Rollup of 8 pull requests

compiler/rustc_borrowck/src/diagnostics/explain_borrow.rs

@@ -5,12 +5,13 @@ use rustc_hir as hir;
 use rustc_hir::intravisit::Visitor;
 use rustc_index::IndexSlice;
 use rustc_infer::infer::NllRegionVariableOrigin;
+use rustc_middle::middle::resolve_bound_vars::ObjectLifetimeDefault;
 use rustc_middle::mir::{
     Body, CallSource, CastKind, ConstraintCategory, FakeReadCause, Local, LocalInfo, Location,
     Operand, Place, Rvalue, Statement, StatementKind, TerminatorKind,
 };
 use rustc_middle::ty::adjustment::PointerCoercion;
-use rustc_middle::ty::{self, RegionVid, TyCtxt};
+use rustc_middle::ty::{self, RegionVid, Ty, TyCtxt};
 use rustc_span::symbol::{kw, Symbol};
 use rustc_span::{sym, DesugaringKind, Span};
 use rustc_trait_selection::traits::error_reporting::FindExprBySpan;
@@ -290,12 +291,69 @@ impl<'tcx> BorrowExplanation<'tcx> {
                     }
                 }
 
+                if let ConstraintCategory::Cast { unsize_to: Some(unsize_ty) } = category {
+                    self.add_object_lifetime_default_note(tcx, err, unsize_ty);
+                }
                 self.add_lifetime_bound_suggestion_to_diagnostic(err, &category, span, region_name);
             }
             _ => {}
         }
     }
 
+    fn add_object_lifetime_default_note(
+        &self,
+        tcx: TyCtxt<'tcx>,
+        err: &mut Diagnostic,
+        unsize_ty: Ty<'tcx>,
+    ) {
+        if let ty::Adt(def, args) = unsize_ty.kind() {
+            // We try to elaborate the object lifetime defaults and present those to the user. This should
+            // make it clear where the region constraint is coming from.
+            let generics = tcx.generics_of(def.did());
+
+            let mut has_dyn = false;
+            let mut failed = false;
+
+            let elaborated_args = std::iter::zip(*args, &generics.params).map(|(arg, param)| {
+                if let Some(ty::Dynamic(obj, _, ty::DynKind::Dyn)) = arg.as_type().map(Ty::kind) {
+                    let default = tcx.object_lifetime_default(param.def_id);
+
+                    let re_static = tcx.lifetimes.re_static;
+
+                    let implied_region = match default {
+                        // This is not entirely precise.
+                        ObjectLifetimeDefault::Empty => re_static,
+                        ObjectLifetimeDefault::Ambiguous => {
+                            failed = true;
+                            re_static
+                        }
+                        ObjectLifetimeDefault::Param(param_def_id) => {
+                            let index = generics.param_def_id_to_index[&param_def_id] as usize;
+                            args.get(index).and_then(|arg| arg.as_region()).unwrap_or_else(|| {
+                                failed = true;
+                                re_static
+                            })
+                        }
+                        ObjectLifetimeDefault::Static => re_static,
+                    };
+
+                    has_dyn = true;
+
+                    Ty::new_dynamic(tcx, obj, implied_region, ty::DynKind::Dyn).into()
+                } else {
+                    arg
+                }
+            });
+            let elaborated_ty = Ty::new_adt(tcx, *def, tcx.mk_args_from_iter(elaborated_args));
+
+            if has_dyn && !failed {
+                err.note(format!(
+                    "due to object lifetime defaults, `{unsize_ty}` actually means `{elaborated_ty}`"
+                ));
+            }
+        }
+    }
+
     fn add_lifetime_bound_suggestion_to_diagnostic(
         &self,
         err: &mut Diagnostic,

compiler/rustc_borrowck/src/diagnostics/region_errors.rs

@@ -53,7 +53,7 @@ impl<'tcx> ConstraintDescription for ConstraintCategory<'tcx> {
             ConstraintCategory::Yield => "yielding this value ",
             ConstraintCategory::UseAsConst => "using this value as a constant ",
             ConstraintCategory::UseAsStatic => "using this value as a static ",
-            ConstraintCategory::Cast => "cast ",
+            ConstraintCategory::Cast { .. } => "cast ",
             ConstraintCategory::CallArgument(_) => "argument ",
             ConstraintCategory::TypeAnnotation => "type annotation ",
             ConstraintCategory::ClosureBounds => "closure body ",

compiler/rustc_borrowck/src/type_check/mod.rs

@@ -1934,7 +1934,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
                             *ty,
                             ty_fn_ptr_from,
                             location.to_locations(),
-                            ConstraintCategory::Cast,
+                            ConstraintCategory::Cast { unsize_to: None },
                         ) {
                             span_mirbug!(
                                 self,
@@ -1959,7 +1959,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
                             *ty,
                             ty_fn_ptr_from,
                             location.to_locations(),
-                            ConstraintCategory::Cast,
+                            ConstraintCategory::Cast { unsize_to: None },
                         ) {
                             span_mirbug!(
                                 self,
@@ -1988,7 +1988,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
                             *ty,
                             ty_fn_ptr_from,
                             location.to_locations(),
-                            ConstraintCategory::Cast,
+                            ConstraintCategory::Cast { unsize_to: None },
                         ) {
                             span_mirbug!(
                                 self,
@@ -2013,7 +2013,15 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
                         self.prove_trait_ref(
                             trait_ref,
                             location.to_locations(),
-                            ConstraintCategory::Cast,
+                            ConstraintCategory::Cast {
+                                unsize_to: Some(tcx.fold_regions(ty, |r, _| {
+                                    if let ty::ReVar(_) = r.kind() {
+                                        tcx.lifetimes.re_erased
+                                    } else {
+                                        r
+                                    }
+                                })),
+                            },
                         );
                     }
 
@@ -2033,7 +2041,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
                                 .iter()
                                 .map(|predicate| predicate.with_self_ty(tcx, self_ty)),
                             location.to_locations(),
-                            ConstraintCategory::Cast,
+                            ConstraintCategory::Cast { unsize_to: None },
                         );
 
                         let outlives_predicate = tcx.mk_predicate(Binder::dummy(
@@ -2044,7 +2052,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
                         self.prove_predicate(
                             outlives_predicate,
                             location.to_locations(),
-                            ConstraintCategory::Cast,
+                            ConstraintCategory::Cast { unsize_to: None },
                         );
                     }
 
@@ -2065,7 +2073,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
                             *ty_from,
                             *ty_to,
                             location.to_locations(),
-                            ConstraintCategory::Cast,
+                            ConstraintCategory::Cast { unsize_to: None },
                         ) {
                             span_mirbug!(
                                 self,
@@ -2131,7 +2139,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
                             *ty_elem,
                             *ty_to,
                             location.to_locations(),
-                            ConstraintCategory::Cast,
+                            ConstraintCategory::Cast { unsize_to: None },
                         ) {
                             span_mirbug!(
                                 self,

compiler/rustc_hir_typeck/src/expr.rs

@@ -626,15 +626,18 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     }
                 };
 
-                let coerce_to = match opt_coerce_to {
-                    Some(c) => c,
-                    None => {
-                        // If the loop context is not a `loop { }`, then break with
-                        // a value is illegal, and `opt_coerce_to` will be `None`.
-                        // Return error in that case (#114529).
-                        return Ty::new_misc_error(tcx);
-                    }
-                };
+                // If the loop context is not a `loop { }`, then break with
+                // a value is illegal, and `opt_coerce_to` will be `None`.
+                // Set expectation to error in that case and set tainted
+                // by error (#114529)
+                let coerce_to = opt_coerce_to.unwrap_or_else(|| {
+                    let guar = tcx.sess.delay_span_bug(
+                        expr.span,
+                        "illegal break with value found but no error reported",
+                    );
+                    self.set_tainted_by_errors(guar);
+                    Ty::new_error(tcx, guar)
+                });
 
                 // Recurse without `enclosing_breakables` borrowed.
                 e_ty = self.check_expr_with_hint(e, coerce_to);

compiler/rustc_infer/src/infer/at.rs

@@ -65,8 +65,15 @@ impl<'tcx> InferCtxt<'tcx> {
 
     /// Forks the inference context, creating a new inference context with the same inference
     /// variables in the same state. This can be used to "branch off" many tests from the same
-    /// common state. Used in coherence.
+    /// common state.
     pub fn fork(&self) -> Self {
+        self.fork_with_intercrate(self.intercrate)
+    }
+
+    /// Forks the inference context, creating a new inference context with the same inference
+    /// variables in the same state, except possibly changing the intercrate mode. This can be
+    /// used to "branch off" many tests from the same common state. Used in negative coherence.
+    pub fn fork_with_intercrate(&self, intercrate: bool) -> Self {
         Self {
             tcx: self.tcx,
             defining_use_anchor: self.defining_use_anchor,
@@ -81,7 +88,7 @@ impl<'tcx> InferCtxt<'tcx> {
             tainted_by_errors: self.tainted_by_errors.clone(),
             err_count_on_creation: self.err_count_on_creation,
             universe: self.universe.clone(),
-            intercrate: self.intercrate,
+            intercrate,
             next_trait_solver: self.next_trait_solver,
         }
     }

compiler/rustc_lint/src/deref_into_dyn_supertrait.rs

@@ -50,7 +50,7 @@ declare_lint! {
     Warn,
     "`Deref` implementation usage with a supertrait trait object for output might be shadowed in the future",
     @future_incompatible = FutureIncompatibleInfo {
-        reason: FutureIncompatibilityReason::FutureReleaseErrorDontReportInDeps,
+        reason: FutureIncompatibilityReason::FutureReleaseSemanticsChange,
         reference: "issue #89460 <https://github.com/rust-lang/rust/issues/89460>",
     };
 }
@@ -59,12 +59,13 @@ declare_lint_pass!(DerefIntoDynSupertrait => [DEREF_INTO_DYN_SUPERTRAIT]);
 
 impl<'tcx> LateLintPass<'tcx> for DerefIntoDynSupertrait {
     fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx hir::Item<'tcx>) {
+        let tcx = cx.tcx;
         // `Deref` is being implemented for `t`
         if let hir::ItemKind::Impl(impl_) = item.kind
             && let Some(trait_) = &impl_.of_trait
-            && let t = cx.tcx.type_of(item.owner_id).instantiate_identity()
+            && let t = tcx.type_of(item.owner_id).instantiate_identity()
             && let opt_did @ Some(did) = trait_.trait_def_id()
-            && opt_did == cx.tcx.lang_items().deref_trait()
+            && opt_did == tcx.lang_items().deref_trait()
             // `t` is `dyn t_principal`
             && let ty::Dynamic(data, _, ty::Dyn) = t.kind()
             && let Some(t_principal) = data.principal()
@@ -73,17 +74,22 @@ impl<'tcx> LateLintPass<'tcx> for DerefIntoDynSupertrait {
             && let ty::Dynamic(data, _, ty::Dyn) = target.kind()
             && let Some(target_principal) = data.principal()
             // `target_principal` is a supertrait of `t_principal`
-            && supertraits(cx.tcx, t_principal.with_self_ty(cx.tcx, cx.tcx.types.trait_object_dummy_self))
-                .any(|sup| sup.map_bound(|x| ty::ExistentialTraitRef::erase_self_ty(cx.tcx, x)) == target_principal)
+            && supertraits(tcx, t_principal.with_self_ty(tcx, tcx.types.trait_object_dummy_self))
+                .any(|sup| {
+                    tcx.erase_regions(
+                        sup.map_bound(|x| ty::ExistentialTraitRef::erase_self_ty(tcx, x)),
+                    ) == tcx.erase_regions(target_principal)
+                })
         {
+            let t = tcx.erase_regions(t);
             let label = impl_
                 .items
                 .iter()
                 .find_map(|i| (i.ident.name == sym::Target).then_some(i.span))
                 .map(|label| SupertraitAsDerefTargetLabel { label });
             cx.emit_spanned_lint(
                 DEREF_INTO_DYN_SUPERTRAIT,
-                cx.tcx.def_span(item.owner_id.def_id),
+                tcx.def_span(item.owner_id.def_id),
                 SupertraitAsDerefTarget { t, target_principal, label },
             );
         }

compiler/rustc_middle/src/mir/query.rs

@@ -341,7 +341,11 @@ pub enum ConstraintCategory<'tcx> {
     UseAsConst,
     UseAsStatic,
     TypeAnnotation,
-    Cast,
+    Cast {
+        /// Whether this is an unsizing cast and if yes, this contains the target type.
+        /// Region variables are erased to ReErased.
+        unsize_to: Option<Ty<'tcx>>,
+    },
 
     /// A constraint that came from checking the body of a closure.
     ///

compiler/rustc_middle/src/query/mod.rs

@@ -109,10 +109,12 @@ pub use plumbing::{IntoQueryParam, TyCtxtAt, TyCtxtEnsure, TyCtxtEnsureWithValue
 // Queries marked with `fatal_cycle` do not need the latter implementation,
 // as they will raise an fatal error on query cycles instead.
 rustc_queries! {
+    /// This exists purely for testing the interactions between delay_span_bug and incremental.
     query trigger_delay_span_bug(key: DefId) -> () {
-        desc { "triggering a delay span bug" }
+        desc { "triggering a delay span bug for testing incremental" }
     }
 
+    /// Collects the list of all tools registered using `#![register_tool]`.
     query registered_tools(_: ()) -> &'tcx ty::RegisteredTools {
         arena_cache
         desc { "compute registered tools for crate" }
@@ -286,6 +288,7 @@ rustc_queries! {
         }
     }
 
+    /// The root query triggering all analysis passes like typeck or borrowck.
     query analysis(key: ()) -> Result<(), ErrorGuaranteed> {
         eval_always
         desc { "running analysis passes on this crate" }
@@ -1781,10 +1784,17 @@ rustc_queries! {
         desc { "calculating the missing lang items in a crate" }
         separate_provide_extern
     }
+
+    /// The visible parent map is a map from every item to a visible parent.
+    /// It prefers the shortest visible path to an item.
+    /// Used for diagnostics, for example path trimming.
+    /// The parents are modules, enums or traits.
     query visible_parent_map(_: ()) -> &'tcx DefIdMap<DefId> {
         arena_cache
         desc { "calculating the visible parent map" }
     }
+    /// Collects the "trimmed", shortest accessible paths to all items for diagnostics.
+    /// See the [provider docs](`rustc_middle::ty::print::trimmed_def_paths`) for more info.
     query trimmed_def_paths(_: ()) -> &'tcx FxHashMap<DefId, Symbol> {
         arena_cache
         desc { "calculating trimmed def paths" }

compiler/rustc_middle/src/ty/consts/kind.rs

@@ -3,7 +3,6 @@ use crate::mir;
 use crate::ty::abstract_const::CastKind;
 use crate::ty::GenericArgsRef;
 use crate::ty::{self, visit::TypeVisitableExt as _, List, Ty, TyCtxt};
-use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use rustc_hir::def_id::DefId;
 use rustc_macros::HashStable;
 
@@ -77,28 +76,3 @@ static_assert_size!(Expr<'_>, 24);
 
 #[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
 static_assert_size!(super::ConstKind<'_>, 32);
-
-/// An inference variable for a const, for use in const generics.
-#[derive(Copy, Clone, Eq, PartialEq, PartialOrd, Ord, TyEncodable, TyDecodable, Hash)]
-pub enum InferConst {
-    /// Infer the value of the const.
-    Var(ty::ConstVid),
-    /// Infer the value of the effect.
-    ///
-    /// For why this is separate from the `Var` variant above, see the
-    /// documentation on `EffectVid`.
-    EffectVar(ty::EffectVid),
-    /// A fresh const variable. See `infer::freshen` for more details.
-    Fresh(u32),
-}
-
-impl<CTX> HashStable<CTX> for InferConst {
-    fn hash_stable(&self, hcx: &mut CTX, hasher: &mut StableHasher) {
-        match self {
-            InferConst::Var(_) | InferConst::EffectVar(_) => {
-                panic!("const variables should not be hashed: {self:?}")
-            }
-            InferConst::Fresh(i) => i.hash_stable(hcx, hasher),
-        }
-    }
-}

compiler/rustc_middle/src/ty/context.rs

@@ -26,9 +26,9 @@ use crate::traits::solve::{
 };
 use crate::ty::{
     self, AdtDef, AdtDefData, AdtKind, Binder, Clause, Const, ConstData, GenericParamDefKind,
-    ImplPolarity, InferTy, List, ParamConst, ParamTy, PolyExistentialPredicate, PolyFnSig,
-    Predicate, PredicateKind, Region, RegionKind, ReprOptions, TraitObjectVisitor, Ty, TyKind,
-    TyVid, TypeAndMut, Visibility,
+    ImplPolarity, List, ParamConst, ParamTy, PolyExistentialPredicate, PolyFnSig, Predicate,
+    PredicateKind, Region, RegionKind, ReprOptions, TraitObjectVisitor, Ty, TyKind, TyVid,
+    TypeAndMut, Visibility,
 };
 use crate::ty::{GenericArg, GenericArgs, GenericArgsRef};
 use rustc_ast::{self as ast, attr};
@@ -95,15 +95,13 @@ impl<'tcx> Interner for TyCtxt<'tcx> {
     type ParamTy = ParamTy;
     type BoundTy = ty::BoundTy;
     type PlaceholderTy = ty::PlaceholderType;
-    type InferTy = InferTy;
 
     type ErrorGuaranteed = ErrorGuaranteed;
     type BoundExistentialPredicates = &'tcx List<PolyExistentialPredicate<'tcx>>;
     type PolyFnSig = PolyFnSig<'tcx>;
     type AllocId = crate::mir::interpret::AllocId;
 
     type Const = ty::Const<'tcx>;
-    type InferConst = ty::InferConst;
     type AliasConst = ty::UnevaluatedConst<'tcx>;
     type PlaceholderConst = ty::PlaceholderConst;
     type ParamConst = ty::ParamConst;