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

Tweak E0597

CC rust-lang#99430

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 |     }

tests/ui/async-await/issue-75785-confusing-named-region.stderr

@@ -4,9 +4,9 @@ error[E0506]: cannot assign to `*x` because it is borrowed
 LL | pub async fn async_fn(x: &mut i32) -> (&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 |     (&32, y)
    |     -------- returning this value requires that `*x` is borrowed for `'1`
 

tests/ui/async-await/multiple-lifetimes/ret-ref.stderr

@@ -2,9 +2,9 @@ error[E0506]: cannot assign to `a` because it is borrowed
   --> $DIR/ret-ref.rs:16:5
    |
 LL |     let future = multiple_named_lifetimes(&a, &b);
-   |                                           -- borrow of `a` occurs here
+   |                                           -- `a` is borrowed here
 LL |     a += 1;
-   |     ^^^^^^ assignment to borrowed `a` occurs here
+   |     ^^^^^^ `a` is assigned to here but it was already borrowed
 LL |     b += 1;
 LL |     let p = future.await;
    |             ------ borrow later used here
@@ -13,21 +13,21 @@ error[E0506]: cannot assign to `b` because it is borrowed
   --> $DIR/ret-ref.rs:17:5
    |
 LL |     let future = multiple_named_lifetimes(&a, &b);
-   |                                               -- borrow of `b` occurs here
+   |                                               -- `b` is borrowed here
 LL |     a += 1;
 LL |     b += 1;
-   |     ^^^^^^ assignment to borrowed `b` occurs here
+   |     ^^^^^^ `b` is assigned to here but it was already borrowed
 LL |     let p = future.await;
    |             ------ borrow later used here
 
 error[E0506]: cannot assign to `a` because it is borrowed
   --> $DIR/ret-ref.rs:28:5
    |
 LL |     let future = multiple_named_lifetimes(&a, &b);
-   |                                           -- borrow of `a` occurs here
+   |                                           -- `a` is borrowed here
 LL |     let p = future.await;
 LL |     a += 1;
-   |     ^^^^^^ assignment to borrowed `a` occurs here
+   |     ^^^^^^ `a` is assigned to here but it was already borrowed
 LL |     b += 1;
 LL |     drop(p);
    |          - borrow later used here

tests/ui/augmented-assignments.rs

@@ -9,7 +9,7 @@ impl AddAssign for Int {
 }
 
 fn main() {
-    let mut x = Int(1);
+    let mut x = Int(1); //~ NOTE binding `x` declared here
     x
     //~^ NOTE borrow of `x` occurs here
     +=

tests/ui/augmented-assignments.stderr

@@ -1,6 +1,8 @@
 error[E0505]: cannot move out of `x` because it is borrowed
   --> $DIR/augmented-assignments.rs:16:5
    |
+LL |     let mut x = Int(1);
+   |         ----- binding `x` declared here
 LL |     x
    |     - borrow of `x` occurs here
 ...

tests/ui/binop/binop-move-semantics.stderr

@@ -41,6 +41,8 @@ LL | fn move_then_borrow<T: Add<Output=()> + Clone + Copy>(x: T) {
 error[E0505]: cannot move out of `x` because it is borrowed
   --> $DIR/binop-move-semantics.rs:21:5
    |
+LL | fn move_borrowed<T: Add<Output=()>>(x: T, mut y: T) {
+   |                                     - binding `x` declared here
 LL |     let m = &x;
    |             -- borrow of `x` occurs here
 ...
@@ -53,6 +55,9 @@ LL |     use_mut(n); use_imm(m);
 error[E0505]: cannot move out of `y` because it is borrowed
   --> $DIR/binop-move-semantics.rs:23:5
    |
+LL | fn move_borrowed<T: Add<Output=()>>(x: T, mut y: T) {
+   |                                           ----- binding `y` declared here
+LL |     let m = &x;
 LL |     let n = &mut y;
    |             ------ borrow of `y` occurs here
 ...

tests/ui/borrowck/borrow-tuple-fields.stderr

@@ -1,6 +1,8 @@
 error[E0505]: cannot move out of `x` because it is borrowed
   --> $DIR/borrow-tuple-fields.rs:12:13
    |
+LL |     let x: (Box<_>, _) = (Box::new(1), 2);
+   |         - binding `x` declared here
 LL |     let r = &x.0;
    |             ---- borrow of `x.0` occurs here
 LL |     let y = x;
@@ -32,6 +34,8 @@ LL |     a.use_ref();
 error[E0505]: cannot move out of `x` because it is borrowed
   --> $DIR/borrow-tuple-fields.rs:28:13
    |
+LL |     let x = Foo(Box::new(1), 2);
+   |         - binding `x` declared here
 LL |     let r = &x.0;
    |             ---- borrow of `x.0` occurs here
 LL |     let y = x;

tests/ui/borrowck/borrowck-anon-fields-variant.stderr

@@ -2,7 +2,7 @@ error[E0503]: cannot use `y` because it was mutably borrowed
   --> $DIR/borrowck-anon-fields-variant.rs:16:19
    |
 LL |       Foo::Y(ref mut a, _) => a,
-   |              --------- borrow of `y.0` occurs here
+   |              --------- `y.0` is borrowed here
 ...
 LL |     let b = match y {
    |                   ^ use of borrowed `y.0`
@@ -14,7 +14,7 @@ error[E0503]: cannot use `y` because it was mutably borrowed
   --> $DIR/borrowck-anon-fields-variant.rs:34:19
    |
 LL |       Foo::Y(ref mut a, _) => a,
-   |              --------- borrow of `y.0` occurs here
+   |              --------- `y.0` is borrowed here
 ...
 LL |     let b = match y {
    |                   ^ use of borrowed `y.0`

tests/ui/borrowck/borrowck-assign-comp.stderr

@@ -2,20 +2,20 @@ error[E0506]: cannot assign to `p.x` because it is borrowed
   --> $DIR/borrowck-assign-comp.rs:10:5
    |
 LL |     let q = &p;
-   |             -- borrow of `p.x` occurs here
+   |             -- `p.x` is borrowed here
 ...
 LL |     p.x = 5;
-   |     ^^^^^^^ assignment to borrowed `p.x` occurs here
+   |     ^^^^^^^ `p.x` is assigned to here but it was already borrowed
 LL |     q.x;
    |     --- borrow later used here
 
 error[E0506]: cannot assign to `p` because it is borrowed
   --> $DIR/borrowck-assign-comp.rs:20:5
    |
 LL |     let q = &p.y;
-   |             ---- borrow of `p` occurs here
+   |             ---- `p` is borrowed here
 LL |     p = Point {x: 5, y: 7};
-   |     ^^^^^^^^^^^^^^^^^^^^^^ assignment to borrowed `p` occurs here
+   |     ^^^^^^^^^^^^^^^^^^^^^^ `p` is assigned to here but it was already borrowed
 LL |     p.x; // silence warning
 LL |     *q; // stretch loan
    |     -- borrow later used here
@@ -24,9 +24,9 @@ error[E0506]: cannot assign to `p.y` because it is borrowed
   --> $DIR/borrowck-assign-comp.rs:31:5
    |
 LL |     let q = &p.y;
-   |             ---- borrow of `p.y` occurs here
+   |             ---- `p.y` is borrowed here
 LL |     p.y = 5;
-   |     ^^^^^^^ assignment to borrowed `p.y` occurs here
+   |     ^^^^^^^ `p.y` is assigned to here but it was already borrowed
 LL |     *q;
    |     -- borrow later used here
 

tests/ui/borrowck/borrowck-assign-to-andmut-in-borrowed-loc.stderr

@@ -2,7 +2,7 @@ error[E0503]: cannot use `*y.pointer` because it was mutably borrowed
   --> $DIR/borrowck-assign-to-andmut-in-borrowed-loc.rs:18:9
    |
 LL |         let z = copy_borrowed_ptr(&mut y);
-   |                                   ------ borrow of `y` occurs here
+   |                                   ------ `y` is borrowed here
 LL |         *y.pointer += 1;
    |         ^^^^^^^^^^^^^^^ use of borrowed `y`
 ...
@@ -13,9 +13,9 @@ error[E0506]: cannot assign to `*y.pointer` because it is borrowed
   --> $DIR/borrowck-assign-to-andmut-in-borrowed-loc.rs:18:9
    |
 LL |         let z = copy_borrowed_ptr(&mut y);
-   |                                   ------ borrow of `*y.pointer` occurs here
+   |                                   ------ `*y.pointer` is borrowed here
 LL |         *y.pointer += 1;
-   |         ^^^^^^^^^^^^^^^ assignment to borrowed `*y.pointer` occurs here
+   |         ^^^^^^^^^^^^^^^ `*y.pointer` is assigned to here but it was already borrowed
 ...
 LL |         *z.pointer += 1;
    |         --------------- borrow later used here

tests/ui/borrowck/borrowck-bad-nested-calls-move.stderr

@@ -1,6 +1,9 @@
 error[E0505]: cannot move out of `a` because it is borrowed
   --> $DIR/borrowck-bad-nested-calls-move.rs:25:9
    |
+LL |     let mut a: Box<_> = Box::new(1);
+   |         ----- binding `a` declared here
+...
 LL |     add(
    |     --- borrow later used by call
 LL |         &*a,
@@ -11,6 +14,8 @@ LL |         a);
 error[E0505]: cannot move out of `a` because it is borrowed
   --> $DIR/borrowck-bad-nested-calls-move.rs:32:9
    |
+LL |     let mut a: Box<_> = Box::new(1);
+   |         ----- binding `a` declared here
 LL |     add(
    |     --- borrow later used by call
 LL |         &*a,