Merging upstream version 1.67.1+dfsg1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 672 insertions, 0 deletions

diff --git a/compiler/rustc_infer/src/infer/error_reporting/suggest.rs b/compiler/rustc_infer/src/infer/error_reporting/suggest.rs
new file mode 100644
index 000000000..73b5a2cc4
--- /dev/null
+++ b/compiler/rustc_infer/src/infer/error_reporting/suggest.rs
@@ -0,0 +1,672 @@
+use hir::def::CtorKind;
+use hir::intravisit::{walk_expr, walk_stmt, Visitor};
+use rustc_data_structures::fx::FxIndexSet;
+use rustc_errors::{Applicability, Diagnostic};
+use rustc_hir as hir;
+use rustc_middle::traits::{
+    IfExpressionCause, MatchExpressionArmCause, ObligationCause, ObligationCauseCode,
+    StatementAsExpression,
+};
+use rustc_middle::ty::print::with_no_trimmed_paths;
+use rustc_middle::ty::{self as ty, Ty, TypeVisitable};
+use rustc_span::{sym, BytePos, Span};
+
+use crate::errors::SuggAddLetForLetChains;
+
+use super::TypeErrCtxt;
+
+impl<'tcx> TypeErrCtxt<'_, 'tcx> {
+    pub(super) fn suggest_remove_semi_or_return_binding(
+        &self,
+        err: &mut Diagnostic,
+        first_id: Option<hir::HirId>,
+        first_ty: Ty<'tcx>,
+        first_span: Span,
+        second_id: Option<hir::HirId>,
+        second_ty: Ty<'tcx>,
+        second_span: Span,
+    ) {
+        let remove_semicolon = [
+            (first_id, self.resolve_vars_if_possible(second_ty)),
+            (second_id, self.resolve_vars_if_possible(first_ty)),
+        ]
+        .into_iter()
+        .find_map(|(id, ty)| {
+            let hir::Node::Block(blk) = self.tcx.hir().get(id?) else { return None };
+            self.could_remove_semicolon(blk, ty)
+        });
+        match remove_semicolon {
+            Some((sp, StatementAsExpression::NeedsBoxing)) => {
+                err.multipart_suggestion(
+                    "consider removing this semicolon and boxing the expressions",
+                    vec![
+                        (first_span.shrink_to_lo(), "Box::new(".to_string()),
+                        (first_span.shrink_to_hi(), ")".to_string()),
+                        (second_span.shrink_to_lo(), "Box::new(".to_string()),
+                        (second_span.shrink_to_hi(), ")".to_string()),
+                        (sp, String::new()),
+                    ],
+                    Applicability::MachineApplicable,
+                );
+            }
+            Some((sp, StatementAsExpression::CorrectType)) => {
+                err.span_suggestion_short(
+                    sp,
+                    "consider removing this semicolon",
+                    "",
+                    Applicability::MachineApplicable,
+                );
+            }
+            None => {
+                for (id, ty) in [(first_id, second_ty), (second_id, first_ty)] {
+                    if let Some(id) = id
+                        && let hir::Node::Block(blk) = self.tcx.hir().get(id)
+                        && self.consider_returning_binding(blk, ty, err)
+                    {
+                        break;
+                    }
+                }
+            }
+        }
+    }
+
+    pub(super) fn suggest_boxing_for_return_impl_trait(
+        &self,
+        err: &mut Diagnostic,
+        return_sp: Span,
+        arm_spans: impl Iterator<Item = Span>,
+    ) {
+        err.multipart_suggestion(
+            "you could change the return type to be a boxed trait object",
+            vec![
+                (return_sp.with_hi(return_sp.lo() + BytePos(4)), "Box<dyn".to_string()),
+                (return_sp.shrink_to_hi(), ">".to_string()),
+            ],
+            Applicability::MaybeIncorrect,
+        );
+        let sugg = arm_spans
+            .flat_map(|sp| {
+                [(sp.shrink_to_lo(), "Box::new(".to_string()), (sp.shrink_to_hi(), ")".to_string())]
+                    .into_iter()
+            })
+            .collect::<Vec<_>>();
+        err.multipart_suggestion(
+            "if you change the return type to expect trait objects, box the returned expressions",
+            sugg,
+            Applicability::MaybeIncorrect,
+        );
+    }
+
+    pub(super) fn suggest_tuple_pattern(
+        &self,
+        cause: &ObligationCause<'tcx>,
+        exp_found: &ty::error::ExpectedFound<Ty<'tcx>>,
+        diag: &mut Diagnostic,
+    ) {
+        // Heavily inspired by `FnCtxt::suggest_compatible_variants`, with
+        // some modifications due to that being in typeck and this being in infer.
+        if let ObligationCauseCode::Pattern { .. } = cause.code() {
+            if let ty::Adt(expected_adt, substs) = exp_found.expected.kind() {
+                let compatible_variants: Vec<_> = expected_adt
+                    .variants()
+                    .iter()
+                    .filter(|variant| {
+                        variant.fields.len() == 1 && variant.ctor_kind() == Some(CtorKind::Fn)
+                    })
+                    .filter_map(|variant| {
+                        let sole_field = &variant.fields[0];
+                        let sole_field_ty = sole_field.ty(self.tcx, substs);
+                        if self.same_type_modulo_infer(sole_field_ty, exp_found.found) {
+                            let variant_path =
+                                with_no_trimmed_paths!(self.tcx.def_path_str(variant.def_id));
+                            // FIXME #56861: DRYer prelude filtering
+                            if let Some(path) = variant_path.strip_prefix("std::prelude::") {
+                                if let Some((_, path)) = path.split_once("::") {
+                                    return Some(path.to_string());
+                                }
+                            }
+                            Some(variant_path)
+                        } else {
+                            None
+                        }
+                    })
+                    .collect();
+                match &compatible_variants[..] {
+                    [] => {}
+                    [variant] => {
+                        diag.multipart_suggestion_verbose(
+                            &format!("try wrapping the pattern in `{}`", variant),
+                            vec![
+                                (cause.span.shrink_to_lo(), format!("{}(", variant)),
+                                (cause.span.shrink_to_hi(), ")".to_string()),
+                            ],
+                            Applicability::MaybeIncorrect,
+                        );
+                    }
+                    _ => {
+                        // More than one matching variant.
+                        diag.multipart_suggestions(
+                            &format!(
+                                "try wrapping the pattern in a variant of `{}`",
+                                self.tcx.def_path_str(expected_adt.did())
+                            ),
+                            compatible_variants.into_iter().map(|variant| {
+                                vec![
+                                    (cause.span.shrink_to_lo(), format!("{}(", variant)),
+                                    (cause.span.shrink_to_hi(), ")".to_string()),
+                                ]
+                            }),
+                            Applicability::MaybeIncorrect,
+                        );
+                    }
+                }
+            }
+        }
+    }
+
+    /// A possible error is to forget to add `.await` when using futures:
+    ///
+    /// ```compile_fail,E0308
+    /// async fn make_u32() -> u32 {
+    ///     22
+    /// }
+    ///
+    /// fn take_u32(x: u32) {}
+    ///
+    /// async fn foo() {
+    ///     let x = make_u32();
+    ///     take_u32(x);
+    /// }
+    /// ```
+    ///
+    /// This routine checks if the found type `T` implements `Future<Output=U>` where `U` is the
+    /// expected type. If this is the case, and we are inside of an async body, it suggests adding
+    /// `.await` to the tail of the expression.
+    pub(super) fn suggest_await_on_expect_found(
+        &self,
+        cause: &ObligationCause<'tcx>,
+        exp_span: Span,
+        exp_found: &ty::error::ExpectedFound<Ty<'tcx>>,
+        diag: &mut Diagnostic,
+    ) {
+        debug!(
+            "suggest_await_on_expect_found: exp_span={:?}, expected_ty={:?}, found_ty={:?}",
+            exp_span, exp_found.expected, exp_found.found,
+        );
+
+        if let ObligationCauseCode::CompareImplItemObligation { .. } = cause.code() {
+            return;
+        }
+
+        match (
+            self.get_impl_future_output_ty(exp_found.expected),
+            self.get_impl_future_output_ty(exp_found.found),
+        ) {
+            (Some(exp), Some(found)) if self.same_type_modulo_infer(exp, found) => match cause
+                .code()
+            {
+                ObligationCauseCode::IfExpression(box IfExpressionCause { then_id, .. }) => {
+                    let then_span = self.find_block_span_from_hir_id(*then_id);
+                    diag.multipart_suggestion(
+                        "consider `await`ing on both `Future`s",
+                        vec![
+                            (then_span.shrink_to_hi(), ".await".to_string()),
+                            (exp_span.shrink_to_hi(), ".await".to_string()),
+                        ],
+                        Applicability::MaybeIncorrect,
+                    );
+                }
+                ObligationCauseCode::MatchExpressionArm(box MatchExpressionArmCause {
+                    prior_arms,
+                    ..
+                }) => {
+                    if let [.., arm_span] = &prior_arms[..] {
+                        diag.multipart_suggestion(
+                            "consider `await`ing on both `Future`s",
+                            vec![
+                                (arm_span.shrink_to_hi(), ".await".to_string()),
+                                (exp_span.shrink_to_hi(), ".await".to_string()),
+                            ],
+                            Applicability::MaybeIncorrect,
+                        );
+                    } else {
+                        diag.help("consider `await`ing on both `Future`s");
+                    }
+                }
+                _ => {
+                    diag.help("consider `await`ing on both `Future`s");
+                }
+            },
+            (_, Some(ty)) if self.same_type_modulo_infer(exp_found.expected, ty) => {
+                diag.span_suggestion_verbose(
+                    exp_span.shrink_to_hi(),
+                    "consider `await`ing on the `Future`",
+                    ".await",
+                    Applicability::MaybeIncorrect,
+                );
+            }
+            (Some(ty), _) if self.same_type_modulo_infer(ty, exp_found.found) => match cause.code()
+            {
+                ObligationCauseCode::Pattern { span: Some(then_span), .. } => {
+                    diag.span_suggestion_verbose(
+                        then_span.shrink_to_hi(),
+                        "consider `await`ing on the `Future`",
+                        ".await",
+                        Applicability::MaybeIncorrect,
+                    );
+                }
+                ObligationCauseCode::IfExpression(box IfExpressionCause { then_id, .. }) => {
+                    let then_span = self.find_block_span_from_hir_id(*then_id);
+                    diag.span_suggestion_verbose(
+                        then_span.shrink_to_hi(),
+                        "consider `await`ing on the `Future`",
+                        ".await",
+                        Applicability::MaybeIncorrect,
+                    );
+                }
+                ObligationCauseCode::MatchExpressionArm(box MatchExpressionArmCause {
+                    ref prior_arms,
+                    ..
+                }) => {
+                    diag.multipart_suggestion_verbose(
+                        "consider `await`ing on the `Future`",
+                        prior_arms
+                            .iter()
+                            .map(|arm| (arm.shrink_to_hi(), ".await".to_string()))
+                            .collect(),
+                        Applicability::MaybeIncorrect,
+                    );
+                }
+                _ => {}
+            },
+            _ => {}
+        }
+    }
+
+    pub(super) fn suggest_accessing_field_where_appropriate(
+        &self,
+        cause: &ObligationCause<'tcx>,
+        exp_found: &ty::error::ExpectedFound<Ty<'tcx>>,
+        diag: &mut Diagnostic,
+    ) {
+        debug!(
+            "suggest_accessing_field_where_appropriate(cause={:?}, exp_found={:?})",
+            cause, exp_found
+        );
+        if let ty::Adt(expected_def, expected_substs) = exp_found.expected.kind() {
+            if expected_def.is_enum() {
+                return;
+            }
+
+            if let Some((name, ty)) = expected_def
+                .non_enum_variant()
+                .fields
+                .iter()
+                .filter(|field| field.vis.is_accessible_from(field.did, self.tcx))
+                .map(|field| (field.name, field.ty(self.tcx, expected_substs)))
+                .find(|(_, ty)| self.same_type_modulo_infer(*ty, exp_found.found))
+            {
+                if let ObligationCauseCode::Pattern { span: Some(span), .. } = *cause.code() {
+                    if let Ok(snippet) = self.tcx.sess.source_map().span_to_snippet(span) {
+                        let suggestion = if expected_def.is_struct() {
+                            format!("{}.{}", snippet, name)
+                        } else if expected_def.is_union() {
+                            format!("unsafe {{ {}.{} }}", snippet, name)
+                        } else {
+                            return;
+                        };
+                        diag.span_suggestion(
+                            span,
+                            &format!(
+                                "you might have meant to use field `{}` whose type is `{}`",
+                                name, ty
+                            ),
+                            suggestion,
+                            Applicability::MaybeIncorrect,
+                        );
+                    }
+                }
+            }
+        }
+    }
+
+    /// When encountering a case where `.as_ref()` on a `Result` or `Option` would be appropriate,
+    /// suggests it.
+    pub(super) fn suggest_as_ref_where_appropriate(
+        &self,
+        span: Span,
+        exp_found: &ty::error::ExpectedFound<Ty<'tcx>>,
+        diag: &mut Diagnostic,
+    ) {
+        if let Ok(snippet) = self.tcx.sess.source_map().span_to_snippet(span)
+            && let Some(msg) = self.should_suggest_as_ref(exp_found.expected, exp_found.found)
+        {
+            diag.span_suggestion(
+                span,
+                msg,
+                // HACK: fix issue# 100605, suggesting convert from &Option<T> to Option<&T>, remove the extra `&`
+                format!("{}.as_ref()", snippet.trim_start_matches('&')),
+                Applicability::MachineApplicable,
+            );
+        }
+    }
+
+    pub fn should_suggest_as_ref(&self, expected: Ty<'tcx>, found: Ty<'tcx>) -> Option<&str> {
+        if let (ty::Adt(exp_def, exp_substs), ty::Ref(_, found_ty, _)) =
+            (expected.kind(), found.kind())
+        {
+            if let ty::Adt(found_def, found_substs) = *found_ty.kind() {
+                if exp_def == &found_def {
+                    let have_as_ref = &[
+                        (
+                            sym::Option,
+                            "you can convert from `&Option<T>` to `Option<&T>` using \
+                        `.as_ref()`",
+                        ),
+                        (
+                            sym::Result,
+                            "you can convert from `&Result<T, E>` to \
+                        `Result<&T, &E>` using `.as_ref()`",
+                        ),
+                    ];
+                    if let Some(msg) = have_as_ref.iter().find_map(|(name, msg)| {
+                        self.tcx.is_diagnostic_item(*name, exp_def.did()).then_some(msg)
+                    }) {
+                        let mut show_suggestion = true;
+                        for (exp_ty, found_ty) in
+                            std::iter::zip(exp_substs.types(), found_substs.types())
+                        {
+                            match *exp_ty.kind() {
+                                ty::Ref(_, exp_ty, _) => {
+                                    match (exp_ty.kind(), found_ty.kind()) {
+                                        (_, ty::Param(_))
+                                        | (_, ty::Infer(_))
+                                        | (ty::Param(_), _)
+                                        | (ty::Infer(_), _) => {}
+                                        _ if self.same_type_modulo_infer(exp_ty, found_ty) => {}
+                                        _ => show_suggestion = false,
+                                    };
+                                }
+                                ty::Param(_) | ty::Infer(_) => {}
+                                _ => show_suggestion = false,
+                            }
+                        }
+                        if show_suggestion {
+                            return Some(*msg);
+                        }
+                    }
+                }
+            }
+        }
+        None
+    }
+
+    /// Try to find code with pattern `if Some(..) = expr`
+    /// use a `visitor` to mark the `if` which its span contains given error span,
+    /// and then try to find a assignment in the `cond` part, which span is equal with error span
+    pub(super) fn suggest_let_for_letchains(
+        &self,
+        err: &mut Diagnostic,
+        cause: &ObligationCause<'_>,
+        span: Span,
+    ) {
+        let hir = self.tcx.hir();
+        let fn_hir_id = hir.get_parent_node(cause.body_id);
+        if let Some(node) = self.tcx.hir().find(fn_hir_id) &&
+            let hir::Node::Item(hir::Item {
+                    kind: hir::ItemKind::Fn(_sig, _, body_id), ..
+                }) = node {
+        let body = hir.body(*body_id);
+
+        /// Find the if expression with given span
+        struct IfVisitor {
+            pub result: bool,
+            pub found_if: bool,
+            pub err_span: Span,
+        }
+
+        impl<'v> Visitor<'v> for IfVisitor {
+            fn visit_expr(&mut self, ex: &'v hir::Expr<'v>) {
+                if self.result { return; }
+                match ex.kind {
+                    hir::ExprKind::If(cond, _, _) => {
+                        self.found_if = true;
+                        walk_expr(self, cond);
+                        self.found_if = false;
+                    }
+                    _ => walk_expr(self, ex),
+                }
+            }
+
+            fn visit_stmt(&mut self, ex: &'v hir::Stmt<'v>) {
+                if let hir::StmtKind::Local(hir::Local {
+                        span, pat: hir::Pat{..}, ty: None, init: Some(_), ..
+                    }) = &ex.kind
+                    && self.found_if
+                    && span.eq(&self.err_span) {
+                        self.result = true;
+                }
+                walk_stmt(self, ex);
+            }
+
+            fn visit_body(&mut self, body: &'v hir::Body<'v>) {
+                hir::intravisit::walk_body(self, body);
+            }
+        }
+
+        let mut visitor = IfVisitor { err_span: span, found_if: false, result: false };
+        visitor.visit_body(&body);
+        if visitor.result {
+                err.subdiagnostic(SuggAddLetForLetChains{span: span.shrink_to_lo()});
+            }
+        }
+    }
+}
+
+impl<'tcx> TypeErrCtxt<'_, 'tcx> {
+    /// Be helpful when the user wrote `{... expr; }` and taking the `;` off
+    /// is enough to fix the error.
+    pub fn could_remove_semicolon(
+        &self,
+        blk: &'tcx hir::Block<'tcx>,
+        expected_ty: Ty<'tcx>,
+    ) -> Option<(Span, StatementAsExpression)> {
+        let blk = blk.innermost_block();
+        // Do not suggest if we have a tail expr.
+        if blk.expr.is_some() {
+            return None;
+        }
+        let last_stmt = blk.stmts.last()?;
+        let hir::StmtKind::Semi(ref last_expr) = last_stmt.kind else {
+            return None;
+        };
+        let last_expr_ty = self.typeck_results.as_ref()?.expr_ty_opt(*last_expr)?;
+        let needs_box = match (last_expr_ty.kind(), expected_ty.kind()) {
+            _ if last_expr_ty.references_error() => return None,
+            _ if self.same_type_modulo_infer(last_expr_ty, expected_ty) => {
+                StatementAsExpression::CorrectType
+            }
+            (ty::Opaque(last_def_id, _), ty::Opaque(exp_def_id, _))
+                if last_def_id == exp_def_id =>
+            {
+                StatementAsExpression::CorrectType
+            }
+            (ty::Opaque(last_def_id, last_bounds), ty::Opaque(exp_def_id, exp_bounds)) => {
+                debug!(
+                    "both opaque, likely future {:?} {:?} {:?} {:?}",
+                    last_def_id, last_bounds, exp_def_id, exp_bounds
+                );
+
+                let last_local_id = last_def_id.as_local()?;
+                let exp_local_id = exp_def_id.as_local()?;
+
+                match (
+                    &self.tcx.hir().expect_item(last_local_id).kind,
+                    &self.tcx.hir().expect_item(exp_local_id).kind,
+                ) {
+                    (
+                        hir::ItemKind::OpaqueTy(hir::OpaqueTy { bounds: last_bounds, .. }),
+                        hir::ItemKind::OpaqueTy(hir::OpaqueTy { bounds: exp_bounds, .. }),
+                    ) if std::iter::zip(*last_bounds, *exp_bounds).all(|(left, right)| {
+                        match (left, right) {
+                            (
+                                hir::GenericBound::Trait(tl, ml),
+                                hir::GenericBound::Trait(tr, mr),
+                            ) if tl.trait_ref.trait_def_id() == tr.trait_ref.trait_def_id()
+                                && ml == mr =>
+                            {
+                                true
+                            }
+                            (
+                                hir::GenericBound::LangItemTrait(langl, _, _, argsl),
+                                hir::GenericBound::LangItemTrait(langr, _, _, argsr),
+                            ) if langl == langr => {
+                                // FIXME: consider the bounds!
+                                debug!("{:?} {:?}", argsl, argsr);
+                                true
+                            }
+                            _ => false,
+                        }
+                    }) =>
+                    {
+                        StatementAsExpression::NeedsBoxing
+                    }
+                    _ => StatementAsExpression::CorrectType,
+                }
+            }
+            _ => return None,
+        };
+        let span = if last_stmt.span.from_expansion() {
+            let mac_call = rustc_span::source_map::original_sp(last_stmt.span, blk.span);
+            self.tcx.sess.source_map().mac_call_stmt_semi_span(mac_call)?
+        } else {
+            last_stmt.span.with_lo(last_stmt.span.hi() - BytePos(1))
+        };
+        Some((span, needs_box))
+    }
+
+    /// Suggest returning a local binding with a compatible type if the block
+    /// has no return expression.
+    pub fn consider_returning_binding(
+        &self,
+        blk: &'tcx hir::Block<'tcx>,
+        expected_ty: Ty<'tcx>,
+        err: &mut Diagnostic,
+    ) -> bool {
+        let blk = blk.innermost_block();
+        // Do not suggest if we have a tail expr.
+        if blk.expr.is_some() {
+            return false;
+        }
+        let mut shadowed = FxIndexSet::default();
+        let mut candidate_idents = vec![];
+        let mut find_compatible_candidates = |pat: &hir::Pat<'_>| {
+            if let hir::PatKind::Binding(_, hir_id, ident, _) = &pat.kind
+                && let Some(pat_ty) = self
+                    .typeck_results
+                    .as_ref()
+                    .and_then(|typeck_results| typeck_results.node_type_opt(*hir_id))
+            {
+                let pat_ty = self.resolve_vars_if_possible(pat_ty);
+                if self.same_type_modulo_infer(pat_ty, expected_ty)
+                    && !(pat_ty, expected_ty).references_error()
+                    && shadowed.insert(ident.name)
+                {
+                    candidate_idents.push((*ident, pat_ty));
+                }
+            }
+            true
+        };
+
+        let hir = self.tcx.hir();
+        for stmt in blk.stmts.iter().rev() {
+            let hir::StmtKind::Local(local) = &stmt.kind else { continue; };
+            local.pat.walk(&mut find_compatible_candidates);
+        }
+        match hir.find(hir.get_parent_node(blk.hir_id)) {
+            Some(hir::Node::Expr(hir::Expr { hir_id, .. })) => {
+                match hir.find(hir.get_parent_node(*hir_id)) {
+                    Some(hir::Node::Arm(hir::Arm { pat, .. })) => {
+                        pat.walk(&mut find_compatible_candidates);
+                    }
+                    Some(
+                        hir::Node::Item(hir::Item { kind: hir::ItemKind::Fn(_, _, body), .. })
+                        | hir::Node::ImplItem(hir::ImplItem {
+                            kind: hir::ImplItemKind::Fn(_, body),
+                            ..
+                        })
+                        | hir::Node::TraitItem(hir::TraitItem {
+                            kind: hir::TraitItemKind::Fn(_, hir::TraitFn::Provided(body)),
+                            ..
+                        })
+                        | hir::Node::Expr(hir::Expr {
+                            kind: hir::ExprKind::Closure(hir::Closure { body, .. }),
+                            ..
+                        }),
+                    ) => {
+                        for param in hir.body(*body).params {
+                            param.pat.walk(&mut find_compatible_candidates);
+                        }
+                    }
+                    Some(hir::Node::Expr(hir::Expr {
+                        kind:
+                            hir::ExprKind::If(
+                                hir::Expr { kind: hir::ExprKind::Let(let_), .. },
+                                then_block,
+                                _,
+                            ),
+                        ..
+                    })) if then_block.hir_id == *hir_id => {
+                        let_.pat.walk(&mut find_compatible_candidates);
+                    }
+                    _ => {}
+                }
+            }
+            _ => {}
+        }
+
+        match &candidate_idents[..] {
+            [(ident, _ty)] => {
+                let sm = self.tcx.sess.source_map();
+                if let Some(stmt) = blk.stmts.last() {
+                    let stmt_span = sm.stmt_span(stmt.span, blk.span);
+                    let sugg = if sm.is_multiline(blk.span)
+                        && let Some(spacing) = sm.indentation_before(stmt_span)
+                    {
+                        format!("\n{spacing}{ident}")
+                    } else {
+                        format!(" {ident}")
+                    };
+                    err.span_suggestion_verbose(
+                        stmt_span.shrink_to_hi(),
+                        format!("consider returning the local binding `{ident}`"),
+                        sugg,
+                        Applicability::MaybeIncorrect,
+                    );
+                } else {
+                    let sugg = if sm.is_multiline(blk.span)
+                        && let Some(spacing) = sm.indentation_before(blk.span.shrink_to_lo())
+                    {
+                        format!("\n{spacing}    {ident}\n{spacing}")
+                    } else {
+                        format!(" {ident} ")
+                    };
+                    let left_span = sm.span_through_char(blk.span, '{').shrink_to_hi();
+                    err.span_suggestion_verbose(
+                        sm.span_extend_while(left_span, |c| c.is_whitespace()).unwrap_or(left_span),
+                        format!("consider returning the local binding `{ident}`"),
+                        sugg,
+                        Applicability::MaybeIncorrect,
+                    );
+                }
+                true
+            }
+            values if (1..3).contains(&values.len()) => {
+                let spans = values.iter().map(|(ident, _)| ident.span).collect::<Vec<_>>();
+                err.span_note(spans, "consider returning one of these bindings");
+                true
+            }
+            _ => false,
+        }
+    }
+}