describe index with accurate _

Author: csmoe

src/librustc_mir/borrow_check/error_reporting.rs

@@ -1566,7 +1566,7 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
                         )?;
                         buf.push_str("[");
                         if self.append_local_to_string(index, buf).is_err() {
-                            buf.push_str("..");
+                            buf.push_str("_");
                         }
                         buf.push_str("]");
                     }

src/test/ui/borrowck/borrowck-describe-lvalue.mir.stderr

@@ -316,7 +316,7 @@ LL |         v[0].y;
 LL |         drop(x);
    |              - borrow later used here
 
-error[E0503]: cannot use `v[..].y` because it was mutably borrowed
+error[E0503]: cannot use `v[_].y` because it was mutably borrowed
   --> $DIR/borrowck-describe-lvalue.rs:271:9
    |
 LL |         let x = &mut v;

src/test/ui/borrowck/borrowck-describe-lvalue.rs

@@ -270,7 +270,7 @@ fn main() {
         let x = &mut v;
         v[0].y;
         //[ast]~^ ERROR cannot use `v[..].y` because it was mutably borrowed
-        //[mir]~^^ ERROR cannot use `v[..].y` because it was mutably borrowed
+        //[mir]~^^ ERROR cannot use `v[_].y` because it was mutably borrowed
         //[mir]~| ERROR cannot use `*v` because it was mutably borrowed
         drop(x);
     }

src/test/ui/borrowck/borrowck-vec-pattern-move-tail.cmp.stderr

@@ -7,14 +7,14 @@ LL |         [1, 2, ref tail..] => tail,
 LL |     a[2] = 0; //[ast]~ ERROR cannot assign to `a[..]` because it is borrowed
    |     ^^^^^^^^ assignment to borrowed `a[..]` occurs here
 
-error[E0506]: cannot assign to `a[..]` because it is borrowed (Mir)
+error[E0506]: cannot assign to `a[_]` because it is borrowed (Mir)
   --> $DIR/borrowck-vec-pattern-move-tail.rs:24:5
    |
 LL |         [1, 2, ref tail..] => tail,
-   |                -------- borrow of `a[..]` occurs here
+   |                -------- borrow of `a[_]` occurs here
 ...
 LL |     a[2] = 0; //[ast]~ ERROR cannot assign to `a[..]` because it is borrowed
-   |     ^^^^^^^^ assignment to borrowed `a[..]` occurs here
+   |     ^^^^^^^^ assignment to borrowed `a[_]` occurs here
 ...
 LL |     println!("t[0]: {}", t[0]);
    |                          ---- borrow later used here

src/test/ui/borrowck/borrowck-vec-pattern-move-tail.rs

@@ -23,7 +23,7 @@ fn main() {
     println!("t[0]: {}", t[0]);
     a[2] = 0; //[ast]~ ERROR cannot assign to `a[..]` because it is borrowed
               //[cmp]~^ ERROR cannot assign to `a[..]` because it is borrowed (Ast)
-              //[cmp]~| ERROR cannot assign to `a[..]` because it is borrowed (Mir)
+              //[cmp]~| ERROR cannot assign to `a[_]` because it is borrowed (Mir)
     println!("t[0]: {}", t[0]);
     t[0];
 }

src/test/ui/issues/issue-46604.mir.stderr

@@ -4,7 +4,7 @@ error[E0017]: references in statics may only refer to immutable values
 LL | static buf: &mut [u8] = &mut [1u8,2,3,4,5,7];   //[ast]~ ERROR E0017
    |                         ^^^^^^^^^^^^^^^^^^^^ statics require immutable values
 
-error[E0594]: cannot assign to `buf[..]`, as `buf` is an immutable static item
+error[E0594]: cannot assign to `buf[_]`, as `buf` is an immutable static item
   --> $DIR/issue-46604.rs:20:5
    |
 LL |     buf[0]=2;                                   //[ast]~ ERROR E0389

src/test/ui/nll/drop-no-may-dangle.rs

@@ -27,10 +27,10 @@ fn main() {
         use_x(*p.value);
     } else {
         use_x(22);
-        v[0] += 1; //~ ERROR cannot assign to `v[..]` because it is borrowed
+        v[0] += 1; //~ ERROR cannot assign to `v[_]` because it is borrowed
     }
 
-    v[0] += 1; //~ ERROR cannot assign to `v[..]` because it is borrowed
+    v[0] += 1; //~ ERROR cannot assign to `v[_]` because it is borrowed
 }
 
 struct WrapMayNotDangle<T> {

src/test/ui/nll/drop-no-may-dangle.stderr

@@ -1,23 +1,23 @@
-error[E0506]: cannot assign to `v[..]` because it is borrowed
+error[E0506]: cannot assign to `v[_]` because it is borrowed
   --> $DIR/drop-no-may-dangle.rs:30:9
    |
 LL |     let p: WrapMayNotDangle<&usize> = WrapMayNotDangle { value: &v[0] };
-   |                                                                 ----- borrow of `v[..]` occurs here
+   |                                                                 ----- borrow of `v[_]` occurs here
 ...
-LL |         v[0] += 1; //~ ERROR cannot assign to `v[..]` because it is borrowed
-   |         ^^^^^^^^^ assignment to borrowed `v[..]` occurs here
+LL |         v[0] += 1; //~ ERROR cannot assign to `v[_]` because it is borrowed
+   |         ^^^^^^^^^ assignment to borrowed `v[_]` occurs here
 ...
 LL | }
    | - borrow might be used here, when `p` is dropped and runs the `Drop` code for type `WrapMayNotDangle`
 
-error[E0506]: cannot assign to `v[..]` because it is borrowed
+error[E0506]: cannot assign to `v[_]` because it is borrowed
   --> $DIR/drop-no-may-dangle.rs:33:5
    |
 LL |     let p: WrapMayNotDangle<&usize> = WrapMayNotDangle { value: &v[0] };
-   |                                                                 ----- borrow of `v[..]` occurs here
+   |                                                                 ----- borrow of `v[_]` occurs here
 ...
-LL |     v[0] += 1; //~ ERROR cannot assign to `v[..]` because it is borrowed
-   |     ^^^^^^^^^ assignment to borrowed `v[..]` occurs here
+LL |     v[0] += 1; //~ ERROR cannot assign to `v[_]` because it is borrowed
+   |     ^^^^^^^^^ assignment to borrowed `v[_]` occurs here
 LL | }
    | - borrow might be used here, when `p` is dropped and runs the `Drop` code for type `WrapMayNotDangle`