Rollup merge of rust-lang#61332 - kennethbgoodin:borrowck-remove-aste…

…risk-suggestion, r=matthewjasper

Remove asterisk suggestion for move errors in borrowck

As per the decision in rust-lang#54985 completely removes the suggestion to add an asterisk when checking move errors. I believe I've preserved the correct behavior with the "consider borrowing here" branch of the original match arm, but I'm not positive on that.

This is my first PR to rustc so any feedback is greatly appreciated. Thanks.

src/librustc_mir/borrow_check/move_errors.rs

@@ -503,32 +503,12 @@ impl<'a, 'gcx, 'tcx> MirBorrowckCtxt<'a, 'gcx, 'tcx> {
                 move_from,
                 ..
             } => {
-                let try_remove_deref = match move_from {
-                    Place::Projection(box Projection {
-                        elem: ProjectionElem::Deref,
-                        ..
-                    }) => true,
-                    _ => false,
-                };
-                if try_remove_deref && snippet.starts_with('*') {
-                    // The snippet doesn't start with `*` in (e.g.) index
-                    // expressions `a[b]`, which roughly desugar to
-                    // `*Index::index(&a, b)` or
-                    // `*IndexMut::index_mut(&mut a, b)`.
-                    err.span_suggestion(
-                        span,
-                        "consider removing the `*`",
-                        snippet[1..].to_owned(),
-                        Applicability::Unspecified,
-                    );
-                } else {
-                    err.span_suggestion(
-                        span,
-                        "consider borrowing here",
-                        format!("&{}", snippet),
-                        Applicability::Unspecified,
-                    );
-                }
+                err.span_suggestion(
+                    span,
+                    "consider borrowing here",
+                    format!("&{}", snippet),
+                    Applicability::Unspecified,
+                );
 
                 if binds_to.is_empty() {
                     let place_ty = move_from.ty(self.mir, self.infcx.tcx).ty;

src/test/ui/access-mode-in-closures.stderr

@@ -6,7 +6,7 @@ LL |         match *s { S(v) => v }
    |               |      |
    |               |      data moved here
    |               |      move occurs because `v` has type `std::vec::Vec<isize>`, which does not implement the `Copy` trait
-   |               help: consider removing the `*`: `s`
+   |               help: consider borrowing here: `&*s`
 
 error: aborting due to previous error
 

src/test/ui/borrowck/borrowck-issue-2657-2.stderr

@@ -5,7 +5,7 @@ LL |         let _b = *y;
    |                  ^^
    |                  |
    |                  move occurs because `*y` has type `std::boxed::Box<i32>`, which does not implement the `Copy` trait
-   |                  help: consider removing the `*`: `y`
+   |                  help: consider borrowing here: `&*y`
 
 error: aborting due to previous error
 

src/test/ui/borrowck/borrowck-move-error-with-note.stderr

@@ -2,7 +2,7 @@ error[E0507]: cannot move out of `f.0` which is behind a shared reference
   --> $DIR/borrowck-move-error-with-note.rs:11:11
    |
 LL |     match *f {
-   |           ^^ help: consider removing the `*`: `f`
+   |           ^^ help: consider borrowing here: `&*f`
 LL |         Foo::Foo1(num1,
    |                   ---- data moved here
 LL |                   num2) => (),

src/test/ui/borrowck/borrowck-move-from-unsafe-ptr.stderr

@@ -5,7 +5,7 @@ LL |     let y = *x;
    |             ^^
    |             |
    |             move occurs because `*x` has type `std::boxed::Box<isize>`, which does not implement the `Copy` trait
-   |             help: consider removing the `*`: `x`
+   |             help: consider borrowing here: `&*x`
 
 error: aborting due to previous error
 

src/test/ui/borrowck/borrowck-move-out-of-overloaded-deref.stderr

@@ -5,7 +5,7 @@ LL |     let _x = *Rc::new("hi".to_string());
    |              ^^^^^^^^^^^^^^^^^^^^^^^^^^
    |              |
    |              move occurs because value has type `std::string::String`, which does not implement the `Copy` trait
-   |              help: consider removing the `*`: `Rc::new("hi".to_string())`
+   |              help: consider borrowing here: `&*Rc::new("hi".to_string())`
 
 error: aborting due to previous error
 

src/test/ui/borrowck/issue-54597-reject-move-out-of-borrow-via-pat.stderr

@@ -5,7 +5,7 @@ LL |             *array
    |             ^^^^^^
    |             |
    |             move occurs because `*array` has type `std::vec::Vec<Value>`, which does not implement the `Copy` trait
-   |             help: consider removing the `*`: `array`
+   |             help: consider borrowing here: `&*array`
 
 error: aborting due to previous error
 

src/test/ui/issues/issue-20801.stderr

@@ -5,7 +5,7 @@ LL |     let a = unsafe { *mut_ref() };
    |                      ^^^^^^^^^^
    |                      |
    |                      move occurs because value has type `T`, which does not implement the `Copy` trait
-   |                      help: consider removing the `*`: `mut_ref()`
+   |                      help: consider borrowing here: `&*mut_ref()`
 
 error[E0507]: cannot move out of a shared reference
   --> $DIR/issue-20801.rs:29:22
@@ -14,7 +14,7 @@ LL |     let b = unsafe { *imm_ref() };
    |                      ^^^^^^^^^^
    |                      |
    |                      move occurs because value has type `T`, which does not implement the `Copy` trait
-   |                      help: consider removing the `*`: `imm_ref()`
+   |                      help: consider borrowing here: `&*imm_ref()`
 
 error[E0507]: cannot move out of a raw pointer
   --> $DIR/issue-20801.rs:32:22
@@ -23,7 +23,7 @@ LL |     let c = unsafe { *mut_ptr() };
    |                      ^^^^^^^^^^
    |                      |
    |                      move occurs because value has type `T`, which does not implement the `Copy` trait
-   |                      help: consider removing the `*`: `mut_ptr()`
+   |                      help: consider borrowing here: `&*mut_ptr()`
 
 error[E0507]: cannot move out of a raw pointer
   --> $DIR/issue-20801.rs:35:22
@@ -32,7 +32,7 @@ LL |     let d = unsafe { *const_ptr() };
    |                      ^^^^^^^^^^^^
    |                      |
    |                      move occurs because value has type `T`, which does not implement the `Copy` trait
-   |                      help: consider removing the `*`: `const_ptr()`
+   |                      help: consider borrowing here: `&*const_ptr()`
 
 error: aborting due to 4 previous errors
 

src/test/ui/nll/cannot-move-block-spans.stderr

@@ -5,7 +5,7 @@ LL |     let x = { *r };
    |               ^^
    |               |
    |               move occurs because `*r` has type `std::string::String`, which does not implement the `Copy` trait
-   |               help: consider removing the `*`: `r`
+   |               help: consider borrowing here: `&*r`
 
 error[E0507]: cannot move out of `*r` which is behind a shared reference
   --> $DIR/cannot-move-block-spans.rs:6:22
@@ -14,7 +14,7 @@ LL |     let y = unsafe { *r };
    |                      ^^
    |                      |
    |                      move occurs because `*r` has type `std::string::String`, which does not implement the `Copy` trait
-   |                      help: consider removing the `*`: `r`
+   |                      help: consider borrowing here: `&*r`
 
 error[E0507]: cannot move out of `*r` which is behind a shared reference
   --> $DIR/cannot-move-block-spans.rs:7:26
@@ -23,7 +23,7 @@ LL |     let z = loop { break *r; };
    |                          ^^
    |                          |
    |                          move occurs because `*r` has type `std::string::String`, which does not implement the `Copy` trait
-   |                          help: consider removing the `*`: `r`
+   |                          help: consider borrowing here: `&*r`
 
 error[E0508]: cannot move out of type `[std::string::String; 2]`, a non-copy array
   --> $DIR/cannot-move-block-spans.rs:11:15
@@ -62,7 +62,7 @@ LL |     let x = { let mut u = 0; u += 1; *r };
    |                                      ^^
    |                                      |
    |                                      move occurs because `*r` has type `std::string::String`, which does not implement the `Copy` trait
-   |                                      help: consider removing the `*`: `r`
+   |                                      help: consider borrowing here: `&*r`
 
 error[E0507]: cannot move out of `*r` which is behind a shared reference
   --> $DIR/cannot-move-block-spans.rs:18:45
@@ -71,7 +71,7 @@ LL |     let y = unsafe { let mut u = 0; u += 1; *r };
    |                                             ^^
    |                                             |
    |                                             move occurs because `*r` has type `std::string::String`, which does not implement the `Copy` trait
-   |                                             help: consider removing the `*`: `r`
+   |                                             help: consider borrowing here: `&*r`
 
 error[E0507]: cannot move out of `*r` which is behind a shared reference
   --> $DIR/cannot-move-block-spans.rs:19:49
@@ -80,7 +80,7 @@ LL |     let z = loop { let mut u = 0; u += 1; break *r; u += 2; };
    |                                                 ^^
    |                                                 |
    |                                                 move occurs because `*r` has type `std::string::String`, which does not implement the `Copy` trait
-   |                                                 help: consider removing the `*`: `r`
+   |                                                 help: consider borrowing here: `&*r`
 
 error: aborting due to 9 previous errors
 

src/test/ui/nll/move-errors.stderr

@@ -5,7 +5,7 @@ LL |     let b = *a;
    |             ^^
    |             |
    |             move occurs because `*a` has type `A`, which does not implement the `Copy` trait
-   |             help: consider removing the `*`: `a`
+   |             help: consider borrowing here: `&*a`
 
 error[E0508]: cannot move out of type `[A; 1]`, a non-copy array
   --> $DIR/move-errors.rs:12:13
@@ -24,7 +24,7 @@ LL |     let s = **r;
    |             ^^^
    |             |
    |             move occurs because `**r` has type `A`, which does not implement the `Copy` trait
-   |             help: consider removing the `*`: `*r`
+   |             help: consider borrowing here: `&**r`
 
 error[E0507]: cannot move out of an `Rc`
   --> $DIR/move-errors.rs:27:13
@@ -33,7 +33,7 @@ LL |     let s = *r;
    |             ^^
    |             |
    |             move occurs because value has type `A`, which does not implement the `Copy` trait
-   |             help: consider removing the `*`: `r`
+   |             help: consider borrowing here: `&*r`
 
 error[E0508]: cannot move out of type `[A; 1]`, a non-copy array
   --> $DIR/move-errors.rs:32:13
@@ -49,7 +49,7 @@ error[E0507]: cannot move out of `a.0` which is behind a shared reference
   --> $DIR/move-errors.rs:38:16
    |
 LL |     let A(s) = *a;
-   |           -    ^^ help: consider removing the `*`: `a`
+   |           -    ^^ help: consider borrowing here: `&*a`
    |           |
    |           data moved here
    |           move occurs because `s` has type `std::string::String`, which does not implement the `Copy` trait
@@ -148,7 +148,7 @@ error[E0507]: cannot move out of `x.0` which is behind a shared reference
   --> $DIR/move-errors.rs:110:11
    |
 LL |     match *x {
-   |           ^^ help: consider removing the `*`: `x`
+   |           ^^ help: consider borrowing here: `&*x`
 LL |
 LL |         Ok(s) | Err(s) => (),
    |            -

src/test/ui/std-uncopyable-atomics.stderr

@@ -5,7 +5,7 @@ LL |     let x = *&x;
    |             ^^^
    |             |
    |             move occurs because value has type `std::sync::atomic::AtomicBool`, which does not implement the `Copy` trait
-   |             help: consider removing the `*`: `&x`
+   |             help: consider borrowing here: `&*&x`
 
 error[E0507]: cannot move out of a shared reference
   --> $DIR/std-uncopyable-atomics.rs:11:13
@@ -14,7 +14,7 @@ LL |     let x = *&x;
    |             ^^^
    |             |
    |             move occurs because value has type `std::sync::atomic::AtomicIsize`, which does not implement the `Copy` trait
-   |             help: consider removing the `*`: `&x`
+   |             help: consider borrowing here: `&*&x`
 
 error[E0507]: cannot move out of a shared reference
   --> $DIR/std-uncopyable-atomics.rs:13:13
@@ -23,7 +23,7 @@ LL |     let x = *&x;
    |             ^^^
    |             |
    |             move occurs because value has type `std::sync::atomic::AtomicUsize`, which does not implement the `Copy` trait
-   |             help: consider removing the `*`: `&x`
+   |             help: consider borrowing here: `&*&x`
 
 error[E0507]: cannot move out of a shared reference
   --> $DIR/std-uncopyable-atomics.rs:15:13
@@ -32,7 +32,7 @@ LL |     let x = *&x;
    |             ^^^
    |             |
    |             move occurs because value has type `std::sync::atomic::AtomicPtr<usize>`, which does not implement the `Copy` trait
-   |             help: consider removing the `*`: `&x`
+   |             help: consider borrowing here: `&*&x`
 
 error: aborting due to 4 previous errors
 

src/test/ui/suggestions/dont-suggest-ref/simple.rs

@@ -37,26 +37,26 @@ pub fn main() {
 
     let X(_t) = *s;
     //~^ ERROR cannot move
-    //~| HELP consider removing the `*`
+    //~| HELP consider borrowing here
     //~| SUGGESTION s
     if let Either::One(_t) = *r { }
     //~^ ERROR cannot move
-    //~| HELP consider removing the `*`
+    //~| HELP consider borrowing here
     //~| SUGGESTION r
     while let Either::One(_t) = *r { }
     //~^ ERROR cannot move
-    //~| HELP consider removing the `*`
+    //~| HELP consider borrowing here
     //~| SUGGESTION r
     match *r {
         //~^ ERROR cannot move
-        //~| HELP consider removing the `*`
+        //~| HELP consider borrowing here
         //~| SUGGESTION r
         Either::One(_t)
         | Either::Two(_t) => (),
     }
     match *r {
         //~^ ERROR cannot move
-        //~| HELP consider removing the `*`
+        //~| HELP consider borrowing here
         //~| SUGGESTION r
         Either::One(_t) => (),
         Either::Two(ref _t) => (),
@@ -65,34 +65,34 @@ pub fn main() {
 
     let X(_t) = *sm;
     //~^ ERROR cannot move
-    //~| HELP consider removing the `*`
+    //~| HELP consider borrowing here
     //~| SUGGESTION sm
     if let Either::One(_t) = *rm { }
     //~^ ERROR cannot move
-    //~| HELP consider removing the `*`
+    //~| HELP consider borrowing here
     //~| SUGGESTION rm
     while let Either::One(_t) = *rm { }
     //~^ ERROR cannot move
-    //~| HELP consider removing the `*`
+    //~| HELP consider borrowing here
     //~| SUGGESTION rm
     match *rm {
         //~^ ERROR cannot move
-        //~| HELP consider removing the `*`
+        //~| HELP consider borrowing here
         //~| SUGGESTION rm
         Either::One(_t)
         | Either::Two(_t) => (),
     }
     match *rm {
         //~^ ERROR cannot move
-        //~| HELP consider removing the `*`
+        //~| HELP consider borrowing here
         //~| SUGGESTION rm
         Either::One(_t) => (),
         Either::Two(ref _t) => (),
         // FIXME: should suggest removing `ref` too
     }
     match *rm {
         //~^ ERROR cannot move
-        //~| HELP consider removing the `*`
+        //~| HELP consider borrowing here
         //~| SUGGESTION rm
         Either::One(_t) => (),
         Either::Two(ref mut _t) => (),