Rollup merge of rust-lang#106897 - estebank:issue-99430, r=davidtwco

Tweak E0597

CC rust-lang#99430

Author: matthiaskrgr

compiler/rustc_borrowck/src/borrowck_errors.rs

@@ -37,7 +37,7 @@ impl<'cx, 'tcx> crate::MirBorrowckCtxt<'cx, 'tcx> {
             desc,
         );
 
-        err.span_label(borrow_span, format!("borrow of {} occurs here", borrow_desc));
+        err.span_label(borrow_span, format!("{} is borrowed here", borrow_desc));
         err.span_label(span, format!("use of borrowed {}", borrow_desc));
         err
     }
@@ -250,8 +250,8 @@ impl<'cx, 'tcx> crate::MirBorrowckCtxt<'cx, 'tcx> {
             desc,
         );
 
-        err.span_label(borrow_span, format!("borrow of {} occurs here", desc));
-        err.span_label(span, format!("assignment to borrowed {} occurs here", desc));
+        err.span_label(borrow_span, format!("{} is borrowed here", desc));
+        err.span_label(span, format!("{} is assigned to here but it was already borrowed", desc));
         err
     }
 

compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs

@@ -1736,7 +1736,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                 &self.local_names,
                 &mut err,
                 "",
-                None,
+                Some(borrow_span),
                 None,
             );
         }

compiler/rustc_borrowck/src/diagnostics/explain_borrow.rs

@@ -1,6 +1,8 @@
 //! Print diagnostics to explain why values are borrowed.
 
 use rustc_errors::{Applicability, Diagnostic};
+use rustc_hir as hir;
+use rustc_hir::intravisit::Visitor;
 use rustc_index::vec::IndexVec;
 use rustc_infer::infer::NllRegionVariableOrigin;
 use rustc_middle::mir::{
@@ -11,6 +13,7 @@ use rustc_middle::ty::adjustment::PointerCast;
 use rustc_middle::ty::{self, RegionVid, TyCtxt};
 use rustc_span::symbol::{kw, Symbol};
 use rustc_span::{sym, DesugaringKind, Span};
+use rustc_trait_selection::traits::error_reporting::FindExprBySpan;
 
 use crate::region_infer::{BlameConstraint, ExtraConstraintInfo};
 use crate::{
@@ -63,6 +66,36 @@ impl<'tcx> BorrowExplanation<'tcx> {
         borrow_span: Option<Span>,
         multiple_borrow_span: Option<(Span, Span)>,
     ) {
+        if let Some(span) = borrow_span {
+            let def_id = body.source.def_id();
+            if let Some(node) = tcx.hir().get_if_local(def_id)
+                && let Some(body_id) = node.body_id()
+            {
+                let body = tcx.hir().body(body_id);
+                let mut expr_finder = FindExprBySpan::new(span);
+                expr_finder.visit_expr(body.value);
+                if let Some(mut expr) = expr_finder.result {
+                    while let hir::ExprKind::AddrOf(_, _, inner)
+                        | hir::ExprKind::Unary(hir::UnOp::Deref, inner)
+                        | hir::ExprKind::Field(inner, _)
+                        | hir::ExprKind::MethodCall(_, inner, _, _)
+                        | hir::ExprKind::Index(inner, _) = &expr.kind
+                    {
+                        expr = inner;
+                    }
+                    if let hir::ExprKind::Path(hir::QPath::Resolved(None, p)) = expr.kind
+                        && let [hir::PathSegment { ident, args: None, .. }] = p.segments
+                        && let hir::def::Res::Local(hir_id) = p.res
+                        && let Some(hir::Node::Pat(pat)) = tcx.hir().find(hir_id)
+                    {
+                        err.span_label(
+                            pat.span,
+                            &format!("binding `{ident}` declared here"),
+                        );
+                    }
+                }
+            }
+        }
         match *self {
             BorrowExplanation::UsedLater(later_use_kind, var_or_use_span, path_span) => {
                 let message = match later_use_kind {

compiler/rustc_borrowck/src/diagnostics/move_errors.rs

@@ -448,7 +448,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
                 };
                 self.note_type_does_not_implement_copy(err, &place_desc, place_ty, Some(span), "");
 
-                use_spans.args_span_label(err, format!("move out of {place_desc} occurs here"));
+                use_spans.args_span_label(err, format!("{place_desc} is moved here"));
             }
         }
     }

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

@@ -2825,7 +2825,7 @@ pub struct FindExprBySpan<'hir> {
 }
 
 impl<'hir> FindExprBySpan<'hir> {
-    fn new(span: Span) -> Self {
+    pub fn new(span: Span) -> Self {
         Self { span, result: None, ty_result: None }
     }
 }

tests/ui-fulldeps/dropck-tarena-cycle-checked.stderr

@@ -1,6 +1,8 @@
 error[E0597]: `arena` does not live long enough
   --> $DIR/dropck-tarena-cycle-checked.rs:116:7
    |
+LL |     let arena = TypedArena::default();
+   |         ----- binding `arena` declared here
 LL |     f(&arena);
    |       ^^^^^^ borrowed value does not live long enough
 LL | }

tests/ui-fulldeps/dropck-tarena-unsound-drop.stderr

@@ -1,6 +1,8 @@
 error[E0597]: `arena` does not live long enough
   --> $DIR/dropck-tarena-unsound-drop.rs:41:7
    |
+LL |     let arena: TypedArena<C> = TypedArena::default();
+   |         ----- binding `arena` declared here
 LL |     f(&arena);
    |       ^^^^^^ borrowed value does not live long enough
 LL | }

tests/ui/asm/type-check-4.stderr

@@ -2,9 +2,9 @@ error[E0506]: cannot assign to `a` because it is borrowed
   --> $DIR/type-check-4.rs:14:9
    |
 LL |         let p = &a;
-   |                 -- borrow of `a` occurs here
+   |                 -- `a` is borrowed here
 LL |         asm!("{}", out(reg) a);
-   |         ^^^^^^^^^^^^^^^^^^^^^^ assignment to borrowed `a` occurs here
+   |         ^^^^^^^^^^^^^^^^^^^^^^ `a` is assigned to here but it was already borrowed
 LL |
 LL |         println!("{}", p);
    |                        - borrow later used here
@@ -13,7 +13,7 @@ error[E0503]: cannot use `a` because it was mutably borrowed
   --> $DIR/type-check-4.rs:22:28
    |
 LL |         let p = &mut a;
-   |                 ------ borrow of `a` occurs here
+   |                 ------ `a` is borrowed here
 LL |         asm!("{}", in(reg) a);
    |                            ^ use of borrowed `a`
 LL |

tests/ui/associated-types/associated-types-outlives.stderr

@@ -1,6 +1,9 @@
 error[E0505]: cannot move out of `x` because it is borrowed
   --> $DIR/associated-types-outlives.rs:22:14
    |
+LL |                     F: for<'a> FnOnce(<T as Foo<'a>>::Bar)>(x: T, f: F) {
+   |                                                             - binding `x` declared here
+...
 LL |         's: loop { y = denormalise(&x); break }
    |                                    -- borrow of `x` occurs here
 LL |         drop(x);

tests/ui/async-await/issue-74072-lifetime-name-annotations.stderr

@@ -4,19 +4,19 @@ error[E0506]: cannot assign to `*x` because it is borrowed
 LL | pub async fn async_fn(x: &mut i32) -> &i32 {
    |                          - let's call the lifetime of this reference `'1`
 LL |     let y = &*x;
-   |             --- borrow of `*x` occurs here
+   |             --- `*x` is borrowed here
 LL |     *x += 1;
-   |     ^^^^^^^ assignment to borrowed `*x` occurs here
+   |     ^^^^^^^ `*x` is assigned to here but it was already borrowed
 LL |     y
    |     - returning this value requires that `*x` is borrowed for `'1`
 
 error[E0506]: cannot assign to `*x` because it is borrowed
   --> $DIR/issue-74072-lifetime-name-annotations.rs:16:9
    |
 LL |         let y = &*x;
-   |                 --- borrow of `*x` occurs here
+   |                 --- `*x` is borrowed here
 LL |         *x += 1;
-   |         ^^^^^^^ assignment to borrowed `*x` occurs here
+   |         ^^^^^^^ `*x` is assigned to here but it was already borrowed
 LL |         y
    |         - returning this value requires that `*x` is borrowed for `'1`
 LL |     })()
@@ -28,19 +28,19 @@ error[E0506]: cannot assign to `*x` because it is borrowed
 LL |     (async move || -> &i32 {
    |                       - let's call the lifetime of this reference `'1`
 LL |         let y = &*x;
-   |                 --- borrow of `*x` occurs here
+   |                 --- `*x` is borrowed here
 LL |         *x += 1;
-   |         ^^^^^^^ assignment to borrowed `*x` occurs here
+   |         ^^^^^^^ `*x` is assigned to here but it was already borrowed
 LL |         y
    |         - returning this value requires that `*x` is borrowed for `'1`
 
 error[E0506]: cannot assign to `*x` because it is borrowed
   --> $DIR/issue-74072-lifetime-name-annotations.rs:32:9
    |
 LL |         let y = &*x;
-   |                 --- borrow of `*x` occurs here
+   |                 --- `*x` is borrowed here
 LL |         *x += 1;
-   |         ^^^^^^^ assignment to borrowed `*x` occurs here
+   |         ^^^^^^^ `*x` is assigned to here but it was already borrowed
 LL |         y
    |         - returning this value requires that `*x` is borrowed for `'1`
 LL |     }