Rollup of 7 pull requests

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

@@ -621,13 +621,7 @@ impl<'tcx> LivenessContext<'_, '_, '_, 'tcx> {
                         &ocx, op, span,
                     ) {
                         Ok(_) => ocx.select_all_or_error(),
-                        Err(e) => {
-                            if e.is_empty() {
-                                ocx.select_all_or_error()
-                            } else {
-                                e
-                            }
-                        }
+                        Err(e) => e,
                     };
 
                     // Could have no errors if a type lowering error, say, caused the query

compiler/rustc_lint/messages.ftl

@@ -362,6 +362,10 @@ lint_impl_trait_redundant_captures = all possible in-scope parameters are alread
 
 lint_implicit_unsafe_autorefs = implicit autoref creates a reference to the dereference of a raw pointer
     .note = creating a reference requires the pointer target to be valid and imposes aliasing requirements
+    .raw_ptr = this raw pointer has type `{$raw_ptr_ty}`
+    .autoref = autoref is being applied to this expression, resulting in: `{$autoref_ty}`
+    .overloaded_deref = references are created through calls to explicit `Deref(Mut)::deref(_mut)` implementations
+    .method_def = method calls to `{$method_name}` require a reference
     .suggestion = try using a raw pointer method instead; or if this reference is intentional, make it explicit
 
 lint_improper_ctypes = `extern` {$desc} uses type `{$ty}`, which is not FFI-safe

compiler/rustc_lint/src/autorefs.rs

@@ -4,7 +4,10 @@ use rustc_middle::ty::adjustment::{Adjust, Adjustment, AutoBorrow, OverloadedDer
 use rustc_session::{declare_lint, declare_lint_pass};
 use rustc_span::sym;
 
-use crate::lints::{ImplicitUnsafeAutorefsDiag, ImplicitUnsafeAutorefsSuggestion};
+use crate::lints::{
+    ImplicitUnsafeAutorefsDiag, ImplicitUnsafeAutorefsMethodNote, ImplicitUnsafeAutorefsOrigin,
+    ImplicitUnsafeAutorefsSuggestion,
+};
 use crate::{LateContext, LateLintPass, LintContext};
 
 declare_lint! {
@@ -92,25 +95,37 @@ impl<'tcx> LateLintPass<'tcx> for ImplicitAutorefs {
             && let adjustments = peel_derefs_adjustments(&**adjustments)
             // 3. An automatically inserted reference (might come from a deref).
             && let [adjustment] = adjustments
-            && let Some(borrow_mutbl) = has_implicit_borrow(adjustment)
+            && let Some((borrow_mutbl, through_overloaded_deref)) = has_implicit_borrow(adjustment)
             && let ExprKind::Unary(UnOp::Deref, dereferenced) =
                 // 2. Any number of place projections.
                 peel_place_mappers(inner).kind
             // 1. Deref of a raw pointer.
             && typeck.expr_ty(dereferenced).is_raw_ptr()
-            // PERF: 5. b. A method call annotated with `#[rustc_no_implicit_refs]`
-            && match expr.kind {
-                ExprKind::MethodCall(..) => matches!(
-                    cx.typeck_results().type_dependent_def_id(expr.hir_id),
-                    Some(def_id) if cx.tcx.has_attr(def_id, sym::rustc_no_implicit_autorefs)
-                ),
-                _ => true,
+            && let method_did = match expr.kind {
+                // PERF: 5. b. A method call annotated with `#[rustc_no_implicit_refs]`
+                ExprKind::MethodCall(..) => cx.typeck_results().type_dependent_def_id(expr.hir_id),
+                _ => None,
             }
+            && method_did.map(|did| cx.tcx.has_attr(did, sym::rustc_no_implicit_autorefs)).unwrap_or(true)
         {
             cx.emit_span_lint(
                 DANGEROUS_IMPLICIT_AUTOREFS,
                 expr.span.source_callsite(),
                 ImplicitUnsafeAutorefsDiag {
+                    raw_ptr_span: dereferenced.span,
+                    raw_ptr_ty: typeck.expr_ty(dereferenced),
+                    origin: if through_overloaded_deref {
+                        ImplicitUnsafeAutorefsOrigin::OverloadedDeref
+                    } else {
+                        ImplicitUnsafeAutorefsOrigin::Autoref {
+                            autoref_span: inner.span,
+                            autoref_ty: typeck.expr_ty_adjusted(inner),
+                        }
+                    },
+                    method: method_did.map(|did| ImplicitUnsafeAutorefsMethodNote {
+                        def_span: cx.tcx.def_span(did),
+                        method_name: cx.tcx.item_name(did),
+                    }),
                     suggestion: ImplicitUnsafeAutorefsSuggestion {
                         mutbl: borrow_mutbl.ref_prefix_str(),
                         deref: if is_coming_from_deref { "*" } else { "" },
@@ -146,11 +161,12 @@ fn peel_derefs_adjustments<'a>(mut adjs: &'a [Adjustment<'a>]) -> &'a [Adjustmen
 
 /// Test if some adjustment has some implicit borrow.
 ///
-/// Returns `Some(mutability)` if the argument adjustment has implicit borrow in it.
-fn has_implicit_borrow(Adjustment { kind, .. }: &Adjustment<'_>) -> Option<Mutability> {
+/// Returns `Some((mutability, was_an_overloaded_deref))` if the argument adjustment is
+/// an implicit borrow (or has an implicit borrow via an overloaded deref).
+fn has_implicit_borrow(Adjustment { kind, .. }: &Adjustment<'_>) -> Option<(Mutability, bool)> {
     match kind {
-        &Adjust::Deref(Some(OverloadedDeref { mutbl, .. })) => Some(mutbl),
-        &Adjust::Borrow(AutoBorrow::Ref(mutbl)) => Some(mutbl.into()),
+        &Adjust::Deref(Some(OverloadedDeref { mutbl, .. })) => Some((mutbl, true)),
+        &Adjust::Borrow(AutoBorrow::Ref(mutbl)) => Some((mutbl.into(), false)),
         Adjust::NeverToAny
         | Adjust::Pointer(..)
         | Adjust::ReborrowPin(..)

compiler/rustc_lint/src/lints.rs

@@ -59,11 +59,38 @@ pub(crate) enum ShadowedIntoIterDiagSub {
 #[derive(LintDiagnostic)]
 #[diag(lint_implicit_unsafe_autorefs)]
 #[note]
-pub(crate) struct ImplicitUnsafeAutorefsDiag {
+pub(crate) struct ImplicitUnsafeAutorefsDiag<'a> {
+    #[label(lint_raw_ptr)]
+    pub raw_ptr_span: Span,
+    pub raw_ptr_ty: Ty<'a>,
+    #[subdiagnostic]
+    pub origin: ImplicitUnsafeAutorefsOrigin<'a>,
+    #[subdiagnostic]
+    pub method: Option<ImplicitUnsafeAutorefsMethodNote>,
     #[subdiagnostic]
     pub suggestion: ImplicitUnsafeAutorefsSuggestion,
 }
 
+#[derive(Subdiagnostic)]
+pub(crate) enum ImplicitUnsafeAutorefsOrigin<'a> {
+    #[note(lint_autoref)]
+    Autoref {
+        #[primary_span]
+        autoref_span: Span,
+        autoref_ty: Ty<'a>,
+    },
+    #[note(lint_overloaded_deref)]
+    OverloadedDeref,
+}
+
+#[derive(Subdiagnostic)]
+#[note(lint_method_def)]
+pub(crate) struct ImplicitUnsafeAutorefsMethodNote {
+    #[primary_span]
+    pub def_span: Span,
+    pub method_name: Symbol,
+}
+
 #[derive(Subdiagnostic)]
 #[multipart_suggestion(lint_suggestion, applicability = "maybe-incorrect")]
 pub(crate) struct ImplicitUnsafeAutorefsSuggestion {

compiler/rustc_next_trait_solver/src/solve/assembly/mod.rs

@@ -2,6 +2,7 @@
 
 pub(super) mod structural_traits;
 
+use std::cell::Cell;
 use std::ops::ControlFlow;
 
 use derive_where::derive_where;
@@ -117,24 +118,24 @@ where
     ) -> Result<Candidate<I>, NoSolution> {
         Self::fast_reject_assumption(ecx, goal, assumption)?;
 
-        ecx.probe(|candidate: &Result<Candidate<I>, NoSolution>| match candidate {
-            Ok(candidate) => inspect::ProbeKind::TraitCandidate {
-                source: candidate.source,
-                result: Ok(candidate.result),
-            },
-            Err(NoSolution) => inspect::ProbeKind::TraitCandidate {
-                source: CandidateSource::ParamEnv(ParamEnvSource::Global),
-                result: Err(NoSolution),
-            },
+        // Dealing with `ParamEnv` candidates is a bit of a mess as we need to lazily
+        // check whether the candidate is global while considering normalization.
+        //
+        // We need to write into `source` inside of `match_assumption`, but need to access it
+        // in `probe` even if the candidate does not apply before we get there. We handle this
+        // by using a `Cell` here. We only ever write into it inside of `match_assumption`.
+        let source = Cell::new(CandidateSource::ParamEnv(ParamEnvSource::Global));
+        ecx.probe(|result: &QueryResult<I>| inspect::ProbeKind::TraitCandidate {
+            source: source.get(),
+            result: *result,
         })
         .enter(|ecx| {
-            Self::match_assumption(ecx, goal, assumption)?;
-            let source = ecx.characterize_param_env_assumption(goal.param_env, assumption)?;
-            Ok(Candidate {
-                source,
-                result: ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes)?,
+            Self::match_assumption(ecx, goal, assumption, |ecx| {
+                source.set(ecx.characterize_param_env_assumption(goal.param_env, assumption)?);
+                ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes)
             })
         })
+        .map(|result| Candidate { source: source.get(), result })
     }
 
     /// Try equating an assumption predicate against a goal's predicate. If it
@@ -150,10 +151,8 @@ where
     ) -> Result<Candidate<I>, NoSolution> {
         Self::fast_reject_assumption(ecx, goal, assumption)?;
 
-        ecx.probe_trait_candidate(source).enter(|ecx| {
-            Self::match_assumption(ecx, goal, assumption)?;
-            then(ecx)
-        })
+        ecx.probe_trait_candidate(source)
+            .enter(|ecx| Self::match_assumption(ecx, goal, assumption, then))
     }
 
     /// Try to reject the assumption based off of simple heuristics, such as [`ty::ClauseKind`]
@@ -169,7 +168,8 @@ where
         ecx: &mut EvalCtxt<'_, D>,
         goal: Goal<I, Self>,
         assumption: I::Clause,
-    ) -> Result<(), NoSolution>;
+        then: impl FnOnce(&mut EvalCtxt<'_, D>) -> QueryResult<I>,
+    ) -> QueryResult<I>;
 
     fn consider_impl_candidate(
         ecx: &mut EvalCtxt<'_, D>,

compiler/rustc_next_trait_solver/src/solve/effect_goals.rs

@@ -61,13 +61,14 @@ where
         ecx: &mut EvalCtxt<'_, D>,
         goal: Goal<I, Self>,
         assumption: I::Clause,
-    ) -> Result<(), NoSolution> {
+        then: impl FnOnce(&mut EvalCtxt<'_, D>) -> QueryResult<I>,
+    ) -> QueryResult<I> {
         let host_clause = assumption.as_host_effect_clause().unwrap();
 
         let assumption_trait_pred = ecx.instantiate_binder_with_infer(host_clause);
         ecx.eq(goal.param_env, goal.predicate.trait_ref, assumption_trait_pred.trait_ref)?;
 
-        Ok(())
+        then(ecx)
     }
 
     /// Register additional assumptions for aliases corresponding to `~const` item bounds.

compiler/rustc_next_trait_solver/src/solve/normalizes_to/mod.rs

@@ -129,7 +129,40 @@ where
         ecx: &mut EvalCtxt<'_, D>,
         goal: Goal<I, Self>,
         assumption: I::Clause,
-    ) -> Result<(), NoSolution> {
+        then: impl FnOnce(&mut EvalCtxt<'_, D>) -> QueryResult<I>,
+    ) -> QueryResult<I> {
+        let cx = ecx.cx();
+        // FIXME(generic_associated_types): Addresses aggressive inference in #92917.
+        //
+        // If this type is a GAT with currently unconstrained arguments, we do not
+        // want to normalize it via a candidate which only applies for a specific
+        // instantiation. We could otherwise keep the GAT as rigid and succeed this way.
+        // See tests/ui/generic-associated-types/no-incomplete-gat-arg-inference.rs.
+        //
+        // This only avoids normalization if the GAT arguments are fully unconstrained.
+        // This is quite arbitrary but fixing it causes some ambiguity, see #125196.
+        match goal.predicate.alias.kind(cx) {
+            ty::AliasTermKind::ProjectionTy | ty::AliasTermKind::ProjectionConst => {
+                for arg in goal.predicate.alias.own_args(cx).iter() {
+                    let Some(term) = arg.as_term() else {
+                        continue;
+                    };
+                    let term = ecx.structurally_normalize_term(goal.param_env, term)?;
+                    if term.is_infer() {
+                        return ecx.evaluate_added_goals_and_make_canonical_response(
+                            Certainty::AMBIGUOUS,
+                        );
+                    }
+                }
+            }
+            ty::AliasTermKind::OpaqueTy
+            | ty::AliasTermKind::InherentTy
+            | ty::AliasTermKind::InherentConst
+            | ty::AliasTermKind::FreeTy
+            | ty::AliasTermKind::FreeConst
+            | ty::AliasTermKind::UnevaluatedConst => {}
+        }
+
         let projection_pred = assumption.as_projection_clause().unwrap();
 
         let assumption_projection_pred = ecx.instantiate_binder_with_infer(projection_pred);
@@ -139,15 +172,14 @@ where
 
         // Add GAT where clauses from the trait's definition
         // FIXME: We don't need these, since these are the type's own WF obligations.
-        let cx = ecx.cx();
         ecx.add_goals(
             GoalSource::AliasWellFormed,
             cx.own_predicates_of(goal.predicate.def_id())
                 .iter_instantiated(cx, goal.predicate.alias.args)
                 .map(|pred| goal.with(cx, pred)),
         );
 
-        Ok(())
+        then(ecx)
     }
 
     fn consider_additional_alias_assumptions(

compiler/rustc_next_trait_solver/src/solve/trait_goals.rs

@@ -17,7 +17,7 @@ use crate::solve::assembly::{self, AllowInferenceConstraints, AssembleCandidates
 use crate::solve::inspect::ProbeKind;
 use crate::solve::{
     BuiltinImplSource, CandidateSource, Certainty, EvalCtxt, Goal, GoalSource, MaybeCause,
-    NoSolution, ParamEnvSource,
+    NoSolution, ParamEnvSource, QueryResult,
 };
 
 impl<D, I> assembly::GoalKind<D> for TraitPredicate<I>
@@ -150,13 +150,14 @@ where
         ecx: &mut EvalCtxt<'_, D>,
         goal: Goal<I, Self>,
         assumption: I::Clause,
-    ) -> Result<(), NoSolution> {
+        then: impl FnOnce(&mut EvalCtxt<'_, D>) -> QueryResult<I>,
+    ) -> QueryResult<I> {
         let trait_clause = assumption.as_trait_clause().unwrap();
 
         let assumption_trait_pred = ecx.instantiate_binder_with_infer(trait_clause);
         ecx.eq(goal.param_env, goal.predicate.trait_ref, assumption_trait_pred.trait_ref)?;
 
-        Ok(())
+        then(ecx)
     }
 
     fn consider_auto_trait_candidate(

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

@@ -196,11 +196,31 @@ where
                 debug!("dropck_outlives: ty from dtorck_types = {:?}", ty);
                 ty
             } else {
-                ocx.deeply_normalize(&cause, param_env, ty)?;
+                // Flush errors b/c `deeply_normalize` doesn't expect pending
+                // obligations, and we may have pending obligations from the
+                // branch above (from other types).
+                let errors = ocx.select_all_or_error();
+                if !errors.is_empty() {
+                    return Err(errors);
+                }
 
-                let errors = ocx.select_where_possible();
-                debug!("normalize errors: {ty} ~> {errors:#?}");
-                return Err(errors);
+                // When query normalization fails, we don't get back an interesting
+                // reason that we could use to report an error in borrowck. In order to turn
+                // this into a reportable error, we deeply normalize again. We don't expect
+                // this to succeed, so delay a bug if it does.
+                match ocx.deeply_normalize(&cause, param_env, ty) {
+                    Ok(_) => {
+                        tcx.dcx().span_delayed_bug(
+                            span,
+                            format!(
+                                "query normalize succeeded of {ty}, \
+                                but deep normalize failed",
+                            ),
+                        );
+                        ty
+                    }
+                    Err(errors) => return Err(errors),
+                }
             };
 
             match ty.kind() {

compiler/rustc_trait_selection/src/traits/select/mod.rs

@@ -1760,12 +1760,13 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
 
         if is_match {
             let generics = self.tcx().generics_of(obligation.predicate.def_id);
-            // FIXME(generic-associated-types): Addresses aggressive inference in #92917.
+            // FIXME(generic_associated_types): Addresses aggressive inference in #92917.
             // If this type is a GAT, and of the GAT args resolve to something new,
             // that means that we must have newly inferred something about the GAT.
             // We should give up in that case.
-            // FIXME(generic-associated-types): This only detects one layer of inference,
-            // which is probably not what we actually want, but fixing it causes some ambiguity:
+            //
+            // This only detects one layer of inference, which is probably not what we actually
+            // want, but fixing it causes some ambiguity:
             // <https://github.com/rust-lang/rust/issues/125196>.
             if !generics.is_own_empty()
                 && obligation.predicate.args[generics.parent_count..].iter().any(|&p| {

compiler/rustc_type_ir/src/inherent.rs

@@ -298,6 +298,14 @@ pub trait GenericArg<I: Interner<GenericArg = Self>>:
     + From<I::Region>
     + From<I::Const>
 {
+    fn as_term(&self) -> Option<I::Term> {
+        match self.kind() {
+            ty::GenericArgKind::Lifetime(_) => None,
+            ty::GenericArgKind::Type(ty) => Some(ty.into()),
+            ty::GenericArgKind::Const(ct) => Some(ct.into()),
+        }
+    }
+
     fn as_type(&self) -> Option<I::Ty> {
         if let ty::GenericArgKind::Type(ty) = self.kind() { Some(ty) } else { None }
     }

compiler/rustc_type_ir/src/predicate.rs

@@ -682,6 +682,13 @@ impl<I: Interner> AliasTerm<I> {
     pub fn trait_ref(self, interner: I) -> TraitRef<I> {
         self.trait_ref_and_own_args(interner).0
     }
+
+    /// Extract the own args from this projection.
+    /// For example, if this is a projection of `<T as StreamingIterator>::Item<'a>`,
+    /// then this function would return the slice `['a]` as the own args.
+    pub fn own_args(self, interner: I) -> I::GenericArgsSlice {
+        self.trait_ref_and_own_args(interner).1
+    }
 }
 
 /// The following methods work only with inherent associated term projections.