Account for * when looking for inner-most path in expression

Author: estebank

compiler/rustc_borrowck/src/diagnostics/explain_borrow.rs

@@ -75,7 +75,9 @@ impl<'tcx> BorrowExplanation<'tcx> {
                 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) = &expr.kind {
+                    while let hir::ExprKind::AddrOf(_, _, inner)
+                        | hir::ExprKind::Unary(hir::UnOp::Deref, inner) = &expr.kind
+                    {
                         expr = inner;
                     }
                     if let hir::ExprKind::Path(hir::QPath::Resolved(None, p)) = expr.kind

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,

tests/ui/borrowck/borrowck-move-mut-base-ptr.stderr

@@ -1,6 +1,8 @@
 error[E0505]: cannot move out of `t0` because it is borrowed
   --> $DIR/borrowck-move-mut-base-ptr.rs:10:14
    |
+LL | fn foo(t0: &mut isize) {
+   |        -- binding `t0` declared here
 LL |     let p: &isize = &*t0; // Freezes `*t0`
    |                     ---- borrow of `*t0` occurs here
 LL |     let t1 = t0;

tests/ui/borrowck/borrowck-unary-move.stderr

@@ -1,6 +1,8 @@
 error[E0505]: cannot move out of `x` because it is borrowed
   --> $DIR/borrowck-unary-move.rs:3:10
    |
+LL | fn foo(x: Box<isize>) -> isize {
+   |        - binding `x` declared here
 LL |     let y = &*x;
    |             --- borrow of `*x` occurs here
 LL |     free(x);

tests/ui/nll/polonius/polonius-smoke-test.stderr

@@ -18,7 +18,9 @@ error[E0505]: cannot move out of `x` because it is borrowed
   --> $DIR/polonius-smoke-test.rs:18:13
    |
 LL | pub fn use_while_mut_fr(x: &mut i32) -> &mut i32 {
-   |                            - let's call the lifetime of this reference `'1`
+   |                         -  - let's call the lifetime of this reference `'1`
+   |                         |
+   |                         binding `x` declared here
 LL |     let y = &mut *x;
    |             ------- borrow of `*x` occurs here
 LL |     let z = x;
@@ -29,6 +31,8 @@ LL |     y
 error[E0505]: cannot move out of `s` because it is borrowed
   --> $DIR/polonius-smoke-test.rs:42:5
    |
+LL |     let s = &mut 1;
+   |         - binding `s` declared here
 LL |     let r = &mut *s;
    |             ------- borrow of `*s` occurs here
 LL |     let tmp = foo(&r);

tests/ui/span/dropck-object-cycle.stderr

@@ -1,6 +1,8 @@
 error[E0597]: `*m` does not live long enough
   --> $DIR/dropck-object-cycle.rs:27:31
    |
+LL |     let m : Box<dyn Trait+'static> = make_val();
+   |         - binding `m` declared here
 LL |     assert_eq!(object_invoke1(&*m), (4,5));
    |                               ^^^ borrowed value does not live long enough
 ...

tests/ui/span/regions-infer-borrow-scope-within-loop.stderr

@@ -1,6 +1,9 @@
 error[E0597]: `*x` does not live long enough
   --> $DIR/regions-infer-borrow-scope-within-loop.rs:13:20
    |
+LL |         let x = make_box();
+   |             - binding `x` declared here
+...
 LL |         y = borrow(&*x);
    |                    ^^^ borrowed value does not live long enough
 ...

tests/ui/span/send-is-not-static-std-sync.stderr

@@ -1,6 +1,9 @@
 error[E0505]: cannot move out of `y` because it is borrowed
   --> $DIR/send-is-not-static-std-sync.rs:13:10
    |
+LL |     let y = Box::new(1);
+   |         - binding `y` declared here
+LL |     let lock = Mutex::new(&x);
 LL |     *lock.lock().unwrap() = &*y;
    |                             --- borrow of `*y` occurs here
 LL |     drop(y);
@@ -25,6 +28,9 @@ LL |     lock.use_ref(); // (Mutex is #[may_dangle] so its dtor does not use `z`
 error[E0505]: cannot move out of `y` because it is borrowed
   --> $DIR/send-is-not-static-std-sync.rs:27:10
    |
+LL |     let y = Box::new(1);
+   |         - binding `y` declared here
+LL |     let lock = RwLock::new(&x);
 LL |     *lock.write().unwrap() = &*y;
    |                              --- borrow of `*y` occurs here
 LL |     drop(y);
@@ -49,6 +55,9 @@ LL |     lock.use_ref(); // (RwLock is #[may_dangle] so its dtor does not use `z
 error[E0505]: cannot move out of `y` because it is borrowed
   --> $DIR/send-is-not-static-std-sync.rs:43:10
    |
+LL |     let y = Box::new(1);
+   |         - binding `y` declared here
+...
 LL |     tx.send(&*y);
    |             --- borrow of `*y` occurs here
 LL |     drop(y);