Rollup of 7 pull requests

compiler/rustc_hir/src/hir.rs

@@ -2025,6 +2025,22 @@ pub fn is_range_literal(expr: &Expr<'_>) -> bool {
     }
 }
 
+/// Checks if the specified expression needs parentheses for prefix
+/// or postfix suggestions to be valid.
+/// For example, `a + b` requires parentheses to suggest `&(a + b)`,
+/// but just `a` does not.
+/// Similarly, `(a + b).c()` also requires parentheses.
+/// This should not be used for other types of suggestions.
+pub fn expr_needs_parens(expr: &Expr<'_>) -> bool {
+    match expr.kind {
+        // parenthesize if needed (Issue #46756)
+        ExprKind::Cast(_, _) | ExprKind::Binary(_, _, _) => true,
+        // parenthesize borrows of range literals (Issue #54505)
+        _ if is_range_literal(expr) => true,
+        _ => false,
+    }
+}
+
 #[derive(Debug, Clone, Copy, HashStable_Generic)]
 pub enum ExprKind<'hir> {
     /// Allow anonymous constants from an inline `const` block

compiler/rustc_hir_analysis/messages.ftl

@@ -249,6 +249,12 @@ hir_analysis_invalid_receiver_ty_help =
 hir_analysis_invalid_receiver_ty_help_no_arbitrary_self_types =
     consider changing to `self`, `&self`, `&mut self`, `self: Box<Self>`, `self: Rc<Self>`, `self: Arc<Self>`, or `self: Pin<P>` (where P is one of the previous types except `Self`)
 
+hir_analysis_invalid_receiver_ty_help_nonnull_note =
+    `NonNull` does not implement `Receiver` because it has methods that may shadow the referent; consider wrapping your `NonNull` in a newtype wrapper for which you implement `Receiver`
+
+hir_analysis_invalid_receiver_ty_help_weak_note =
+    `Weak` does not implement `Receiver` because it has methods that may shadow the referent; consider wrapping your `Weak` in a newtype wrapper for which you implement `Receiver`
+
 hir_analysis_invalid_receiver_ty_no_arbitrary_self_types = invalid `self` parameter type: `{$receiver_ty}`
     .note = type of `self` must be `Self` or a type that dereferences to it
 

compiler/rustc_hir_analysis/src/check/wfcheck.rs

@@ -44,6 +44,7 @@ use {rustc_ast as ast, rustc_hir as hir};
 use crate::autoderef::Autoderef;
 use crate::collect::CollectItemTypesVisitor;
 use crate::constrained_generic_params::{Parameter, identify_constrained_generic_params};
+use crate::errors::InvalidReceiverTyHint;
 use crate::{errors, fluent_generated as fluent};
 
 pub(super) struct WfCheckingCtxt<'a, 'tcx> {
@@ -1749,7 +1750,18 @@ fn check_method_receiver<'tcx>(
             {
                 match receiver_validity_err {
                     ReceiverValidityError::DoesNotDeref if arbitrary_self_types_level.is_some() => {
-                        tcx.dcx().emit_err(errors::InvalidReceiverTy { span, receiver_ty })
+                        let hint = match receiver_ty
+                            .builtin_deref(false)
+                            .unwrap_or(receiver_ty)
+                            .ty_adt_def()
+                            .and_then(|adt_def| tcx.get_diagnostic_name(adt_def.did()))
+                        {
+                            Some(sym::RcWeak | sym::ArcWeak) => Some(InvalidReceiverTyHint::Weak),
+                            Some(sym::NonNull) => Some(InvalidReceiverTyHint::NonNull),
+                            _ => None,
+                        };
+
+                        tcx.dcx().emit_err(errors::InvalidReceiverTy { span, receiver_ty, hint })
                     }
                     ReceiverValidityError::DoesNotDeref => {
                         tcx.dcx().emit_err(errors::InvalidReceiverTyNoArbitrarySelfTypes {

compiler/rustc_hir_analysis/src/collect.rs

@@ -1340,7 +1340,7 @@ fn fn_sig(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::EarlyBinder<'_, ty::PolyFn
             ..
         })
         | Item(hir::Item { kind: ItemKind::Fn(sig, generics, _), .. }) => {
-            infer_return_ty_for_fn_sig(sig, generics, def_id, &icx)
+            lower_fn_sig_recovering_infer_ret_ty(&icx, sig, generics, def_id)
         }
 
         ImplItem(hir::ImplItem { kind: ImplItemKind::Fn(sig, _), generics, .. }) => {
@@ -1357,7 +1357,7 @@ fn fn_sig(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::EarlyBinder<'_, ty::PolyFn
                     None,
                 )
             } else {
-                infer_return_ty_for_fn_sig(sig, generics, def_id, &icx)
+                lower_fn_sig_recovering_infer_ret_ty(&icx, sig, generics, def_id)
             }
         }
 
@@ -1407,99 +1407,108 @@ fn fn_sig(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::EarlyBinder<'_, ty::PolyFn
     ty::EarlyBinder::bind(output)
 }
 
-fn infer_return_ty_for_fn_sig<'tcx>(
-    sig: &hir::FnSig<'tcx>,
-    generics: &hir::Generics<'_>,
+fn lower_fn_sig_recovering_infer_ret_ty<'tcx>(
+    icx: &ItemCtxt<'tcx>,
+    sig: &'tcx hir::FnSig<'tcx>,
+    generics: &'tcx hir::Generics<'tcx>,
     def_id: LocalDefId,
+) -> ty::PolyFnSig<'tcx> {
+    if let Some(infer_ret_ty) = sig.decl.output.get_infer_ret_ty() {
+        return recover_infer_ret_ty(icx, infer_ret_ty, generics, def_id);
+    }
+
+    icx.lowerer().lower_fn_ty(
+        icx.tcx().local_def_id_to_hir_id(def_id),
+        sig.header.safety,
+        sig.header.abi,
+        sig.decl,
+        Some(generics),
+        None,
+    )
+}
+
+fn recover_infer_ret_ty<'tcx>(
     icx: &ItemCtxt<'tcx>,
+    infer_ret_ty: &'tcx hir::Ty<'tcx>,
+    generics: &'tcx hir::Generics<'tcx>,
+    def_id: LocalDefId,
 ) -> ty::PolyFnSig<'tcx> {
     let tcx = icx.tcx;
     let hir_id = tcx.local_def_id_to_hir_id(def_id);
 
-    match sig.decl.output.get_infer_ret_ty() {
-        Some(ty) => {
-            let fn_sig = tcx.typeck(def_id).liberated_fn_sigs()[hir_id];
-            // Typeck doesn't expect erased regions to be returned from `type_of`.
-            // This is a heuristic approach. If the scope has region parameters,
-            // we should change fn_sig's lifetime from `ReErased` to `ReError`,
-            // otherwise to `ReStatic`.
-            let has_region_params = generics.params.iter().any(|param| match param.kind {
-                GenericParamKind::Lifetime { .. } => true,
-                _ => false,
-            });
-            let fn_sig = fold_regions(tcx, fn_sig, |r, _| match *r {
-                ty::ReErased => {
-                    if has_region_params {
-                        ty::Region::new_error_with_message(
-                            tcx,
-                            DUMMY_SP,
-                            "erased region is not allowed here in return type",
-                        )
-                    } else {
-                        tcx.lifetimes.re_static
-                    }
-                }
-                _ => r,
-            });
+    let fn_sig = tcx.typeck(def_id).liberated_fn_sigs()[hir_id];
 
-            let mut visitor = HirPlaceholderCollector::default();
-            visitor.visit_ty(ty);
-
-            let mut diag = bad_placeholder(icx.lowerer(), visitor.0, "return type");
-            let ret_ty = fn_sig.output();
-            // Don't leak types into signatures unless they're nameable!
-            // For example, if a function returns itself, we don't want that
-            // recursive function definition to leak out into the fn sig.
-            let mut recovered_ret_ty = None;
-
-            if let Some(suggestable_ret_ty) = ret_ty.make_suggestable(tcx, false, None) {
-                diag.span_suggestion(
-                    ty.span,
-                    "replace with the correct return type",
-                    suggestable_ret_ty,
-                    Applicability::MachineApplicable,
-                );
-                recovered_ret_ty = Some(suggestable_ret_ty);
-            } else if let Some(sugg) = suggest_impl_trait(
-                &tcx.infer_ctxt().build(TypingMode::non_body_analysis()),
-                tcx.param_env(def_id),
-                ret_ty,
-            ) {
-                diag.span_suggestion(
-                    ty.span,
-                    "replace with an appropriate return type",
-                    sugg,
-                    Applicability::MachineApplicable,
-                );
-            } else if ret_ty.is_closure() {
-                diag.help("consider using an `Fn`, `FnMut`, or `FnOnce` trait bound");
-            }
-            // Also note how `Fn` traits work just in case!
-            if ret_ty.is_closure() {
-                diag.note(
-                    "for more information on `Fn` traits and closure types, see \
-                     https://doc.rust-lang.org/book/ch13-01-closures.html",
-                );
+    // Typeck doesn't expect erased regions to be returned from `type_of`.
+    // This is a heuristic approach. If the scope has region parameters,
+    // we should change fn_sig's lifetime from `ReErased` to `ReError`,
+    // otherwise to `ReStatic`.
+    let has_region_params = generics.params.iter().any(|param| match param.kind {
+        GenericParamKind::Lifetime { .. } => true,
+        _ => false,
+    });
+    let fn_sig = fold_regions(tcx, fn_sig, |r, _| match *r {
+        ty::ReErased => {
+            if has_region_params {
+                ty::Region::new_error_with_message(
+                    tcx,
+                    DUMMY_SP,
+                    "erased region is not allowed here in return type",
+                )
+            } else {
+                tcx.lifetimes.re_static
             }
-
-            let guar = diag.emit();
-            ty::Binder::dummy(tcx.mk_fn_sig(
-                fn_sig.inputs().iter().copied(),
-                recovered_ret_ty.unwrap_or_else(|| Ty::new_error(tcx, guar)),
-                fn_sig.c_variadic,
-                fn_sig.safety,
-                fn_sig.abi,
-            ))
         }
-        None => icx.lowerer().lower_fn_ty(
-            hir_id,
-            sig.header.safety,
-            sig.header.abi,
-            sig.decl,
-            Some(generics),
-            None,
-        ),
+        _ => r,
+    });
+
+    let mut visitor = HirPlaceholderCollector::default();
+    visitor.visit_ty(infer_ret_ty);
+
+    let mut diag = bad_placeholder(icx.lowerer(), visitor.0, "return type");
+    let ret_ty = fn_sig.output();
+
+    // Don't leak types into signatures unless they're nameable!
+    // For example, if a function returns itself, we don't want that
+    // recursive function definition to leak out into the fn sig.
+    let mut recovered_ret_ty = None;
+    if let Some(suggestable_ret_ty) = ret_ty.make_suggestable(tcx, false, None) {
+        diag.span_suggestion(
+            infer_ret_ty.span,
+            "replace with the correct return type",
+            suggestable_ret_ty,
+            Applicability::MachineApplicable,
+        );
+        recovered_ret_ty = Some(suggestable_ret_ty);
+    } else if let Some(sugg) = suggest_impl_trait(
+        &tcx.infer_ctxt().build(TypingMode::non_body_analysis()),
+        tcx.param_env(def_id),
+        ret_ty,
+    ) {
+        diag.span_suggestion(
+            infer_ret_ty.span,
+            "replace with an appropriate return type",
+            sugg,
+            Applicability::MachineApplicable,
+        );
+    } else if ret_ty.is_closure() {
+        diag.help("consider using an `Fn`, `FnMut`, or `FnOnce` trait bound");
+    }
+
+    // Also note how `Fn` traits work just in case!
+    if ret_ty.is_closure() {
+        diag.note(
+            "for more information on `Fn` traits and closure types, see \
+                     https://doc.rust-lang.org/book/ch13-01-closures.html",
+        );
     }
+    let guar = diag.emit();
+    ty::Binder::dummy(tcx.mk_fn_sig(
+        fn_sig.inputs().iter().copied(),
+        recovered_ret_ty.unwrap_or_else(|| Ty::new_error(tcx, guar)),
+        fn_sig.c_variadic,
+        fn_sig.safety,
+        fn_sig.abi,
+    ))
 }
 
 pub fn suggest_impl_trait<'tcx>(

compiler/rustc_hir_analysis/src/errors.rs

@@ -1655,6 +1655,14 @@ pub(crate) struct NonConstRange {
     pub span: Span,
 }
 
+#[derive(Subdiagnostic)]
+pub(crate) enum InvalidReceiverTyHint {
+    #[note(hir_analysis_invalid_receiver_ty_help_weak_note)]
+    Weak,
+    #[note(hir_analysis_invalid_receiver_ty_help_nonnull_note)]
+    NonNull,
+}
+
 #[derive(Diagnostic)]
 #[diag(hir_analysis_invalid_receiver_ty_no_arbitrary_self_types, code = E0307)]
 #[note]
@@ -1673,6 +1681,8 @@ pub(crate) struct InvalidReceiverTy<'tcx> {
     #[primary_span]
     pub span: Span,
     pub receiver_ty: Ty<'tcx>,
+    #[subdiagnostic]
+    pub hint: Option<InvalidReceiverTyHint>,
 }
 
 #[derive(Diagnostic)]

compiler/rustc_hir_analysis/src/hir_ty_lowering/dyn_compatibility.rs

@@ -1,17 +1,16 @@
-use rustc_data_structures::fx::{FxHashSet, FxIndexMap, FxIndexSet};
+use rustc_data_structures::fx::{FxHashSet, FxIndexSet};
 use rustc_errors::codes::*;
 use rustc_errors::struct_span_code_err;
 use rustc_hir as hir;
 use rustc_hir::def::{DefKind, Res};
-use rustc_hir::def_id::DefId;
 use rustc_lint_defs::builtin::UNUSED_ASSOCIATED_TYPE_BOUNDS;
 use rustc_middle::span_bug;
 use rustc_middle::ty::fold::BottomUpFolder;
 use rustc_middle::ty::{
     self, DynKind, ExistentialPredicateStableCmpExt as _, Ty, TyCtxt, TypeFoldable,
     TypeVisitableExt, Upcast,
 };
-use rustc_span::{ErrorGuaranteed, Span};
+use rustc_span::{DUMMY_SP, 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;
@@ -128,8 +127,9 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
             }
         }
 
-        let mut associated_types: FxIndexMap<Span, FxIndexSet<DefId>> = FxIndexMap::default();
+        let mut needed_associated_types = FxIndexSet::default();
 
+        let principal_span = regular_traits.first().map_or(DUMMY_SP, |info| info.bottom().1);
         let regular_traits_refs_spans = trait_bounds
             .into_iter()
             .filter(|(trait_ref, _)| !tcx.trait_is_auto(trait_ref.def_id()));
@@ -145,13 +145,18 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
                 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(original_span).or_default().extend(
-                            tcx.associated_items(pred.def_id())
+                        // FIXME(negative_bounds): Handle this correctly...
+                        let trait_ref =
+                            tcx.anonymize_bound_vars(bound_predicate.rebind(pred.trait_ref));
+                        needed_associated_types.extend(
+                            tcx.associated_items(trait_ref.def_id())
                                 .in_definition_order()
                                 .filter(|item| item.kind == ty::AssocKind::Type)
                                 .filter(|item| !item.is_impl_trait_in_trait())
-                                .map(|item| item.def_id),
+                                // If the associated type has a `where Self: Sized` bound,
+                                // we do not need to constrain the associated type.
+                                .filter(|item| !tcx.generics_require_sized_self(item.def_id))
+                                .map(|item| (item.def_id, trait_ref)),
                         );
                     }
                     ty::PredicateKind::Clause(ty::ClauseKind::Projection(pred)) => {
@@ -201,26 +206,25 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
         // So every `Projection` clause is an `Assoc = Foo` bound. `associated_types` contains all associated
         // types's `DefId`, so the following loop removes all the `DefIds` of the associated types that have a
         // corresponding `Projection` clause
-        for def_ids in associated_types.values_mut() {
-            for (projection_bound, span) in &projection_bounds {
-                let def_id = projection_bound.item_def_id();
-                def_ids.swap_remove(&def_id);
-                if tcx.generics_require_sized_self(def_id) {
-                    tcx.emit_node_span_lint(
-                        UNUSED_ASSOCIATED_TYPE_BOUNDS,
-                        hir_id,
-                        *span,
-                        crate::errors::UnusedAssociatedTypeBounds { span: *span },
-                    );
-                }
+        for (projection_bound, span) in &projection_bounds {
+            let def_id = projection_bound.item_def_id();
+            let trait_ref = tcx.anonymize_bound_vars(
+                projection_bound.map_bound(|p| p.projection_term.trait_ref(tcx)),
+            );
+            needed_associated_types.swap_remove(&(def_id, trait_ref));
+            if tcx.generics_require_sized_self(def_id) {
+                tcx.emit_node_span_lint(
+                    UNUSED_ASSOCIATED_TYPE_BOUNDS,
+                    hir_id,
+                    *span,
+                    crate::errors::UnusedAssociatedTypeBounds { span: *span },
+                );
             }
-            // If the associated type has a `where Self: Sized` bound, we do not need to constrain the associated
-            // type in the `dyn Trait`.
-            def_ids.retain(|def_id| !tcx.generics_require_sized_self(def_id));
         }
 
         if let Err(guar) = self.check_for_required_assoc_tys(
-            associated_types,
+            principal_span,
+            needed_associated_types,
             potential_assoc_types,
             hir_trait_bounds,
         ) {