment::ReborrowPin(mutbl)) => match mutbl {
+                hir::Mutability::Mut => "Pin<&mut ",
+                hir::Mutability::Not => "Pin<&",
+            },
         };
 
         let (expr_text, precise) = if let Some(expr_text) = expr
@@ -412,7 +427,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             ("(..)".to_string(), false)
         };
 
-        let adjusted_text = if let Some(probe::AutorefOrPtrAdjustment::ToConstPtr) =
+        let mut adjusted_text = if let Some(probe::AutorefOrPtrAdjustment::ToConstPtr) =
             pick.autoref_or_ptr_adjustment
         {
             format!("{derefs}{expr_text} as *const _")
@@ -420,6 +435,11 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             format!("{autoref}{derefs}{expr_text}")
         };
 
+        if let Some(probe::AutorefOrPtrAdjustment::ReborrowPin(_)) = pick.autoref_or_ptr_adjustment
+        {
+            adjusted_text.push('>');
+        }
+
         (adjusted_text, precise)
     }
 }

compiler/rustc_hir_typeck/src/method/probe.rs

@@ -136,7 +136,7 @@ enum ProbeResult {
 /// `mut`), or it has type `*mut T` and we convert it to `*const T`.
 #[derive(Debug, PartialEq, Copy, Clone)]
 pub(crate) enum AutorefOrPtrAdjustment {
-    /// Receiver has type `T`, add `&` or `&mut` (it `T` is `mut`), and maybe also "unsize" it.
+    /// Receiver has type `T`, add `&` or `&mut` (if `T` is `mut`), and maybe also "unsize" it.
     /// Unsizing is used to convert a `[T; N]` to `[T]`, which only makes sense when autorefing.
     Autoref {
         mutbl: hir::Mutability,
@@ -147,6 +147,9 @@ pub(crate) enum AutorefOrPtrAdjustment {
     },
     /// Receiver has type `*mut T`, convert to `*const T`
     ToConstPtr,
+
+    /// Reborrow a `Pin<&mut T>` or `Pin<&T>`.
+    ReborrowPin(hir::Mutability),
 }
 
 impl AutorefOrPtrAdjustment {
@@ -154,6 +157,7 @@ impl AutorefOrPtrAdjustment {
         match self {
             AutorefOrPtrAdjustment::Autoref { mutbl: _, unsize } => *unsize,
             AutorefOrPtrAdjustment::ToConstPtr => false,
+            AutorefOrPtrAdjustment::ReborrowPin(_) => false,
         }
     }
 }
@@ -1103,6 +1107,13 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
                                 unstable_candidates.as_deref_mut(),
                             )
                         })
+                        .or_else(|| {
+                            self.pick_reborrow_pin_method(
+                                step,
+                                self_ty,
+                                unstable_candidates.as_deref_mut(),
+                            )
+                        })
                     })
             })
     }
@@ -1127,13 +1138,28 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
             r.map(|mut pick| {
                 pick.autoderefs = step.autoderefs;
 
-                // Insert a `&*` or `&mut *` if this is a reference type:
+                match *step.self_ty.value.value.kind() {
-                if let ty::Ref(_, _, mutbl) = *step.self_ty.value.value.kind() {
+                    // Insert a `&*` or `&mut *` if this is a reference type:
-                    pick.autoderefs += 1;
+                    ty::Ref(_, _, mutbl) => {
-                    pick.autoref_or_ptr_adjustment = Some(AutorefOrPtrAdjustment::Autoref {
+                        pick.autoderefs += 1;
-                        mutbl,
+                        pick.autoref_or_ptr_adjustment = Some(AutorefOrPtrAdjustment::Autoref {
-                        unsize: pick.autoref_or_ptr_adjustment.is_some_and(|a| a.get_unsize()),
+                            mutbl,
-                    })
+                            unsize: pick.autoref_or_ptr_adjustment.is_some_and(|a| a.get_unsize()),
+                        })
+                    }
+
+                    ty::Adt(def, args)
+                        if self.tcx.features().pin_ergonomics
+                            && self.tcx.is_lang_item(def.did(), hir::LangItem::Pin) =>
+                    {
+                        // make sure this is a pinned reference (and not a `Pin<Box>` or something)
+                        if let ty::Ref(_, _, mutbl) = args[0].expect_ty().kind() {
+                            pick.autoref_or_ptr_adjustment =
+                                Some(AutorefOrPtrAdjustment::ReborrowPin(*mutbl));
+                        }
+                    }
+
+                    _ => (),
                 }
 
                 pick
@@ -1164,6 +1190,43 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
         })
     }
 
+    /// Looks for applicable methods if we reborrow a `Pin<&mut T>` as a `Pin<&T>`.
+    #[instrument(level = "debug", skip(self, step, unstable_candidates))]
+    fn pick_reborrow_pin_method(
+        &self,
+        step: &CandidateStep<'tcx>,
+        self_ty: Ty<'tcx>,
+        unstable_candidates: Option<&mut Vec<(Candidate<'tcx>, Symbol)>>,
+    ) -> Option<PickResult<'tcx>> {
+        if !self.tcx.features().pin_ergonomics {
+            return None;
+        }
+
+        // make sure self is a Pin<&mut T>
+        let inner_ty = match self_ty.kind() {
+            ty::Adt(def, args) if self.tcx.is_lang_item(def.did(), hir::LangItem::Pin) => {
+                match args[0].expect_ty().kind() {
+                    ty::Ref(_, ty, hir::Mutability::Mut) => *ty,
+                    _ => {
+                        return None;
+                    }
+                }
+            }
+            _ => return None,
+        };
+
+        let region = self.tcx.lifetimes.re_erased;
+        let autopin_ty = Ty::new_pinned_ref(self.tcx, region, inner_ty, hir::Mutability::Not);
+        self.pick_method(autopin_ty, unstable_candidates).map(|r| {
+            r.map(|mut pick| {
+                pick.autoderefs = step.autoderefs;
+                pick.autoref_or_ptr_adjustment =
+                    Some(AutorefOrPtrAdjustment::ReborrowPin(hir::Mutability::Not));
+                pick
+            })
+        })
+    }
+
     /// If `self_ty` is `*mut T` then this picks `*const T` methods. The reason why we have a
     /// special case for this is because going from `*mut T` to `*const T` with autoderefs and
     /// autorefs would require dereferencing the pointer, which is not safe.

compiler/rustc_middle/src/ty/predicate.rs

@@ -179,6 +179,10 @@ pub struct Clause<'tcx>(
 );
 
 impl<'tcx> rustc_type_ir::inherent::Clause<TyCtxt<'tcx>> for Clause<'tcx> {
+    fn as_predicate(self) -> Predicate<'tcx> {
+        self.as_predicate()
+    }
+
     fn instantiate_supertrait(self, tcx: TyCtxt<'tcx>, trait_ref: ty::PolyTraitRef<'tcx>) -> Self {
         self.instantiate_supertrait(tcx, trait_ref)
     }

compiler/rustc_middle/src/ty/sty.rs

@@ -584,6 +584,16 @@ impl<'tcx> Ty<'tcx> {
         Ty::new_ref(tcx, r, ty, hir::Mutability::Not)
     }
 
+    pub fn new_pinned_ref(
+        tcx: TyCtxt<'tcx>,
+        r: Region<'tcx>,
+        ty: Ty<'tcx>,
+        mutbl: ty::Mutability,
+    ) -> Ty<'tcx> {
+        let pin = tcx.adt_def(tcx.require_lang_item(LangItem::Pin, None));
+        Ty::new_adt(tcx, pin, tcx.mk_args(&[Ty::new_ref(tcx, r, ty, mutbl).into()]))
+    }
+
     #[inline]
     pub fn new_ptr(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>, mutbl: ty::Mutability) -> Ty<'tcx> {
         Ty::new(tcx, ty::RawPtr(ty, mutbl))

compiler/rustc_mir_transform/src/known_panics_lint.rs

@@ -600,13 +600,15 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
             }
 
             Len(place) => {
-                let len = match self.get_const(place)? {
+                let len = if let ty::Array(_, n) = place.ty(self.local_decls(), self.tcx).ty.kind()
-                    Value::Immediate(src) => src.len(&self.ecx).discard_err()?,
+                {
-                    Value::Aggregate { fields, .. } => fields.len() as u64,
+                    n.try_eval_target_usize(self.tcx, self.param_env)?
-                    Value::Uninit => match place.ty(self.local_decls(), self.tcx).ty.kind() {
+                } else {
-                        ty::Array(_, n) => n.try_eval_target_usize(self.tcx, self.param_env)?,
+                    match self.get_const(place)? {
-                        _ => return None,
+                        Value::Immediate(src) => src.len(&self.ecx).discard_err()?,
-                    },
+                        Value::Aggregate { fields, .. } => fields.len() as u64,
+                        Value::Uninit => return None,
+                    }
                 };
                 ImmTy::from_scalar(Scalar::from_target_usize(len, self), layout).into()
             }

compiler/rustc_trait_selection/src/error_reporting/traits/fulfillment_errors.rs

@@ -1,6 +1,7 @@
 use core::ops::ControlFlow;
 use std::borrow::Cow;
 
+use rustc_ast::TraitObjectSyntax;
 use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::unord::UnordSet;
 use rustc_errors::codes::*;
@@ -573,7 +574,26 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
 
                     ty::PredicateKind::DynCompatible(trait_def_id) => {
                         let violations = self.tcx.dyn_compatibility_violations(trait_def_id);
-                        report_dyn_incompatibility(self.tcx, span, None, trait_def_id, violations)
+                        let mut err = report_dyn_incompatibility(
+                            self.tcx,
+                            span,
+                            None,
+                            trait_def_id,
+                            violations,
+                        );
+                        if let hir::Node::Item(item) =
+                            self.tcx.hir_node_by_def_id(obligation.cause.body_id)
+                            && let hir::ItemKind::Impl(impl_) = item.kind
+                            && let None = impl_.of_trait
+                            && let hir::TyKind::TraitObject(_, _, syntax) = impl_.self_ty.kind
+                            && let TraitObjectSyntax::None = syntax
+                            && impl_.self_ty.span.edition().at_least_rust_2021()
+                        {
+                            // Silence the dyn-compatibility error in favor of the missing dyn on
+                            // self type error. #131051.
+                            err.downgrade_to_delayed_bug();
+                        }
+                        err
                     }
 
                     ty::PredicateKind::Clause(ty::ClauseKind::WellFormed(ty)) => {

compiler/rustc_type_ir/src/elaborate.rs

@@ -44,6 +44,46 @@ pub trait Elaboratable<I: Interner> {
     ) -> Self;
 }
 
+pub struct ClauseWithSupertraitSpan<I: Interner> {
+    pub pred: I::Predicate,
+    // Span of the original elaborated predicate.
+    pub original_span: I::Span,
+    // Span of the supertrait predicatae that lead to this clause.
+    pub supertrait_span: I::Span,
+}
+impl<I: Interner> ClauseWithSupertraitSpan<I> {
+    pub fn new(pred: I::Predicate, span: I::Span) -> Self {
+        ClauseWithSupertraitSpan { pred, original_span: span, supertrait_span: span }
+    }
+}
+impl<I: Interner> Elaboratable<I> for ClauseWithSupertraitSpan<I> {
+    fn predicate(&self) -> <I as Interner>::Predicate {
+        self.pred
+    }
+
+    fn child(&self, clause: <I as Interner>::Clause) -> Self {
+        ClauseWithSupertraitSpan {
+            pred: clause.as_predicate(),
+            original_span: self.original_span,
+            supertrait_span: self.supertrait_span,
+        }
+    }
+
+    fn child_with_derived_cause(
+        &self,
+        clause: <I as Interner>::Clause,
+        supertrait_span: <I as Interner>::Span,
+        _parent_trait_pred: crate::Binder<I, crate::TraitPredicate<I>>,
+        _index: usize,
+    ) -> Self {
+        ClauseWithSupertraitSpan {
+            pred: clause.as_predicate(),
+            original_span: self.original_span,
+            supertrait_span: supertrait_span,
+        }
+    }
+}
+
 pub fn elaborate<I: Interner, O: Elaboratable<I>>(
     cx: I,
     obligations: impl IntoIterator<Item = O>,

compiler/rustc_type_ir/src/inherent.rs

@@ -460,6 +460,8 @@ pub trait Clause<I: Interner<Clause = Self>>:
     + IntoKind<Kind = ty::Binder<I, ty::ClauseKind<I>>>
     + Elaboratable<I>
 {
+    fn as_predicate(self) -> I::Predicate;
+
     fn as_trait_clause(self) -> Option<ty::Binder<I, ty::TraitPredicate<I>>> {
         self.kind()
             .map_bound(|clause| if let ty::ClauseKind::Trait(t) = clause { Some(t) } else { None })

compiler/stable_mir/src/mir/visit.rs

@@ -76,9 +76,9 @@ pub trait MirVisitor {
         self.super_place(place, ptx, location)
     }
 
-    fn visit_projection_elem<'a>(
+    fn visit_projection_elem(
         &mut self,
-        place_ref: PlaceRef<'a>,
+        place_ref: PlaceRef<'_>,
         elem: &ProjectionElem,
         ptx: PlaceContext,
         location: Location,

library/alloc/tests/lib.rs

@@ -7,7 +7,6 @@
 #![feature(const_cow_is_borrowed)]
 #![feature(const_heap)]
 #![cfg_attr(bootstrap, feature(const_mut_refs))]
-#![feature(const_slice_from_raw_parts_mut)]
 #![feature(const_ptr_write)]
 #![feature(const_try)]
 #![feature(core_intrinsics)]

library/core/src/lib.rs

@@ -145,7 +145,6 @@
 #![feature(const_replace)]
 #![feature(const_size_of_val)]
 #![feature(const_size_of_val_raw)]
-#![feature(const_slice_from_raw_parts_mut)]
 #![feature(const_slice_from_ref)]
 #![feature(const_slice_split_at_mut)]
 #![feature(const_strict_overflow_ops)]

library/core/src/ptr/mod.rs

@@ -992,7 +992,7 @@ pub const fn slice_from_raw_parts<T>(data: *const T, len: usize) -> *const [T] {
 /// ```
 #[inline]
 #[stable(feature = "slice_from_raw_parts", since = "1.42.0")]
-#[rustc_const_unstable(feature = "const_slice_from_raw_parts_mut", issue = "67456")]
+#[rustc_const_stable(feature = "const_slice_from_raw_parts_mut", since = "CURRENT_RUSTC_VERSION")]
 #[rustc_diagnostic_item = "ptr_slice_from_raw_parts_mut"]
 pub const fn slice_from_raw_parts_mut<T>(data: *mut T, len: usize) -> *mut [T] {
     from_raw_parts_mut(data, len)

library/core/src/ptr/non_null.rs

@@ -1434,7 +1434,10 @@ impl<T> NonNull<[T]> {
     /// (Note that this example artificially demonstrates a use of this method,
     /// but `let slice = NonNull::from(&x[..]);` would be a better way to write code like this.)
     #[stable(feature = "nonnull_slice_from_raw_parts", since = "1.70.0")]
-    #[rustc_const_unstable(feature = "const_slice_from_raw_parts_mut", issue = "67456")]
+    #[rustc_const_stable(
+        feature = "const_slice_from_raw_parts_mut",
+        since = "CURRENT_RUSTC_VERSION"
+    )]
     #[must_use]
     #[inline]
     pub const fn slice_from_raw_parts(data: NonNull<T>, len: usize) -> Self {

library/core/src/slice/raw.rs

@@ -171,7 +171,8 @@ pub const unsafe fn from_raw_parts<'a, T>(data: *const T, len: usize) -> &'a [T]
 /// [`NonNull::dangling()`]: ptr::NonNull::dangling
 #[inline]
 #[stable(feature = "rust1", since = "1.0.0")]
-#[rustc_const_unstable(feature = "const_slice_from_raw_parts_mut", issue = "67456")]
+#[rustc_const_stable(feature = "const_slice_from_raw_parts_mut", since = "CURRENT_RUSTC_VERSION")]
+#[cfg_attr(bootstrap, rustc_allow_const_fn_unstable(const_mut_refs))]
 #[must_use]
 #[rustc_diagnostic_item = "slice_from_raw_parts_mut"]
 pub const unsafe fn from_raw_parts_mut<'a, T>(data: *mut T, len: usize) -> &'a mut [T] {

library/proc_macro/src/lib.rs

@@ -1166,7 +1166,7 @@ impl fmt::Debug for Ident {
     }
 }
 
-/// A literal string (`"hello"`), byte string (`b"hello"`),
+/// A literal string (`"hello"`), byte string (`b"hello"`), C string (`c"hello"`),
 /// character (`'a'`), byte character (`b'a'`), an integer or floating point number
 /// with or without a suffix (`1`, `1u8`, `2.3`, `2.3f32`).
 /// Boolean literals like `true` and `false` do not belong here, they are `Ident`s.

library/std/src/io/mod.rs

@@ -2382,8 +2382,6 @@ pub trait BufRead: Read {
     /// about Ferris from a binary string, skipping the fun fact:
     ///
     /// ```
-    /// #![feature(bufread_skip_until)]
-    ///
     /// use std::io::{self, BufRead};
     ///
     /// let mut cursor = io::Cursor::new(b"Ferris\0Likes long walks on the beach\0Crustacean\0");
@@ -2407,7 +2405,7 @@ pub trait BufRead: Read {
     /// assert_eq!(num_bytes, 11);
     /// assert_eq!(animal, b"Crustacean\0");
     /// ```
-    #[unstable(feature = "bufread_skip_until", issue = "111735")]
+    #[stable(feature = "bufread_skip_until", since = "CURRENT_RUSTC_VERSION")]
     fn skip_until(&mut self, byte: u8) -> Result<usize> {
         skip_until(self, byte)
     }

src/librustdoc/passes/collect_intra_doc_links.rs

@@ -1996,11 +1996,22 @@ fn resolution_failure(
                             &diag_info,
                         );
 
-                        format!(
+                        if let Some(disambiguator) = disambiguator
-                            "this link resolves to {}, which is not in the {} namespace",
+                            && !matches!(disambiguator, Disambiguator::Namespace(..))
-                            item(res),
+                        {
-                            expected_ns.descr()
+                            format!(
-                        )
+                                "this link resolves to {}, which is not {} {}",
+                                item(res),
+                                disambiguator.article(),
+                                disambiguator.descr()
+                            )
+                        } else {
+                            format!(
+                                "this link resolves to {}, which is not in the {} namespace",
+                                item(res),
+                                expected_ns.descr()
+                            )
+                        }
                     }
                 };
                 if let Some(span) = sp {

src/tools/clippy/tests/ui-toml/unwrap_used/unwrap_used.fixed

@@ -86,6 +86,7 @@ mod issue9612 {
         util();
     }
 
+    #[allow(unconditional_panic)]
     fn util() {
         let _a: u8 = 4.try_into().unwrap();
         let _a: u8 = 5.try_into().expect("");

src/tools/clippy/tests/ui-toml/unwrap_used/unwrap_used.rs

@@ -86,6 +86,7 @@ mod issue9612 {
         util();
     }
 
+    #[allow(unconditional_panic)]
     fn util() {
         let _a: u8 = 4.try_into().unwrap();
         let _a: u8 = 5.try_into().expect("");

src/tools/clippy/tests/ui-toml/unwrap_used/unwrap_used.stderr

@@ -274,7 +274,7 @@ LL |     let _ = &boxed_slice[1];
    |             ~~~~~~~~~~~~~~~
 
 error: called `.get().unwrap()` on a slice
-  --> tests/ui-toml/unwrap_used/unwrap_used.rs:93:17
+  --> tests/ui-toml/unwrap_used/unwrap_used.rs:94:17
    |
 LL |         let _ = Box::new([0]).get(1).unwrap();
    |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

src/tools/clippy/tests/ui/get_unwrap.fixed

@@ -70,6 +70,7 @@ fn main() {
 mod issue9909 {
     #![allow(clippy::identity_op, clippy::unwrap_used, dead_code)]
 
+    #[allow(unconditional_panic)]
     fn reduced() {
         let f = &[1, 2, 3];
 

src/tools/clippy/tests/ui/get_unwrap.rs

@@ -70,6 +70,7 @@ fn main() {
 mod issue9909 {
     #![allow(clippy::identity_op, clippy::unwrap_used, dead_code)]
 
+    #[allow(unconditional_panic)]
     fn reduced() {
         let f = &[1, 2, 3];
 

src/tools/clippy/tests/ui/get_unwrap.stderr

@@ -266,7 +266,7 @@ LL |         let _ = some_vec.get_mut(0..1).unwrap().to_vec();
    = help: consider using `expect()` to provide a better panic message
 
 error: called `.get().unwrap()` on a slice
-  --> tests/ui/get_unwrap.rs:77:24
+  --> tests/ui/get_unwrap.rs:78:24
    |
 LL |         let _x: &i32 = f.get(1 + 2).unwrap();
    |                        ^^^^^^^^^^^^^^^^^^^^^
@@ -277,7 +277,7 @@ LL |         let _x: &i32 = &f[1 + 2];
    |                        ~~~~~~~~~
 
 error: called `.get().unwrap()` on a slice
-  --> tests/ui/get_unwrap.rs:80:18
+  --> tests/ui/get_unwrap.rs:81:18
    |
 LL |         let _x = f.get(1 + 2).unwrap().to_string();
    |                  ^^^^^^^^^^^^^^^^^^^^^
@@ -288,7 +288,7 @@ LL |         let _x = f[1 + 2].to_string();
    |                  ~~~~~~~~
 
 error: called `.get().unwrap()` on a slice
-  --> tests/ui/get_unwrap.rs:83:18
+  --> tests/ui/get_unwrap.rs:84:18
    |
 LL |         let _x = f.get(1 + 2).unwrap().abs();
    |                  ^^^^^^^^^^^^^^^^^^^^^
@@ -299,7 +299,7 @@ LL |         let _x = f[1 + 2].abs();
    |                  ~~~~~~~~
 
 error: called `.get_mut().unwrap()` on a slice
-  --> tests/ui/get_unwrap.rs:100:33
+  --> tests/ui/get_unwrap.rs:101:33
    |
 LL |                         let b = rest.get_mut(linidx(j, k) - linidx(i, k) - 1).unwrap();
    |                                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

tests/rustdoc-ui/intra-doc/disambiguator-mismatch.stderr

@@ -74,7 +74,7 @@ error: unresolved link to `m`
   --> $DIR/disambiguator-mismatch.rs:52:14
    |
 LL | /// Link to [m()]
-   |              ^^^ this link resolves to the macro `m`, which is not in the value namespace
+   |              ^^^ this link resolves to the macro `m`, which is not a function
    |
 help: to link to the macro, add an exclamation mark
    |
@@ -142,7 +142,7 @@ error: unresolved link to `std`
   --> $DIR/disambiguator-mismatch.rs:83:14
    |
 LL | /// Link to [fn@std]
-   |              ^^^^^^ this link resolves to the crate `std`, which is not in the value namespace
+   |              ^^^^^^ this link resolves to the crate `std`, which is not a function
    |
 help: to link to the crate, prefix with `mod@`
    |
@@ -164,7 +164,7 @@ error: unresolved link to `S::A`
   --> $DIR/disambiguator-mismatch.rs:93:14
    |
 LL | /// Link to [field@S::A]
-   |              ^^^^^^^^^^ this link resolves to the variant `A`, which is not in the value namespace
+   |              ^^^^^^^^^^ this link resolves to the variant `A`, which is not a field
    |
 help: to link to the variant, prefix with `variant@`
    |

tests/rustdoc-ui/intra-doc/errors.rs

@@ -98,7 +98,7 @@ pub trait T {
 /// [m()]
 //~^ ERROR unresolved link
 //~| HELP to link to the macro
-//~| NOTE not in the value namespace
+//~| NOTE not a function
 #[macro_export]
 macro_rules! m {
     () => {};

tests/rustdoc-ui/intra-doc/errors.stderr

@@ -104,7 +104,7 @@ error: unresolved link to `S`
   --> $DIR/errors.rs:68:6
    |
 LL | /// [S!]
-   |      ^^ this link resolves to the struct `S`, which is not in the macro namespace
+   |      ^^ this link resolves to the struct `S`, which is not a macro
    |
 help: to link to the struct, prefix with `struct@`
    |
@@ -158,7 +158,7 @@ error: unresolved link to `m`
   --> $DIR/errors.rs:98:6
    |
 LL | /// [m()]
-   |      ^^^ this link resolves to the macro `m`, which is not in the value namespace
+   |      ^^^ this link resolves to the macro `m`, which is not a function
    |
 help: to link to the macro, add an exclamation mark
    |

tests/rustdoc-ui/intra-doc/issue-110495-suffix-with-space.stderr

@@ -2,7 +2,7 @@ error: unresolved link to `Clone`
   --> $DIR/issue-110495-suffix-with-space.rs:3:6
    |
 LL | //! [Clone ()].
-   |      ^^^^^^^^ this link resolves to the trait `Clone`, which is not in the value namespace
+   |      ^^^^^^^^ this link resolves to the trait `Clone`, which is not a function
    |
 note: the lint level is defined here
   --> $DIR/issue-110495-suffix-with-space.rs:2:9
@@ -31,7 +31,7 @@ error: unresolved link to `Clone`
   --> $DIR/issue-110495-suffix-with-space.rs:5:7
    |
 LL | //! [`Clone ()`].
-   |       ^^^^^^^^ this link resolves to the trait `Clone`, which is not in the value namespace
+   |       ^^^^^^^^ this link resolves to the trait `Clone`, which is not a function
    |
 help: to link to the trait, prefix with `trait@`
    |

tests/rustdoc-ui/intra-doc/weird-syntax.stderr

@@ -40,7 +40,7 @@ error: unresolved link to `Clone`
   --> $DIR/weird-syntax.rs:27:9
    |
 LL | /// [  `Clone ()`  ]
-   |         ^^^^^^^^ this link resolves to the trait `Clone`, which is not in the value namespace
+   |         ^^^^^^^^ this link resolves to the trait `Clone`, which is not a function
    |
 help: to link to the trait, prefix with `trait@`
    |
@@ -52,7 +52,7 @@ error: unresolved link to `Clone`
   --> $DIR/weird-syntax.rs:30:7
    |
 LL | /// [`Clone ()`  ]
-   |       ^^^^^^^^ this link resolves to the trait `Clone`, which is not in the value namespace
+   |       ^^^^^^^^ this link resolves to the trait `Clone`, which is not a function
    |
 help: to link to the trait, prefix with `trait@`
    |
@@ -64,7 +64,7 @@ error: unresolved link to `Clone`
   --> $DIR/weird-syntax.rs:33:9
    |
 LL | /// [  `Clone ()`]
-   |         ^^^^^^^^ this link resolves to the trait `Clone`, which is not in the value namespace
+   |         ^^^^^^^^ this link resolves to the trait `Clone`, which is not a function
    |
 help: to link to the trait, prefix with `trait@`
    |
@@ -76,7 +76,7 @@ error: unresolved link to `Clone`
   --> $DIR/weird-syntax.rs:36:9
    |
 LL | /// [```Clone ()```]
-   |         ^^^^^^^^ this link resolves to the trait `Clone`, which is not in the value namespace
+   |         ^^^^^^^^ this link resolves to the trait `Clone`, which is not a function
    |
 help: to link to the trait, prefix with `trait@`
    |
@@ -88,7 +88,7 @@ error: unresolved link to `Clone`
   --> $DIR/weird-syntax.rs:42:13
    |
 LL | /// [  ```  Clone ()  ```  ]
-   |             ^^^^^^^^ this link resolves to the trait `Clone`, which is not in the value namespace
+   |             ^^^^^^^^ this link resolves to the trait `Clone`, which is not a function
    |
 help: to link to the trait, prefix with `trait@`
    |
@@ -122,7 +122,7 @@ error: unresolved link to `Clone`
   --> $DIR/weird-syntax.rs:74:9
    |
 LL | /// [x][Clone()]
-   |         ^^^^^^^ this link resolves to the trait `Clone`, which is not in the value namespace
+   |         ^^^^^^^ this link resolves to the trait `Clone`, which is not a function
    |
 help: to link to the trait, prefix with `trait@`
    |
@@ -134,7 +134,7 @@ error: unresolved link to `Clone`
   --> $DIR/weird-syntax.rs:77:9
    |
 LL | /// [x][Clone  ()]
-   |         ^^^^^^^^^ this link resolves to the trait `Clone`, which is not in the value namespace
+   |         ^^^^^^^^^ this link resolves to the trait `Clone`, which is not a function
    |
 help: to link to the trait, prefix with `trait@`
    |
@@ -176,7 +176,7 @@ error: unresolved link to `Clone`
   --> $DIR/weird-syntax.rs:97:9
    |
 LL | /// [w](Clone\(\))
-   |         ^^^^^^^^^ this link resolves to the trait `Clone`, which is not in the value namespace
+   |         ^^^^^^^^^ this link resolves to the trait `Clone`, which is not a function
    |
 help: to link to the trait, prefix with `trait@`
    |
@@ -188,7 +188,7 @@ error: unresolved link to `Clone`
   --> $DIR/weird-syntax.rs:103:9
    |
 LL | /// [w](Clone())
-   |         ^^^^^^^ this link resolves to the trait `Clone`, which is not in the value namespace
+   |         ^^^^^^^ this link resolves to the trait `Clone`, which is not a function
    |
 help: to link to the trait, prefix with `trait@`
    |
@@ -256,7 +256,7 @@ error: unresolved link to `Clone`
   --> $DIR/weird-syntax.rs:132:9
    |
 LL | /// The [cln][] link here will produce a plain text suggestion
-   |         ^^^^^ this link resolves to the trait `Clone`, which is not in the value namespace
+   |         ^^^^^ this link resolves to the trait `Clone`, which is not a function
    |
    = help: to link to the trait, prefix with `trait@`: trait@Clone
 

tests/ui/async-await/pin-reborrow-self.rs

@@ -1,24 +1,33 @@
 //@ check-pass
-//@ignore-test
-
-// Currently ignored due to self reborrowing not being implemented for Pin
 
 #![feature(pin_ergonomics)]
 #![allow(incomplete_features)]
 
 use std::pin::Pin;
 
-struct Foo;
+pub struct Foo;
 
 impl Foo {
     fn foo(self: Pin<&mut Self>) {
     }
+
+    fn baz(self: Pin<&Self>) {
+    }
 }
 
-fn bar(x: Pin<&mut Foo>) {
+pub fn bar(x: Pin<&mut Foo>) {
     x.foo();
     x.foo(); // for this to work we need to automatically reborrow,
              // as if the user had written `x.as_mut().foo()`.
+
+    Foo::baz(x);
+
+    x.baz();
+}
+
+pub fn baaz(x: Pin<&Foo>) {
+    x.baz();
+    x.baz();
 }
 
 fn main() {}

tests/ui/feature-gates/feature-gate-pin_ergonomics.rs

@@ -4,6 +4,11 @@ use std::pin::Pin;
 
 struct Foo;
 
+impl Foo {
+    fn foo(self: Pin<&mut Self>) {
+    }
+}
+
 fn foo(_: Pin<&mut Foo>) {
 }
 
@@ -12,4 +17,9 @@ fn bar(mut x: Pin<&mut Foo>) {
     foo(x); //~ ERROR use of moved value: `x`
 }
 
+fn baz(mut x: Pin<&mut Foo>) {
+    x.foo();
+    x.foo(); //~ ERROR use of moved value: `x`
+}
+
 fn main() {}

tests/ui/feature-gates/feature-gate-pin_ergonomics.stderr

@@ -1,5 +1,5 @@
 error[E0382]: use of moved value: `x`
-  --> $DIR/feature-gate-pin_ergonomics.rs:12:9
+  --> $DIR/feature-gate-pin_ergonomics.rs:17:9
    |
 LL | fn bar(mut x: Pin<&mut Foo>) {
    |        ----- move occurs because `x` has type `Pin<&mut Foo>`, which does not implement the `Copy` trait
@@ -9,13 +9,33 @@ LL |     foo(x);
    |         ^ value used here after move
    |
 note: consider changing this parameter type in function `foo` to borrow instead if owning the value isn't necessary
-  --> $DIR/feature-gate-pin_ergonomics.rs:7:11
+  --> $DIR/feature-gate-pin_ergonomics.rs:12:11
    |
 LL | fn foo(_: Pin<&mut Foo>) {
    |    ---    ^^^^^^^^^^^^^ this parameter takes ownership of the value
    |    |
    |    in this function
 
-error: aborting due to 1 previous error
+error[E0382]: use of moved value: `x`
+  --> $DIR/feature-gate-pin_ergonomics.rs:22:5
+   |
+LL | fn baz(mut x: Pin<&mut Foo>) {
+   |        ----- move occurs because `x` has type `Pin<&mut Foo>`, which does not implement the `Copy` trait
+LL |     x.foo();
+   |       ----- `x` moved due to this method call
+LL |     x.foo();
+   |     ^ value used here after move
+   |
+note: `Foo::foo` takes ownership of the receiver `self`, which moves `x`
+  --> $DIR/feature-gate-pin_ergonomics.rs:8:12
+   |
+LL |     fn foo(self: Pin<&mut Self>) {
+   |            ^^^^
+help: consider reborrowing the `Pin` instead of moving it
+   |
+LL |     x.as_mut().foo();
+   |      +++++++++
+
+error: aborting due to 2 previous errors
 
 For more information about this error, try `rustc --explain E0382`.

tests/ui/lint/unconditional_panic_promoted.rs

@@ -0,0 +1,8 @@
+//@ build-fail
+
+fn main() {
+    // MIR encodes this as a reborrow from a promoted constant.
+    // But the array lenth can still be gotten from the type.
+    let slice = &[0, 1];
+    let _ = slice[2]; //~ ERROR: this operation will panic at runtime [unconditional_panic]
+}

tests/ui/lint/unconditional_panic_promoted.stderr

@@ -0,0 +1,10 @@
+error: this operation will panic at runtime
+  --> $DIR/unconditional_panic_promoted.rs:7:13
+   |
+LL |     let _ = slice[2];
+   |             ^^^^^^^^ index out of bounds: the length is 2 but the index is 2
+   |
+   = note: `#[deny(unconditional_panic)]` on by default
+
+error: aborting due to 1 previous error
+

tests/ui/traits/missing-for-type-in-impl.e2015.stderr

@@ -0,0 +1,74 @@
+warning: trait objects without an explicit `dyn` are deprecated
+  --> $DIR/missing-for-type-in-impl.rs:8:6
+   |
+LL | impl Foo<i64> {
+   |      ^^^^^^^^
+   |
+   = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
+   = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
+   = note: `#[warn(bare_trait_objects)]` on by default
+help: if this is a dyn-compatible trait, use `dyn`
+   |
+LL | impl dyn Foo<i64> {
+   |      +++
+help: you might have intended to implement this trait for a given type
+   |
+LL | impl Foo<i64> for /* Type */ {
+   |               ++++++++++++++
+
+warning: trait objects without an explicit `dyn` are deprecated
+  --> $DIR/missing-for-type-in-impl.rs:8:6
+   |
+LL | impl Foo<i64> {
+   |      ^^^^^^^^
+   |
+   = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
+   = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
+help: if this is a dyn-compatible trait, use `dyn`
+   |
+LL | impl dyn Foo<i64> {
+   |      +++
+help: you might have intended to implement this trait for a given type
+   |
+LL | impl Foo<i64> for /* Type */ {
+   |               ++++++++++++++
+
+error[E0038]: the trait `Foo` cannot be made into an object
+  --> $DIR/missing-for-type-in-impl.rs:8:6
+   |
+LL | impl Foo<i64> {
+   |      ^^^^^^^^ `Foo` cannot be made into an object
+   |
+note: for a trait to be "dyn-compatible" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit <https://doc.rust-lang.org/reference/items/traits.html#object-safety>
+  --> $DIR/missing-for-type-in-impl.rs:4:8
+   |
+LL | trait Foo<T> {
+   |       --- this trait cannot be made into an object...
+LL |     fn id(me: T) -> T;
+   |        ^^ ...because associated function `id` has no `self` parameter
+help: consider turning `id` into a method by giving it a `&self` argument
+   |
+LL |     fn id(&self, me: T) -> T;
+   |           ++++++
+help: alternatively, consider constraining `id` so it does not apply to trait objects
+   |
+LL |     fn id(me: T) -> T where Self: Sized;
+   |                       +++++++++++++++++
+
+error[E0277]: the trait bound `i64: Foo<i64>` is not satisfied
+  --> $DIR/missing-for-type-in-impl.rs:19:19
+   |
+LL |     let x: i64 = <i64 as Foo<i64>>::id(10);
+   |                   ^^^ the trait `Foo<i64>` is not implemented for `i64`
+   |
+help: this trait has no implementations, consider adding one
+  --> $DIR/missing-for-type-in-impl.rs:3:1
+   |
+LL | trait Foo<T> {
+   | ^^^^^^^^^^^^
+
+error: aborting due to 2 previous errors; 2 warnings emitted
+
+Some errors have detailed explanations: E0038, E0277.
+For more information about an error, try `rustc --explain E0038`.

tests/ui/traits/missing-for-type-in-impl.e2021.stderr

@@ -0,0 +1,31 @@
+error[E0277]: the trait bound `i64: Foo<i64>` is not satisfied
+  --> $DIR/missing-for-type-in-impl.rs:19:19
+   |
+LL |     let x: i64 = <i64 as Foo<i64>>::id(10);
+   |                   ^^^ the trait `Foo<i64>` is not implemented for `i64`
+   |
+help: this trait has no implementations, consider adding one
+  --> $DIR/missing-for-type-in-impl.rs:3:1
+   |
+LL | trait Foo<T> {
+   | ^^^^^^^^^^^^
+
+error[E0782]: trait objects must include the `dyn` keyword
+  --> $DIR/missing-for-type-in-impl.rs:8:6
+   |
+LL | impl Foo<i64> {
+   |      ^^^^^^^^
+   |
+help: add `dyn` keyword before this trait
+   |
+LL | impl dyn Foo<i64> {
+   |      +++
+help: you might have intended to implement this trait for a given type
+   |
+LL | impl Foo<i64> for /* Type */ {
+   |               ++++++++++++++
+
+error: aborting due to 2 previous errors
+
+Some errors have detailed explanations: E0277, E0782.
+For more information about an error, try `rustc --explain E0277`.

tests/ui/traits/missing-for-type-in-impl.rs

@@ -0,0 +1,22 @@
+//@revisions: e2021 e2015
+//@[e2021]edition: 2021
+trait Foo<T> {
+    fn id(me: T) -> T;
+}
+
+/* note the "missing" for ... (in this case for i64, in order for this to compile) */
+impl Foo<i64> {
+//[e2021]~^ ERROR trait objects must include the `dyn` keyword
+//[e2015]~^^ WARNING trait objects without an explicit `dyn` are deprecated
+//[e2015]~| WARNING trait objects without an explicit `dyn` are deprecated
+//[e2015]~| WARNING this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
+//[e2015]~| WARNING this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
+//[e2015]~| ERROR the trait `Foo` cannot be made into an object
+    fn id(me: i64) -> i64 {me}
+}
+
+fn main() {
+    let x: i64 = <i64 as Foo<i64>>::id(10);
+    //~^ ERROR the trait bound `i64: Foo<i64>` is not satisfied
+    println!("{}", x);
+}

tests/ui/traits/object/elaborated-predicates-unconstrained-late-bound.rs

@@ -0,0 +1,24 @@
+// Make sure that when elaborating the principal of a dyn trait for projection predicates
+//  we don't end up in a situation where we have an unconstrained late-bound lifetime in
+// the output of a projection.
+
+// Fix for <https://github.com/rust-lang/rust/issues/130347>.
+
+trait A<T>: B<T = T> {}
+
+trait B {
+    type T;
+}
+
+struct Erase<T: ?Sized + B>(T::T);
+
+fn main() {
+    let x = {
+        let x = String::from("hello");
+
+        Erase::<dyn for<'a> A<&'a _>>(x.as_str())
+        //~^ ERROR binding for associated type `T` references lifetime `'a`, which does not appear in the trait input types
+    };
+
+    dbg!(x.0);
+}

tests/ui/traits/object/elaborated-predicates-unconstrained-late-bound.stderr

@@ -0,0 +1,12 @@
+error[E0582]: binding for associated type `T` references lifetime `'a`, which does not appear in the trait input types
+  --> $DIR/elaborated-predicates-unconstrained-late-bound.rs:19:21
+   |
+LL | trait A<T>: B<T = T> {}
+   |               ----- due to this supertrait
+...
+LL |         Erase::<dyn for<'a> A<&'a _>>(x.as_str())
+   |                     ^^^^^^^^^^^^^^^^
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0582`.

tests/ui/traits/object/pretty.rs

@@ -13,7 +13,7 @@ trait SuperGeneric<'a> {
 }
 trait AnyGeneric<'a>: SuperGeneric<'a> {}
 trait FixedGeneric1<'a>: SuperGeneric<'a, Assoc2 = &'a u8> {}
-trait FixedGeneric2<'a>: Super<Assoc = &'a u8> {}
+// trait FixedGeneric2<'a>: Super<Assoc = &'a u8> {} // Unsound!
 trait FixedHrtb: for<'a> SuperGeneric<'a, Assoc2 = &'a u8> {}
 trait AnyDifferentBinders: for<'a> SuperGeneric<'a, Assoc2 = &'a u8> + Super {}
 trait FixedDifferentBinders: for<'a> SuperGeneric<'a, Assoc2 = &'a u8> + Super<Assoc = u8> {}
@@ -32,7 +32,7 @@ fn dyn_fixed_static(x: &dyn FixedStatic) { x } //~ERROR mismatched types
 fn dyn_super_generic(x: &dyn for<'a> SuperGeneric<'a, Assoc2 = &'a u8>) { x } //~ERROR mismatched types
 fn dyn_any_generic(x: &dyn for<'a> AnyGeneric<'a, Assoc2 = &'a u8>) { x } //~ERROR mismatched types
 fn dyn_fixed_generic1(x: &dyn for<'a> FixedGeneric1<'a>) { x } //~ERROR mismatched types
-fn dyn_fixed_generic2(x: &dyn for<'a> FixedGeneric2<'a>) { x } //~ERROR mismatched types
+// fn dyn_fixed_generic2(x: &dyn for<'a> FixedGeneric2<'a>) { x } // Unsound!
 fn dyn_fixed_generic_multi(x: &dyn for<'a> FixedGeneric1<'a, Assoc2 = &u8>) { x } //~ERROR mismatched types
 fn dyn_fixed_hrtb(x: &dyn FixedHrtb) { x } //~ERROR mismatched types
 fn dyn_any_different_binders(x: &dyn AnyDifferentBinders<Assoc = u8>) { x } //~ERROR mismatched types

tests/ui/traits/object/pretty.stderr

@@ -106,17 +106,6 @@ LL | fn dyn_fixed_generic1(x: &dyn for<'a> FixedGeneric1<'a>) { x }
    = note: expected unit type `()`
               found reference `&dyn for<'a> FixedGeneric1<'a>`
 
-error[E0308]: mismatched types
-  --> $DIR/pretty.rs:35:60
-   |
-LL | fn dyn_fixed_generic2(x: &dyn for<'a> FixedGeneric2<'a>) { x }
-   |                                                         -  ^ expected `()`, found `&dyn FixedGeneric2<'a>`
-   |                                                         |
-   |                                                         help: try adding a return type: `-> &dyn for<'a> FixedGeneric2<'a>`
-   |
-   = note: expected unit type `()`
-              found reference `&dyn for<'a> FixedGeneric2<'a>`
-
 error[E0308]: mismatched types
   --> $DIR/pretty.rs:36:79
    |
@@ -172,6 +161,6 @@ LL | fn dyn_has_gat(x: &dyn HasGat<u8, Assoc<bool> = ()>) { x }
    = note: expected unit type `()`
               found reference `&dyn HasGat<u8, Assoc<bool> = ()>`
 
-error: aborting due to 15 previous errors; 1 warning emitted
+error: aborting due to 14 previous errors; 1 warning emitted
 
 For more information about this error, try `rustc --explain E0308`.