Auto merge of rust-lang#121003 - matthiaskrgr:rollup-u5wyztn, r=matth…

…iaskrgr

Rollup of 10 pull requests

Successful merges:

 - rust-lang#120696 (Properly handle `async` block and `async fn` in `if` exprs without `else`)
 - rust-lang#120751 (Provide more suggestions on invalid equality where bounds)
 - rust-lang#120802 (Bail out of drop elaboration when encountering error types)
 - rust-lang#120967 (docs: mention round-to-even in precision formatting)
 - rust-lang#120973 (allow static_mut_ref in some tests that specifically test mutable statics)
 - rust-lang#120974 (llvm-wrapper: adapt for LLVM API change: Add support for EXPORTAS name types)
 - rust-lang#120986 (iterator.rs: remove "Basic usage" text)
 - rust-lang#120987 (remove redundant logic)
 - rust-lang#120988 (fix comment)
 - rust-lang#120995 (PassWrapper: adapt for llvm/llvm-project@93cdd1b5cfa3735c)

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

compiler/rustc_ast_passes/src/ast_validation.rs

@@ -1593,44 +1593,98 @@ fn deny_equality_constraints(
             }
         }
     }
-    // Given `A: Foo, A::Bar = RhsTy`, suggest `A: Foo<Bar = RhsTy>`.
-    if let TyKind::Path(None, full_path) = &predicate.lhs_ty.kind {
-        if let [potential_param, potential_assoc] = &full_path.segments[..] {
-            for param in &generics.params {
-                if param.ident == potential_param.ident {
-                    for bound in &param.bounds {
-                        if let ast::GenericBound::Trait(trait_ref, TraitBoundModifiers::NONE) =
-                            bound
+
+    let mut suggest =
+        |poly: &PolyTraitRef, potential_assoc: &PathSegment, predicate: &WhereEqPredicate| {
+            if let [trait_segment] = &poly.trait_ref.path.segments[..] {
+                let assoc = pprust::path_to_string(&ast::Path::from_ident(potential_assoc.ident));
+                let ty = pprust::ty_to_string(&predicate.rhs_ty);
+                let (args, span) = match &trait_segment.args {
+                    Some(args) => match args.deref() {
+                        ast::GenericArgs::AngleBracketed(args) => {
+                            let Some(arg) = args.args.last() else {
+                                return;
+                            };
+                            (format!(", {assoc} = {ty}"), arg.span().shrink_to_hi())
+                        }
+                        _ => return,
+                    },
+                    None => (format!("<{assoc} = {ty}>"), trait_segment.span().shrink_to_hi()),
+                };
+                let removal_span = if generics.where_clause.predicates.len() == 1 {
+                    // We're removing th eonly where bound left, remove the whole thing.
+                    generics.where_clause.span
+                } else {
+                    let mut span = predicate.span;
+                    let mut prev: Option<Span> = None;
+                    let mut preds = generics.where_clause.predicates.iter().peekable();
+                    // Find the predicate that shouldn't have been in the where bound list.
+                    while let Some(pred) = preds.next() {
+                        if let WherePredicate::EqPredicate(pred) = pred
+                            && pred.span == predicate.span
                         {
-                            if let [trait_segment] = &trait_ref.trait_ref.path.segments[..] {
-                                let assoc = pprust::path_to_string(&ast::Path::from_ident(
-                                    potential_assoc.ident,
-                                ));
-                                let ty = pprust::ty_to_string(&predicate.rhs_ty);
-                                let (args, span) = match &trait_segment.args {
-                                    Some(args) => match args.deref() {
-                                        ast::GenericArgs::AngleBracketed(args) => {
-                                            let Some(arg) = args.args.last() else {
-                                                continue;
-                                            };
-                                            (format!(", {assoc} = {ty}"), arg.span().shrink_to_hi())
-                                        }
-                                        _ => continue,
-                                    },
-                                    None => (
-                                        format!("<{assoc} = {ty}>"),
-                                        trait_segment.span().shrink_to_hi(),
-                                    ),
-                                };
-                                err.assoc2 = Some(errors::AssociatedSuggestion2 {
-                                    span,
-                                    args,
-                                    predicate: predicate.span,
-                                    trait_segment: trait_segment.ident,
-                                    potential_assoc: potential_assoc.ident,
-                                });
+                            if let Some(next) = preds.peek() {
+                                // This is the first predicate, remove the trailing comma as well.
+                                span = span.with_hi(next.span().lo());
+                            } else if let Some(prev) = prev {
+                                // Remove the previous comma as well.
+                                span = span.with_lo(prev.hi());
                             }
                         }
+                        prev = Some(pred.span());
+                    }
+                    span
+                };
+                err.assoc2 = Some(errors::AssociatedSuggestion2 {
+                    span,
+                    args,
+                    predicate: removal_span,
+                    trait_segment: trait_segment.ident,
+                    potential_assoc: potential_assoc.ident,
+                });
+            }
+        };
+
+    if let TyKind::Path(None, full_path) = &predicate.lhs_ty.kind {
+        // Given `A: Foo, Foo::Bar = RhsTy`, suggest `A: Foo<Bar = RhsTy>`.
+        for bounds in generics.params.iter().map(|p| &p.bounds).chain(
+            generics.where_clause.predicates.iter().filter_map(|pred| match pred {
+                WherePredicate::BoundPredicate(p) => Some(&p.bounds),
+                _ => None,
+            }),
+        ) {
+            for bound in bounds {
+                if let GenericBound::Trait(poly, TraitBoundModifiers::NONE) = bound {
+                    if full_path.segments[..full_path.segments.len() - 1]
+                        .iter()
+                        .map(|segment| segment.ident.name)
+                        .zip(poly.trait_ref.path.segments.iter().map(|segment| segment.ident.name))
+                        .all(|(a, b)| a == b)
+                        && let Some(potential_assoc) = full_path.segments.iter().last()
+                    {
+                        suggest(poly, potential_assoc, predicate);
+                    }
+                }
+            }
+        }
+        // Given `A: Foo, A::Bar = RhsTy`, suggest `A: Foo<Bar = RhsTy>`.
+        if let [potential_param, potential_assoc] = &full_path.segments[..] {
+            for (ident, bounds) in generics.params.iter().map(|p| (p.ident, &p.bounds)).chain(
+                generics.where_clause.predicates.iter().filter_map(|pred| match pred {
+                    WherePredicate::BoundPredicate(p)
+                        if let ast::TyKind::Path(None, path) = &p.bounded_ty.kind
+                            && let [segment] = &path.segments[..] =>
+                    {
+                        Some((segment.ident, &p.bounds))
+                    }
+                    _ => None,
+                }),
+            ) {
+                if ident == potential_param.ident {
+                    for bound in bounds {
+                        if let ast::GenericBound::Trait(poly, TraitBoundModifiers::NONE) = bound {
+                            suggest(poly, potential_assoc, predicate);
+                        }
                     }
                 }
             }

compiler/rustc_hir_typeck/src/coercion.rs

@@ -98,8 +98,11 @@ struct CollectRetsVisitor<'tcx> {
 
 impl<'tcx> Visitor<'tcx> for CollectRetsVisitor<'tcx> {
     fn visit_expr(&mut self, expr: &'tcx Expr<'tcx>) {
-        if let hir::ExprKind::Ret(_) = expr.kind {
-            self.ret_exprs.push(expr);
+        match expr.kind {
+            hir::ExprKind::Ret(_) => self.ret_exprs.push(expr),
+            // `return` in closures does not return from the outer function
+            hir::ExprKind::Closure(_) => return,
+            _ => {}
         }
         intravisit::walk_expr(self, expr);
     }
@@ -1845,13 +1848,31 @@ impl<'tcx, 'exprs, E: AsCoercionSite> CoerceMany<'tcx, 'exprs, E> {
         }
 
         let parent_id = fcx.tcx.hir().get_parent_item(id);
-        let parent_item = fcx.tcx.hir_node_by_def_id(parent_id.def_id);
+        let mut parent_item = fcx.tcx.hir_node_by_def_id(parent_id.def_id);
+        // When suggesting return, we need to account for closures and async blocks, not just items.
+        for (_, node) in fcx.tcx.hir().parent_iter(id) {
+            match node {
+                hir::Node::Expr(&hir::Expr {
+                    kind: hir::ExprKind::Closure(hir::Closure { .. }),
+                    ..
+                }) => {
+                    parent_item = node;
+                    break;
+                }
+                hir::Node::Item(_) | hir::Node::TraitItem(_) | hir::Node::ImplItem(_) => break,
+                _ => {}
+            }
+        }
 
-        if let (Some(expr), Some(_), Some((fn_id, fn_decl, _, _))) =
-            (expression, blk_id, fcx.get_node_fn_decl(parent_item))
-        {
+        if let (Some(expr), Some(_), Some(fn_decl)) = (expression, blk_id, parent_item.fn_decl()) {
             fcx.suggest_missing_break_or_return_expr(
-                &mut err, expr, fn_decl, expected, found, id, fn_id,
+                &mut err,
+                expr,
+                fn_decl,
+                expected,
+                found,
+                id,
+                parent_id.into(),
             );
         }
 

compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs

@@ -963,14 +963,35 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 owner_id,
                 ..
             }) => Some((hir::HirId::make_owner(owner_id.def_id), &sig.decl, ident, false)),
-            Node::Expr(&hir::Expr { hir_id, kind: hir::ExprKind::Closure(..), .. })
-                if let Node::Item(&hir::Item {
-                    ident,
-                    kind: hir::ItemKind::Fn(ref sig, ..),
-                    owner_id,
-                    ..
-                }) = self.tcx.parent_hir_node(hir_id) =>
-            {
+            Node::Expr(&hir::Expr {
+                hir_id,
+                kind:
+                    hir::ExprKind::Closure(hir::Closure {
+                        kind: hir::ClosureKind::Coroutine(..), ..
+                    }),
+                ..
+            }) => {
+                let (ident, sig, owner_id) = match self.tcx.parent_hir_node(hir_id) {
+                    Node::Item(&hir::Item {
+                        ident,
+                        kind: hir::ItemKind::Fn(ref sig, ..),
+                        owner_id,
+                        ..
+                    }) => (ident, sig, owner_id),
+                    Node::TraitItem(&hir::TraitItem {
+                        ident,
+                        kind: hir::TraitItemKind::Fn(ref sig, ..),
+                        owner_id,
+                        ..
+                    }) => (ident, sig, owner_id),
+                    Node::ImplItem(&hir::ImplItem {
+                        ident,
+                        kind: hir::ImplItemKind::Fn(ref sig, ..),
+                        owner_id,
+                        ..
+                    }) => (ident, sig, owner_id),
+                    _ => return None,
+                };
                 Some((
                     hir::HirId::make_owner(owner_id.def_id),
                     &sig.decl,

compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs

@@ -1726,7 +1726,10 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
     }
 
     /// Given a function block's `HirId`, returns its `FnDecl` if it exists, or `None` otherwise.
-    fn get_parent_fn_decl(&self, blk_id: hir::HirId) -> Option<(&'tcx hir::FnDecl<'tcx>, Ident)> {
+    pub(crate) fn get_parent_fn_decl(
+        &self,
+        blk_id: hir::HirId,
+    ) -> Option<(&'tcx hir::FnDecl<'tcx>, Ident)> {
         let parent = self.tcx.hir_node_by_def_id(self.tcx.hir().get_parent_item(blk_id).def_id);
         self.get_node_fn_decl(parent).map(|(_, fn_decl, ident, _)| (fn_decl, ident))
     }

compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs

@@ -827,6 +827,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             }
             hir::FnRetTy::Return(hir_ty) => {
                 if let hir::TyKind::OpaqueDef(item_id, ..) = hir_ty.kind
+                    // FIXME: account for RPITIT.
                     && let hir::Node::Item(hir::Item {
                         kind: hir::ItemKind::OpaqueTy(op_ty), ..
                     }) = self.tcx.hir_node(item_id.hir_id())
@@ -1038,33 +1039,62 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             return;
         }
 
-        if let hir::FnRetTy::Return(ty) = fn_decl.output {
-            let ty = self.astconv().ast_ty_to_ty(ty);
-            let bound_vars = self.tcx.late_bound_vars(fn_id);
-            let ty = self
-                .tcx
-                .instantiate_bound_regions_with_erased(Binder::bind_with_vars(ty, bound_vars));
-            let ty = match self.tcx.asyncness(fn_id.owner) {
-                ty::Asyncness::Yes => self.get_impl_future_output_ty(ty).unwrap_or_else(|| {
-                    span_bug!(fn_decl.output.span(), "failed to get output type of async function")
-                }),
-                ty::Asyncness::No => ty,
-            };
-            let ty = self.normalize(expr.span, ty);
-            if self.can_coerce(found, ty) {
-                if let Some(owner_node) = self.tcx.hir_node(fn_id).as_owner()
-                    && let Some(span) = expr.span.find_ancestor_inside(*owner_node.span())
-                {
-                    err.multipart_suggestion(
-                        "you might have meant to return this value",
-                        vec![
-                            (span.shrink_to_lo(), "return ".to_string()),
-                            (span.shrink_to_hi(), ";".to_string()),
-                        ],
-                        Applicability::MaybeIncorrect,
-                    );
-                }
+        let scope = self
+            .tcx
+            .hir()
+            .parent_iter(id)
+            .filter(|(_, node)| {
+                matches!(
+                    node,
+                    Node::Expr(Expr { kind: ExprKind::Closure(..), .. })
+                        | Node::Item(_)
+                        | Node::TraitItem(_)
+                        | Node::ImplItem(_)
+                )
+            })
+            .next();
+        let in_closure =
+            matches!(scope, Some((_, Node::Expr(Expr { kind: ExprKind::Closure(..), .. }))));
+
+        let can_return = match fn_decl.output {
+            hir::FnRetTy::Return(ty) => {
+                let ty = self.astconv().ast_ty_to_ty(ty);
+                let bound_vars = self.tcx.late_bound_vars(fn_id);
+                let ty = self
+                    .tcx
+                    .instantiate_bound_regions_with_erased(Binder::bind_with_vars(ty, bound_vars));
+                let ty = match self.tcx.asyncness(fn_id.owner) {
+                    ty::Asyncness::Yes => self.get_impl_future_output_ty(ty).unwrap_or_else(|| {
+                        span_bug!(
+                            fn_decl.output.span(),
+                            "failed to get output type of async function"
+                        )
+                    }),
+                    ty::Asyncness::No => ty,
+                };
+                let ty = self.normalize(expr.span, ty);
+                self.can_coerce(found, ty)
+            }
+            hir::FnRetTy::DefaultReturn(_) if in_closure => {
+                self.ret_coercion.as_ref().map_or(false, |ret| {
+                    let ret_ty = ret.borrow().expected_ty();
+                    self.can_coerce(found, ret_ty)
+                })
             }
+            _ => false,
+        };
+        if can_return
+            && let Some(owner_node) = self.tcx.hir_node(fn_id).as_owner()
+            && let Some(span) = expr.span.find_ancestor_inside(*owner_node.span())
+        {
+            err.multipart_suggestion(
+                "you might have meant to return this value",
+                vec![
+                    (span.shrink_to_lo(), "return ".to_string()),
+                    (span.shrink_to_hi(), ";".to_string()),
+                ],
+                Applicability::MaybeIncorrect,
+            );
         }
     }
 

compiler/rustc_hir_typeck/src/method/suggest.rs

@@ -1073,12 +1073,6 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                                         // for instance
                                         self.tcx.at(span).type_of(*def_id).instantiate_identity()
                                             != rcvr_ty
-                                            && self
-                                                .tcx
-                                                .at(span)
-                                                .type_of(*def_id)
-                                                .instantiate_identity()
-                                                != rcvr_ty
                                     }
                                     (Mode::Path, false, _) => true,
                                     _ => false,
@@ -1092,7 +1086,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                         inherent_impls_candidate.sort();
                         inherent_impls_candidate.dedup();
 
-                        // number of type to shows at most.
+                        // number of types to show at most
                         let limit = if inherent_impls_candidate.len() == 5 { 5 } else { 4 };
                         let type_candidates = inherent_impls_candidate
                             .iter()