Rollup of 6 pull requests

compiler/rustc_ast_lowering/src/expr.rs

@@ -130,7 +130,15 @@ impl<'hir> LoweringContext<'_, 'hir> {
                         hir::AsyncGeneratorKind::Block,
                         |this| this.with_new_scopes(|this| this.lower_block_expr(block)),
                     ),
-                ExprKind::Await(ref expr) => self.lower_expr_await(e.span, expr),
+                ExprKind::Await(ref expr) => {
+                    let span = if expr.span.hi() < e.span.hi() {
+                        expr.span.shrink_to_hi().with_hi(e.span.hi())
+                    } else {
+                        // this is a recovered `await expr`
+                        e.span
+                    };
+                    self.lower_expr_await(span, expr)
+                }
                 ExprKind::Closure(
                     capture_clause,
                     asyncness,
@@ -479,8 +487,12 @@ impl<'hir> LoweringContext<'_, 'hir> {
         expr: &'hir hir::Expr<'hir>,
         overall_span: Span,
     ) -> &'hir hir::Expr<'hir> {
-        let constructor =
-            self.arena.alloc(self.expr_lang_item_path(method_span, lang_item, ThinVec::new()));
+        let constructor = self.arena.alloc(self.expr_lang_item_path(
+            method_span,
+            lang_item,
+            ThinVec::new(),
+            None,
+        ));
         self.expr_call(overall_span, constructor, std::slice::from_ref(expr))
     }
 
@@ -584,8 +596,12 @@ impl<'hir> LoweringContext<'_, 'hir> {
         // `future::from_generator`:
         let unstable_span =
             self.mark_span_with_reason(DesugaringKind::Async, span, self.allow_gen_future.clone());
-        let gen_future =
-            self.expr_lang_item_path(unstable_span, hir::LangItem::FromGenerator, ThinVec::new());
+        let gen_future = self.expr_lang_item_path(
+            unstable_span,
+            hir::LangItem::FromGenerator,
+            ThinVec::new(),
+            None,
+        );
 
         // `future::from_generator(generator)`:
         hir::ExprKind::Call(self.arena.alloc(gen_future), arena_vec![self; generator])
@@ -607,6 +623,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
     /// }
     /// ```
     fn lower_expr_await(&mut self, await_span: Span, expr: &Expr) -> hir::ExprKind<'hir> {
+        let dot_await_span = expr.span.shrink_to_hi().to(await_span);
         match self.generator_kind {
             Some(hir::GeneratorKind::Async(_)) => {}
             Some(hir::GeneratorKind::Gen) | None => {
@@ -623,13 +640,14 @@ impl<'hir> LoweringContext<'_, 'hir> {
                 err.emit();
             }
         }
-        let span = self.mark_span_with_reason(DesugaringKind::Await, await_span, None);
+        let span = self.mark_span_with_reason(DesugaringKind::Await, dot_await_span, None);
         let gen_future_span = self.mark_span_with_reason(
             DesugaringKind::Await,
             await_span,
             self.allow_gen_future.clone(),
         );
         let expr = self.lower_expr_mut(expr);
+        let expr_hir_id = expr.hir_id;
 
         let pinned_ident = Ident::with_dummy_span(sym::pinned);
         let (pinned_pat, pinned_pat_hid) =
@@ -656,16 +674,19 @@ impl<'hir> LoweringContext<'_, 'hir> {
                 span,
                 hir::LangItem::PinNewUnchecked,
                 arena_vec![self; ref_mut_pinned],
+                Some(expr_hir_id),
             );
             let get_context = self.expr_call_lang_item_fn_mut(
                 gen_future_span,
                 hir::LangItem::GetContext,
                 arena_vec![self; task_context],
+                Some(expr_hir_id),
             );
             let call = self.expr_call_lang_item_fn(
                 span,
                 hir::LangItem::FuturePoll,
                 arena_vec![self; new_unchecked, get_context],
+                Some(expr_hir_id),
             );
             self.arena.alloc(self.expr_unsafe(call))
         };
@@ -678,18 +699,28 @@ impl<'hir> LoweringContext<'_, 'hir> {
             let (x_pat, x_pat_hid) = self.pat_ident(span, x_ident);
             let x_expr = self.expr_ident(span, x_ident, x_pat_hid);
             let ready_field = self.single_pat_field(span, x_pat);
-            let ready_pat = self.pat_lang_item_variant(span, hir::LangItem::PollReady, ready_field);
+            let ready_pat = self.pat_lang_item_variant(
+                span,
+                hir::LangItem::PollReady,
+                ready_field,
+                Some(expr_hir_id),
+            );
             let break_x = self.with_loop_scope(loop_node_id, move |this| {
                 let expr_break =
                     hir::ExprKind::Break(this.lower_loop_destination(None), Some(x_expr));
-                this.arena.alloc(this.expr(await_span, expr_break, ThinVec::new()))
+                this.arena.alloc(this.expr(span, expr_break, ThinVec::new()))
             });
             self.arm(ready_pat, break_x)
         };
 
         // `::std::task::Poll::Pending => {}`
         let pending_arm = {
-            let pending_pat = self.pat_lang_item_variant(span, hir::LangItem::PollPending, &[]);
+            let pending_pat = self.pat_lang_item_variant(
+                span,
+                hir::LangItem::PollPending,
+                &[],
+                Some(expr_hir_id),
+            );
             let empty_block = self.expr_block_empty(span);
             self.arm(pending_pat, empty_block)
         };
@@ -709,7 +740,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
             let unit = self.expr_unit(span);
             let yield_expr = self.expr(
                 span,
-                hir::ExprKind::Yield(unit, hir::YieldSource::Await { expr: Some(expr.hir_id) }),
+                hir::ExprKind::Yield(unit, hir::YieldSource::Await { expr: Some(expr_hir_id) }),
                 ThinVec::new(),
             );
             let yield_expr = self.arena.alloc(yield_expr);
@@ -756,6 +787,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
             into_future_span,
             hir::LangItem::IntoFutureIntoFuture,
             arena_vec![self; expr],
+            Some(expr_hir_id),
         );
 
         // match <into_future_expr> {
@@ -1160,7 +1192,8 @@ impl<'hir> LoweringContext<'_, 'hir> {
     fn lower_expr_range_closed(&mut self, span: Span, e1: &Expr, e2: &Expr) -> hir::ExprKind<'hir> {
         let e1 = self.lower_expr_mut(e1);
         let e2 = self.lower_expr_mut(e2);
-        let fn_path = hir::QPath::LangItem(hir::LangItem::RangeInclusiveNew, self.lower_span(span));
+        let fn_path =
+            hir::QPath::LangItem(hir::LangItem::RangeInclusiveNew, self.lower_span(span), None);
         let fn_expr =
             self.arena.alloc(self.expr(span, hir::ExprKind::Path(fn_path), ThinVec::new()));
         hir::ExprKind::Call(fn_expr, arena_vec![self; e1, e2])
@@ -1194,7 +1227,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
         );
 
         hir::ExprKind::Struct(
-            self.arena.alloc(hir::QPath::LangItem(lang_item, self.lower_span(span))),
+            self.arena.alloc(hir::QPath::LangItem(lang_item, self.lower_span(span), None)),
             fields,
             None,
         )
@@ -1389,6 +1422,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                 head_span,
                 hir::LangItem::IteratorNext,
                 arena_vec![self; ref_mut_iter],
+                None,
             );
             let arms = arena_vec![self; none_arm, some_arm];
 
@@ -1417,6 +1451,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                 head_span,
                 hir::LangItem::IntoIterIntoIter,
                 arena_vec![self; head],
+                None,
             )
         };
 
@@ -1472,6 +1507,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                 unstable_span,
                 hir::LangItem::TryTraitBranch,
                 arena_vec![self; sub_expr],
+                None,
             )
         };
 
@@ -1628,8 +1664,10 @@ impl<'hir> LoweringContext<'_, 'hir> {
         span: Span,
         lang_item: hir::LangItem,
         args: &'hir [hir::Expr<'hir>],
+        hir_id: Option<hir::HirId>,
     ) -> hir::Expr<'hir> {
-        let path = self.arena.alloc(self.expr_lang_item_path(span, lang_item, ThinVec::new()));
+        let path =
+            self.arena.alloc(self.expr_lang_item_path(span, lang_item, ThinVec::new(), hir_id));
         self.expr_call_mut(span, path, args)
     }
 
@@ -1638,19 +1676,21 @@ impl<'hir> LoweringContext<'_, 'hir> {
         span: Span,
         lang_item: hir::LangItem,
         args: &'hir [hir::Expr<'hir>],
+        hir_id: Option<hir::HirId>,
     ) -> &'hir hir::Expr<'hir> {
-        self.arena.alloc(self.expr_call_lang_item_fn_mut(span, lang_item, args))
+        self.arena.alloc(self.expr_call_lang_item_fn_mut(span, lang_item, args, hir_id))
     }
 
     fn expr_lang_item_path(
         &mut self,
         span: Span,
         lang_item: hir::LangItem,
         attrs: AttrVec,
+        hir_id: Option<hir::HirId>,
     ) -> hir::Expr<'hir> {
         self.expr(
             span,
-            hir::ExprKind::Path(hir::QPath::LangItem(lang_item, self.lower_span(span))),
+            hir::ExprKind::Path(hir::QPath::LangItem(lang_item, self.lower_span(span), hir_id)),
             attrs,
         )
     }

compiler/rustc_ast_lowering/src/lib.rs

@@ -2140,21 +2140,21 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
 
     fn pat_cf_continue(&mut self, span: Span, pat: &'hir hir::Pat<'hir>) -> &'hir hir::Pat<'hir> {
         let field = self.single_pat_field(span, pat);
-        self.pat_lang_item_variant(span, hir::LangItem::ControlFlowContinue, field)
+        self.pat_lang_item_variant(span, hir::LangItem::ControlFlowContinue, field, None)
     }
 
     fn pat_cf_break(&mut self, span: Span, pat: &'hir hir::Pat<'hir>) -> &'hir hir::Pat<'hir> {
         let field = self.single_pat_field(span, pat);
-        self.pat_lang_item_variant(span, hir::LangItem::ControlFlowBreak, field)
+        self.pat_lang_item_variant(span, hir::LangItem::ControlFlowBreak, field, None)
     }
 
     fn pat_some(&mut self, span: Span, pat: &'hir hir::Pat<'hir>) -> &'hir hir::Pat<'hir> {
         let field = self.single_pat_field(span, pat);
-        self.pat_lang_item_variant(span, hir::LangItem::OptionSome, field)
+        self.pat_lang_item_variant(span, hir::LangItem::OptionSome, field, None)
     }
 
     fn pat_none(&mut self, span: Span) -> &'hir hir::Pat<'hir> {
-        self.pat_lang_item_variant(span, hir::LangItem::OptionNone, &[])
+        self.pat_lang_item_variant(span, hir::LangItem::OptionNone, &[], None)
     }
 
     fn single_pat_field(
@@ -2177,8 +2177,9 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         span: Span,
         lang_item: hir::LangItem,
         fields: &'hir [hir::PatField<'hir>],
+        hir_id: Option<hir::HirId>,
     ) -> &'hir hir::Pat<'hir> {
-        let qpath = hir::QPath::LangItem(lang_item, self.lower_span(span));
+        let qpath = hir::QPath::LangItem(lang_item, self.lower_span(span), hir_id);
         self.pat(span, hir::PatKind::Struct(qpath, fields, false))
     }
 

compiler/rustc_borrowck/src/diagnostics/bound_region_errors.rs

@@ -368,6 +368,7 @@ fn try_extract_error_from_fulfill_cx<'tcx>(
                 error_region,
                 cause.clone(),
                 placeholder_region,
+                vec![],
             ),
         ),
         (Some(error_region), _) => NiceRegionError::new(

compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs

@@ -15,16 +15,18 @@ use rustc_span::symbol::sym;
 use rustc_span::{BytePos, MultiSpan, Span, DUMMY_SP};
 use rustc_trait_selection::infer::InferCtxtExt;
 
+use crate::borrow_set::TwoPhaseActivation;
 use crate::borrowck_errors;
 
+use crate::diagnostics::find_all_local_uses;
 use crate::{
     borrow_set::BorrowData, diagnostics::Instance, prefixes::IsPrefixOf,
     InitializationRequiringAction, MirBorrowckCtxt, PrefixSet, WriteKind,
 };
 
 use super::{
-    explain_borrow::BorrowExplanation, FnSelfUseKind, IncludingDowncast, RegionName,
-    RegionNameSource, UseSpans,
+    explain_borrow::{BorrowExplanation, LaterUseKind},
+    FnSelfUseKind, IncludingDowncast, RegionName, RegionNameSource, UseSpans,
 };
 
 #[derive(Debug)]
@@ -768,9 +770,92 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
             Some((issued_span, span)),
         );
 
+        self.suggest_using_local_if_applicable(
+            &mut err,
+            location,
+            (place, span),
+            gen_borrow_kind,
+            issued_borrow,
+            explanation,
+        );
+
         err
     }
 
+    #[instrument(level = "debug", skip(self, err))]
+    fn suggest_using_local_if_applicable(
+        &self,
+        err: &mut DiagnosticBuilder<'_>,
+        location: Location,
+        (place, span): (Place<'tcx>, Span),
+        gen_borrow_kind: BorrowKind,
+        issued_borrow: &BorrowData<'tcx>,
+        explanation: BorrowExplanation,
+    ) {
+        let used_in_call =
+            matches!(explanation, BorrowExplanation::UsedLater(LaterUseKind::Call, _call_span, _));
+        if !used_in_call {
+            debug!("not later used in call");
+            return;
+        }
+
+        let outer_call_loc =
+            if let TwoPhaseActivation::ActivatedAt(loc) = issued_borrow.activation_location {
+                loc
+            } else {
+                issued_borrow.reserve_location
+            };
+        let outer_call_stmt = self.body.stmt_at(outer_call_loc);
+
+        let inner_param_location = location;
+        let Some(inner_param_stmt) = self.body.stmt_at(inner_param_location).left() else {
+            debug!("`inner_param_location` {:?} is not for a statement", inner_param_location);
+            return;
+        };
+        let Some(&inner_param) = inner_param_stmt.kind.as_assign().map(|(p, _)| p) else {
+            debug!(
+                "`inner_param_location` {:?} is not for an assignment: {:?}",
+                inner_param_location, inner_param_stmt
+            );
+            return;
+        };
+        let inner_param_uses = find_all_local_uses::find(self.body, inner_param.local);
+        let Some((inner_call_loc,inner_call_term)) = inner_param_uses.into_iter().find_map(|loc| {
+            let Either::Right(term) = self.body.stmt_at(loc) else {
+                debug!("{:?} is a statement, so it can't be a call", loc);
+                return None;
+            };
+            let TerminatorKind::Call { args, .. } = &term.kind else {
+                debug!("not a call: {:?}", term);
+                return None;
+            };
+            debug!("checking call args for uses of inner_param: {:?}", args);
+            if args.contains(&Operand::Move(inner_param)) {
+                Some((loc,term))
+            } else {
+                None
+            }
+        }) else {
+            debug!("no uses of inner_param found as a by-move call arg");
+            return;
+        };
+        debug!("===> outer_call_loc = {:?}, inner_call_loc = {:?}", outer_call_loc, inner_call_loc);
+
+        let inner_call_span = inner_call_term.source_info.span;
+        let outer_call_span = outer_call_stmt.either(|s| s.source_info, |t| t.source_info).span;
+        if outer_call_span == inner_call_span || !outer_call_span.contains(inner_call_span) {
+            // FIXME: This stops the suggestion in some cases where it should be emitted.
+            //        Fix the spans for those cases so it's emitted correctly.
+            debug!(
+                "outer span {:?} does not strictly contain inner span {:?}",
+                outer_call_span, inner_call_span
+            );
+            return;
+        }
+        err.span_help(inner_call_span, "try adding a local storing this argument...");
+        err.span_help(outer_call_span, "...and then using that local as the argument to this call");
+    }
+
     fn suggest_split_at_mut_if_applicable(
         &self,
         err: &mut DiagnosticBuilder<'_>,